GD 362

GD 362 is a white dwarf approximately 150 light years from Earth.[4] In 2004, spectroscopic observations showed that it had a relatively high concentration of metals in its atmosphere. Since the high gravitational field of white dwarfs quickly forces heavy elements to settle towards the bottom of the atmosphere, this meant that the atmosphere was being polluted by an external source.[3] In 2005, infrared photometric observations suggested that it was surrounded by a ring of dust with size comparable to the rings of Saturn, providing an explanation for this pollution.[8]

GD 362
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Hercules[1]
Right ascension 17h 31m 34.33s[2]
Declination +37° 05′ 20.6″[2]
Apparent magnitude (V) 16.23[2]
Characteristics
B−V color index 0.2[3]
Astrometry
Proper motion (μ) RA: 27[2] mas/yr
Dec.: -223[2] mas/yr
Distance~150[4] ly
(50.6[5] pc)
Details
Mass0.73±0.02[6] M☉
Surface gravity (log g)8.24±0.04[6] cgs
Temperature10540±200[6] K
Other designations
G 204-14, NLTT 44986, WD 1729+371, EGGR 545, 2MASS J17313433+3705209, PG 1729+371[7]
Database references
SIMBADdata

In 2006, Benjamin Zuckerman, Michael Jura and other astronomers used the Keck telescope to obtain high-resolution spectra of GD 362 which showed that heavy elements in the star's atmosphere occurred in concentrations similar to those in the Earth-Moon system.[6] The group concluded that a possible origin for GD 362's dust ring and atmospheric pollutants was that a rocky asteroid about 200 km in diameter was disintegrated by tidal effects between 100,000 and 1 million years ago. If this was the origin, the spectra indicate that the asteroid should have had composition similar to the Earth's crust, suggesting that the star might have had an Earth-like planet before it entered its red giant phase.[4][6][9]

GD 362 has been a white dwarf for approximately 900 million years.[10]

References
  1. Constellation boundaries, CDS. Accessed on line October 4, 2007.
  2. Improved Astrometry and Photometry for the Luyten Catalog. II. Faint Stars and the Revised Catalog, Samir Salim and Andrew Gould, Astrophysical Journal 582, #2 (January 2003), pp. 1011–1031; CDS ID J/ApJ/582/1011. Entry for NLTT 44986. Accessed on line October 4, 2007.
  3. Discovery of a Cool, Massive, and Metal-rich DAZ White Dwarf, A. Gianninas, P. Dufour, and P. Bergeron, The Astrophysical Journal 617, #1 (December 2004), pp. L57–L60.
  4. Dunham, Will (2007-08-16). "Burned-out star harbors signs of Earthlike planets". Reuters. Retrieved 2007-08-17.
  5. Direct Distance Measurement to the Dusty White Dwarf GD 362, Mukremin Kilic, John R. Thorstensen, and D. Koester, ApJL,689,1
  6. Zuckerman; et al. (2007). "The Chemical Composition of an Extrasolar Minor Planet". The Astrophysical Journal. 671 (1): 872–877. arXiv:0708.0198. Bibcode:2007ApJ...671..872Z. doi:10.1086/522223.
  7. "GD 362". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved October 4, 2007.
  8. A Dusty Disk around GD 362, a White Dwarf with a Uniquely High Photospheric Metal Abundance, E.E. Becklin, J. Farihi, M. Jura, Inseok Song, A. J. Weinberger, and B. Zuckerman, The Astrophysical Journal 632, #2 (October 2005), pp. L119–L122.
  9. "GD 362 Shows Signs It Had An Earthlike Planet". Scientificblogging.com. 2007-08-16. Archived from the original on 2013-02-02. Retrieved 2007-08-17.
  10. "Stars with Exoplanets: GD 362". Retrieved 2007-08-17.
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