WD 0137-349
Encyclopedia
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! style="background-color: #FFFFC0;" colspan="2" | Astrometry
|- style="vertical-align: top;"
| Distance
| 333 Ly
|-
! style="background-color: #FFFFC0;" colspan="2" | Binary orbit
|- style="vertical-align: top;"
| Period
(P)
| 2 h
s
|- style="vertical-align: top;"
| Space between A and B:
| 0.006 AU
WD 0137-349 is a binary star 300 light years from Earth. It is composed of a white dwarf
and a brown dwarf
in orbit around it. The orbital period is 2 hours. The orbit of the brown dwarf is slowly decaying.
It is thought that the red giant phase of the current white dwarf was dramatically shortened from around 100 million years on average, to a few decades, because of the actions of the brown dwarf. The brown dwarf was swallowed into the envelope of the red giant, and hastened the expulsion of matter during this phase by rapidly heating gas and accreting a portion of it. During this phase, the gas drag also decreased the orbit of the brown dwarf.
In about 1.4 billion years, it is thought that the orbit of the brown dwarf will have decayed sufficiently to allow the white dwarf to draw matter away and accrete it on its surface, leading to a recurrent nova.
As of 2006, this brown dwarf is the smallest object known to survive being engulfed by a red giant phase. Previously, only red dwarf
s had been known to survive being enveloped during a red giant phase. It is thought that objects smaller than 20 Jupiter masses would have evaporated.
! style="background-color: #FFFFC0;" colspan="2" | Astrometry
|- style="vertical-align: top;"
| Distance
Cosmic distance ladder
The cosmic distance ladder is the succession of methods by which astronomers determine the distances to celestial objects. A real direct distance measurement of an astronomical object is possible only for those objects that are "close enough" to Earth...
| 333 Ly
|-
! style="background-color: #FFFFC0;" colspan="2" | Binary orbit
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
|- style="vertical-align: top;"
| Period
Orbital period
The orbital period is the time taken for a given object to make one complete orbit about another object.When mentioned without further qualification in astronomy this refers to the sidereal period of an astronomical object, which is calculated with respect to the stars.There are several kinds of...
(P)
| 2 h
Hour
The hour is a unit of measurement of time. In modern usage, an hour comprises 60 minutes, or 3,600 seconds...
s
|- style="vertical-align: top;"
| Space between A and B:
| 0.006 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
WD 0137-349 is a binary star 300 light years from Earth. It is composed of a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
and a brown dwarf
Brown dwarf
Brown dwarfs are sub-stellar objects which are too low in mass to sustain hydrogen-1 fusion reactions in their cores, which is characteristic of stars on the main sequence. Brown dwarfs have fully convective surfaces and interiors, with no chemical differentiation by depth...
in orbit around it. The orbital period is 2 hours. The orbit of the brown dwarf is slowly decaying.
It is thought that the red giant phase of the current white dwarf was dramatically shortened from around 100 million years on average, to a few decades, because of the actions of the brown dwarf. The brown dwarf was swallowed into the envelope of the red giant, and hastened the expulsion of matter during this phase by rapidly heating gas and accreting a portion of it. During this phase, the gas drag also decreased the orbit of the brown dwarf.
In about 1.4 billion years, it is thought that the orbit of the brown dwarf will have decayed sufficiently to allow the white dwarf to draw matter away and accrete it on its surface, leading to a recurrent nova.
As of 2006, this brown dwarf is the smallest object known to survive being engulfed by a red giant phase. Previously, only red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....
s had been known to survive being enveloped during a red giant phase. It is thought that objects smaller than 20 Jupiter masses would have evaporated.
External links
- SPACE.com: Object Survives Being Swallowed by a Star (Ker Than) 2 August 2006 01:05 pm ET
- http://jumk.de/astronomie/special-stars/wd0137-349.shtml
- http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=WD0137-349&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id