New finding of metal-rich extremely low mass white dwarf
Main Point:
Scientists have reported an unusual, tidally-distorted extremely low mass white dwarf having almost the same amount of metal as that of our sun.
Published in:
arXiv accepted for publication in The Astrophysical Journal
Study Further:
White Dwarf:
White dwarf is a small, dim, extremely dense star that has collapsed on itself and is in the final stages of its evolution. Mass of white dwarf is almost same as that of the Sun and its volume is same as that of our planet – Earth.
Binary system:
In astronomy, binary system refers to a system of two objects in space usually stars or dwarfs, such as brown dwarfs or white dwarfs that are very close to each other and revolving around a common center of mass.
Present Study:
In the present study, astronomers have reported SDSS J074511.56+194926.5 that was first observed on Nov 5th, 2010 using the FLWO 1.5 m telescope and the FAST spectrograph.
It is a cool, tidally distorted extremely low mass white dwarf present in a compact binary with an orbital period of about 2.7 hrs. Mass of this object is found to be about 0.16 times that of sun and it has a cooling age of about 4.2 billion years. It has an effective temperature of 8380 K. The mass ratio of the system is q > 0.36. Binary mass transfer models suggest that a system with this mass ratio will undergo unstable mass transfer and merge to form a single white dwarf.
An extremely unusual feature of this object is the high abundances of metals. It has almost the same lines of metals as that of sun such as Ca, Mg, Ti, Cr and Fe, though scientists found no evidences of “a debris disk from which these metals would be accreted”.
Reference:
A. Gianninas, J. J. Hermes, Warren R. Brown, P. Dufour, Sara D. Barber, Mukremin Kilic, Scott J. Kenyon, & Samuel T. Harrold (2013). SDSS J074511.56+194926.5: Discovery of a Metal-Rich and Tidally Distorted Extremely Low Mass White Dwarf arXiv arXiv: 1312.1665v1
