Warning: Black Hole Dead Ahead!

14 Dec

Every starship captain knows the true prime directive: steer clear of black holes. Well it appears that one object didn’t get the memo. According to a new study, a small cloud of gas and dust is racing toward the black hole at the center of the Milky Way—and when it hits, be prepared for some astronomical fireworks.

The black hole, named Sagittarius A*, weighs 4 million times as much as our sun and is 27,000 light-years away. Every star in the Milky Way revolves around it. Our sun takes 230 million years to complete an orbit, but one known star is so close that it revolves around Sagittarius A* in just 16 years.

Now astronomers have spotted a new object near the black hole. Stefan Gillessen and Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, Germany, and their colleagues used the European Southern Observatory’s Very Large Telescope in Chile to observe the Milky Way’s center at infrared wavelengths, which penetrate the thick dust between it and us. The instrument picked up a small gas cloud that, over 9 years of observations, appeared to be getting closer and closer to Sagittarius A*. The astronomers detected the object at a wavelength of 3.76 microns but not at 2.16 microns. This indicates it is a cloud of gas and dust rather than a star, they say, because a star is so hot that it should be brighter at the shorter wavelength.

The cloud is about three times as massive as Earth, emits five times as much energy as the sun, and spans 250 times the distance from the Earth to the sun. Its temperature is about 550 kelvin—somewhat cooler than the surface of Venus. Sagittarius A*’s immense gravity is accelerating the cloud dramatically: in 2004, the cloud was hurtling toward the black hole at 1200 kilometers per second; by 2011, the speed had nearly doubled, reaching 2350 kilometers per second. At that velocity, an airplane could circle the Earth in 17 seconds.

The cloud will approach Sagittarius A* in the summer of 2013, when the center of the gas and dust will be 260 times as far from the black hole as Earth is from the sun. But as the cloud hits hot gas already orbiting the black hole, it will likely meet its end. “It became really exciting when we noticed in the 2011 data that the cloud is starting to be stretched like spaghetti,” Gillessen says. “So right in front of our eyes, we can see the black hole is destroying the cloud. The material will rain down into the black hole and release a tremendous amount of energy.” As pieces of the cloud fall into Sagittarius A* over the next decade, friction and gravity will heat them to temperatures of millions of degrees, producing x-rays , the team reports online today in Nature. Other astronomers have detected “echos” of x-rays near the galactic center—reflections of radiation that have lit up large clouds hundreds of light-years away and that likely arose when past clouds dove into the black hole and sparked outbursts of x-rays.

Astronomer Andrea Ghez of the University of California, Los Angeles, who has seen the same object in her data, wouldn’t bet her house on such drama unfolding, however. “A much more likely interpretation is that this is a star that has an infrared excess,” she says, noting that dust surrounding a star can absorb visible light and reemit it in at infrared wavelengths. If the object is merely a star, then it won’t fall into the black hole but will shoot past it as the star loops around Sagittarius A* every 140 years. Ghez says other stars with infrared excesses exist near the galactic center.

Who’s right? We’ll find out by 2013. If the object really is a gas cloud, the fireworks (at x-ray and infrared wavelengths) should reveal the extreme conditions that prevail around the galaxy’s biggest black hole — useful information not only for astronomers studying supermassive black holes in other galaxies but also for starship captains the next time they voyage to the Milky Way’s hub.


Posted by on December 14, 2011 in News Article, Science, Space


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6 responses to “Warning: Black Hole Dead Ahead!

  1. in every atom

    December 16, 2011 at 3:40 am

    This sound exciting. I hope you will let us know what happens in 2013. 🙂 The blue ball in the photo appears to have very compassionate human-like eyes, it is kind of cute. Is that the black hole itself?

    • Craig & Joe

      December 19, 2011 at 5:25 pm

      I will definitely be waiting for this event and blogging it like crazy! Fireworks from the “gods”, who would miss that! The black hole is the extremely small and very bright white light in the center. Black holes are extremely hard to see and most are found by the sight of the “warping” of starlight. I just wish I knew where they went. Do they spit out what they eat into another universe? I guess that’s the billion-dollar question!

      • in every atom

        December 23, 2011 at 9:06 am

        If the center is a very bright white light, then it is strange that they call it a black hole. Your description of the black hole sounds like the description of a near-death experience for humans, going through darkness, seeing a white light tunnel, being drawn into it, being lead to infinity (ie, god). Kind of nice that universes too may have a similar fate as humans when they go through the black hole. Sorry, I am bring metaphysics into the physics of the universe. But, hey, that is what quantum physics is all leading to anyway. 😉

      • Craig & Joe

        December 23, 2011 at 4:54 pm

        The very center of the black hole is black, the bright white to see is the mass of stars and dust that are reflecting light in a concentrated mass prior to entering the event horizon. Once there, light cannot escape. Maybe black holes are the same as human death, when we break things down we are all made of the same stuff. This could make for a great sci-fi story.

  2. charlesmichelduke

    December 17, 2011 at 6:28 am

    I think this will be a fascinating observation to record in the coming few years, and will really help our understanding our how the powerful gravity of Black Holes work and their interaction with objects surrounding them.

    By the way, only three times the size of Earth. I cannot believe that the technology we have is refined enough to observe such a small object – amazing!

    • Craig & Joe

      December 19, 2011 at 5:32 pm

      It is really fascinating how much we have developed technology-wise! I keep praying that I will live to see inter-stellar travel and maybe, just maybe be able to visit another world! I think that would be the most incredible thing a human can do.


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