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Age of our Universe Coming Soon.......

Hubble's Discoveries This is your About Page. It's a great opportunity to give a full background on who you are, what you do and what your website has to offer. Double click on the text box to start editing your content and make sure to add all the relevant details you want to share with site visitors. Presenter please note: Much of the discussion in these slides, and most of the public’s attention, is focused on Hubble’s enormous repertoire of images. Here is a montage of some of Hubble’s best images that symbolize the breadth and depth of Hubble observations and the research being done. ​ In each image that follows, a timeline (shown here) will be shown so that viewers have an appreciation for how far away the object is and how long it takes for the light to travel to Hubble from that object.

TRAPPIST-1 TRAPPIST-1 is a star system located about 39 light-years away from Earth in the constellation Aquarius. It gained significant attention and interest in the scientific community and the public due to the discovery of seven Earth-sized exoplanets orbiting the ultra-cool dwarf star TRAPPIST-1. Here's a detailed explanation of the TRAPPIST-1 system, including information about its characteristics, the potential for atmosphere, and the search for extraterrestrial life or aliens 1. Characteristics of TRAPPIST-1: Star Type: TRAPPIST-1 is an ultra-cool dwarf star classified as an M8V-type star. It is much cooler and smaller than our Sun, with a surface temperature of about 2,550 degrees Celsius (4,622 degrees Fahrenheit). Number of Exoplanets: The TRAPPIST-1 system is known to host seven exoplanets. These exoplanets are designated as TRAPPIST-1b, c, d, e, f, g, and h. They were discovered through the transit method, which involves observing the periodic dimming of the star's light as the planets pass in front of it. Habitability Zone: Several of the exoplanets in the TRAPPIST-1 system are located within the habitable zone, also known as the Goldilocks zone. This is the region around a star where conditions might be suitable for liquid water to exist on the planets' surfaces, a key factor for potential habitability. 2. Atmosphere of TRAPPIST-1 Exoplanets: Information about the specific composition and characteristics of the atmospheres of the TRAPPIST-1 exoplanets is not fully known. Detecting and characterizing exoplanet atmospheres is a challenging task that requires advanced telescopes and instruments. Astronomers have conducted studies to analyze the potential atmospheres of these exoplanets. The presence of atmospheres would be an essential factor in determining their habitability and potential for hosting life. 3. The Search for Extraterrestrial Life or Aliens: The discovery of seven Earth-sized exoplanets in the TRAPPIST-1 system, especially those within the habitable zone, has made TRAPPIST-1 a significant target in the search for extraterrestrial life. The habitable zone is a region where conditions might be right for liquid water to exist, a key ingredient for life as we know it. The search for extraterrestrial life involves looking for signs of habitability and biomarkers, such as the presence of water, oxygen, and methane, in exoplanet atmospheres. It also involves the study of planetary conditions, including surface temperature and radiation levels, to assess the potential for life to thrive. While the discovery of the TRAPPIST-1 exoplanets is exciting, the actual presence of extraterrestrial life remains purely speculative. The search for life beyond Earth is an ongoing scientific endeavor, and it requires more advanced technology and instruments, including next-generation telescopes like the James Webb Space Telescope, to provide more insights. 4. The Possibility of Aliens: The term "aliens" typically refers to intelligent extraterrestrial beings. While the search for microbial life or even simple life forms is a primary focus in astrobiology, the search for intelligent civilizations, often referred to as the search for extraterrestrial intelligence (SETI), remains an active area of research. SETI involves listening for radio signals or other types of communication from advanced civilizations in the universe. So far, no definitive evidence of extraterrestrial intelligent life or aliens has been found. Comparison with Solar System The TRAPPIST-1 system and our solar system are two different planetary systems in the Milky Way galaxy. While both contain multiple celestial bodies, there are significant differences between them. Here's a comparison of the TRAPPIST-1 system and our solar system: Number of Stars: Solar System: Our solar system is a single-star system, with the Sun as the central star. TRAPPIST-1 System: The TRAPPIST-1 system is a multi-star system, consisting of a red dwarf star called TRAPPIST-1 and at least seven confirmed planets orbiting it. Central Star: Solar System: The Sun is a G-type main-sequence star (a yellow dwarf). TRAPPIST-1 System: TRAPPIST-1 is an M-type dwarf star, which is much cooler and less massive than the Sun. Planetary Orbits: Solar System: In the solar system, planets have relatively stable, nearly circular orbits. TRAPPIST-1 System: The TRAPPIST-1 planets have much closer orbits to their star, with some being in the habitable zone. These orbits are closer to their star compared to most planets in our solar system. Planetary Composition: Solar System: The planets in our solar system have diverse compositions. The inner planets (Mercury, Venus, Earth, and Mars) are rocky, while the outer planets (Jupiter, Saturn, Uranus, and Neptune) are gas giants or ice giants. TRAPPIST-1 System: The TRAPPIST-1 planets are believed to be rocky, similar to the inner planets in our solar system. Some may have liquid water on their surfaces. Habitability: Solar System: Earth, in our solar system, is the only known planet with conditions suitable for life as we know it. TRAPPIST-1 System: Some of the TRAPPIST-1 planets are in the habitable zone, where liquid water could exist. This makes them potential candidates for studying the possibility of life beyond Earth. Number of Planets: Solar System: Our solar system has eight recognized planets, with Pluto being classified as a dwarf planet. TRAPPIST-1 System: At least seven planets have been discovered in the TRAPPIST-1 system. Planetary Sizes: Solar System: The planets in our solar system vary in size from small rocky planets like Mercury to massive gas giants like Jupiter. TRAPPIST-1 System: The TRAPPIST-1 planets are thought to be similar in size to Earth and its neighboring planets. Exploration: Solar System: Our solar system has been extensively explored by spacecraft, including missions to all eight recognized planets, numerous moons, and even a few asteroids and comets. TRAPPIST-1 System: As of my knowledge cutoff date in September 2021, the TRAPPIST-1 system had been observed and studied from a distance through telescopes, but no direct spacecraft missions had been sent to explore it. Other Articles..... Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop STAR VFTS102 KEPLER-452b KEPLER-186f Proxima Centauri b

Proxima Centauri b Proxima Centauri b is an exoplanet that orbits the red dwarf star Proxima Centauri, which is the closest known star to our Sun. Here's a detailed explanation of Proxima Centauri b, including information about its characteristics, atmosphere, and the search for extraterrestrial life or aliens 1. Characteristics of Proxima Centauri b: Size: Proxima Centauri b is classified as an exoplanet with a mass roughly similar to Earth's, making it about 1.3 times the mass of our planet. This places it in the category of terrestrial exoplanets, similar to Earth and Venus. Orbit: Proxima Centauri b orbits its host star, Proxima Centauri, at a very close distance, approximately 0.05 astronomical units (AU), or about 7.5 million kilometers (4.7 million miles). It completes an orbit in just around 11.2 Earth days. Habitability: Proxima Centauri b is located within the habitable zone (Goldilocks zone) of its star. This means it is in the region where conditions for liquid water to exist on the surface are possible, a key factor for potential habitability. 2. Atmosphere of Proxima Centauri b: Information about the specific composition and characteristics of Proxima Centauri b's atmosphere is not currently known. Detecting and analyzing the atmospheres of exoplanets, especially those as distant as Proxima Centauri b, is a challenging task and often requires advanced telescopes and instruments. 3. The Search for Extraterrestrial Life or Aliens: Proxima Centauri b has generated significant interest in the search for extraterrestrial life due to its proximity to Earth and its location within the habitable zone. Scientists and astronomers are particularly interested in studying exoplanets like Proxima Centauri b because they could offer insights into the potential for life beyond our solar system. The search for extraterrestrial life extends beyond Proxima Centauri b and includes the study of other exoplanets both within and outside the habitable zone. Key aspects of this search involve looking for signs of habitability and biomarkers, such as the presence of water, oxygen, and methane, in exoplanet atmospheres. The discovery of life, if it exists, on Proxima Centauri b or any other exoplanet would be a profound scientific breakthrough and could have far-reaching implications for our understanding of life's prevalence in the universe. It's important to note that as of my last knowledge update in September 2021, there is no definitive evidence of extraterrestrial life, and the search continues to be an active and ongoing scientific endeavor. Future missions and advanced technology, such as the James Webb Space Telescope, are expected to provide more data and insights into the atmospheres and potential habitability of exoplanets like Proxima Centauri b. Comparison with Earth Proxima Centauri b and Earth are both planets, but they have significant differences in terms of their characteristics, orbits, and potential habitability. Here's a comparison between the two: 1. Size and Mass: Earth: Earth is approximately 12,742 kilometers (7,918 miles) in diameter and has a mass of about 5.972 × 10^24 kilograms, making it a terrestrial planet with a solid surface. Proxima Centauri b: Proxima Centauri b is classified as an exoplanet, and its size and mass are roughly similar to Earth's, with a mass approximately 1.3 times that of Earth. This places it in the category of terrestrial exoplanets. 2. Parent Star and Orbit: Earth: Earth orbits the Sun, a G-type main-sequence star (G2V), at an average distance of about 149.6 million kilometers (93 million miles). It takes approximately 365.25 days to complete one orbit. Proxima Centauri b: Proxima Centauri b orbits a red dwarf star known as Proxima Centauri, which is cooler and smaller than the Sun. Its orbital distance is very close to its parent star, about 0.05 astronomical units, which is much closer than Earth's distance from the Sun. Proxima Centauri b completes an orbit in approximately 11.2 Earth days. 3. Habitability and Atmosphere: Earth: Earth is known for its diverse and life-sustaining atmosphere composed primarily of nitrogen (about 78%) and oxygen (about 21%), with trace amounts of other gases. It has liquid water on its surface, a stable climate, and a variety of ecosystems that support a wide range of life forms. Proxima Centauri b: Information about the specific composition and characteristics of Proxima Centauri b's atmosphere is not currently known. Detecting and analyzing exoplanet atmospheres, especially those as distant as Proxima Centauri b, is challenging and requires advanced telescopes and instruments. 4. Potential for Extraterrestrial Life: Earth: Earth is the only known planet to host a wide variety of life forms, from microorganisms to complex multicellular organisms, including humans. Proxima Centauri b: Proxima Centauri b is located within the habitable zone of its star, which means it could have conditions suitable for liquid water to exist on its surface. However, the presence of life on Proxima Centauri b is purely speculative at this point, and more research is needed to assess its habitability and the potential for extraterrestrial life. Other Articles...... Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop STAR VFTS102 KEPLER-186f KEPLER-452b

Parallel World Travel We have heard a lot about time travel, it feels good to hear it but only in imagination and theories, we already know the rest of the reality, but today we have brought another theory in front of you which can happen in the past. There is a thesis based on the above but yes, you will definitely feel happy after reading it. Over View.... So let me give you an overview of this theory, in this we have tried to understand how time travel can happen in the past, because we all know that if we want, we can do it in the future, but time can never shrink. This is why it is impossible to travel in the past, but if we say that it is possible and that anti-reaction will increase your interest, then if we have to travel in time then it is possible only in a parallel universe. But we cannot understand the parallel world well yet, so we will have to create this theory accordingly, then the time travel that will happen will happen in the parallel world that we have created with our own thoughts. Because till now the parallel universe has remained only a thesis. So stick to this theory and the whole society will follow you. If you have any questions, you can tell me in the chat box below, I will definitely answer you. Lets begin the journey After starting this I want to ask you question Is time travel in past can be possible because if we do there would be so many paradoxes we have to face like Grandfather paradoxes and Butterfly Effect. If you don’t know about these then might be you think that what’s these..? ​ Grandfather Paradox- Let’s suppose you have a time machine and you traveled in past And unfortunately because of You your Grandfather got killed in his childhood in the age of 6. Then what happen? Just think logically that if your Grandfather never married with any woman then your father will not birth in this world and if he don’t birth in this world You might be not birth in the world So in present if you don’t exists how did you traveled in past and killed your Grandfather? Tricky right… You can read About the Butterfly effect By yourself…. And cause of we are humans and we often made mistakes we can say that there will be a huge chance that we messed up past.. So with this, This is confirm that we cannot travel in past. Even not in the theory. But we are humans and we are free to think and assume don’t we? Of course many scientists claim that past time travel isn’t possible. So my theory is What if we do travel in past and change it but in result nothing will change in our world cause of our mistake or action, Note that I said in our world. As we know we are not alone in the universe there can be a lot of creature like us or advance from us or lower from us in different sector. And there would be a chance that there would be an parallel universe like us. Parallel Universe is a universe which had many similarities and many differences too. This is a hypothesis universe but it can be true. My theory is a mixture of parallel universe and time travel. There are huge chance that we humans will be able to travel in past but the problem will be we can only observe them but can’t change anything if we dare and try to change anything then The past that we traveled will become a parallel universe and continuous it’s own different future than us. In short if we do the grandfather paradox there then even if we kill the grandfather we will be secure but in that died grandfather universe we actually never be able to exists there. It might be the reason why the party of the time travelers by Stephen hawking was empty cause maybe the travelers don’t want to change the universe. With this almost every paradox can be solved. And whenever we felt Déjà vu there would be the cause of we already felt it on parallel universe and we are connected by that ourselves from that universe to this Universe.. Every action has an appropriate reaction We all know that every action has an appropriate reaction, so you must be thinking that you have said that time travel will happen in the past but not in our parallel universe, but will it have any impact in our universe? , Can it have any opposing impact? Well, we can think something now, but because we have given you this universe, it must have been created by imagination and if we do anything in it, we will not see any effect on the present. We will not get it, that is a different matter that this is just our thought, so maybe there can be some reaction. You can tell in the chat box given below whether you have any idea whether this could be a reaction? Chat Section If you have any question ask me here.... Other Articles...... Theories Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop Today Onward Theory STAR VFTS102 KEPLER-452b Proxima Centauri b TRAPPIST-1

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Map of our solar system Heliocentric System Heliocentric system is a fully functional detail map of our solar system with sun and all planets and natural satellites of all planets, asteroids and comets also. we designed this map as natural and graphical and easy to understand our solar system at first time. SOLAR SYSTEM

Blackhole Information Paradox The Black Hole Information Paradox is a long-standing problem in theoretical physics and astrophysics, concerning the conservation of information in the presence of black holes, which are regions of spacetime where gravity is so strong that not even light can escape from them. The paradox arises from the clash between the principles of quantum mechanics and general relativity. ​ In classical physics, black holes are described by solutions to Einstein's field equations of general relativity, which predict that anything that falls into a black hole will be irretrievably lost behind its event horizon, a boundary beyond which nothing can escape. This implies that any information about the matter that formed the black hole, such as its mass, charge, and angular momentum, is lost to the outside universe. ​ However, according to the principles of quantum mechanics, information cannot be destroyed. Instead, it should always be possible, in principle, to trace the evolution of a quantum system backwards in time and reconstruct the initial state from the final state. This principle is known as unitarity. ​ The paradox arises because the classical description of black holes seems to violate the principles of quantum mechanics. If information is lost behind the event horizon, then the evolution of a black hole's state seems to violate unitarity, leading to a breakdown of quantum mechanics. ​ Various proposed solutions to the Black Hole Information Paradox have been put forward over the years, but none have been universally accepted. Some of these proposals include: ​ Hawking Radiation and Information Loss: Stephen Hawking proposed that black holes emit radiation (now known as Hawking radiation) due to quantum effects near the event horizon. This radiation carries away energy from the black hole, eventually causing it to evaporate completely. Initially, it was believed that this process led to the loss of information, but later work suggested that information might be encoded in the radiation, leading to the idea of "black hole complementarity" or the "firewall paradox." Firewall Paradox: Proposed as a resolution to the information paradox, the firewall paradox suggests that an observer falling into a black hole would encounter a firewall of high-energy particles at the event horizon, contradicting the smooth spacetime predicted by general relativity. This proposal has sparked significant debate within the physics community. Holographic Principle and AdS/CFT Correspondence: The holographic principle suggests that all the information contained within a region of space can be encoded on its boundary. The AdS/CFT correspondence, a conjectured equivalence between certain gravitational theories and quantum field theories, has been used to study black hole physics in this context, offering potential insights into the resolution of the information paradox. Quantum Gravity and String Theory: Some researchers believe that a theory of quantum gravity, which successfully unifies quantum mechanics and general relativity, could resolve the information paradox. String theory is one candidate for such a theory, but it remains highly speculative and has not yet been definitively confirmed. Information Preservation: Other proposals suggest that information may somehow be preserved in a subtle way within the black hole or its radiation, allowing for the eventual recovery of the initial state.Despite decades of research, the Black Hole Information Paradox remains unsolved, and it continues to be a topic of active investigation and debate within the physics community. Resolving this paradox is crucial for developing a complete understanding of the fundamental laws governing the universe. Chat Section Other Articles...... Theories Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop Today Onward Theory Parallel World Travel We are our GOD Inflationary Cosmology STAR VFTS102 KEPLER-452b Proxima Centauri b TRAPPIST-1

Today Onward Theory What is Today Onward Theory?, This is a theory that will shock you, I will explain this theory today but only if you can relate to it then you will be able to understand it, I have given my strong point of view in this. Over View.... What is Today Onward Theory?, This is a theory that will shock you, I will explain this theory today but only if you can relate to it then you will be able to understand it, I have given my strong point of view in this. What is science?, Have we made much progress in science?, How will science be in the future?, Can we become a Type 2 civilization?, you will get the answers to these questions later, but let me say one thing that if today's From the point of view, science has not done anything, according to scientists, if we want to become a Type 2 civilization, then we still have a lot of research left to do, now you will say that we have discovered so much in space science, how much more?, let me tell you. We are not going to become great by going to space or going to the moon 2-3 times, because we do not even know how to take people out of the solar system, we have not even reached Mars, nor have we established our colony on any planet. If it has been made, then how can we say that science has progressed a lot. One step towards the future Now if you say, what do we have to do so that we can progress?, and where is science today? You will get answers, all your questions will be answered, if you have any question after reading this theory then you can tell me in the chat box below, I will answer all your questions. So what is my point of view, I will tell you, if we have shared something before, then where are we now?, right now we have definitely made a lot of progress in science but that progress is not enough, if we want to become a Type 2 civilization then there is still a lot of work to be done. The journey is still left, all the space we have traveled in comes within the solar system only, we have only taken people to the moon, and for the last many years we have not even been able to send humans again, if you look at science. It has made considerable progress in the last 100 years, but is it enough? No, if we want to reach Alpha Centauri, the system we have today, it will take thousands and millions of years, and we will never be able to reach the nearest galaxy. Then how can we say that we can become a Type 2 civilization? Now I will explain my point of view to you by listening to a story, "Once everyone was present in the king's court, then the king said to a minister that I am very happy with your work and want to give you a gift, tell me what do you want, minister. He was as intelligent as all of you, he said, King, I don't need much, just one square of Chokha in the first square of a chess board and its double in the next one, give me as many Chokha's dens as will be made in the last square, King. The king ordered to give him whatever he wanted, then a servant came and said that the king has asked for so many grains that there are not so many of them in our entire kingdom, then the king was very impressed by him, you will think how many grains would have been there which the king would have given. If I couldn't give it, then I have counted it for you all, and it comes to more than 2305843007575253120, and this is so much that its count has not been discovered till date, and this is exactly how our space science is progressing. , How progress is doubling every day, NASA has been established for only about 70 years and how many discoveries have been made in these 70 years, ISRO was also established 60 years ago and how far it has progressed, in the coming 10- Science would have advanced a lot in 20 years, just take the example of A.I. Most of the people would not even know about A.I before 2020 and it has increased in just three years. In this way our science is progressing and will continue to do so. Chat Section..... Other Articles...... Theories Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop Parallel World Travel STAR VFTS102 KEPLER-452b Proxima Centauri b TRAPPIST-1

Research Papers Articles STAR VFTS102 We present a spectroscopic analysis of an extremely rapidly rotating late O-type star, VFTS102, observed during a spectroscopic survey of 30 Doradus. VFTS102 has a projected rotational velocity larger than 500 km s−1 and probably as large as 600 km s−1; as such it would appear to be the most rapidly rotating massive star currently identified. Its radial velocity differs by 40 km s−1 from the mean for 30 Doradus, suggesting that it is a runaway. View More Dark Energy In the late 1990s, astronomers found evidence that the expansion of the universe was not slowing down due to gravity as expected. Instead, the expansion speed was increasing. Something had to be powering this accelerating universe and, in part due to its unknown nature, this “something” was called dark energy. View More Zombie Planet Zombie planets, also known as "pulsar planets" or "planets around pulsars," are a fascinating and relatively rare astronomical phenomenon. View More The Dream Mission People must have had many dreams and those dreams would be very unique, but my dream is very unique. Today I will share with you this dream journey full of very interesting and adventures. In this dream of mine, I have done the complete mission of Mars and there are many twists in that too, which I will tell you further in this article. The article is The Dream Mission View More Creation of Mind Loop What we doing, what we experiencing, what we thinking is a creation of mind, and it's just a thoughts View More

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O-TYPE STAR VFTS102 We present a spectroscopic analysis of an extremely rapidly rotating late O-type star, VFTS102, observed during a spectroscopic survey of 30 Doradus. VFTS102 has a projected rotational velocity larger than 500 km s−1 and probably as large as 600 km s−1; as such it would appear to be the most rapidly rotating massive star currently identified. Its radial velocity differs by 40 km s−1 from the mean for 30 Doradus, suggesting that it is a runaway. By : P. Dufton et al 1. Introduction ​ In recent years the importance of binarity in the evolution of massive stars has been increasingly recognised. This arises from most OB-type stars residing in multiple systems (Mason et al. 2009) and the significant changes to stellar properties that binarity can cause (see, for example, Podsiadlowski et al. 1992; Langer et al. 2008; Eldridge et al. 2011). Here we present a spectroscopic analysis of a rapidly rotating (veq sin i ∼ 600 km s−1) O-type star in the 30 Doradus region of the Large Magellanic Cloud (LMC). Designated VFTS102 (Evans et al. 2011, hereafter Paper I)1, the star is rotating more rapidly than any observed in recent large surveys (Martayan et al. 2006; Hunter et al. 2009) and may also be a runaway. It lies less than one arcminute from the X-ray pulsar, PSR J0537-6910, which is moving away from it. We suggest that VFTS102 might originally have been part of a binary system with the progenitor of the pulsar. ​ 2. Observations ​ Spectroscopy of VFTS102 was obtained as part of the VLT-FLAMES Tarantula Survey, covering the 3980-5050˚A region at a spectral resolving power of 7000 to 8500. Spectroscopy of the Hα region was also available, although this was not used in the quantitative analysis. Details of the observations and initial data reduction are available in Paper I. The spectra were normalised to selected continuum windows using a sigma-clipping rejection algorithm to exclude cosmic rays. No velocity shifts were observed between different epochs, although simulations (see, Sana et al. 2009) indicate that 30% of short period (less 1Aliases include: ST92 1-32; 2MASS J05373924-6909510 –3– than 10 days) and effectively all longer term binaries would not have been detected. We have therefore assumed VFTS102 to be single and the sigma-clipped merged spectrum displays a signal-to-noise ratio of approximately 130 and 60 for the 4000-4500 and 4500-5000˚A regions respectively. An O9: Vnnne spectral classification was obtained by smoothing and rebinning the spectrum to an effective resolving power of 4000 and comparing with standards compiled for the Tarantula Survey (Sana et al. in preparation). The principle uncertainties arise from the extremely large rotational broadening and significant nebular contamination of the He I lines, with the two suffixes indicating extreme line broadening (‘nnn’) and an emission-line star (‘e’). ​ 3. Analysis 3.1. Projected rotational velocity ​ The large rotational broadening of the spectral features makes reliable measurements of the projected rotational velocity, veq sin i , difficult. We have used a Fourier Transform (FT) approach as discussed by Sim´on-D´ıaz & Herrero (2007), supplemented by fitting rotational broadened profiles (PF) to the observed spectral features. The Balmer lines have significant nebular emission and hence the weaker helium spectra were utilized, as illustrated in Fig. 1. The He I line at 4471˚A, although well observed, also showed significant nebular emission and was not analysed. By contrast the line at 4026˚A showed no evidence of emission and yielded a plausible minimum in the Fourier Transform for a veq sin i of 560 km s−1. The PF methodology leads to a slightly higher estimate (580 km s−1). The He I lines at 4143 and 4387˚A were observed although they are relatively weak. They and the line at 4026˚A were converted into velocity space, merged and analysed. The two methodologies yielded effectively identical estimates of 640 km s−1; a similar procedure was undertaken for the He II lines at 4200 and 4541˚A yielding 540 km s−1 (FT) and 510 km s−1 (PF). The He II line at 4686˚A was found to be sensitive to the normalisation with a veq sin i of ∼560 km s−1 being estimated. The individual results should be treated with caution but overall they imply that this star is rotating near to its critical velocity, with the mean value for the FT estimates being 580 km s−1. As discussed by Townsend et al. (2004), projected rotational velocities may be underestimated at these large velocities. For a B0 star rotating at 95% of the critical velocity, this underestimation will be approximately 10%. Hence our best estimate for the projected rotational velocity is ∼600 km s−1. A lower limit of 500 km s−1 has been adopted, whilst the upper value will be constrained by the critical velocity of approximately 700 km s−1 from the models of Brott et al. (2011). This estimate is significantly higher than those (! 370 km s−1) found by Martayan et al. (2006) and Hunter et al. (2009) in their LMC B-type stellar samples. It is also larger than any of the preliminary estimates (!450 km s−1) for ∼ 270 B-type stars in the Tarantula survey, although other rapidly rotating O-type stars have been identified. As such it would appear to have the highest projected rotational velocity estimate of any massive star yet analysed. ​ 3.2. Radial velocity ​ Radial velocities were measured by cross-correlating spectral features against a theoretical template spectrum taken from a grid calculated using the code TLUSTY Hubeny (1988) – see Dufton et al. (2005) for details. Five spectral regions were considered, viz. Hδ and Hγ (with the cores excluded); He I at 4026˚A; 4630-4700˚A with strong multiplets due to C III and O II and an He II line; 4000-4500˚A (with nebular emission being excluded). The measurements are in excellent agreement with a mean value of 228±12 km s−1; if the error distribution is normally distributed the uncertainty in this mean value would be 6 km s−1. From a study of ∼180 presumably single O-type stars in the Tarantula survey Sana et al. (in preparation) find a mean velocity of 271 km s−1 with a standard deviation of 10 km s−1. Preliminary analysis of the B-type stars in the same survey has yielded 270±17 km s−1. VFTS102 lies more than two standard deviations away from these results, implying that it might be a runaway. ​ 3.3. Atmospheric parameters ​ While the equatorial regions of VFTS102 will have a lower gravity than the poles (because of centrifugal forces), and hence a lower temperature (because of von Zeipel gravity darkening), we first characterise the spectrum by comparison with those generated with spatially homogeneous models, convolved with a simple rotational-broadening function. We have used both our TLUSTY grid and FASTWIND calculations (Puls et al. 2005), adopting an LMC chemical composition. For the former, the strength of the He II spectrum implies an effective temperature (Teff) of ∼32500–35000 K, whilst the wings of the Balmer lines lead to a surface-gravity estimate of ∼3.5 dex (cgs). For the latter after allowing for wind effects, the corresponding parameters are 37000 K and 3.7 dex. The helium spectra are consistent with a solar abundance but with the observational and theoretical uncertainties we cannot rule out an enhancement. Given its projected equatorial rotation velocity, VFTS102 is almost certainly viewed at sin i ∼ 1. Hence the relatively cool, low-gravity equatorial regions will contribute significantly to the spectrum. Although their surface flux is lower than for the brighter poles, the analyses discussed above may underestimate the global effective temperature and gravity. However, the rotating-star models discussed below suggest that the effects are not very large. We therefore adopt global estimates for the effective temperature of 36000 K and 3.6 dex but note that the polar gravity could be as large as 4.0 dex. Varying the global parameters by the error estimates listed in Table 1 leads to significantly poorer matches between observation and the standard models, but, given the caveats discussed above, those errors should still be treated with caution. For near critical rotational velocities, the stellar mass can be estimated. Howarth & Smith (2001) show that the stellar mass can be written in terms of ω/ωc 2, veq and the polar radius. Assuming that sin i ∼ 1 and adopting the critical velocities from our single star models, we can estimate the first two quantities. Additionally for any given value of ω/ωc, the polar radius can be inferred from the absolute visual magnitude and the unreddened (B-V). The former can be estimated from the luminosity (see Sect. 3.4) and the latter from our effective temperature estimate and the LMC broad-band intensities calculated by Howarth (2011). We find M " 20 M# for veq ∼ 600 km s−1 and Teff ! 38000 K. Only by adopting a smaller value for veq can we push the mass limit down, but even with veq ∼ 500 km s−1 the mass must exceed ∼17M#. ​ 3.4. Luminosity ​ From extant photometry (see Paper I), the (B-V) colour of VFTS102 is 0.35, implying an E(B-V) of 0.6 using colours calculated from our TLUSTY grid. Adopting a standard reddening law leads to a logarithmic luminosity (in solar units) of 5.0 dex, with an E(B-V) error of ±0.1 corresponding to an uncertainty of ±0.1 dex. However there are other possible sources of error, for example deviations from a standard reddening law and hence we have adopted a larger random error estimate of ±0.2 dex. 2The ratio of the equatorial angular velocity to that at which the centrifugal acceleration equals the gravitational acceleration. As VFTS102 is an Oe-type star, its intrinsic colours may be redder than predicted by our TLUSTY grid and indeed an infrared excess is found from published (de-reddened) 2MASS photometry. Inspection of a K-band VISTA image shows no evidence of contamination by nearby sources. Further evidence for circumstellar material is found in the strong Hα emission, which is double peaked as is the nearby He I line at 6678˚A, which supports our adoption of a sin i ∼ 1. Additionally there are weak double-peaked Fe II emission features (e.g. at 4233˚A), consistent with an Oe-type classification. Unfortunately our photometry and spectroscopy are not contemporaneous but if VFTS102 was in a high state when the optical photometry was taken, we may have overestimated the luminosity of the central star (see de Wit et al. 2006, for colour and magnitude variations of Be stars). ​ 4. Past and future evolution ​ Stellar evolution calculations for both single and binary stars are available in the literature (see Maeder & Meynet 2011). For very fast rotation, they suggest that rotational mixing is so efficient that stars may evolve quasi-chemically homogeneously (Maeder 1987; Woosley & Heger 2006; Cantiello et al. 2007; de Mink et al. 2009; Brott et al. 2011). However, with different physical assumptions, models do not evolve chemically homogeneously even for the fastest rotation rates (Cantiello et al. 2007; Ekstr¨om et al. 2008). ​ 4.1. Single star evolution ​ Fig. 2 illustrates evolutionary tracks for LMC single stars calculated using the methodology of Brott et al. (2011) for an initial equatorial rotational velocity of 600 km s−1, together with that for a more slowly rotating model. The former are evolving chemically homogeneously whilst the latter follows a ‘normal’ evolutionary path. Ekstr¨om et al. (2008) calculated models for a range of metallicities and masses between 3 and 60 M# but found that the stars followed normal evolutionary paths even for near critical rotational velocities. The estimated parameters of VFTS102 are consistent with our tracks for initial masses of ∼20-30 M#. Our models show a relatively rapid increase in the surface helium abundance due to their homogeneous evolution. For example the 25 M# model shows an enrichment of a factor of two after approximately 4 million years and when the effective temperature has increased to approximately 39000 K. By contrast the models of Ekstr¨om et al. (2008) show no significant helium abundance implying that an accurate helium abundance estimate for VFTS102 would help constrain the physical assumptions. –7– ​ 4.2. Binary star evolution ​ Below, we first discuss the environment of VFTS102 and then consider a possible evolutionary scenario. ​ 4.2.1. A pulsar near VFTS102 ​ VFTS102 lies in a complex environment near the open cluster NGC 2060. In particular it lies close to a young X-ray pulsar PSR J0537-6910 (Marshall et al. 1998) and the Crab-like supernova remnant B0538-691 (Micelotta et al. 2009). VFTS102 has an angular separation of approximately 0.8 arcminutes from PSR J0537-6910 implying a spatial separation (in the plane of the sky) of approximately 12 pc. The X-ray emission consists of a pulsed localised component and a more spatially diffuse component, with the latter providing the majority of the energy. The diffuse component was identified in ROSAT and ASCA observations by Wang & Gotthelf (1998a) and interpreted as coming from ram-pressure-confined material with the X-ray pulsar being identified soon afterwards by Marshall et al. (1998). Wang & Gotthelf (1998b) analysed ROSAT HRI observations and suggested that the emission could come from the remnants of a bow shock if the pulsar was moving with a velocity of ∼1000 km s−1. Wang et al. (2001) subsequently analysed higher spatial resolution CHANDRA observations, which clearly delineated this emission and implied that the pulsar was moving away from VFTS102. Fig. 3 superimposes these emission contours onto an HST optical image with VFTS102 being near the tail of these contours. As discussed by Wang et al. (2001) the spatial distribution of the diffuse X-ray emission and the SNR optical emission are well correlated. Differences probably arise from a foreground dark cloud and photoionization and mechanical energy input from the nearby open cluster. Timing measurements imply that the pulsar has a characteristic age of 5000 years (Marshall et al. 1998), consistent with the age estimate of Wang & Gotthelf (1998b) from analysis of X-ray emission. Spyrou & Stergioulas (2002) discuss the estimation of ages from spin rates and find the results to be sensitive to both the breaking index and the composition of the pulsar core. Indeed phase connected braking index measurements for young pulsars (see Zhang et al. 2001, and references therein) yield breaking indices lower than the n=3 normally adopted with corresponding increases in the characteristic ages. Additionally, Chu et al. (1992) found an age of approximately 24000 years from the kinematics of the supernova remnant. Adopting an age of 5000 years would imply that if these objects had been part of a binary system, their relative velocity (vs ) in the plane of the sky would be approximately 2500 km s−1. Increasing this age to 24000 years would then imply vs ∼ 500 km s−1. These values although large are consistent with a pulsar velocity of 1000 km s−1 in the model of Wang & Gotthelf (1998b) and of ∼600 km s−1 from the separation of the diffuse X-ray and radio emission (Wang et al. 2001). Additionally Hobbs et al. (2005) found a mean space velocity of approximately 400 km s−1 for a sample of young pulsars with velocities as high as 1600 km s−1. From the theoretical point of view, Stone (1982) found supernova kick velocities normally in excess of 300 km s−1, while more recently Eldridge et al. (2011) estimated kickvelocities for a single neutron star of more than 1000 km s−1with a mean value of ∼500 km s−1. ​ 4.2.2. A binary evolution scenario for VFTS1 02 ​ While the fast rotation of VFTS102 might be the result of the star formation process, it could also have arisen from spin-up due to mass transfer in a binary system (Packet 1981). A subsequent supernova explosion of the donor star could then lead to an anomalous radial velocity for VFTS102 (Blaauw 1961; Stone 1982). The nearby pulsar and supernova remnant make this an attractive scenario. Of course, we cannot eliminate other possible scenarios, e.g. dynamical ejection from a cluster (see Gvaramadze & Gualandris 2011) but it is unclear whether these could produce the very large rotational velocity of VFTS102. Cantiello et al. (2007) have modelled a binary system with initial masses of 15 and 16 M# adopting SMC metallicity. After mass transfer the primary exploded as a type Ib/c supernova. At that stage the secondary has a mass of approximately 21 M#, a rotational velocity close to critical and a logarithmic luminosity of approximately 4.9 dex (see Fig. 2 for its subsequent evolution). These properties closely match the estimates for VFTS102 summarized in Table 1. Based on grids of detailed binary evolutionary models (Wellstein et al. 2001; de Mink et al. 2007), the initial masses of the two components of such a binary system should be comparable, with M2/M1 " 0.7. If the initial mass of the secondary was in the range of 14-18 M#, that of the primary would need to be smaller than about 25 M#. This agrees with the estimated initial mass of the supernova progenitor based on the kinematics of the supernova remnant (Micelotta et al. 2009). In this scenario, it takes the primary star about 11 Myr to evolve to the supernova stage. While the most massive stars in 30 Doradus have ages of a few million years (Walborn et al. 1999), there is also evidence for different massive stellar populations with ages ranging up to about 10 Myr (Walborn & Blades 1997). Recently, De Marchi et al. (2011) have undertaken an extensive study of lower mass (!4 M#) main sequence and pre-main sequence stars in 30 Doradus. They obtain a median age of 12 Myr with ages of up 30 Myr. Hence it would appear possible that the putative binary system formed in the vicinity of 30 Doradus approximately 10 Myr ago and underwent an evolutionary history similar to that modelled by Cantiello et al. (2007). Proper motion information would be extremely valuable to further test this hypothesis. PSR J0537-6910 has not been definitely identified in other wavelength regions. Mignani et al. (2005) using ACS imaging from the Hubble Space telescope found two plausible identifications that would imply an optical luminosity similar to the Crab-like pulsars. A radio survey by Manchester et al. (2006) only yielded an upper limit to its luminosity consistent with other millisecond pulsars. However estimates for both components may be obtained from the HST proper motion study (Programme: 12499; PI: D.J. Lennon) that is currently underway. ​ 4.3. Evolutionary future ​ Irrespective of the origin of VFTS102, it is interesting to consider its likely fate. Stellar evolutionary models of rapidly rotating stars have recently been generated by Woosley & Heger (2006) and Yoon et al. (2006). The latter consider the fate of objects with rotational velocities up to the critical value (vc ). The evolution is shown to depend not only on initial mass and rotational velocity but also on the metallicity. In particular GRBs are predicted to occur only at sub-solar metallicities. Based on our single star models, VFTS102 has a rotational velocity above ∼ 0.8vc and is thus expected to evolve quasi-chemically homogeneously. While Yoon et al. (2006) and Woosley & Heger (2006) estimate the metallicity threshold for GRB formation from chemically homogeneous evolution to be somewhat below the LMC metallicity, the latter note its sensitivity to the mass loss rate (Vink & de Koter 2005). Indeed all our most rapidly rotating 20 − 30 M# models are evolving chemically homogeneously throughout core hydrogen burning (Fig. 2), a prerequisite to qualify for a GRB progenitor. In any case, within the context of homogeneous evolution VFTS102 is expected to form a rapidly rotating black hole, and a Type Ic hypernova. This conjecture remains the same within the binary scenario of Cantiello et al. (2007). Assuming a space velocity of 40 km s−1 for VFTS102 (compatible with its anomalous radial velocity), our evolutionary models imply that VFTS102 will travel ∼300-400 pc before ending its life. This is consistent with the finding of Hammer et al. (2006) that the locations of three nearby GRBs were found several hundred parsecs away from their most likely progenitor birth locations (see, however, Margutti et al. 2007; Wiersema et al. 2007; Han et al. 2010). ​ 5. Conclusions ​ VFTS102 has a projected rotational velocity far higher than those found in previous surveys of massive stars in the LMC, and indeed it would appear to qualify as the most rapidly rotating massive star yet identified. With a luminosity of 105 L# we estimate its current mass to be approximately 25 M#. Its extreme rotation, peculiar radial velocity, proximity to the X-ray pulsar PSR J0537-6910 and to a supernova remnant suggest that the star is the result of binary interaction. It is proposed that VFTS102 and the pulsar originated in a binary system with mass transfer spinning-up VFTS102 and the supernova explosion imparting radial velocity kicks to both components. If evolving chemically homogeneously, as suggested by recent models, VFTS102 could become a GRB or hypernova at the end of its life. Additionally it may provide a critical test case for chemically homogeneous evolution. SdM acknowledges NASA Hubble Fellowship grant HST-HF- 51270.01-A awarded by STScI, operated by AURA for NASA, contract NAS 5-26555. NM acknowledges support from the Bulgarian NSF (DO 02-85). We would like to thank Paul Quinn, Stephen Smartt, Jorick Vink and Nolan Walborn for useful discussions. This paper makes use of spectra obtained as part of the VLT-FLAMES Tarantula Survey (ESO programme 182.D-0222). Facilities VLT:Kueyen (FLAMES) Other Articles...... Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop Zombie Planets Proxima Centauri b TRAPPIST-1

Hubble's Nebula Discoveries This is your About Page. It's a great opportunity to give a full background on who you are, what you do and what your website has to offer. Double click on the text box to start editing your content and make sure to add all the relevant details you want to share with site visitors. Beyond the solar system, Hubble has studied star formation and death in our Galaxy and nearby galaxies. As a first example, this image of the Carina Nebula was released for Hubble’s 17th anniversary. At the time (2007), it was one of the largest panoramic images ever taken with Hubble’s Advanced Camera for Surveys. It is a 50-light-year-wide view of the central region of the Carina Nebula, where a maelstrom of star birth -- and death -- is taking place. The nebula is sculpted by the action of outflowing winds and scorching ultraviolet radiation from the monster stars that inhabit this inferno. The stars are shredding the surrounding material that is the last vestige of the giant cloud from which the stars were born. The immense nebula contains at least a dozen brilliant stars that are roughly estimated to be at least 50 to 100 times the mass of our Sun. The most unique and opulent inhabitant is the star Eta Carinae, at far left. Eta Carinae is in the final stages of its brief and eruptive lifespan, as evidenced by two billowing lobes of gas and dust that presage its upcoming explosion as a titanic supernova. The outflow in the Carina region started three million years ago when the nebula's first generation of newborn stars condensed and ignited in the middle of a huge cloud of cold molecular hydrogen. Radiation from these stars carved out an expanding bubble of hot gas. The island-like clumps of dark clouds scattered across the nebula are nodules of dust and gas that are resisting being eaten away by photoionization. The blast of stellar winds and blistering ultraviolet radiation within the cavity is now compressing the surrounding walls of cold hydrogen. This is triggering a second stage of new star formation. Carina is about 7,500 light years away (2,300 parsecs). Using Hubble’s newer cameras provides a stunning image of an old favorite. This image of the Pillars of Creation in the Eagle Nebula has twice the resolution, several times the area, and more than twenty times the pixels of the 1995 version. The image was obtained with the optical bands of the Wide Field Camera 3 (WFC3) in 2015. This taller image includes the gas at the bottom of the pillars being blown down and trailing away. Numerous small features indicate the pervasiveness of pillars of every size in this region. This is the first of a sequence of three images to be shown relatively rapidly. We begin the anniversary year by revisiting a legendary image: the “Pillars of Creation” in the Eagle Nebula. This image was the first Hubble image to fascinate the public, and still remains one of Hubble’s most popular images. It was obtained in 1995 with the Wide Field and Planetary Camera 2 (WFPC2). Inside the gaseous towers, which are light-years long, the interstellar gas is dense enough to collapse under its own weight, forming young stars that continue to grow as they accumulate more and more mass from their surroundings. The object is 6,500 light years away (2,000 parsecs). Like the pillars in Carina, these dark clouds are being eroded by winds and radiation from hot, young stars. The stars forming within the pillars give them their “creation” nickname. Using the infrared capabilities of Wide Field Camera 3 (WFC3), one can see the pillars in a whole new light. Much of the gas of the nebula is transparent to the longer wavelengths of infrared light, revealing a tremendous number of stars. The seemingly solid, visible-light pillars are shown in the infrared to be a combination of dense clouds and the shadows they cast behind them. Such high resolution visible light and infrared light comparisons point toward a bright future when Hubble and James Webb Space Telescope observations can be similarly compared and contrasted. This is the first of two images to be shown of the Horsehead Nebula. The transition should be done without too much delay to the next image. In 2001, after asking the public which object should be observed, the Hubble Heritage Project took this image of the Horsehead Nebula with the Wide Field and Planetary Camera 2 (WFPC2). While the nebula makes for a striking silhouette, the dark cloud is short on detail in a visible light image. The small inset shows a ground-based optical image of the surrounding region. The distance to the object is about 1,200 light years (490 parsec). Using the enhanced infrared sensitivity of Wide Field Camera 3, Hubble was able to get much more detail in this 2013 infrared portrait of the Horsehead. The relatively featureless dark clouds are transformed into a glowing gaseous landscape that almost appears three-dimensional in the image. There are videos that zoom into the nebula and also show the 3D effect. This image of the Orion Nebula shows the discovery of debris disks – planetary systems in formation around newly created stars. As the gas and dust collapses under gravity, stars are born, and in the process, disks and planets often form out of the residual material. The distance to the Orion Nebula is 1,500 light years (460 parsecs). http://hubblesite.org/newscenter/archive/releases/1995/45/ A beautiful composite image of the Orion Nebula from both the HST ACS and the ESO MPI at La Silla is available: http://hubblesite.org/newscenter/archive/releases/2006/01/ ​ Supplemental Movies: Orion Fly through: http://hubblesite.org/newscenter/archive/releases/2001/13/video/a/ Zoom into Orion: http://hubblesite.org/newscenter/archive/releases/2001/13/video/a/ At the heart of this star-forming region lies star cluster NGC 602. It is a cluster of newly formed stars that are blowing a cavity in the center of a star-forming region in the Small Magellanic Cloud, a companion galaxy to our own Milky Way. The high-energy radiation blazing out from the hot young stars is sculpting the inner edge of the outer portions of the nebula, slowly eroding it away and eating into the material beyond. The diffuse outer reaches of the nebula prevent the energetic outflows from streaming away from the cluster. Ridges of dust and gaseous filaments are seen surrounding the cluster. Elephant trunk-like dust pillars point towards the hot blue stars and are telltale signs of their eroding effect. ​ It is possible to trace how the star formation started at the center of the cluster and propagated outward, with the youngest stars still forming today along the dust ridges. The Small Magellanic Cloud, in the constellation Tucana, is roughly 200,000 light-years from the Earth. Its proximity to us makes it an exceptional laboratory to perform in-depth studies of star formation processes and their evolution in an environment slightly different from our own Milky Way. ​ This image was taken with Hubble’s Advanced Camera for Surveys. http://hubblesite.org/newscenter/archive/releases/2007/04/ X-ray from Chandra plus Hubble observations: http://hubblesite.org/newscenter/archive/releases/2013/17/image/a/ The Cat’s Eye Nebula, formally cataloged NGC 6543, was one of the first planetary nebulae to be discovered. Hubble observations show it is one of the most complex such nebulae seen in space. A planetary nebula forms when Sun-like stars gently eject their outer gaseous layers, which eventually form bright nebulae with amazing and confounding shapes. This image taken with Hubble's Advanced Camera for Surveys (ACS) reveals the full beauty of a bull's eye pattern of eleven or even more concentric rings, or shells, around the Cat's Eye. Each 'ring' is actually the edge of a spherical bubble seen projected onto the sky — that's why it appears bright along its outer edge. Observations suggest the star ejected its mass in a series of pulses at 1,500- year intervals. These convulsions created dust shells, each of which contains as much mass as all of the planets in our solar system combined (still only one percent of the Sun's mass). These concentric shells make a layered, onionskin structure around the dying star. The view from Hubble is like seeing an onion cut in half, where each skin layer is discernible. The Nebula is 3000 light years (1000 parsecs) away. This beautiful image was taken soon after Servicing Mission 4 as part of the release announcing Hubble’s return to science operations. This planetary nebula is the material blown off of a dying star. A disk around the center restricts the outflows into two oppositely directed lobes, creating a distinct resemblance to a butterfly. Although named the Bug Nebula, many began calling this object the Butterfly Nebula after this image was released. The Crab Nebula derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844, using a 36-inch telescope. The Crab Nebula is a six-light-year-wide expanding remnant of a star's supernova explosion. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054, as did -- almost certainly -- Native Americans. This composite image was assembled from 24 individual exposures taken with the Hubble Space Telescope’s Wide Field and Planetary Camera 2 in October 1999, January 2000, and December 2000. The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the center of the nebula is the dynamo powering the nebula's eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star. This shell, or bubble, is the result of gas that is being shocked by the expanding blast wave from a supernova. Notice its completely different appearance from the Crab Nebula in the previous slide. Called SNR 0509-67.5 (or SNR 0509 for short), the bubble is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud (LMC), a small galaxy about 160,000 light-years from Earth. Ripples in the shell's surface may be caused by either subtle variations in the density of the ambient interstellar gas, or possibly driven from the interior by pieces of the ejecta. The bubble-shaped shroud of gas is 23 light-years across and is expanding at more than 11 million miles per hour (5,000 kilometers per second). ​ http://hubblesite.org/newscenter/archive/releases/2010/27/ Supplemental Movie: 3D look at SN remnant http://hubblesite.org/newscenter/archive/releases/2010/27/video/a/

Dark Energy In the late 1990s, astronomers found evidence that the expansion of the universe was not slowing down due to gravity as expected. Instead, the expansion speed was increasing. Something had to be powering this accelerating universe and, in part due to its unknown nature, this “something” was called dark energy. What Is Dark Energy? In the late 1990s, astronomers found evidence that the expansion of the universe was not slowing down due to gravity as expected. Instead, the expansion speed was increasing. Something had to be powering this accelerating universe and, in part due to its unknown nature, this “something” was called dark energy. Hubble plays an important role in verifying, characterizing and constraining dark energy. Both Hubble and ground-based observations measures a special type of stellar explosion, a white dwarf supernova, to measure accurate distances to galaxies. ​ A galaxy located a billion light-years away provides a data point for the universe as it was a billion years ago. Meanwhile, as the universe expands, the light traveling to Earth from distant galaxies (and their supernovas) is stretched out to longer wavelengths — a phenomenon called cosmological redshift. The cosmological redshifts of galaxies at different distances provides a history of the expansion of the universe over time. However, only Hubble had the resolution to extend these observations to very distant galaxies. The discovery of supernova 1997ff, located about 10 billion light-years away, provided evidence for dark energy. About halfway into the universe’s history — several billion years ago — dark energy became dominant and the expansion accelerated. While ground-based studies had measured this accelerating period, Hubble’s observation of 1997ff stretched back to the decelerating part of the expansion. This shift between two different eras of the universe — a change from a decelerating universe to an accelerating universe — showed that dark energy exists. Hubble continued to explore the nature of dark energy with observations such as the Great Observatories Origins Deep Survey (GOODS), structured to help uncover distant supernovas. The 42 supernovas found by Hubble not only solidified the conclusions about dark energy, but also began to constrain some of its possible explanations. Later Hubble results identified how early in the universe dark energy began to influence the expansion as well as constrained the current expansion rate. ​ The view that emerged was that dark energy was consistent with the slow, steady force of Einstein’s cosmological constant, a concept that the physicist had initially introduced into his equations to prevent his theoretical universe from collapsing, then later retracted when the expansion of the universe was discovered. But instead of holding the universe in a steady state, dark energy is pushing outward to expand the universe faster and faster. The discovery of dark energy was recognized by the Nobel Prize in Physics in 2011. Astronomers now know that there is much more to the universe than meets the eye. The luminous and non-luminous normal matter makes up about 4 percent of the total mass and energy density of the universe. Dark matter, which emits no light and cannot be directly observed, comprises another 24 percent of the total, while dark energy dominates with about 72 percent. Most of the universe is unknown and only indirectly detected. We can see its effects on galaxies and the expansion of the universe, but we have yet to identify the underlying source. That may seem unsettling, but to a scientist, it is exciting. There are more great mysteries to explore and solve! The universe is expanding, and that expansion stretches light traveling through space in a phenomenon known as cosmological redshift. The greater the redshift, the greater the distance the light has traveled. Within the Hubble Deep Field-North region, astronomers pinpointed a blaze of light from one of the farthest supernovas ever seen. In a close-up view of that region (left) a white arrow points to a faint elliptical, the home of the exploding SN 1997ff. The supernova itself (right) is distinguished by the white dot in the center. This diagram reveals changes in the rate of expansion since the universe's birth 15 billion years ago. The more shallow the curve, the faster the rate of expansion. The curve changes noticeably about 7.5 billion years ago, when objects in the universe began flying apart as a faster rate. Astronomers theorize that the faster expansion rate is due to a mysterious, dark force that is pulling galaxies apart. This image is a portion of the GOODS-North field. The field features approximately 15,000 galaxies, about 12,000 of which are forming stars. Hubble’s ultraviolet vision opened a new window on the evolving universe, tracking the birth of stars over the last 11 billion years back to the cosmos’ busiest star-forming period about 3 billion years after the big bang. Spiral galaxy NGC 3021 (background) was one of several hosts of Type Ia supernovae observed by astronomers to refine the measure of the universe's expansion rate, called the Hubble constant. Hubble made precise measurements of Cepheid variable stars in the galaxy, highlighted by green circles in the inset boxes. Other Articles...... Zombie Planets Multiness of Thoughts The Dream Mission Creation of Mind Loop STAR VFTS102 KEPLER-186f Proxima Centauri b TRAPPIST-1

KEPLER-452b Kepler-452b, often referred to as "Earth's cousin," is an exoplanet that was discovered by NASA's Kepler Space Telescope. It was announced as a significant discovery in July 2015. Here's a detailed explanation of Kepler-452b, including information about its characteristics, atmosphere, and the potential for extraterrestrial life 1. Characteristics of Kepler-452b: Size and Mass: Kepler-452b is considered a super-Earth, as it is larger than Earth, with an estimated radius about 1.6 times that of Earth. However, its exact mass is still uncertain, as it depends on its composition, which is not precisely known. Orbit: Kepler-452b orbits a star known as Kepler-452, which is very similar to our Sun in terms of both size and temperature. Its orbit around Kepler-452 takes approximately 385 days, making it roughly analogous to Earth's year. Distance from Star: Kepler-452b is located within the habitable zone of its parent star. The habitable zone, also known as the "Goldilocks zone," is the region around a star where conditions may be right for liquid water to exist on the planet's surface—a key factor for the potential development of life as we know it. Age: The host star Kepler-452 is older than our Sun, estimated to be around 6 billion years old, which could have allowed more time for life to potentially develop on Kepler-452b. ​ 2. Atmosphere of Kepler-452b: The exact composition and characteristics of Kepler-452b's atmosphere are not currently known. The detection and analysis of exoplanet atmospheres are challenging tasks and often require advanced instruments like the James Webb Space Telescope (scheduled for launch) to provide more detailed information. The presence and composition of an atmosphere are critical factors in determining the potential habitability of an exoplanet. An atmosphere can help regulate temperature, protect against harmful radiation, and play a role in supporting life processes. ​ 3. Potential for Extraterrestrial Life: Kepler-452b's location within the habitable zone of its star makes it an intriguing candidate for the potential existence of extraterrestrial life. The habitable zone represents the region where conditions might be suitable for liquid water, a fundamental ingredient for life as we know it, to exist on the planet's surface. However, the presence of liquid water alone does not guarantee the existence of life. Many other factors, such as the planet's atmosphere, geological activity, and the availability of essential chemical ingredients, would also influence its habitability. Detecting signs of life on Kepler-452b or any exoplanet is extremely challenging and would likely require advanced telescopes capable of analyzing the planet's atmosphere for biomarkers (e.g., oxygen and methane) or other potential signs of biological activity. Kepler-452b and Earth are both planets, but they have some significant differences, as well as similarities. Here's a comparison between the two: 1. Size and Mass: Earth: Earth is approximately 12,742 kilometers (7,918 miles) in diameter and has a mass of about 5.972 × 10^24 kilograms. Kepler-452b: Kepler-452b is estimated to be about 1.6 times the size (radius) of Earth, but its mass is not precisely known. It's considered a super-Earth. 2. Orbit and Parent Star: Earth: Earth orbits the Sun, a G-type main-sequence star (G2V), at an average distance of about 149.6 million kilometers (93 million miles). Kepler-452b: Kepler-452b orbits a G-type main-sequence star (G2V) known as Kepler-452, which is very similar to the Sun. Its orbital period is approximately 385 Earth days. 3. Habitability and Atmosphere: Earth: Earth has a diverse and life-sustaining atmosphere composed primarily of nitrogen (78%) and oxygen (21%), with trace amounts of other gases. It has liquid water on its surface and a stable climate, making it highly habitable. Kepler-452b: The exact composition of Kepler-452b's atmosphere is not known, and its habitability is still uncertain. It's located within the habitable zone of its star, indicating the potential for liquid water, but more information about its atmosphere is needed to assess its suitability for life. 4. Age: Earth: Earth is approximately 4.5 billion years old. Kepler-452b: The host star Kepler-452 is estimated to be about 6 billion years old, making it older than the Sun. This could have implications for the potential development of life on the planet. 5. Surface Conditions: Earth: Earth has a diverse range of surface conditions, including continents, oceans, and various climate zones. It supports a wide variety of life forms and ecosystems. Kepler-452b: The specific surface conditions of Kepler-452b, such as the presence of oceans or continents, are not known due to limited observational data. 6. Potential for Extraterrestrial Life: Earth: Earth is known to host a vast array of life, from microorganisms to complex multicellular organisms, including humans. Kepler-452b: Kepler-452b is considered a potentially habitable exoplanet due to its location within the habitable zone, but the presence of extraterrestrial life on the planet is purely speculative at this point. More research and observations are needed to assess its habitability and the potential for life. Other Articles...... Dark Energy Multiness of Thoughts The Dream Mission Creation of Mind Loop STAR VFTS102 KEPLER-186f Proxima Centauri b TRAPPIST-1