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  • richardmitnick 11:25 am on August 30, 2019 Permalink | Reply
    Tags: "Life on alien worlds could be more diverse than on Earth", , Astronomy magazine, , , ,   

    From Astronomy Magazine: “Life on alien worlds could be more diverse than on Earth” 

    Astronomy magazine

    From Astronomy Magazine

    August 23, 2019
    Mara Johnson-Groh

    Earth is the only place in the universe where we know life exists. But with billions of other star systems out there, it might not be the best place for life.

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    When you stack up the most promising recent exoplanet finds, as illustrated here, it becomes clear none is Earth’s true twin. But even more habitable worlds may be out there waiting to be found. NASA/Ames/JPL-Caltech

    Earth is the only place in the universe where we know life exists. But with billions of other star systems out there, it might not be the best place for life. In a new study [Goldschmidt2019 Barcelona], astronomers modeled the potential for life on other watery planets and found some conditions that can create oceans maximized for habitability.

    The model suggests that watery planets with dense atmospheres, continents, and long days — slowly rotating planets that is — were most conducive to life. These conditions stimulate ocean circulation, which brings nutrients from the depths to the surface where it’s available for biologic activity.

    “The research shows us that conditions on some exoplanets with favorable ocean circulation patterns could be better suited to support life that is more abundant or more active than life on Earth,” Stephanie Olson, a University of Chicago researcher who lead the new study, said in a press release.

    To date, over 4,000 exoplanets have been confirmed, and a handful of those worlds orbit at a safe enough distance from their host star to have liquid water on the surface. These habitable zone planets are at the forefront of the search for alien life and the new research, presented Friday at the Goldschmidt Conference in Barcelona, Spain, will help astronomers narrow down that search.

    Previous studies looking at exoplanet habitability had largely neglected the role that oceans play in regulating global climate and heat transportation. The researchers focused in on this niche, using a computer model to compare different combinations of climates and ocean habitats that could exist on exoplanets across the galaxy. The study aimed to look for things like upwelling, a type of ocean circulation driven by wind.

    Upwelling and ocean circulation have long played a major role in sustaining life in Earth’s oceans. And since the oceans and atmospheres are interlinked, the evolution of life in the oceans has been reflected in certain chemical changes in the atmosphere. It’s unlikely astronomers will directly see life on other planets, but seeing these so-called biosignatures in exoplanet atmospheres could be possible with the next generation of telescopes. Ultimately, this research will help scientists select the best candidates out of the growing census of exoplanets for follow up study.

    “One of the things we don’t really understand particularly well in the exoplanet community is how oceans on some of these planets might be working,” said Chris Reinhard, professor at the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, who was not involved in the new study. “Part of that is because we haven’t had the computer models or people working on them to really explore these things, so there’s a lot to learn. This is a really huge step in the right direction to figure some of those things out.”

    See the full article here .


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  • richardmitnick 10:03 am on July 31, 2019 Permalink | Reply
    Tags: "Astronomers Once Watched a Star Turn Directly Into a Black Hole", , Astronomy magazine, , , , Curiosity News   

    From Astronomy Magazine via Curiosity: “Astronomers Once Watched a Star Turn Directly Into a Black Hole” 

    Astronomy magazine

    From Astronomy Magazine

    via

    2
    Curiosity

    2
    Curiosity

    Most dying stars go out with a bang — a supernova, more specifically. But scientists recently observed a star that went out with a whisper, skipping the supernova phase and going straight into a black hole. The discovery not only teaches us more about stars, but it could also uncover the mysteries behind some of the universe’s most massive black holes.

    Go Directly to Black Hole, Do Not Pass Go

    Scientists at Ohio State University have, for some time, been watching a galaxy 22 million light-years away. That galaxy, called NGC 6946 and nicknamed the “Fireworks Galaxy,” sees a large number of supernovae that scientists observe via the help of the Large Binocular Telescope (LBT).

    In 2009, scientists noticed that one star, N6946-BH1, was beginning to weaken. In 2015, it disappeared — no big flash, no epic supernova. The scientists concluded that it had instead become a black hole, something that scientists usually believe can only happen after a supernova. Scientists aptly called this unusual trajectory a “massive fail,” and published their results in the Monthly Notices of the Royal Astronomical Society.

    3
    Star N6946-BH1 before and after it vanished out of sight by imploding to form a black hole. Image: NASA, ESA, and C. Kochanek (OSU).

    “The typical view is that a star can form a black hole only after it goes supernova,” said Ohio State astronomy professor and study researcher Christopher Kochanek in the press release. “If a star can fall short of a supernova and still make a black hole, that would help explain why we don’t see supernovae from the most massive stars.”

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    The doomed star, named N6946-BH1, was 25 times as massive as our sun. It began to brighten weakly in 2009. But, by 2015, it appeared to have winked out of existence. By a careful process of elimination, based on observations researchers eventually concluded that the star must have become a black hole. This may be the fate for extremely massive stars in the universe. Image: NASA, ESA, and P. Jeffries (STScI)

    What This Could Tell Us About Black Holes

    Scientists still don’t know how often stars go through massive fails, but researcher Scott Adams predicts that it occurs in about 10 to 30 percent of massive stars.

    The findings could help explain the origins of very massive black holes, since they may be easier to form if no supernova is necessary. That’s because the explosion of the supernova ends up blasting out the star’s outer layers, leaving behind less mass to create a black hole. If no supernova was involved, more of the star’s mass would be available to transform into a more massive black hole.

    See the full article here .


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  • richardmitnick 7:53 am on July 26, 2019 Permalink | Reply
    Tags: , Astronomy magazine, , , , , Dark Stars,   

    From Astronomy Magazine- “Dark stars: The seeds of supermassive black holes?” 

    Astronomy magazine

    From Astronomy Magazine

    July 19, 2019
    Jake Parks

    The early universe was a very different place than it is now. But it may have been the perfect environment for a strange class of giant, puffy stars that used dark matter as fuel.

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    Dark matter annihilations may have fueled some of the universe’s first stars, allowing them to grow into giant, puffy clouds that are millions of times the mass and billions of times the brightness of the Sun. Astronomy: Roen Kelly after NSF.

    Powered by dark matter, dark stars are hypothetical objects that may have inhabited the early universe. If they existed, these mysterious beasts would not only have been the first stars to form in the cosmos, they also might explain how supermassive black holes got their start.

    Fueled by dark matter

    2
    Astronomy: Roen Kelly

    Normal stars all power themselves in the same way: nuclear fusion. Stars are so massive that they’re constantly on the verge of collapsing in on themselves. But as gravity squeezes a star, it generates so much heat in the star’s core that it smooshes the atoms together, releasing energy. This energy provides just enough outward pressure to precisely counterbalance a star’s gravitational collapse.

    But for dark stars, the story’s a little different.

    Theories suggest that dark stars would be mostly made from the same material as normal stars — namely, hydrogen and helium. But because these hypothetical dark stars would have formed in the early universe, when the cosmos was a lot denser, they also likely contain a small but significant amount of dark matter in the form of Weakly Interacting Massive Particles (WIMPs) — a leading dark matter candidate.

    These WIMPs are thought to serve as their own antimatter particles, they can annihilate with one another, producing pure energy. Within a dark star, these extremely powerful WIMP annihilations could offer enough outward pressure to prevent the star’s collapse without the need for core fusion.

    According to dark star researcher Katherine Freese, the Kodosky Endowed Chair of Physics at UT-Austin, WIMPs only make up about 0.1 percent of a dark star’s total mass. But just this tiny bit of WIMP fuel could keep a dark star chugging along for millions or even billions of years.

    3
    Astronomy: Roen Kelly

    What did dark stars look like?

    Dark stars don’t just behave differently than normal stars. They also look different.

    Because dark stars don’t rely on core fusion to stave off gravitational collapse, they’re not extremely compressed like normal stars. Instead, dark stars are likely giant, puffy clouds that shine extremely bright. Due to their bloated nature, Freese says, dark stars could even reach diameters of up to about 10 astronomical units (AU), where 1 AU is the average Earth-Sun distance of 93 million miles (150 million kilometers).

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    Astronomy: Roen Kelly

    “They can keep growing as long as there is dark matter fuel,” Freese told Astronomy. “We’ve assumed they can get up to 10 million times the mass of the Sun and 10 billion times as bright as the Sun, but we don’t really know. There is no cutoff in principle.”

    Searching for dark stars

    One of the hurdles to proving dark stars truly exist, though, is that these ironically bright objects depend on dark-matter annihilations to survive. However, such annihilations primarily occurred in the very early universe, when dark-matter particles were sharing close quarters. So, in order to spot ancient dark stars, we need telescopes capable of peering back to the extremely distant past.

    Fortunately, according to Freese, the upcoming James Webb Space Telescope should be able to spot dark stars — as long as we know what to look for.

    NASA/ESA/CSA Webb Telescope annotated

    “They would look completely different from hot stars,” Freese told Astronomy. “Dark stars are cool [17,500 °F (9,700 °C)]. So, they would look more like the Sun in terms of frequency of light, even though they’re much brighter. That combination of cool and bright is hard to explain with other objects.”

    “It is an exciting prospect that an entirely new type of star may be discovered in these upcoming data,” Freese and her colleagues wrote in a review paper.

    Seeding supermassive black holes

    If researchers are able to uncover evidence for the existence of dark stars, it would change how we think about the early stages of the universe. Darks stars would swiftly become the top candidates for the first generation of stars, which formed some 200 million years after the Big Bang.

    But dark stars might also explain one of the most nagging questions in cosmology: How did supermassive black holes first form?

    “If a dark star of a million solar masses were found [by James Webb] from very early on, it’s pretty clear that such an object would end up as a big black hole,” Freese says. “Then these could merge together to make supermassive black holes. A very reasonable scenario!”

    See the full article here .


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  • richardmitnick 8:22 am on June 21, 2019 Permalink | Reply
    Tags: , Astronomy magazine, , , , Dark matter may have punched a hole in the Milky Way   

    From Astronomy Magazine: “Dark matter may have punched a hole in the Milky Way” 

    Astronomy magazine

    From Astronomy Magazine

    June 12, 2019
    Jake Parks

    A wrecking ball of dark matter 5 million times the mass of the Sun may be the best explanation for a disrupted stream of stars.

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    An artist’s rendition shows the dark matter halo (blue) that astronomers believe surrounds the Milky Way. ESO/L. Calçada

    A massive clump of dark matter may have plowed through a conga line of stars streaming around the Milky Way, according to new research presented Tuesday at the 234th Meeting of the American Astronomical Society.

    The research, led by Ana Bonaca of the Harvard-Smithsonian Center for Astrophysics, reveals a curious abnormality in an otherwise uniform stream of stars orbiting in the Milky Way’s outer halo. Specifically, the researchers found an odd kink within the stream that they think was caused by a “close encounter with a massive and dense perturber,” according to the presentation’s abstract.

    Because there are no obvious culprits made of normal matter that fit the bill, the researchers believe the intervening object could be a 5 million-solar-mass blob of dark matter that ripped through the stream at over 500,000 miles (800,000 kilometers) per hour roughly half a billion years ago.

    Although this theory is far from confirmed, the unique observation does open the door to the possibility of using stellar streams like this one to constrain the properties of dark matter in the Milky Way. For example, if it was truly dark matter that tore through this stellar stream, Bonaca says it would suggest dark matter is “cold,” meaning it’s heavy, relatively slow moving (non-relativistic), and effectively clumps together.

    A cosmic bullet

    To carry out the study, Bonaca and her team used data from the ESA’s Gaia space observatory, which has observed over a billion objects with unparalleled precision. Using this data, they mapped the positions and motions of stars in the stellar stream GD-1, which astronomers believe is the remains of a 70,000-solar-mass collection of old stars (called a globular cluster) that was shredded by past gravitational interactions with the Milky Way.

    After noticing that GD-1 has an impact scar — a line of ejected stars — that indicates a past interaction, the researchers ran simulations to try to reproduce what they saw. After testing a variety of models, they found that the gravity of an object millions of times more massive than the Sun would do the trick.

    The team naturally went searching for the object responsible. “Any massive and dense object orbiting in the halo could be the perturber,” Bonaca told Astronomy, “so a wandering supermassive black hole is definitely a possibility.” But so far, the team has failed to find any objects, black holes or otherwise, with the right trajectory and mass.

    According to a preprint of their paper, “Orbit integrations back in time show that the stream encounter could not have been caused by any known globular cluster or dwarf galaxy.” This led the team to conclude the “most plausible explanation” is that GD-1 had a past encounter with a clump of dark matter, like those expected to reside in the halos of galaxies.

    Still hunting

    Bonaca admits the current research is not conclusive. “However, if we can locate where the perturber is now, that would open new research directions, including searching for additional observational evidence [indicating it is dark matter].” Such evidence could take the form of other stars or gas clouds being jostled around by the dark matter’s gravity, or even gamma-rays associated with dark matter annihilations, which occur when two dark matter particles slam into and destroy each other, releasing a flash of energy.

    Bonaca says her team recently obtained measurements of the motion of stars in the disrupted part of the stream. By mapping out where the stars are now and how they are moving, the team should be able to better calculate where the perturber could be now to locate it. That would tell them were on the sky to look for that additional evidence that the cosmic cannonball is indeed dark matter.

    But since there’s currently only one disrupted star stream to study, Bonaca and her team are also searching through more Gaia data to search for other examples like GD-1. In fact, they recently found another stream called Jhelum, which likewise has a strange structure. However, Bonaca says they currently do not have a good explanation for what might have happened to this stream.

    This research has been accepted June 6 for publication in The Astrophysical Journal. An updated version of the research is expected to be published to the preprint site arXiv.org soon.

    See the full article here .


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  • richardmitnick 10:48 am on December 28, 2018 Permalink | Reply
    Tags: , Astronomy magazine, , , , Did a nearby supernova cause one of Earth’s mass extinctions?,   

    From Astronomy Magazine: “Did a nearby supernova cause one of Earth’s mass extinctions?” 

    Astronomy magazine

    From Astronomy Magazine

    December 13, 2018
    Alison Klesman

    Astronomers say radiation arriving from a powerful stellar explosion may be the event that wiped coastal ocean animals off the planet 2.6 million years ago.

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    This composite image shows supernova remnant 1E 0102.2-7219, which lies 190,000 light-years away. The supernova that may have caused a mass extinction on Earth was much closer, only about 150 light-years distant. X-ray (NASA/CXC/MIT/D.Dewey et al. & NASA/CXC/SAO/J.DePasquale); Optical (NASA/STScI)

    NASA/Chandra X-ray Telescope

    NASA/ESA Hubble Telescope

    Supernovae are the explosive end stages of massive stars. About 2.6 million years ago, one such supernova lit up Earth’s sky from about 150 light-years away. A few hundred years later, after the new star had long since faded from the sky, cosmic rays from the event finally reached Earth, slamming into our planet. Now, a group of researchers led by Adrian Melott at the University of Kansas believes this cosmic onslaught is linked to a mass extinction of ocean animals roaming Earth’s waters at the time — including the Megalodon. Their work was published November 27 in Astrobiology.

    “Supernovae should have affected Earth at some time or another,” Melott said in a press release. However, in the past, it’s been hard to determine exactly how or when such events would have had an effect. But, according to the group’s paper, “a newly documented marine megafaunal extinction” lines up with the arrival of a potentially lethal influx of radiation, indicating they might be able to pin a particular supernova on a particular event.

    That event, which occurred at the Pliocene-Pleistocene boundary, caused about 36 percent of the genera in coastal waters — where the penetration of radiation would have been greater in the shallower water — to go extinct. “We have evidence of nearby [supernova] events at a specific time. We know about how far away they were, so we can actually compute how that would have affected Earth and compare it to what we know about what happened at that time,” Melott said.

    Incoming!

    The killer radiation came in the form of cosmic rays made up of fast-moving muons, which are a few hundred times the mass of an electron, according to Melott. “They’re very penetrating. Even normally, there are lots of them passing through us. Nearly all of them pass through harmlessly, yet about one-fifth of our radiation dose comes by muons,” he said.

    But what about under abnormal conditions, such as the wave of material from a supernova? “When this wave of cosmic rays hits, multiply those muons by a few hundred. Only a small fraction of them will interact in any way, but when the number is so large and their energy so high, you get increased mutations and cancer,” Melott said. Based on the rates of muons hitting Earth from the stellar explosion, the team estimated that in human-sized animals, the cancer rate would increase by about 50 percent. But in larger animals, that effect would have also been larger. “For an elephant or a whale, the radiation dose goes way up,” he said. And because high-energy muons can penetrate hundreds of yards into water, they could have peppered the coastal waters where the extinctions occurred, essentially targeting the animals that lived there for death.

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    Our Local Bubble is of a bubble of hot, diffuse gas that was likely generated by one or more supernovae. NASA; modified from original version by Wikipedia User Geni.

    Tracing the Source

    The other piece of the puzzle was pinpointing the event that could have caused that wave of radiation. Iron-60 is a radioactive isotope of iron with a half-life of about 2.6 million years — which means that any iron-60 that formed with Earth is now long gone. Thus, the only way scientists could still find iron-60 today is if it arrived via cosmic means, such as “raining down” in the wave from a supernova. And there’s a huge spike of iron-60 that was deposited about 2.6 million years ago, indicating the material from a supernova event reached us then.

    As for where that supernova came from, our Sun sits inside what astronomers call the Local Bubble. It’s a relatively empty area of the interstellar medium (ISM) that fills the space between stars. The Local Bubble is a 300-light-year-wide region filled with hot, diffuse gas, bounded by the cold, dense gas of the “regular” ISM. In our region of the galaxy, several bubbles exist, and astronomers think these bubbles — including our own — were caused by supernovae, whose energy can sweep away material and heat anything that remains, forming just such a bubble.

    The Local Bubble may have been caused by not one, but a chain of supernovae, one of which went off extremely close to Earth 2.6 million years ago, depositing that layer of radioactive material. And the Local Bubble itself could have exacerbated the amount of cosmic rays Earth received, increasing the deadliness of such events. According to Melott, the boundaries of the bubble could have reflected cosmic rays back when they hit it, creating a “cosmic-ray bath” lasting 10,000–100,000 years for each supernova. A chain of supernovae going off relatively close to each other in time could send cosmic rays bouncing throughout the Local Bubble for millions of years, he said.

    All of this boils down to a tantalizing connection between the supernovae that clearly changed our local region of the galaxy and an unexplained major extinction event. “There really hasn’t been any good explanation for the marine megafaunal extinction,” Melott concluded. “This could be one.”

    See the full article here .


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  • richardmitnick 3:54 pm on May 4, 2018 Permalink | Reply
    Tags: , Astronomy magazine, , , , , Wandering supermassive black holes   

    From Astronomy Magazine: “The Milky Way’s supermassive black hole may have a dozen nomadic siblings” 

    Astronomy magazine

    Astronomy Magazine

    April 27, 2018
    Jake Parks

    New research suggests that ‘wandering’ supermassive black holes are common within many types of galaxies — including the Milky Way.

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    Like most galaxies, the Andromeda galaxy (pictured above) is thought to house a supermassive black hole at its core. According to new research, galaxies roughly the mass of the Milky Way also likely contain about a dozen more ‘wandering’ supermassive black holes. NASA/JPL-Caltech

    At the center of the Milky Way sits a dark and dangerous beast: Sagittarius A*.

    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory

    Located about 26,000 light-years from Earth, our galaxy’s only known supermassive black hole is roughly 4 million times as massive as the Sun, and its immense gravitational pull can nonchalantly annihilate any object that strays too close. Fortunately for us, Sagittarius A* is like a troll under a bridge — it does not leave its post.

    This tends to be the case for most supermassive black holes (SMBHs) found throughout the universe. However, sometimes a SMBH can be forced from the center of its host galaxy, particularly if it’s involved in a galactic merger with a bigger counterpart. For example, if a small galaxy merges with a larger one, the smaller galaxy’s SMBH will likely be thrown into a wide orbit around the newly formed galaxy, therefore becoming a ‘wandering’ supermassive black hole. Though astronomers have previously found evidence of these nomadic SMBHs on the outskirts of other galaxies, their overall prevalence is still largely unknown.

    But according to a new study published April 24 in The Astrophysical Journal Letters, wandering supermassive black holes may be quite common (and even observable) within many different types of galaxies — including the Milky Way.

    To carry out the study, the researchers took advantage of a new, state-of-the-art cosmological simulation called ROMULUS25. This N-body simulation uses an advanced supercomputer called Blue Waters to model how billions of individual particles interact and evolve over time.

    U Illinois Urbana-Champaign Blue Waters Cray Linux XE/XK hybrid machine supercomputer

    Though the ROMULUS25 simulation encompasses an astounding volume of over 15,000 cubic Megaparsecs (1 Megaparsec = 3 million light-years), it is still able to resolve the internal structure of galaxies and dwarf galaxies, as well as capture the orbital evolution of SMBHs following galactic mergers.

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    A sample of the ROMULUS25 simulation at redshift z = 0.4. The three slices of the simulation are focused on the same central group of galaxies (about 10 times as massive as the Milky Way), and shows the distribution of dark matter (left), the distribution of stars color-coded by composition (center; red are metal poor, blue are metal rich), and the distribution of stars color-coded by age (right; red are old, blue are young). White dots mark black holes. N-Body Shop (University of Washington).

    By extracting a sample of Milky-Way-mass galaxies from the simulation, the researchers were able to determine that any galaxy roughly the mass of the Milky Way, regardless of its recent merger history or morphology, likely contains about a dozen supermassive black holes, with roughly five being located within 30,000 light-years of the galaxy’s center. Although this slew of meandering SMBHs may seem intimidating (especially considering they roam for at least a few billion years), according to the study, they pose little threat to our tiny corner of the cosmos.

    “It is extremely unlikely that any wandering supermassive black hole will come close enough to our Sun to have any impact on our solar system,” said lead author Michael Tremmel, a postdoctoral fellow at the Yale Center for Astronomy and Astrophysics, in a press release. “We estimate that a close approach of one of these wanderers that is able to affect our solar system should occur every 100 billion years or so, or nearly 10 times the age of the universe.”

    So, even though the supermassive black hole at the center of the Milky Way may have a dozen disenfranchised siblings, by the time they could pose a threat to Earth, the Sun will have likely already burnt out. In the meantime, astronomers will continue working hard to definitely prove these wandering Goliaths actually exist. And once they do, the real fun can begin.

    See the full article here .

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  • richardmitnick 11:37 am on April 6, 2018 Permalink | Reply
    Tags: A telescope bigger than our planet reveals minute details in a nearby galaxy's center, Astronomers zoom in on a supermassive black hole's jets, , Astronomy magazine, , , , , Perseus Cluster of galaxies,   

    From Astronomy Magazine: “Astronomers zoom in on a supermassive black hole’s jets” 

    Astronomy magazine

    Astronomy Magazine

    April 03, 2018
    Alison Klesman

    A telescope bigger than our planet reveals minute details in a nearby galaxy’s center.

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    This image shows how radio telescopes on Earth and in space (left) combined to observe a very small region around another galaxy’s supermassive black hole (right). In this radio image, the black hole is located in the bright yellow-green spot at the top; a young jet about 3 light-years long shoots away from the black hole.
    Pier Raffaele Platania INAF/IRA (compilation); ASC Lebedev Institute (RadioAstron image).

    Supermassive black holes millions to billions of times the mass of our Sun lurk in the centers of most galaxies. In addition to feeding on nearby gas and dust, some of these black holes launch massive jets of plasma that not only dwarf the black hole itself, but the entire galaxy in which they reside. The mechanics of these jets, including exactly where they are launched, are still poorly understood, but observations such as those recently achieved using a combination of Earth- and space-based radio telescopes will help unlock the mysteries surrounding these dramatic structures.

    In a paper published April 2 in Nature Astronomy, an international collaboration of astronomers released observations of the jets around the black hole in the galaxy NGC 1275, located in the Perseus Cluster of galaxies about 230 million light-years away.

    Perseus galaxy cluster by NASA/Chandra

    Also known as Perseus A or 3C 84, this galaxy is classified as a Seyfert galaxy, meaning it has an “active” black hole currently feeding on surrounding material. That black hole is in the early stages of generating massive jets, which have now been mapped out via radio observations down to a mere 12 light-days from their origin around the black hole. That’s just a few hundred times the radius of the black hole itself (1 light-day is about 16 billion miles [26 billion kilometers]).

    What they found surprised them. “It turned out that the observed width of the jet was significantly wider than what was expected in the currently favored models where the jet is launched from the black hole’s ergosphere — an area of space right next to a spinning black hole where space itself is dragged to a circling motion around the hole,” said the paper’s lead author, Gabriele Giovannini from the Italian National Institute for Astrophysics, in a press release.

    Instead, “this may imply that at least the outer part of the jet is launched from the [much larger] accretion disk surrounding the black hole,” said said Tuomas Savolainen of Aalto University in Finland, and leader of the RadioAstron observing program that created the images.

    These images took advantage of a technique called very long baseline interferometry, or VLBI. This technique links several radio telescopes together to essentially observe with a “virtual” dish as large as the distance between the telescopes. In this case, the team linked Earth-based radio telescopes with a Russian 10-meter (33 feet) radio telescope orbiting Earth as part of the RadioAstron project, creating a virtual radio telescope with a diameter of over 200,000 miles (350,000 km), nearly the distance between Earth and the Moon.

    RadioAstron Spektr R satellite, the Astro Space Center of Lebedev Physical Institute in Moscow, Russia

    The larger the radio telescope, the finer the detail it can see, which allowed astronomers to zoom in on the region around NGC 1275’s black hole to look for clues about how and where the jet is generated. Their resulting images are 10 times better than anything previously achieved using ground-based radio telescopes alone. This same technique is the one utilized by the Event Horizon Telescope last year in an attempt to image the shadow of a supermassive black hole on its accretion disk; astronomers are eagerly awaiting the results, which should be announced later this year.

    Event Horizon Telescope Array

    Arizona Radio Observatory
    Arizona Radio Observatory/Submillimeter-wave Astronomy (ARO/SMT)

    ESO/APEX
    Atacama Pathfinder EXperiment

    CARMA Array no longer in service
    Combined Array for Research in Millimeter-wave Astronomy (CARMA)

    Atacama Submillimeter Telescope Experiment (ASTE)
    Atacama Submillimeter Telescope Experiment (ASTE)

    Caltech Submillimeter Observatory
    Caltech Submillimeter Observatory (CSO)

    IRAM NOEMA interferometer
    Institut de Radioastronomie Millimetrique (IRAM) 30m

    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA
    James Clerk Maxwell Telescope interior, Mauna Kea, Hawaii, USA

    Large Millimeter Telescope Alfonso Serrano
    Large Millimeter Telescope Alfonso Serrano

    CfA Submillimeter Array Hawaii SAO
    Submillimeter Array Hawaii SAO

    ESO/NRAO/NAOJ ALMA Array
    ESO/NRAO/NAOJ ALMA Array, Chile

    South Pole Telescope SPTPOL
    South Pole Telescope SPTPOL

    Future Array/Telescopes

    Plateau de Bure interferometer
    Plateau de Bure interferometer

    NSF CfA Greenland telescope

    But while these observations don’t mesh exactly with expectations, “Our result does not yet falsify the current models where the jets are launched from the ergosphere, but it hopefully gives the theorists insight about the jet structure close to the launching site and clues how to develop the models,” said Savolainen.

    5
    The galaxy NGC 1275 contains the black hole around which jets were imaged in this study. This composite image shows detail from optical, radio, and X-ray observations. The purple X-ray lobes near the brightest part of the galaxy contain the young radio jets from the black hole.
    NASA, ESA, NRAO and L. Frattare (STScI). Science Credit: X-ray: NASA/CXC/IoA/A.Fabian et al.; Radio: NRAO/VLA/G. Taylor; Optical: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Fabian (Institute of Astronomy, University of Cambridge, UK)

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    NASA/Chandra Telescope

    NRAO/Karl V Jansky VLA, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    NASA/ESA Hubble Telescope

    This is only the second observation of jets at such close proximity to the black hole; the only other system that has been observed with this level of detail is M87. But the jets in M87 are much older, which, researchers say, may be why they look different from those in NGC 1275. “The jet in NGC 1275 was re-started just over a decade ago and is currently still forming, which provides a unique opportunity to follow the very early growth of a black hole jet,” said Masanori Nakamura from Academia Sinica in Taiwan, a co-author on the paper. “Continuing these observations will be very important.”

    See the full article here .

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  • richardmitnick 1:41 pm on March 2, 2018 Permalink | Reply
    Tags: , Astronomy magazine, , , , DOGs-dust-obscured galaxies, WISE1029   

    From Astronomy: “Can galaxies ignore their supermassive black holes?” 

    Astronomy magazine

    Astronomy Magazine

    February 22, 2018
    Alison Klesman

    Galaxies and their central supermassive black holes may not co-evolve as simply as we thought.

    1
    Supermassive black holes can generate massive outflows of gas as they grow. These outflows were believed to have a significant effect on the black hole’s host galaxy until an outlier was found. ESA/AOES Medialab.

    In recent decades, astronomers have discovered a supermassive black hole in the center of every large galaxy we see — including our own.

    2
    MASSIVE MONSTER. Hidden behind crowded thick dust is Sagittarius A*, the nearest supermassive black hole. While many other galaxies’ central supermassive black holes spew matter or energy, the monster at the center of our Milky Way remains strangely quiet.
    NASA/CXC/MIT/Frederick K. Baganoff, et al.

    SgrA* NASA/Chandra

    SGR A* , the supermassive black hole at the center of the Milky Way. NASA’s Chandra X-Ray Observatory

    They’ve even observed several apparent connections between the mass of the central black hole and the properties of the galaxy in which it resides. Such connections have led to theories that galaxies and their central supermassive black holes evolve together somehow, but recent findings have just thrown a wrench in that particular idea.

    Milky Way Galaxy Credits: NASA/JPL-Caltech/R. Hurt

    A team led by Yoshiki Toba of the Academia Sinica Institute of Astronomy and Astrophysics has used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe a set of dust-obscured galaxies (DOGs) that give off bright infrared emission.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    DOGs are believed to harbor black holes currently undergoing growth spurts, which typically spur outflows from the region around the feasting black hole. In one such galaxy, WISE1029, they observed that carbon monoxide (CO) gas in the galaxy’s disk, a crucial star-forming ingredient, was not affected by outflowing ionized gas (gas whose atoms have been stripped of electrons by strong radiation) from the central supermassive black hole. The total lack of a connection goes against current theory, which states that outflows should affect such star-forming gas, either by activating star formation or by stopping it. Their result was published December 18 in The Astrophysical Journal.

    “It has made the co-evolution of galaxies and supermassive black holes more puzzling,” said Yoshiki in a press release.

    2
    Emission from WISE1029’s carbon monoxide (left) and cold dust (right) shows no disruption associated with an outflow from the galaxy’s central supermassive black hole. ALMA (ESO/NAOJ/NRAO), Toba et al.

    WISE1029 is a particularly interesting target because the outflow of ionized gas from its black hole is considered extreme, which should have a significant effect on the molecular gas (such as CO) in the galaxy surrounding it. But ALMA’s detailed observations showed that the black hole’s outflow has not affected either the molecular gas or the ability of the galaxy to form stars.

    This is an odd result — outflows of ionized gas are frequently detected from supermassive black holes, but this is the first time the outflow has not been connected to a change in the galaxy’s molecular gas. Such an outlier suggests that astronomers cannot automatically assume such outflows will always change or quench star formation, and casts doubt on the idea that galaxies and their central supermassive black holes co-evolve in a simple way. One possibility is the outflow from the black hole may be shooting out perpendicular to the molecular gas in the disk, preventing the two from interacting — data from the Sloan Digital Sky Survey indicates that the black hole’s outflow of ionized gas is pointed directly toward Earth. So perhaps a specific orientation is needed to either cause or prevent interaction between the two.

    “Astronomers do not understand the real relation between the activity of supermassive black holes and star formation in galaxies,” said co-author Tohru Nagao of Ehime University. Indeed, it is one of the outstanding mysteries in the field of galaxy evolution, and one astronomers are focusing in on as the ability to observe details within single galaxies continues to improve.

    “Understanding such co-evolution is crucial for astronomy,” Yoshiki said. “By collecting statistical data of this kind of galaxies and continuing in more follow-up observations using ALMA, we hope to reveal the truth.”

    See the full article here .

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  • richardmitnick 8:33 am on February 17, 2018 Permalink | Reply
    Tags: , Astronomy magazine, , , ,   

    From Astronomy Magazine: “Celebrating Pluto’s discovery” 

    Astronomy magazine

    Astronomy Magazine

    February 15, 2018
    Alison Klesman

    1
    This is Pluto as it appeared to the New Horizons spacecraft during its approach of the dwarf planet in July 2015. NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

    On February 18, 1930, Pluto was discovered by astronomer Clyde W. Tombaugh at the Lowell Observatory in Flagstaff, Arizona.

    Lowell Observatory, in Flagstaff, Arizona, USA

    Compared with the major planets in our solar system, Pluto has had a shorter but rockier history. Originally hailed as our solar system’s ninth planet, Pluto was reclassified as a dwarf planet by a 2006 vote of the International Astronomical Union — a move that remains controversial and challenged to this day.

    Pluto, regardless of the category into which it is sorted, has played a vital role in our understanding of the formation and evolution of our solar system. We now know it is part of a family of objects called the Kuiper Belt, comprised of icy, rocky remnants from the solar nebula’s earliest days. The Pluto system itself is larger than initially believed; its largest moon, Charon, wasn’t discovered until 1978, and only in the past two decades have astronomers uncovered four more tiny moons using the world’s most powerful telescopes.

    2
    An artist’s concept shows New Horizons flying through the Pluto system. Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

    Until 2015, Pluto remained a dim dot through Earthbound telescopes, and a mere few pixels on images taken by the orbiting Hubble Space Telescope. On July 14, 2015, the New Horizons spacecraft flew past the Pluto system, forever changing our view of this distant world. Astronomy celebrated the accomplishment with our Year of Pluto, a wealth of fascinating articles looking back over our past expectations, guesses, and dreams about Pluto, and highlighting the unrivaled success of and the wealth of information unlocked by New Horizons over the course of just a few short hours.

    Circling the Sun on an elliptical orbit tilted relative to the plane of the planets, Pluto takes about 248 (Earth) years to make one trip; the tiny, icy world has not yet completed even a single orbit since its discovery. But despite its distance and its still-controversial status, Pluto remains one of the most beloved and fascinating objects in our solar system. Below, you can find links to some of our favorite articles on the history of Pluto, leading up to its discovery, its naming, and the 2015 flyby. Or we invite you to explore our full library of Pluto articles here: Year of Pluto.

    And if, like many, you believe Pluto should regain its place among the rightful planets of our solar system, stay tuned — Astronomy will be featuring an exclusive on the definition of the word planet, and how we might rethink it, in an upcoming magazine issue and online bonus feature.

    See the full article here .

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  • richardmitnick 8:19 am on February 17, 2018 Permalink | Reply
    Tags: , Astronomy magazine, , , , Lensed quasar RXJ1131−1231,   

    From Astronomy: “Astronomers report a possible slew of extragalactic exoplanets” 

    Astronomy magazine

    Astronomy Magazine

    February 09, 2018
    Mara Johnson-Groh

    Could a distant galaxy be home to a large population of unbound planets?

    1
    Astronomers have identified a population of rogue planets – planets not bound to or orbiting parent stars – in a lensing galaxy sitting between Earth and a distant quasar.
    NASA/JPL-Caltech

    Discoveries of exoplanets in our galaxy exceed 3,700 to date, but if that’s not enough for you, astronomers are now probing outside of the Milky Way to find exoplanets in other galaxies. A group of researchers at the University of Oklahoma has just announced the discovery of a large population of free-floating planets in a galaxy 3.8 billion light-years away. Their results were published February 2 in The Astrophysical Journal Letters.

    The researchers used a method known as quasar microlensing, which has traditionally been used to study the disk-like regions around supermassive black holes where material gathers as it spirals in toward the event horizon.

    2
    Credit: NASA/Jason Cowan (Astronomy Technology Center).

    When a distant quasar is eclipsed by a closer galaxy, the intervening galaxy will create several magnified replica images of the quasar. These replicas are further magnified by stars in the interloping galaxy to create a final super-magnified image that can be used to study the quasar in detail.

    Wild planets

    While studying the light emitted by the lensed quasar RXJ1131−1231 with the Chandra X-ray Observatory, the researchers noticed a particular wavelength of light emitted by iron was stronger than could be explained solely by the lensing effect of stars in the intervening galaxy.

    NASA/Chandra Telescope

    By modeling their results, the researchers concluded that the shifted energy signature was most likely caused by a huge population of planets with masses ranging from our Moon to Jupiter. The model that best matched the data found a ratio of 2,000 planets for every main sequence star in the galaxy —billions of stars. These planets are specifically “unbound” — not orbiting a star but wandering freely — as bound planets don’t have the same boosting effect seen in the data. Because the models only provided a wide range of potential planet masses, the researchers hope to identify the distribution of the sizes further with additional modeling.

    3
    RX J1131-1231 is about 6 billion light-years away. It is a lensed quasar; gravitational lensing caused by an intervening elliptical galaxy (center, yellow) has magnified and multiplied the image of RX J1131 into four images (pink) as seen with the Chandra X-ray Observatory.
    X-ray: NASA/CXC/Univ of Michigan/R.C.Reis et al; Optical: NASA/STScI

    NASA/ESA Hubble Telescope

    These preliminary results may just be the first out of the floodgates. “There are also other galaxies we’re working on,” says Xinyu Dai, lead author of the paper and researcher at the University of Oklahoma. “We think there are some signatures showing the presence of a small mass population, but we need to run detailed models to see if this is true or not.”

    Other Sightings

    This isn’t the first time astronomers have claimed a discovery of an exoplanet outside our galaxy. A signature consistent with a three-Earth-mass planet was detected in a galaxy 4 billion light-years away, but the one-time chance nature of the alignment causing the microlensing meant the discovery could not be confirmed with further observations. Similarly, a different version of microlensing using a star instead of a galaxy was previously used to probe the Andromeda Galaxy. A team found deviations in the light that they believed could be caused by an exoplanet six times as massive as Jupiter, but again the detection was never confirmed.

    The interloper star HIP 13044 was reported to itself host an exoplanet 25 percent larger than Jupiter, but subsequent follow-up found no evidence for the planet. Though this star is currently a part of the Milky Way, it originally came from a small galaxy that collided with the Milky Way six billion years ago.

    Vagabond stars like HIP 13044 may provide our best chance for examining exoplanets from other galaxies in detail. With current telescope technology, microlensing can point to a detection in other galaxies, but it cannot fully probe the properties of these candidates. Finding relatively nearby exoplanets around stars that originated abroad, however, may help us learn more about how exoplanets form and whether there are differences between planets born in different galaxies.

    See the full article here .

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