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But of course, like most NEOs that periodically make a close pass to Earth, 2017 HX4 passed us by at a very safe distance. In fact, the asteroid's closest approach to Earth was estimated to be at a distance of 3.7 Lunar Distances (LD) – i.e. almost four times the distance between the Earth and the Moon. This, and other pertinent information was tweeted in advance by the International Astronomical Union's Minor Planet Center (IAU MPC) on April 29th. This object was first spotted on April 26th, 2017, using the 1.8 meter Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), located at the summit of Haleakala in Hawaii. Since that time, it has been monitored by multiple telescopes around the world, and its tracking data and information about its orbit and other characteristics has been provided by the IAU MPC. With funding provided by NASA's Near-Earth Object Observations program, the IAU MPC maintains a centralized database that is responsible for the identification, designation and orbit computations of all the minor planets, comets and outer satellites of the Solar System. Since it's inception, it has been maintaining information on 16,202 Near-Earth Objects, 729,626 Minor Planets, and 3,976 comets. But it is the NEOs that are of particular interest, since they periodically make close approaches to Earth. In the case of 2017 HX4, the object has been shown to have an orbital period of 2.37 years, following a path that takes it from beyond the orbit of Venus to well beyond the orbit of Mars. In other words, it orbits our sun at an average distance (semi-major axis) of 1.776 AU, ranging from about 0.88 AU at perihelion to 2.669 AU at aphelion. Since it was first spotted, the object has been viewed a total of 41 times between April 26th and May 4th. In addition to the Pan-STARRS-1 survey, observations were also provided by the Cerro Tololo Observatory, the Mauna Kea Observatories, the Steward Observatory and the Kitt Peak-Spacewatch Telescopes, the Astronomical Research Observatory, the Apache Point Observatory, and the Mount John Observatory. From these combined observations, the IAU MPC was able to compile information on the object's orbital period, when it would cross Earth's orbit, and just how close it would come to us in the process. So, as always, there was nothing to worry about here folks. These objects are always spotted before they cross Earth's orbit, and their paths, periods and velocities and are known about in advance. Even so, it's worth noting that an object of this size was nowhere near to be large enough to cause an Extinction Level Event. In fact, the asteroid that struck Earth 65 millions year ago at the end of Cretaceous era – which created the Chicxulub Crater on the Yucatan Peninsula in Mexico and caused the extinction of the dinosaurs – was estimated to measure 10 km across. At 10 to 33 meters (32.8 to 108 feet), this asteroid would certainly have caused considerable damage if it hit us. But the results would not exactly have been cataclysmic. Still, it might not be too soon to consider getting off this ball of rock. You know, before – as Hawking has warned – a single event is able to claim all of humanity in one fell swoop! The MPC is currently tracking the 13 NEOs that were discovered during the month of May alone, and that's just so far. Expect to hear more about rocks that might cross our path in the future. Explore further: Asteroid to fly safely past Earth on April 19


News Article | May 19, 2017
Site: phys.org

The map precisely measures the expansion history of the universe back to when the universe was less than three billion years old. It will help improve our understanding of 'Dark Energy', the unknown process that is causing the universe's expansion to speed up. The map was created by scientists from the Sloan Digital Sky Survey (SDSS), an international collaboration including astronomers from the University of Portsmouth. As part of the SDSS Extended Baryon Oscillation Spectroscopic Survey (eBOSS), scientists measured the positions of quasars - extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies. The light reaching us from these objects left at a time when the universe was between three and seven billion years old, long before the Earth even existed. The map findings confirm the standard model of cosmology that researchers have built over the last 20 years. In this model, the universe follows the predictions of Einstein's General Theory of Relativity but includes components that, while we can measure their effects, we do not understand what is causing them. Along with the ordinary matter that makes up stars and galaxies, Dark Energy is the dominant component at the present time, and it has special properties that mean that it causes the expansion of the universe to speed up. Will Percival, Professor of Cosmology at the University of Portsmouth, who is the eBOSS survey scientist said: "Even though we understand how gravity works, we still do not understand everything - there is still the question of what exactly Dark Energy is. We would like to understand Dark Energy further. Not with alternative facts, but with the scientific truth, and surveys such as eBOSS are helping us to build up our understanding of the universe." To make the map, scientists used the Sloan telescope to observe more than 147,000 quasars. These observations gave the team the quasars' distances, which they used to create a three-dimensional map of where the quasars are. But to use the map to understand the expansion history of the universe, astronomers had to go a step further and measure the imprint of sound waves, known as baryon acoustic oscillations (BAOs), travelling in the early universe. These sound waves travelled when the universe was much hotter and denser than the universe we see today. When the universe was 380,000 years old, conditions changed suddenly and the sound waves became 'frozen' in place. These frozen waves are left imprinted in the three-dimensional structure of the universe we see today. Using the new map, the observed size of the BAO can be used as a 'standard ruler' to measure distances in our universe. "You have metres for small units of length, kilometres or miles for distances between cities, and we have the BAO for distances between galaxies and quasars in cosmology," explained Pauline Zarrouk, a PhD student at the Irfu/CEA, University Paris-Saclay, who measured the distribution of the observed size of the BAO. The current results cover a range of times where they have never been observed before, measuring the conditions when the universe was only three to seven billion years old, more than two billion years before the Earth formed. The eBOSS experiment continues using the Sloan Telescope, at Apache Point Observatory in New Mexico, USA, observing more quasars and nearer galaxies, increasing the size of the map produced. After it is complete, a new generation of sky surveys will begin, including the Dark Energy Spectroscopic Instrument (DESI) and the European Space Agency Euclid satellite mission. These will increase the fidelity of the maps by a factor of ten compared with eBOSS, revealing the universe and Dark Energy in unprecedented detail. Explore further: Biggest galactic map will throw light on 'dark energy' More information: "The Clustering of the SDSS-IV Extended Baryon Oscillation Spectroscopic Survey DR14 Quasar Sample: First Measurement of Baryon Acoustic Oscillations Between Redshift 0.8 and 2.2," Metin Ata et al., 2017, submitted to Monthly Notices of the Royal Astronomical Society arxiv.org/abs/1705.06373


News Article | May 19, 2017
Site: www.sciencedaily.com

Astronomers have constructed the first map of the Universe based on the positions of supermassive black holes, which reveals the large-scale structure of the Universe. The map precisely measures the expansion history of the Universe back to when the Universe was less than three billion years old. It will help improve our understanding of 'Dark Energy', the unknown process that is causing the Universe's expansion to speed up. The map was created by scientists from the Sloan Digital Sky Survey (SDSS), an international collaboration including astronomers from the University of Portsmouth. As part of the SDSS Extended Baryon Oscillation Spectroscopic Survey (eBOSS), scientists measured the positions of quasars -- extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies. The light reaching us from these objects left at a time when the Universe was between three and seven billion years old, long before Earth even existed. The map findings confirm the standard model of cosmology that researchers have built over the last 20 years. In this model, the Universe follows the predictions of Einstein's General Theory of Relativity but includes components that, while we can measure their effects, we do not understand what is causing them. Along with the ordinary matter that makes up stars and galaxies, Dark Energy is the dominant component at the present time, and it has special properties that mean that it causes the expansion of the Universe to speed up. Will Percival, Professor of Cosmology at the University of Portsmouth, who is the eBOSS survey scientist said: "Even though we understand how gravity works, we still do not understand everything -- there is still the question of what exactly Dark Energy is. We would like to understand Dark Energy further. Not with alternative facts, but with the scientific truth, and surveys such as eBOSS are helping us to build up our understanding of the Universe." To make the map, scientists used the Sloan telescope to observe more than 147,000 quasars. These observations gave the team the quasars' distances, which they used to create a three-dimensional map of where the quasars are. But to use the map to understand the expansion history of the Universe, astronomers had to go a step further and measure the imprint of sound waves, known as baryon acoustic oscillations (BAOs), travelling in the early Universe. These sound waves travelled when the Universe was much hotter and denser than the Universe we see today. When the Universe was 380,000 years old, conditions changed suddenly and the sound waves became 'frozen' in place. These frozen waves are left imprinted in the three-dimensional structure of the Universe we see today. Using the new map, the observed size of the BAO can be used as a 'standard ruler' to measure distances in our universe. "You have metres for small units of length, kilometres or miles for distances between cities, and we have the BAO for distances between galaxies and quasars in cosmology," explained Pauline Zarrouk, a PhD student at the Irfu/CEA, University Paris-Saclay, who measured the distribution of the observed size of the BAO. The current results cover a range of times where they have never been observed before, measuring the conditions when the Universe was only three to seven billion years old, more than two billion years before Earth formed. The eBOSS experiment continues using the Sloan Telescope, at Apache Point Observatory in New Mexico, USA, observing more quasars and nearer galaxies, increasing the size of the map produced. After it is complete, a new generation of sky surveys will begin, including the Dark Energy Spectroscopic Instrument (DESI) and the European Space Agency Euclid satellite mission. These will increase the fidelity of the maps by a factor of ten compared with eBOSS, revealing the Universe and Dark Energy in unprecedented detail.


News Article | May 19, 2017
Site: www.rdmag.com

Astronomers have constructed the first map of the Universe based on the positions of supermassive black holes, which reveals the large-scale structure of the Universe. The map precisely measures the expansion history of the Universe back to when the Universe was less than three billion years old. It will help improve our understanding of ‘Dark Energy’, the unknown process that is causing the Universe's expansion to speed up. The map was created by scientists from the Sloan Digital Sky Survey (SDSS), an international collaboration including astronomers from the University of Portsmouth. As part of the SDSS Extended Baryon Oscillation Spectroscopic Survey (eBOSS), scientists measured the positions of quasars - extremely bright discs of matter swirling around supermassive black holes at the centres of distant galaxies.  The light reaching us from these objects left at a time when the Universe was between three and seven billion years old, long before the Earth even existed. The map findings confirm the standard model of cosmology that researchers have built over the last 20 years. In this model, the Universe follows the predictions of Einstein’s General Theory of Relativity but includes components that, while we can measure their effects, we do not understand what is causing them. Along with the ordinary matter that makes up stars and galaxies, Dark Energy is the dominant component at the present time, and it has special properties that mean that it causes the expansion of the Universe to speed up. Will Percival, Professor of Cosmology at the University of Portsmouth, who is the eBOSS survey scientist said: “Even though we understand how gravity works, we still do not understand everything - there is still the question of what exactly Dark Energy is. We would like to understand Dark Energy further. Not with alternative facts, but with the scientific truth, and surveys such as eBOSS are helping us to build up our understanding of the Universe.” To make the map, scientists used the Sloan telescope to observe more than 147,000 quasars. These observations gave the team the quasars’ distances, which they used to create a three-dimensional map of where the quasars are. But to use the map to understand the expansion history of the Universe, astronomers had to go a step further and measure the imprint of sound waves, known as baryon acoustic oscillations (BAOs), travelling in the early Universe. These sound waves travelled when the Universe was much hotter and denser than the Universe we see today. When the Universe was 380,000 years old, conditions changed suddenly and the sound waves became ‘frozen’ in place. These frozen waves are left imprinted in the three-dimensional structure of the Universe we see today. Using the new map, the observed size of the BAO can be used as a ‘standard ruler’ to measure distances in our universe. "You have metres for small units of length, kilometres or miles for distances between cities, and we have the BAO for distances between galaxies and quasars in cosmology,” explained Pauline Zarrouk, a PhD student at the Irfu/CEA, University Paris-Saclay, who measured the distribution of the observed size of the BAO. The current results cover a range of times where they have never been observed before, measuring the conditions when the Universe was only three to seven billion years old, more than two billion years before the Earth formed. The eBOSS experiment continues using the Sloan Telescope, at Apache Point Observatory in New Mexico, USA, observing more quasars and nearer galaxies, increasing the size of the map produced. After it is complete, a new generation of sky surveys will begin, including the Dark Energy Spectroscopic Instrument (DESI) and the European Space Agency Euclid satellite mission. These will increase the fidelity of the maps by a factor of ten compared with eBOSS, revealing the Universe and Dark Energy in unprecedented detail.


News Article | January 12, 2016
Site: www.rdmag.com

How did the Milky Way Galaxy grow? Astronomers from the Sloan Digital Sky Survey (SDSS) have answered that question with the first map charting the growth of our home galaxy. The results were presented last week at the 227th Meeting of the American Astronomical Society. The map, which utilizes the ages of more than 70,000 red giant stars, spans to halfway across the galaxy, around 50,000 light-years away. “Close to the center of our galaxy, we see old stars that were formed when it was young and small. Farther out, we see young stars. We conclude that our galaxy grew up by growing out,” said Melissa Ness, of the Max Planck Institute for Astronomy. “To see this, we needed an age map spanning large distances, and that’s what this new discovery gives us.” First, Ness and colleagues used spectra taken from SDSS’s Apache Point Observatory Galaxy Evolution Experiment (APOGEE), which took high-quality spectra for 300 stars simultaneously over a large swath of sky. “Seeing so many stars at once means getting spectra of 70,000 red giants is actually possible with a single telescope in a few years’ time,” said Univ. of Virginia’s Steve Majewski, the principal investigator of the APOGEE survey. In a separate study, Marie Martig, also of the Max Planck Institute for Astronomy, used mass and age data of 2,000 stars observed by NASA’s Kepler, and compared the values to the respective stars’ carbon and nitrogen levels obtained by APOGEE, according to Space.com. The relationship gleaned was then applied to determine the mass of the 70,000 red giants APOGEE studied. “After combining information from the APOGEE spectra and Kepler light curves, the researchers could then apply their methods to measure ages for all 70,000 red giant stars,” according to SDSS. “Finding masses of red giants has historically been very difficult, but surveys of the galaxy have made new, revolutionary techniques possible,” said Martig.


News Article | January 9, 2016
Site: www.techtimes.com

An international team of researchers has produced the first comprehensive age map of the Milky Way that shows how the galaxy evolved over the course of billions of years. In a presentation held during the 227th conference of the American Astronomical Society (AAS), Melissa Ness, a researcher from the Max Planck Institute in Germany, described how she and her colleagues were able to create the age map of the galaxy after studying the stars that comprise it. The researchers believe that the age of red giant stars can be determined based on their masses and composition. Using this theory, they discovered that older stars in the Milky Way can often be found near the center of the galaxy, while younger stars tend to form around the edges of its disk. Ness said that the location of the stars in the Milky Way is important to understanding how the spiral galaxy was formed. In order to study the spectra, or light, from the red giant stars, Ness and her team made use of the Sloan Digital Sky Survey (SDSS), which measures a section of the sky using a spectroscope and multi-filter imaging. They then used the data they collected to create the age map of the Milky Way. "Measuring the individual ages of stars from their spectra and combining them with chemical information offers the most powerful constraints in the galaxy," Ness said. Determining The Age Of Red Giant Stars In The Milky Way The Milky Way is well-known for its characteristic spiral arms, which can be seen as a flattened disk consisting of stars and space dust. By sorting out the individual stars in the galaxy based on their age, researchers can get a better understanding on how the Milky Way evolved as a whole. The researchers were able to do this by examining the link between the age and mass of bright, red giant stars found in the galaxy. The life course of stars plays an important role in the relationship between the age and mass of red giant stars. Some stars tend to meet their demise in a violent explosion known as a supernova, while other stars do not even have enough mass to be able to produce such as cataclysmic event. Stars with lesser mass, such as the Solar System's own sun, live out the rest of their existence by swelling up and turning into red giants. These stars may have a larger radii compared to others, but they still only have a relatively low mass. Ness and her colleagues turned to the SDSS' Apache Point Observatory Galaxy Evolution Experiment (APOGEE) to help them find out the ages and locations of 70,000 individual red giants. However, to determine the age of a star, its mass has to be measured first, which is a feat that has eluded astronomers for years. The researchers then enlisted the aid of NASA scientists handling the Kepler space telescope. Despite being known more for discovering more than a thousand exoplanets over the years, Kepler also helped astronomers gather information on different stars. Marie Martig, a researcher from the Swinburne University of Technology in Australia and one of the co-authors of the Max Planck Institute study, carried out a separate research that measured the ages and masses of 2,000 stars that had been previously identified by Kepler scientists. Martig was able to determine the link between the age, mass and gas abundances of red giant stars after she compared the data collected from the earlier study with those gathered through APOGEE. Ness, Martig and the other researchers used this recently discovered relationship to identify the mass of the 70,000 stars that APOGEE scientists observed in the Milky Way's disk. Using the age map of the Milky Way, the scientists successfully charted how the spiral galaxy has developed throughout billions of years. They discovered that the ancient stars were the ones that first populated the galaxy and helped create the growing disk where following generations of stars eventually formed.


A paper published in the Monthly Notices of the Royal Astronomical Society finds evidence supporting the argument that the answer was energy feedback from quasars within the galaxies where stars are born. That is, intense radiation and galaxy-scale winds emitted by the quasars - the most luminous objects in the universe - heats up clouds of dust and gas. The heat prevents that material from cooling and forming more dense clouds, and eventually stars. "I would argue that this is the first convincing observational evidence of the presence of quasar feedback when the universe was only a quarter of its present age, when the cosmic star formation was most vigorous," said Tobias Marriage, an assistant professor in the university's Henry A. Rowland Department of Physics and Astronomy. While the findings appearing in the journal published by the Oxford University Press are not conclusive, Marriage said, the evidence is very compelling and has scientists excited. "It's like finding a smoking gun with fingerprints near the body, but not finding the bullet to match the gun," Marriage said. Specifically, investigators looked at information on 17,468 galaxies and found a tracer of energy known as the Sunyaev-Zel'dovich Effect. The phenomenon, named for two Russian physicists who predicted it nearly 50 years ago, appears when high-energy electrons disturb the Cosmic Microwave Background. The CMB is a pervasive sea of microwave radiation, a remnant from the superheated birth of the universe some 13.7 billion years ago. Devin Crichton, a Johns Hopkins graduate student and the paper's lead author, said the thermal energy levels were analyzed to see if they rise above predictions for what it would take to stop star formation. A large number of galaxies were studied to give the study statistical heft, he said. "For feedback to turn off star formation, it must be occurring broadly," said Crichton, one of five Johns Hopkins scientists who led the work conducted by a total of 23 investigators from 18 institutions. Most of the scientists are members of the Atacama Cosmology Telescope collaboration, named for one of the three instruments used in the study. To take the faint temperature measurements that would show the Sunyaev-Zel'dovich Effect, the scientists used information gathered by two ground-based telescopes and one receiver mounted on a space observatory. Using several instruments with different strengths in search of the SZ Effect is relatively new, Marriage said. "It's a pretty wild sort of thermometer," he said. Information gathered in the Sloan Digital Sky Survey by an optical telescope at the Apache Point Observatory in New Mexico was used to find the quasars. Thermal energy and evidence of the SZ Effect were found using information from the Atacama Cosmology Telescope, an instrument designed to study the CMB that stands in the Atacama Desert in northern Chile. To focus on the dust, investigators used data from the SPIRE, or Spectral and Photometric Imaging Receiver, on the Herschel Space Observatory. Galaxies reached their busiest star-making pace about 11 billion years ago, then slowed down. A team of astronomers more than three years ago estimated that the pace of star formation is one-thirtieth as fast as when it peaked. Scientists have puzzled for years over the question of what happened. The chief suspect has been the feedback process, Marriage said. Nadia L. Zakamska, an assistant professor in the Department of Physics and Astronomy at Johns Hopkins and one of the report's co-authors, said it is only in the last few years that evidence of this phenomenon from direct observation has been compiled. The SZ Effect, she said, is a novel approach to the subject, making clearer the full effect of galactic wind on the surrounding galaxy. "Unlike all other methods that are probing small clumps within the wind, the Sunyaev-Zeldovich Effect is sensitive to the bulk of the wind, the extremely hot plasma that's filling the volume of the wind and is completely undetectable using any other technique," she said. More information: Devin Crichton et al. Evidence for the Thermal Sunyaev-Zel'dovich Effect Associated with Quasar Feedback, Monthly Notices of the Royal Astronomical Society (2016). DOI: 10.1093/mnras/stw344


A new star family in the Milky Way's core was discovered by an astronomer from the Liverpool John Moores University, helping shed light on the beginnings of the galaxy. Published in a paper in the Monthly Notices of the Royal Astronomical Society, the discovery was made through the Apache Point Observatory Galactic Evolution Experiment, which was carried out using the Sloan Digital Sky Survey. LJMU is one of the institutions participating in the SDSS, one of the most ambitious sky surveys in the history of astronomy. The new star family was spotted as the researchers performed infrared observations of the Milky Way's core. According to the researchers they were highly similar to stars seen inside globular clusters, which were formed as the galaxy was formed. The researchers thought it was possible then that the new family of stars actually were previously part of globular clusters before they were destroyed as the Milky Way's core was formed. If this is so, globular clusters would be more numerous, about 10 times more their number in the galaxy's early years compared with their numbers today, pointing to the possibility that a significant portion of the old stars residing in the inner portions of the Milky Way may have come from globular clusters as well. "This is a very exciting finding that helps us address fascinating questions such as what is the nature of the stars in the inner regions of the Milky Way, how globular clusters formed and what role they played in the formation of the early Milky Way," said Ricardo Schiavon, lead researcher for the project. It's not always easy to observe the Milky Way, particularly the galaxy's core, because space dust is in the way. By making observations in infrared, APOGEE was able to take a closer look at the galaxy and see more clearly what is at the core of the Milky Way. According to Schiavon, APOGEE made it possible for the researchers to identify the chemical makeup of stars in the thousands, from which a sizable number appeared to be different from the majority of stars in the Milky Way's inner regions because they had high levels of nitrogen. The researchers are uncertain, but they suspect that the stars in question may have originated from the destruction of globular clusters at the time the galaxy was being formed. However, it is also possible that the stars they observed were byproducts of early star formation occurring as the Milky Way was formed. More studies will have to be conducted to test out their hypotheses. © 2017 Tech Times, All rights reserved. Do not reproduce without permission.


News Article | October 26, 2016
Site: spaceref.com

Everything we know about the formation of solar systems might be wrong, says University of Florida astronomy professor Jian Ge and his postdoc, Bo Ma. They've discovered the first "binary-binary" - two massive companions around one star in a close binary system, one so-called giant planet and one brown dwarf, or "failed star" The first, called MARVELS-7a, is 12 times the mass of Jupiter, while the second, MARVELS-7b, has 57 times the mass of Jupiter. Astronomers believe that planets in our solar system formed from a collapsed disk-like gaseous cloud, with our largest planet, Jupiter, buffered from smaller planets by the asteroid belt. In the new binary system, HD 87646, the two giant companions are close to the minimum mass for burning deuterium and hydrogen, meaning that they have accumulated far more dust and gas than what a typical collapsed disk-like gaseous cloud can provide. They were likely formed through another mechanism. The stability of the system despite such massive bodies in close proximity raises new questions about how protoplanetary disks form. The findings, which are now online, will be published in the November issue of the Astronomical Journal. HD 87646's primary star is 12 percent more massive than our sun, yet is only 22 astronomical units away from its secondary, a star about 10 percent less massive than our sun, roughly the distance between the sun and Uranus in our solar system. An astronomical unit is the mean distance between the center of the Earth and our sun, but in cosmic terms, is a relatively short distance. Within such a short distance, two giant companions are orbiting the primary star at about 0.1 and 1.5 astronomical units away. For such large companion objects to be stable so close together defies our current popular theories on how solar systems form. The planet-hunting Doppler instrument W.M. Keck Exoplanet Tracker, or KeckET, developed by a team led by Ge at the Sloan Digital Sky Survey telescope at Apache Point Observatory in New Mexico, is unusual in that it can simultaneously observe dozens of celestial bodies. Ge says this discovery would not have been possible without a multiple-object Doppler measurement capability such as KeckET to search for a large number of stars to discover a very rare system like this one. The survey of HD 87646 occurred in 2006 during the pilot survey of the Multi-object APO Radial Velocity Exoplanet Large-area Survey (MARVELS) of the SDSS-III program, and Ge led the MARVELS survey from 2008 to 2012. It has taken eight years of follow-up data collection through collaboration with over 30 astronomers at seven other telescopes around the world and careful data analysis, much of which was done by Bo Ma, to confirm what Ge calls a "very bizarre" finding. The team will continue to analyze data from the MARVELS survey. Please follow SpaceRef on Twitter and Like us on Facebook.


News Article | January 19, 2016
Site: news.yahoo.com

KISSIMMEE, Fla. — Many galaxies are LIERS, says Francesco Belfiore, a graduate student at the Kavli Institute for Cosmology at the University of Cambridge. He's not throwing shade at these objects, but rather trying to explain why new stars are no longer born inside them. Earth lies in a galaxy that is flush with new star birth. The Milky Way's spiral shape and blue color are both signs that baby stars are being made inside it. But in elliptical-shaped galaxies with more reddish hues, star birth has stopped, and scientists don't understand why. In trying to study the chemistry of these "dead" galaxies, researchers have found a different chemical fingerprint than the one that dominates star-forming galaxies. To describe what they were seeing, researchers came up with the acronym LINER, which stands for "low-ionization nuclear emission-line region." Belfiore's explanation of the name is more direct: "The reason why we use this acronym is because we don't know what they are," he said. [Gallery: 65 All-Time Great Galaxy Hits] More specifically, scientists don't know what's creating the "LINER" chemical signature in the dead galaxies, and whether it might help explain why they stopped forming stars. Now, new observations by Belfiore and colleagues have added another twist to this LINER mystery: rather than coming from the black hole at the center of the dead galaxy, as researchers previously thought, the signature can be found throughout the galaxies, all the way out to their fringes. According to Belfiore, this new finding that means the "N" in LINER (which stood for "nuclear," referring to the center of the galaxy) should be removed, and these galaxies should be called "LIERs." Belfiore spoke about the new findings on Jan. 8 during a press briefing here at the 227th meeting of the American Astronomical Society. By itself, the new information doesn't answer the big question of why star formation has stopped in those galaxies, but it may resolve a seemingly contradictory observation found in many previous studies: that select patches of living galaxies also exhibit this LINER/LIER chemical fingerprint. In other words, it may help scientists understand what turns living galaxies into LIERs. What does a galactic LIER look like? These "dead" galaxies are different from star-forming galaxies in many ways. They tend to be redder in color, because blue stars have shorter lives than red stars, so for the most part, the blue stars have all died out in the LIER galaxies. The stellar nurseries in star-forming galaxies like the Milky Way emit large amounts of light, and appear as bright, glowing beacons. These are also missing from images of LIER galaxies, which have a more diffuse glow. Dead galaxies are also shaped differently. They're more often elliptical, like an American football, instead of a flat, circular spiral. Without star birth, these galaxies can't develop the massive arms that wrap around the centers of star-forming galaxies like the Milky Way. Once again, scientists don't fully understand why the stop of star birth also means a change in shape for the galaxy, but there is a theory that many elliptical galaxies are created when two or more galaxies collide and merge together. Perhaps that process somehow shuts off star birth, scientists have suggested. These red, dead, football-shaped galaxies contain a cocktail of chemicals that's different from that of their living counterparts. Previous observations of elliptical galaxies have been limited in their resolution, and suggested that the LINER gas signature was coming from the center of these galaxies. This is important because, at the center of most (if not all) large galaxies is a supermassive black hole. According to Belfiore, the leading theory for why dead galaxies have this LIER signature is because of activity near the black hole at the center of the galaxy. This idea is bolstered by a third category of galaxies called active galactic nuclei, or AGNs. The black holes at the center of AGNs are extremely active, meaning they have lots of material falling into them, producing jets of material that spew out into space, and radiating an incredible amount of light. AGNs also have a chemical signature that's different from that of LINER galaxies and star-forming galaxies, Belfiore noted in his talk. Some scientists suspect that LINER galaxies are simply weaker examples of AGNs, where a lower amount of activity around the black hole produces this unique chemical fingerprint, he said. But the new observations presented by Belfiore have allowed scientists to look at the source of the LINER emission at a higher resolution, and revealed that they are not limited to the galaxy's center. Using the Sloan Digital Sky Survey (SDSS), a 2.5-meter (8.2 feet) telescope in New Mexico, as part of a project called MaNGA (Mapping Nearby Galaxies at Apache Point Observatory), Belfiore and colleagues found that, in some cases, LIER signatures can be found emanating from throughout a LINER galaxy, or from separate locations near the outskirts. The new results indicate that the process creating the LINER signature is, most likely, something that can occur throughout the galaxy, Belfiore said. [Gallery: Black Holes of the Universe] Living galaxies can be LIERS, too Belfiore and his collaborators theorize that the LIER chemical fingerprint might be coming from older stars as they reach the twilight hours of their lives. In that stage of life, many stars shed their outer layers, and it may be the chemical signature of this dispelled stellar material that is being detected, Belfiore explained. This would explain why the LIER chemical signature is seen in some galaxies where star formation is still happening, Belfiore told Space.com in an email. In many spiral galaxies, star formation does not shut off suddenly, but gradually. Some spiral galaxies develop regions (often near their centers) where star formation stops, and in those cases, it is possible for scientists to see a LIER emission from the "dead" region of the galaxy. Of course, dying stars are present even where new ones are forming, but the LIER emission is "always fainter than the emission due to star formation," Belfiore told Space.com in an email. Hence, in those living galaxies, the weak LIER emission would be swamped by photons from the star-forming regions and would go undetected by telescopes.   In other words, Belfiore said, it's possible that most galaxies are LIERs.  The idea that LINER galaxies may actually be LIERs — that this chemical signature is not coming from the galactic center but from another source, such as dying stars throughout the galaxy — has been building for some years, Belfiore told Space.com. "Although most astronomers not directly working on this topic would assume that LINERs are weak active galactic nuclei, a paradigm shift has been happening slowly for several years now," he said. He mentioned that some astronomers remain highly skeptical of the idea, but the new SDSS observations may change that. "Compared to previous studies, the new MaNGA data allows, for the first time, a direct test of the stellar hypothesis for LIER emission in a well-defined large sample of galaxies, covering (crucially) both spirals and ellipticals," Belfiore said. "It is the weight of this very direct evidence and its statistical significance that I feel is most compelling about the SDSS MaNGA result." Belfiore said he and his colleagues are preparing to submit their results for publication. Copyright 2016 SPACE.com, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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