March 30, 2009 -- Joseph Neilsen was casting about for a topic for his doctoral thesis when his adviser brought his attention to a black hole in the Milky Way galaxy known as GRS 1915. It's small by astronomical standards, at about 14 times the mass of our sun, and with the temperament of a ornery toddler. "Stellar-mass black holes are variable, and this one is frighteningly so. I've heard it described as almost pathological. It's quite unusual," said Neilsen, a graduate student at Harvard University. Scientists believe black holes come from dead stars so compressed that not even photons of light can escape their gravity. Because they cannot be directly detected, most probably fly around unnoticed. But some black holes, such as GRS 1915, have companions, though it is hardly a relationship of equals. These black holes are consuming their neighbor stars, giving astronomers insight into physical processes that occasionally outpace theory and imagination. Related Content:
Just about every time astronomers looked at GRS 1915, something different was happening. Sometimes it launched powerful jets of gas. Sometimes there were winds blasting off the disk-shaped plate of matter swirling around the black hole's edge. The material, known as an accretion disk, was stolen from the neighbor star. Intrigued, Neilsen took on the job of combing through 10 years of observations of GRS 1915 made by NASA's Chandra X-ray Observatory and discovered a previously unknown symmetry between its jet and its winds. Chandra has made 11 observations of GRS 1915 since its launch in 1999. The measurements were made with Chandra's high-resolution, light-splitting spectrograph which detects X-ray emissions by how they have impacted intervening molecules, such as iron. "We found that sometimes the wind is very strong and sometimes the jet is very strong and when they are both there, they are both weak. They are competing for mass," Neilsen told Discovery News. Get More NewsSpiders, Scorpions Among World's Oldest CreaturesMany creepy crawlies have been on Earth much longer than previously believed.Blood-Sucking Vampire Bats Sing DuetsWhite-winged vampire bats "harmonize" with separated roost mates.Oldest Hebrew Writing Possibly FoundAncient inscriptions on a 3,000-year-old pottery shard could make history.Rare, Prehistoric-Age Reptile Found in N.Z.A tuatara has been spotted on the New Zealand mainland for the first time in 200 years.Iceman Has No Living RelativesOetzi, the 5,300 year-old frozen mummy, left no living genetic legacy.SLIDE SHOW: Landscapes of TerrorWhat makes a place feel scary? There are scientific explanations.It's Official: People Are Warming the PolesHumans are conclusively to blame for polar warming, say scientists.Eight-Armed Animal Preceded DinosaursWhat may be one of Earth's first animals was no bigger than a coaster and had eight arms.Phoenicians Live on in People's GenesOne in 17 Mediterranean men may be descended from ancient Phoenicians.Pesticides, Fertilizers Linked to Frog DeclineA pesticide is found to promote parasites among amphibians.Hubble Telescope Taking Photos AgainThe Hubble Space Telescope is once again snapping stunning photos of the universe.Andean Mummy Hairs Show Hallucinogen UseScientists find direct evidence of hallucinogenic drug use among ancient Andeans.Opals on Mars Reveal Planet's Long Wet PastOpals found on Mars suggest the planet has been wet for much longer. |
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