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Excerpt from hubblesite.org
Scientists using NASA's Hubble Space Telescope have discovered that the immense halo of gas enveloping the Andromeda galaxy, our nearest massive galactic neighbor, is about six times larger and 1,000 times more massive than previously measured. The dark, nearly invisible halo stretches about a million light-years from its host galaxy, halfway to our own Milky Way galaxy. This finding promises to tell astronomers more about the evolution and structure of majestic giant spirals, one of the most common types of galaxies in the universe.
"Halos are the gaseous atmospheres of galaxies. The properties of these gaseous halos control the rate at which stars form in galaxies according to models of galaxy formation," explained the lead investigator, Nicolas Lehner of the University of Notre Dame, Indiana. The gargantuan halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of a hot, diffuse gas. If it could be viewed with the naked eye, the halo would be 100 times the diameter of the full Moon in the sky. This is equivalent to the patch of sky covered by two basketballs held at arm's length.
The Andromeda galaxy, also known as M31, lies 2.5 million light-years away and looks like a faint spindle, about 6 times the diameter of the full Moon. It is considered a near-twin to the Milky Way galaxy.
Because the gas in Andromeda's halo is dark, the team looked at bright background objects through the gas and observed how the light changed. This is a bit like looking at a glowing light at the bottom of a pool at night. The ideal background "lights" for such a study are quasars, which are very distant bright cores of active galaxies powered by black holes. The team used 18 quasars residing far behind Andromeda to probe how material is distributed well beyond the visible disk of the galaxy. Their findings were published in the May 10, 2015, edition of The Astrophysical Journal.
Earlier research from Hubble's Cosmic Origins Spectrograph (COS)-Halos program studied 44 distant galaxies and found halos like Andromeda's, but never before has such a massive halo been seen in a neighboring galaxy. Because the previously studied galaxies were much farther away, they appeared much smaller on the sky. Only one quasar could be detected behind each faraway galaxy, providing only one light anchor point to map their halo size and structure. With its close proximity to Earth and its correspondingly large footprint on the sky, Andromeda provides a far more extensive sampling of a lot of background quasars.
"As the light from the quasars travels toward Hubble, the halo's gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range," explains co-investigator J. Christopher Howk, also of Notre Dame. "By measuring the dip in brightness in that range, we can tell how much halo gas from M31 there is between us and that quasar."
The scientists used Hubble's unique capability to study the ultraviolet light from the quasars. Ultraviolet light is absorbed by Earth's atmosphere, which makes it difficult to observe with a ground-based telescope. The team drew from about 5 years' worth of observations stored in the Hubble data archive to conduct this research. Many previous Hubble campaigns have used quasars to study gas much farther away than — but in the general direction of — Andromeda, so a treasure trove of data already existed.
But where did the giant halo come from? Large-scale simulations of galaxies suggest that the halo formed at the same time as the rest of Andromeda. The team also determined that it is enriched in elements much heavier than hydrogen and helium, and the only way to get these heavy elements is from exploding stars called supernovae. The supernovae erupt in Andromeda's star-filled disk and violently blow these heavier elements far out into space. Over Andromeda's lifetime, nearly half of all the heavy elements made by its stars have been expelled far beyond the galaxy's 200,000-light-year-diameter stellar disk.
What does this mean for our own galaxy? Because we live inside the Milky Way, scientists cannot determine whether or not such an equally massive and extended halo exists around our galaxy. It's a case of not being able to see the forest for the trees. If the Milky Way does possess a similarly huge halo, the two galaxies' halos may be nearly touching already and quiescently merging long before the two massive galaxies collide. Hubble observations indicate that the Andromeda and Milky Way galaxies will merge to form a giant elliptical galaxy beginning about 4 billion years from now.
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| Astronomers have discovered a baby blue galaxy that is the furthest away in distance and time - 13.1 billion years - that they’ve ever seen. Photo: Pascal Oesch and Ivelina Momcheva, NASA, European Space Agency via AP |
Excerpt from smh.com.au
A team of astronomers peering deep into the heavens have discovered the earliest, most distant galaxy yet, just 670 million years after the Big Bang.
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| Close-up of the blue galaxy |
"We're actually looking back through 95 per cent of all time to see this galaxy," said study co-author Garth Illingworth, an astronomer at the University of California, Santa Cruz.
"It's really a galaxy in its infancy ... when the universe was in its infancy."
Capturing an image from a far-off light source is like looking back in time. When we look at the sun, we're seeing a snapshot of what it looked like eight minutes ago.
The same principle applies for the light coming from the galaxy known as EGS-zs8-1. We are seeing this distant galaxy as it existed roughly 13.1 billion years ago.
EGS-zs8-1 is so far away that the light coming from it is exceedingly faint. And yet, compared with other distant galaxies, it is surprisingly active and bright, forming stars at roughly 80 times the rate the Milky Way does today.
This precocious little galaxy has built up the mass equivalent to about 8 billion suns, more than 15 per cent of the mass of the Milky Way, even though it appears to have been in existence for a mere fraction of the Milky Way's more than 13 billion years.
"If it was a galaxy near the Milky Way [today], it would be this vivid blue colour, just because it's forming so many stars," Illingworth said.
One of the many challenges with looking for such faint galaxies is that it's hard to tell if they're bright and far, or dim and near. Astronomers can usually figure out which it is by measuring how much that distant starlight gets stretched, "redshifted", from higher-energy light such as ultraviolet down to optical and then infrared wavelengths. The universe is expanding faster and faster, so the further away a galaxy is, the faster it's going, and the more stretched, or "redder", those wavelengths of light will be.
The astronomers studied the faint light from this galaxy using NASA's Hubble and Spitzer space telescopes. But EGS-zs8-1 seemed to be too bright to be coming from the vast distances that the Hubble data suggested.
To narrow in, they used the MOSFIRE infrared spectrograph at the Keck I telescope in Hawaii to search for a particularly reliable fingerprint of hydrogen in the starlight known as the Lyman-alpha line. This fingerprint lies in the ultraviolet part of the light spectrum, but has been shifted to redder, longer wavelengths over the vast distance between the galaxy and Earth.
It's a dependable line on which to base redshift (and distance) estimates, Illingworth said - and with that settled, the team could put constraints on the star mass, star formation rate and formation epoch of this galaxy.
The telltale Lyman-alpha line also reveals the process through which the universe's haze of neutral hydrogen cleared up, a period called the epoch of reionisation. As stars formed and galaxies grew, their ultraviolet radiation eventually ionised the hydrogen and ended the "dark ages" of the cosmos.
Early galaxies-such as EGS-zs8-1 - are "probably the source of ultraviolet radiation that ionised the whole universe", Illingworth said.
Scientists have looked for the Lyman-alpha line in other distant galaxies and come up empty, which might mean that their light was still being blocked by a haze of neutral hydrogen that had not been ionised yet.
But it's hard to say with just isolated examples, Illingworth pointed out. If scientists can survey many galaxies from different points in the universe's very early history, they can have a better sense of how reionisation may have progressed.
"We're trying to understand how many galaxies do have this line - and that gives us some measure of when the universe itself was reionised," Illingworth said.
"One [galaxy] is interesting, but it's when you have 50 that you can really say something about what galaxies were really like then."
As astronomers push the limits of current telescopes and await the completion of NASA's James Webb Space Telescope, set for launch in 2018, scientists may soon find more of these galaxies even closer to the birth of the universe than this new record breaker.
"You don't get to be record holder very long in this business," Illingworth said, "which is good because ultimately we are trying to learn about the universe. So more is better."
Excerpt from huffingtonpost.comIntroductionWhy is it so hard to find ET? After 50 years of searching, the SETI project has so far found nothing. In the latest development, on April 14, 2015 Penn State researchers announced that after searching through...
Excerpt from nytimes.com
Leapfrogging backward in time to when the universe was apparently feeling its oats, a group of astronomers reported Tuesday that they had measured a bona fide distance to one of the farthest and thus earliest galaxies known.
The galaxy, more than a few billion light-years on the other side of the northern constellation Boötes, is one of the most massive and brightest in the early universe and goes by the name of EGS-zs8-1.
It flowered into stardom only 670 million years after the Big Bang.
The light from that galaxy has taken 13 billion years to reach telescopes on Earth. By now, however, since the universe has continued to expand during that time, the galaxy is about 30 billion light-years away, according to standard cosmological calculations.
The new measurements allow astronomers to see the galaxy in its infancy. Despite its relative youth, however, it is already about one-sixth as massive as the Milky Way, which is 10 billion years old. And it is getting bigger, making stars 80 times faster than the Milky Way is making them today. The discovery was reported in The Astrophysical Journal by Pascal Oesch of Yale University and his colleagues.
By the rules of the expanding universe, the farther away a galaxy is, the faster it is retreating from us, measured by the “redshift” of its light being broadened to longer wavelengths, the way an ambulance siren seems to lower its pitch as it goes by.
In the past few years, as astronomers have raced one another into the past with instruments like the Hubble Space Telescope, galaxies have been found that appear even more distant. Those measurements, however, were estimates based on the colors of the objects — so-called photometric redshifts.
The new galaxy stuck out in a survey of distant galaxies by the Hubble and Spitzer space telescopes known as Candels, for Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. Its redshift was precisely measured with a powerful spectrograph known as Mosfire — Multi-Object Spectrometer for Infrared Exploration — on Keck 1, one of a pair of 10-meter-diameter telescopes on Mauna Kea in Hawaii. That makes it the highest redshift confirmed in this way, said Garth Illingworth, of the University of California, Santa Cruz, one of the astronomers in the study.
How galaxies were able to form and grow so rapidly after the lights came on in the universe is a mystery that will be addressed by a coming generation of instruments like the James Webb Space Telescope and the Thirty Meter Telescope, a goliath planned for Mauna Kea, already home to a dozen telescopes.
Recently, however, construction of the Thirty Meter Telescope, a $1.4 billion project, has been halted by protests by Hawaii residents who feel their mountain has been abused. An echo of that controversy appears in the new paper, in which Dr. Oesch and his colleagues write: “The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.”
In this image, the magenta color indicates the mysterious glow detected by NASA's NuSTAR space telescope.Excerpt from huffingtonpost.com A mysterious glow has been observed at the center of the Milky Way, and scientists are struggling to figure o...
Excerpt from huffingtonpost.comIntroduction 65 years ago, in 1950, while having lunch with colleagues Edward Teller and Herbert York, Nobel physicist Enrico Fermi suddenly blurted out, "Where is everybody?" His question is now known as Fermi's p...
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The Hooker 100-inch reflecting telescope at the Mount Wilson Observatory, just outside Los Angeles. Edwin Hubble's chair, on an elevating platform, is visible at left. A view from this scope first told Hubble our galaxy isn't the only one. Courtesy of The Observatories of the Carnegie Institution for Science Collection at the Huntington Library, San Marino, Calif. |
Excerpt from hnpr.org
The Hubble Space Telescope this week celebrates 25 years in Earth's orbit. In that time the telescope has studied distant galaxies, star nurseries, planets in our solar system and planets orbiting other stars.
But, even with all that, you could argue that the astronomer for whom the telescope is named made even more important discoveries — with far less sophisticated equipment.
A young Edwin Hubble at Mount Wilson's 100-inch telescope circa 1922, ready to make history.
Edwin Hubble Papers/Courtesy of Huntington Library, San Marino, Calif.
In the 1920s, Edwin Hubble was working with the 100-inch Hooker telescope on Mount Wilson, just outside Los Angeles. At the time, it was the largest telescope in the world.
On a chilly evening, I climb up to the dome of that telescope with operator Nik Arkimovich and ask him to show me where Hubble would sit when he was using the telescope. Arkimovich points to a platform near the top of the telescope frame.
"He's got an eyepiece with crosshairs on it," Arkimovich explains. The telescope has gears and motors that let it track a star as it moves across the sky. "He's got a paddle that allows him to make minor adjustments. And his job is to keep the star in the crosshairs for maybe eight hours."
"It's certainly much, much easier today," says John Mulchaey, acting director of the observatories at Carnegie Institution of Science. "Now we sit in control rooms. The telescopes operate brilliantly on their own, so we don't have to worry about tracking and things like this."
The headquarters of the Carnegie observatories is at the foot of Mount Wilson, in the city of Pasadena. It's where Hubble worked during the day.
A century's worth of plates are stored here in the basement. Mulchaey opens a large steel door and ushers me into a room filled with dozens of file cabinets.
"Why don't we go take a look at Hubble's famous Andromeda plates," Mulchaey suggests.
The plates are famous for a reason: They completely changed our view of the universe. Mulchaey points to a plate mounted on a light stand.
"This is a rare treat for you," he says. "This plate doesn't see the light of day very often."
This glass side of a photographic plate shows where Hubble marked novas. The red VAR! in the upper right corner marks his discovery of the first Cepheid variable star — a star that told him the Andromeda galaxy isn't part of our Milky Way.
Courtesy of the Carnegie Observatories
The plate shows the spiral shape of the Andromeda galaxy. Hubble was looking for exploding stars called novas in Andromeda. Hubble marked these on the plate with the letter "N."
"The really interesting thing here," Mulchaey says, "is there's one with the N crossed out in red — and he's changed the N to VAR with an exclamation point."
Hubble had realized that what he was seeing wasn't a nova. VAR stands for a type of star known as a Cepheid variable. It's a kind of star that allows you to make an accurate determination of how far away something is. This Cepheid variable showed that the Andromeda galaxy isn't a part of our galaxy.
At the time, most people thought the Milky Way was it — the only galaxy in existence.
"And what this really shows is that the universe is much, much bigger than anybody realizes," Mulchaey says.
It was another blow to our human conceit that we are the center of the universe.
Hubble went on to use the Mount Wilson telescope to show the universe was expanding, a discovery so astonishing that Hubble had a hard time believing it himself.
If Hubble could make such important discoveries with century-old equipment, it makes you wonder what he might have turned up if he'd had a chance to use the space telescope that bears his name.
Excerpt from thespacereporter.com
According to a NASA statement, the agency’s Spitzer Space Telescope has taken part in the discovery of one of the most distant exoplanets yet found. Spitzer observations were combined with data from the Polish Optical Gravitational Lensing Experiment’s Warsaw Telescope, part of the Las Campanas Observatory in Chile. The newly found exoplanet is approximately 13,000 light-years from Earth, and could yield new clues as to the distribution of planets throughout the Milky Way.
The Warsaw Telescope gathers data through the phenomenon known as microlensing, which occurs when a star passes in front of another, more distant star as seen from Earth’s vantage point. The gravity of the nearer star magnifies and intensifies the distant star’s light; any planets orbiting the distant star appear as small disruptions in the magnification. So far, the microlensing methods has identified around 30 exoplanets, the most distant of which is around 25,000 light-years away.
However, the microlensing method cannot always show how far away are the more distant stars and their planets; the distances to about half of the exoplanets found with microlensing cannot be ascertained. Fortunately, Spitzer is able to help. Located 128 million miles from Earth, Spitzer is able to observe a microlensing event at a different time from the Warsaw Telescope, a method called parallax. In the case of the newly discovered exoplanet, the microlensing event was longer than norman, lasting 150 days.
Spitzer observed the event 20 days earlier than Warsaw. This time delay allowed the distance to the newly found planet to be calculated. With the distance, the planet’s mass, approximately half that of Jupiter, also was determined.
“We’ve mainly explored our own solar neighborhood so far,” said Sebastiano Calchi Novati of NASA’s Exoplanet Science Institute at the California Institute of Technology. “Now we can use these single lenses to do statistics on planets as a whole and learn about their distribution in the galaxy.”
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| WHAT’S FOR DINNER? Signals detected by the Parkes radio telescope (pictured) suggest that intelligent life in the universe has a penchant for leftovers. |
Excerpt from sciencenews.org
Mysterious radio signals detected by the Parkes telescope appear to come from an advanced civilization in the Milky Way.
Unfortunately, it’s the one civilization we already know about.
Microwave ovens opened before they’re done cooking have been muddling the hunt for far more distant radio signals, researchers report online April 9 at arXiv.org. Astronomers have had to contend with enigmatic flares dubbed “perytons” ever since discovering equally puzzling fast radio bursts, or FRBs (SN: 8/9/14, p. 22), in 2007. Perytons and FRBs are quite similar, except that astronomers realized that perytons originate on Earth, possibly from some meteorological phenomenon, while FRBs come from other galaxies.
Three perytons in January coincided with independently detected blasts of 2.4 gigahertz radio waves — the same frequency that microwave ovens use to heat food. So researchers at the Parkes telescope in Australia spent weeks heating mugs of water while moving the massive radio dish around the sky, trying to re-create the phenomenon. Finally, researchers tried opening the oven door mid-cooking instead of letting the timer run out. Suddenly, perytons started showing up in the data.
The source of the galactic FRBs remain an intriguing mystery. Astronomers suspect they have something to do with imploding neutron stars or eruptions on magnetars. At this point, however, they might want to consider extraterrestrials nuking frozen pizzas.
Excerpt from stgist.com
The sun, or the nearest star from Earth, was formed around 5 billion years after the Milky Way galaxy’s peak production of stars, a new research published in the Astrophysical Journal.
It’s like traveling back in time. Researchers from Texas A&M University in College Station, headed by astronomer Casey Papovich, were able to see the undepicted past of our own galaxy by observing similar regions located billions of light years away from us.
The “baby boom” happened around 10 billion years ago, the new study published in Astrophysical Journal revealed. At that time, the Milky Way galaxy was producing 30 times more stars than today. If so, then our solar system’s 4.6 billion years old Sun was formed more than 5 billion years after the production peak.
Sun’s late formation allowed the solar system we know today to produce planets with heavier elements. Scientists say elements heavier than hydrogen and helium became more abundant in “late to the game systems”, and the death of massive stars that were formed before the Sun had provided materials needed to form planets, including Earth and its complex life forms.
Scientists scanned through a collection of more than 24,000 galaxies, and took at least 2,000 snapshots of galaxies that closely resemble our own. The census has provided the most complete picture yet of how spiral galaxies similar to Milky Way form in the universe.
According to Mr. Papovich, the lead author of the study who also serves as an associate professor in the Department of Physics and Astronomy at A&M University in Texas, they know where to find traces by analyzing how galaxies like our own were formed.
Papovich said his team has provided a data that clearly show the rapid phase of growth around 9 to 10 billion years ago, or at least more than 5 billion years after our Sun formed. They also found the connection between the size of the galaxy, and the formation of stars.
Surprisingly, the robust collection of distant galaxies confirmed that stars formed inside the Milky Way, instead of forming in other smaller baby galaxies that later merged to join the system.
In separate studies, scientists were able to confirm that our own solar system is wetter than thought. Beyond Earth, celestial objects like Jupiter’s Galilean moons Europa and Ganymede, Saturn’s Enceladus, and even the dwarf planet Ceres in the asteroid belt, are hosting fluid slightly similar to Earth’s — and it is highly possible that the Sun’s late formation allowed this setup to exist.
Papovich who worked alongside Texas A&M postdoctoral researchers Vithal Tilvi and Ryan Quadri, were joined by at least two dozen astronomers from other countries. The research is published April 9th entitled “ZFOURGE/CANDELS: ON THE EVOLUTION OF M* GALAXY PROGENITORS FROM z = 3 TO 0.5*.” The research was funded by NASA
Excerpt from huffingtonpost.comWhen astronomers began studying other solar systems in the Milky Way galaxy back in the 1990s, they noticed something peculiar: most of these systems have big planets that circle their host stars in tight orbits, a fin...
Excerpt from esbtrib.com
Imagine the distinct possibility that among the billions of stars located in our vast Milky Way Galaxy, there might be a habitable zone where water probably exists and life as we know it as well.
Scientists have studied more than 150 exoplanetary systems with more than one planet circling the host star, thru the Kepler space telescope of NASA.
The new research, published in Monthly Notices of the Royal Astronomical Society, revealed the thousands of planets orbiting stars in our Milky Way galaxy. Researchers were able to compute that the stars in the Milky Way have one to three planets orbiting the habitable zone.
PhD student in the research group Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen, Steffen Kjær Jacobsen said, “In these 31 planetary systems located near the habitable zone, our calculations showed that there was an average of two planets in the habitable zone. According to statistics and the indications we have, a good share of the planets in the habitable zone will be solid planets where there might be liquid water and where life could exist.”
He added, “In 124 of the planetary systems, the Titius-Bode law fit with the position of the planets as good as or better than our own solar system. Using Titus-Bode’s law we tried to predict where there could be more planets further out in the planetary systems. But we only made calculations for planets where there is a good chance you can see them with the Kepler satellite,”
Researchers urged other scientist to look further into the records from the Kepler satellite again for more signs of the planetary systems they have predicted, as a number of them should be quite apparent.
Will this change our perception of religion? That we are not God’s only living creation?
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