Blogs / 80beats

In the violent heart of our Milky Way galaxy lies a supermassive black hole with a mass equivalent to four million suns. But although the gravitational maw gobbles up anything that gets too close, it can also set up conditions that allow for the birth of new stars just a few light years away, according to a new study. Lead researcher Elizabeth Humphreys says the results, which uncovered what appear to be two young stars as close as seven light-years from the galactic center, were surprising, as that is “one of the last places … you would expect to find stars forming” [Scientific American].

Gas clouds that approach a black hole are usually ripped apart by the intense gravitational forces, but the new finding suggests that the molecular gas at the center of the Milky Way from which the stars form is denser than previously thought. The higher density gas makes it easier for the self-gravity of the condensing cloud to overcome the strong pull of the black hole and to collapse to form new stars [SPACE.com].

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We residents of the Milky Way can puff ourselves up with pride: A new study has discovered that our galaxy is more of a force to be reckoned with than previously realized. Astronomers said Monday that the Milky Way is more massive than earlier known, given new measurements showing that the Sun is moving at 600,000 miles per hour around the center of the galaxy, or 100,000 m.p.h. faster than past calculations suggested. The higher speed of the Sun means the galaxy must have more mass — about 50 percent more — so as to generate a stronger gravitational pull to keep hold of the Sun, as well as all its other stars [The New York Times].

The new calculation puts our galaxy’s mass about equal to that of the nearby Andromeda galaxy, which was previously thought to be bigger than the Milky Way, says lead researcher Mark Reid. “Previously we thought Andromeda was dominant, and that we were the little sister of Andromeda,” Reid said. “But now it’s more like we’re fraternal twins” [AP]. But although the estimate gives our galaxy some new bragging rights, it’s not all good news. Being bigger means the gravity between the Milky Way and Andromeda is stronger. So the long-forecast collision between the neighboring galaxies is likely to happen sooner and less likely to be a glancing blow, Reid said [AP]. Luckily, that collision still isn’t expected for 2 to 3 billion years.

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A sugar molecule essential to life as we know it has been found in the far reaches of the Milky Way, scientists report. Astronomers working with the IRAM radio dish array in France report the presence of glycolaldehyde—a simple sugar found in RNA—in a region of our galaxy known to churn out stars. The molecule appears to have formed with all of the other stuff that makes up planets, suggesting that many other worlds are seeded with some of life’s ingredients right from birth [ScienceNOW Daily News].

Glycoladehyde is a building block of ribose, a component of RNA. Many scientists believe RNA preceded DNA in vesting the earliest forms of life with reproductive capabilities; thus the finding of glycoladehyde has particular significance for those searching for extraterrestrial life. The astronomers detected radio and microwave signatures of glycolaldehyde within the core of what appears to be a coalescing disk of dust and gas in a star-forming region called G31.41+0.31, about 26,000 light-years away. The sugar molecule can apparently form in a simple reaction between carbon monoxide molecules and dust grains [ScienceNOW Daily News]. The astronomers believe the molecules they see are a few hundred thousand years old.

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The Fermi Gamma-ray Space Telescope may have just gotten a hint in its hunt for the mysterious dark matter that is thought to make up the bulk of the universe’s mass. A group of astrophysicists has run a simulation of the distribution of dark matter in a galaxy like our Milky Way, and say that if the telescope scans the right region of space it may be able to detect gamma rays given off by collisions between the particles that are thought to make up dark matter (which have never been directly detected, and are still speculative).

Previously, some cosmologists have proposed that the best chance of a detection lies in nearby dwarf galaxies, since they should contain dense nuggets of dark matter that could be relatively easy to pinpoint. But a new study argues that a diffuse dark matter ‘halo’ surrounding the Milky Way offers an even better shot at glimpsing the mysterious stuff. “I would bet on it,” says lead author Volker Springel…. “And I’d be willing to risk a bit of money as well” [New Scientist].

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Just beyond the Milky Way, astronomers have found an extremely dim dwarf galaxy that appears to have just a few hundred stars, but is surprisingly massive. Researchers say the galaxy, called Segue 1, must be packed with mysterious dark matter in order to give it such bulk.

Dark matter has never been directly detected, and its presence can only be deduced: Although dark matter doesn’t emit or absorb light, scientists can measure its gravitational effect on ordinary matter and believe it makes up about 85 percent of the total mass in the universe. Dark matter is thought to play a crucial role in galaxy formation, perhaps by contributing to the clumps that stimulate star formation in a budding galaxy and by contributing to the overall matter of a galaxy that allows it to lure other matter and galaxies inward in a growth-by-merger process [SPACE.com].

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Our sun, which lies 26,000 light years from the center of the the Milky Way, may have been born in a different part of the galaxy and later migrated to its current position, about halfway towards the galaxy’s outer edge. A new study defies the conventional wisdom that stars spend their entire lifespans in the same galactic region, and calls into question astronomers’ theory that galaxies have certain fixed “habitable zones” where life is more likely to evolve.

“Our view of the extent of the habitable zone is based in part on the idea that certain chemical elements necessary for life are available in some parts of a galaxy’s disk but not others,” said [lead researcher] Rok Roskar…. “If stars migrate, then that zone can’t be a stationary place” [Astrobiology Magazine].

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Researchers have gotten the closest look yet at the supermassive black hole that is believed to lurk in the center of the Milky Way, using radio telescopes to peer through the cosmic dust. Lead astronomer Sheperd Doeleman says: “One of the problems with looking at this particular source is that we have to look through our galaxy. It’s a blessing that it’s this close, but it’s a curse because it’s obscured by gas and dust” [SPACE.com].

Black holes can’t be directly observed, because their gravitational pull is so strong that nothing, not even visible light, can escape. To study our local gravitational monster, researchers homed in on Sagittarius A*, the bright radio-emitting body thought to mark the position of the black hole. Because Sagittarius A* is likely fueled by the black hole’s activity, a better look at the radio-emitting body can provide more details about the black hole [Science News].

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Astronomers have discovered that a massive star known as the Peony Nebula star ranks as the second-brightest in our Milky Way galaxy. The astronomers estimate that the star shines 3.2 million times as brightly as our sun, which is enough to get it a galactic silver medal; the brightest star ever detected is Eta Carinae, which is 4.7 million times brighter than our own little star.

The Peony nebula star… doesn’t look all that bright to the naked eye. Sirius is still the undisputed local champion, based on what we can see in the night sky. But a big factor behind Sirius’ apparent brightness is its relative proximity to Earth - a mere 8.7 light-years, or roughly 50 trillion miles [MSNBC]. In contrast, the Peony Nebula star lies about 26,000 light-years away, in the dusty heart of the Milky Way. In their upcoming report in the journal Astronomy & Astrophysics, researchers say the Spitzer telescope could reveal many other super-bright stars in the same region.

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It’s like an out-of-body experience, but on a galactic scale.

Astronomers have put together the best image yet of the Milky Way, the spiral galaxy that is home to the Earth, and more than 200 billion other stars. To map our galaxy from within, they used infrared cameras on NASA’s Spitzer Space Telescope, which allowed them to see through cosmic clouds of dust and gas.

The resulting data painted a radically different picture of our galaxy, and revealed that only two great arms of stars spiral out from the center of the Milky Way, not four as previously thought.

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