A bizarre glow has been detected at the center of the Milky Way, and researchers are struggling to understand what's producing it. One option is that the high-energy X-rays that make up the mysterious glow are "'howls' of dead stars as they nourish on stellar companions." At least that's the way NASA's Jet Propulsion Laboratory put it in a somewhat playful news statement titled "NASA's NuStar Captures Possible 'Screamsfrom Zombie Stars." In more scientific terms, the glow may be an indication of dead stars in binary systems siphoning off stuff from their companions--an occurrence that is known to discharge X-rays. The dead stars, that we are talking about here, might be white dwarfs or small black holes, according to the issued statement by NASA. Or the glow could be triggered by pulsars--the fast-spinning leftovers of stars that have collapsed after blowing up as supernovae--which send out powerful beams of radiation. Otherwise, the glow could arise not from dead stars whatsoever but actually from high-energy charged particles known as cosmic rays.
In this image, the magenta color shows the strange glow detected by NASA's NuSTAR space telescope. Image Credit: NASA/JPL-Caltech
No one knows for certain if that's what's producing the glow, which is detectable in new images taken by NASA's Nuclear SpectroscopicTelescope Array (NuSTAR) space telescope. The pictures show a section of space some 40 light-years across in the locality of Sagittarius A*, the huge black hole at the center of the galaxy. The uncertainty isn't shocking given the distances involved --Sagittarius A* is about 26,000 light-years from Our Sun--and the point that the center of the Milky Way is swarming with old and young stars as well as small black holes. Dr. Kersten Perez, a physicist at Columbia University in New York City and the main author of a paper about the finding, said in the statement. "Almost anything that can emit X-rays is in the galactic center,"
So what precisely is the take-away from the new study? Dr. C. Megan Urry, professor of physics and astronomy at Yale University in New Haven, told The Huffington Post in an email. "This mysterious emission from the Milky Way’s center points out the significance of high spatial resolution at high X-ray energies which improves the clearness of the images. NuSTAR's ability to focus energetic X-rays is improving our understanding of the high-energy universe--and in some cases, like this new study of the galactic center, to raise interesting new questions as well." The paper was issued on April 30, 2015 in the journal Nature.