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Sagittarius A* Dust Cloud: Planets May Be Devoured By Milky Way Black Hole In 2013

Sagittarius A Dust Cloud

  First Posted: 12/27/11 09:45 AM ET Updated: 12/27/11 02:17 PM ET

By John Matson

(Click here for original article.)

Times are tough on planet Earth right now, but at least we don’t have a supermassive black hole lurking just over the horizon.

A new study suggests that stars near the Milky Way’s central black hole may well form planets. The researchers based their analysis on a very recent discovery of a gas cloud making its way toward the galactic center.

On December 14 an international team of astronomers led by Stefan Gillessen of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, announced that they had spotted something heading toward a close encounter with the central black hole, known as Sagittarius A* (Sgr A*), which has as much mass as four million suns. Gillessen and his colleagues interpreted the object to be a dusty gas cloud about three times as massive as Earth, possibly belched out as stellar winds (plasma streaming outward from stars) from the young stars that orbit the black hole.

A few days later, Ruth Murray-Clay and Abraham Loeb of the Harvard–Smithsonian Center for Astrophysics suggested that the newfound object may be much more closely connected to those stars. In a preprint posted to the Web site arXiv.org on December 20, Murray-Clay and Loeb say that the cloud Gillessen and his colleagues discovered could be the disrupted remnants of a planet-forming disk surrounding a star that used to orbit Sagittarius A* at a safe distance but is now plunging toward the black hole. A protoplanetary disk is the swirling pancake of gas and dust surrounding a young star, which can coalesce into planets, asteroids and comets. “This cloud of gas naturally originates from a proto-planetary disk surrounding a low-mass star, which was scattered a century ago from the observed ring of young stars orbiting Sgr A*,” they write.

The star itself would be too faint to see. But as Sagittarius A* has distorted and fried the disk with the black hole’s gravitational pull and the radiation of its environs, it has generated a debris stream around the star that telescopes can detect.

If the young stars orbiting Sagittarius A* host protoplanetary disks, that “implies that planets form in the Galactic centre,” the researchers write. But you wouldn’t want to live on one of those worlds. The galactic center is awash in intense radiation emitted by material swirling around the outside of the black hole, which gets compressed and heated as it falls inward. (It is that radiation from outside the event horizon that allows astronomers to “see” a black hole, which itself holds tight to all matter and photons and hence emits no light.)

Plus there’s always the chance that your host star will get knocked onto an orbit heading right for the black hole, as Murray-Clay and Loeb suspect has happened here. In some cases, the researchers suggest, planets might be torn apart by the black hole’s gravitational pull and produce bright flares as the pieces fall in.

We should soon find out whose explanation for the gas cloud is correct. The cloud, whatever its origin, is on track to swing past Sagittarius A* in mid-2013. If it’s a simple gas cloud, it will get torn apart and partly consumed by the black hole, temporarily brightening the radiation from around Sagittarius A*. If the cloud instead comprises debris from a protoplanetary disk, the star itself should cruise past Sagittarius A* largely unscathed. But the cloud will grow denser as more and more mass from the disk is dragged away from the star. Either way, it ought to be quite a show.

Take a look at the slideshow (below) to see NASA's biggest discoveries from 2011.

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  • Entire Sun Imaged

    In February, <a href="http://www.nasa.gov/mission_pages/stereo/main/index.html" target="_hplink">NASA's STEREO probes</a>, two observatories that were launched in 2006 to survey the sun, reached opposite ends of the sun and thus, were able to give scientists (and the rest of us!) a never-before-seen view of the far side of the star at the center of our universe. The composite image above was captured on June 1, 2011, <a href="http://www.nasa.gov/mission_pages/stereo/news/farside-060111.html" target="_hplink">and according to NASA</a>, "is the first complete image of the solar far side, the half of the sun invisible from Earth." <a href="http://www.huffingtonpost.com/2011/02/07/nasa-stereo-sun-images-video_n_819510.html" target="_hplink">Click here for more</a> on the STEREO probes.

  • Messenger Reaches Mercury

    While it's not a "discovery," <em>per se</em>, it's a milestone that will no doubt lead to many new findings about the smallest and innermost planet in our solar system. In March, after a 6 1/2-year, 4.9 billion mile journey, <a href="http://www.huffingtonpost.com/2011/03/18/nasa-messenger-mercury_n_837503.html" target="_hplink">NASA's Messenger spacecraft reached Mercury's orbit</a>. Messenger, the first spacecraft to orbit Mercury, <a href="http://messenger.jhuapl.edu/mer_orbit.html" target="_hplink">orbits the planet</a> every 12 hours. In November, <a href="http://www.nasa.gov/mission_pages/messenger/media/MissionExtends.html" target="_hplink">NASA announced that the spacecraft's mission</a>, which was supposed to end on March 17, 2012, would be extended for an additional year.

  • Pluto's Tiny Moon

    In July, NASA said that its Hubble Space Telescope <a href="http://www.huffingtonpost.com/2011/07/20/new-pluto-moon-hubble-space-telescope_n_904578.html" target="_hplink">discovered an eight to 21-mile-wide moon</a> circling the dwarf planet.

  • Black Hole Eats A Star

    In March, <a href="http://www.huffingtonpost.com/2011/04/07/nasa-cosmic-blast_n_846333.html" target="_hplink">NASA's Swift satellite saw an unusually long explosion of gamma-rays</a>. After studying the X-rays, <a href="http://www.huffingtonpost.com/2011/08/25/black-hole-eats-star-video_n_937150.html" target="_hplink">scientists found that they came from</a> a black hole that had become reenergized when it devoured a star. <a href="http://www.nasa.gov/home/hqnews/2011/aug/HQ_11-271_Swift_Black_Hole.html" target="_hplink">From NASA</a>: <blockquote>Astronomers soon realized the source, known as Swift J1644+57, was the result of a truly extraordinary event -- the awakening of a distant galaxy's dormant black hole as it shredded and consumed a star. The galaxy is so far away, it took the light from the event approximately 3.9 billion years to reach Earth. </blockquote>

  • Huge Mountain Discovered On Asteroid

    <a href="http://www.nasa.gov/mission_pages/dawn/main/index.html" target="_hplink">NASA's Dawn</a>, an ion-propelled spacecraft that traveled 1.7 billion miles before reaching the asteroid Vesta in July, sent back images in October revealing that <a href="http://www.huffingtonpost.com/2011/10/05/vesta-mountain-dawn-nasa_n_996282.html" target="_hplink">Vesta is home to a mountain larger than any mountain</a> on Earth. In December, NASA released new images that Dawn took when it was orbiting only 130 miles above the asteroid, the closest it will get to Vesta. Dawn will continue to image Vesta until next summer, when it will make its way to Ceres, a bigger asteroid.

  • 'Star Wars'-Like Planet

    <a href="http://www.huffingtonpost.com/2011/09/15/kepler-16b-planet-two-suns_n_964799.html" target="_hplink">NASA's Kepler spacecraft found a planet</a> that orbits two suns, driving fans of the "Star Wars" franchise <a href="http://blog.moviefone.com/2011/09/16/astronomers-discover-real-life-tatooine-star-wars/" target="_hplink">to call it a real-life Tatooine</a>. Astronomers announced Kepler-16b, which is the first circumbinary planet -- meaning it orbits two stars -- in September. <a href="http://www.huffingtonpost.com/2011/09/15/kepler-16b-planet-two-suns_n_964799.html" target="_hplink">Click here for more</a> on Kepler-16b.

  • 'Habitable Zone' Planet Found

    Scientists in early December <a href="http://www.huffingtonpost.com/2011/12/05/kepler-22b-new-planet-discovered-habitable-zone_n_1129591.html" target="_hplink">announced the discovery of Kepler-22b</a>, a planet with a temperature of around 72 degrees that's in the so-called <a href="http://en.wikipedia.org/wiki/Habitable_zone" target="_hplink">"Goldilocks," or habitable zone</a>. While the temperature of the 600-light-year away planet could sustain water, it has a radius of 2.4 times that of Earth's, so <a href="http://www.huffingtonpost.com/huff-wires/20111206/us-sci-alien-planet/" target="_hplink">it's probably too big</a> to harbor life.

  • Biggest Black Holes Ever Discovered

    Astronomers announced in early December that <a href="http://www.huffingtonpost.com/2011/12/05/black-hole-scientists-discover-huge_n_1129727.html" target="_hplink">they had found the biggest black holes to date</a>. The massive black holes, which are 10 billion times the size of the sun, are located over 300 million light years away.

  • Europa's 'Great Lakes'

    Scientists had long-thought that a large body of water existed under the surface of Europa, Jupiter's moon, but it was thought to be tens of miles below an icy crust. In November, though, astronomers analyzing data from <a href="http://solarsystem.nasa.gov/galileo/" target="_hplink">NASA's Galileo spacecraft</a> found evidence that suggests blocks of ice interact with water below the surface, which could mean that nutrients and energy are moving between the underground ocean and icy shell. <a href="http://www.ig.utexas.edu/people/staff/britneys/" target="_hplink">Britney Schmidt</a>, the lead author of the study, <a href="http://www.nature.com/nature/journal/v479/n7374/full/nature10608.html" target="_hplink">which appeared in the journal Nature</a>, said that the interaction "could make Europa and its ocean more habitable for life." <a href="http://www.huffingtonpost.com/2011/11/17/europa-water-jupiter-moon-photo-video_n_1099463.html#s480278&title=Europa" target="_hplink">Click here to read more</a> about water on Europa.

  • 'Bubbles' At The Edge Of Solar System

    NASA's Voyager probes -- launched over 30 years ago -- found huge magnetic "bubbles" at the edge of the solar system. "The sun's magnetic field extends all the way to the edge of the solar system," astronomer Merav Opher of Boston University <a href="http://www.nasa.gov/mission_pages/voyager/heliosphere-surprise.html" target="_hplink">said in a NASA statement</a>. "Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit like a ballerina's skirt. Far, far away from the sun, where the Voyagers are, the folds of the skirt bunch up." Voyager 1 and Voyager 2 were launched in 1977. Voyager 1 is currently 11 billion miles away and may exit our solar system within the next few years.

  • Gypsum On Mars

    In December, scientists announced that NASA's <a href="http://www.huffingtonpost.com/2011/12/08/mars-water-opportunity-rover-gypsum_n_1136483.html" target="_hplink">Mars Rover Opportunity may have found gypsum </a>that had been deposited by water. "This tells a slam-dunk story that water flowed through underground fractures in the rock," <a href="http://astro.cornell.edu/people/facstaff-detail.php?pers_id=112" target="_hplink">Steve Squyres</a>, a planetary scientist at Cornell University and the principal investigator for Opportunity <a href="http://www.nasa.gov/mission_pages/mer/news/mer20111207.html" target="_hplink">said in a NASA statement</a>. NASA's Curiosity Rover <a href="http://www.huffingtonpost.com/2011/11/26/nasa-mars-curiosity-launc_n_1113995.html" target="_hplink">is en route to the Red Planet</a> and will arrive in August 2012.

  • Earth-Size Planets Discovered

    Weeks after <a href="http://www.huffingtonpost.com/2011/12/05/kepler-22b-new-planet-discovered-habitable-zone_n_1129591.html" target="_hplink">the announcement of Kepler-22b</a>, scientists said that <a href="http://www.huffingtonpost.com/2011/12/20/new-planets-kepler-exoplanets_n_1161213.html" target="_hplink">they'd discovered Kepler-20e and Kepler-20f</a>, two planets that are about the size of Earth. While the planets are too close to their sun-like star to harbor life as we know it, the discovery proved that the Kepler spacecraft was capable of spotting planets that are Earth-size, and brings us one step closer to finding a true Earth twin. <a href="http://www.huffingtonpost.com/2011/12/20/new-planets-kepler-exoplanets_n_1161213.html" target="_hplink">Click here for more</a> on the new planets.

  • Charles Camarda: NASA Innovation

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