NASA's Kepler space telescope has found a small exoplanet being torn apart by a white dwarf star:
The devastated planetesimal, or cosmic object formed from dust, rock, and other materials, is estimated to be the size of a large asteroid, and is the first planetary object to be confirmed transiting a white dwarf. It orbits its white dwarf, WD 1145+017, once every 4.5 hours. This orbital period places it extremely close to the white dwarf and its searing heat and shearing gravitational force.
During its first observing campaign from May 30, 2014 to Aug. 21, 2014, K2 trained its gaze on a patch of sky in the constellation Virgo, measuring the minuscule change in brightness of the distant white dwarf. When an object transits or passes in front of a star from the vantage point of the space telescope, a dip in starlight is recorded. The periodic dimming of starlight indicates the presence of an object in orbit about the star.
A research team led by Vanderburg found an unusual, but vaguely familiar pattern in the data. While there was a prominent dip in brightness occurring every 4.5 hours, blocking up to 40 percent of the white dwarf's light, the transit signal of the tiny planet did not exhibit the typical symmetric U-shaped pattern. It showed an asymmetric elongated slope pattern that would indicate the presence of a comet-like tail. Together these features indicated a ring of dusty debris circling the white dwarf, and what could be the signature of a small planet being vaporized.
[...] In addition to the strangely shaped transits, Vanderburg and his team found signs of heavier elements polluting the atmosphere of WD 1145+017, as predicted by theory. Due to intense gravity, white dwarfs are expected to have chemically pure surfaces, covered only with light elements of helium and hydrogen. For years, researchers have found evidence that some white dwarf atmospheres are polluted with traces of heavier elements such as calcium, silicon, magnesium and iron. Scientists have long suspected that the source of this pollution was an asteroid or a small planet being torn apart by the white dwarf's intense gravity.
A disintegrating minor planet transiting a white dwarf [abstract]
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Researchers have recently observed what happens when a star gets too close to a supermassive black hole (SMBH) — the star is shredded with some of the material spiraling into the SMBH and some of it being cast out to space. By examining the X-rays that emanate from this encounter, they have found that the brightest ones come from the material that is closest to the SMBH's event horizon:
When a star comes too close to a black hole, the intense gravity of the black hole results in tidal forces that can rip the star apart. In these events, called tidal disruptions, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole. This causes a distinct X-ray flare that can last for years.
A team of astronomers, including several from the University of Maryland, has observed a tidal disruption event in a galaxy that lies about 290 million light years from Earth. The event is the closest tidal disruption discovered in about a decade, and is described in a paper published in the October 22, 2015 issue of the journal Nature.
[...] The optical light All-Sky Automated Survey for Supernovae (ASAS-SN) originally discovered the tidal disruption, known as ASASSN-14li, in November 2014. The event occurred near a supermassive black hole at the center of the galaxy PGC 043234.
[...] Gas often falls toward a black hole by spiraling inward and forming a disk. But the process that creates these disk structures, known as accretion disks, has remained a mystery. By observing ASASSN-14li, the team of astronomers was able to witness the formation of an accretion disk as it happened, by looking at the X-ray light at different wavelengths and tracking how those emissions changed over time.
[...] The X-ray data also suggest the presence of a wind moving away from the black hole, carrying stellar gas outward. However, this wind does not quite move fast enough to escape the black hole's gravitational grasp. A possible explanation for the low speed of this wind is that gas from the disrupted star follows an elliptical orbit around the black hole, and travels slowest when it reaches the greatest distance from the black hole at the far ends of this elliptical orbit.
I am now trying to imagine the scenario in this story: Kepler K2 Mission Spots a Vaporizing Exoplanet Orbiting a White Dwarf as that white dwarf is in turn being shredded by a SMBH. Shredded turtles all the way down?
Abstract: Flows of X-ray gas reveal the disruption of a star by a massive black hole
(Score: 0) by Anonymous Coward on Friday October 23 2015, @02:03AM
I read the title Kerbal Mission sports a Vaporizing Exoplanet Orbiting a White Dwarf and thought there had been a cool new update.
(Score: 0) by Anonymous Coward on Friday October 23 2015, @04:02PM
And I wondered since when they have a telescope on K2. [wikipedia.org]
(Score: 0) by Anonymous Coward on Friday October 23 2015, @03:41PM
I thought that irregular light profiles are now attributed to massive alien structures.
(Score: 0) by Anonymous Coward on Friday October 23 2015, @03:59PM
Is it a planet, or a dwarf planet?