GD 362
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| Observation data Epoch J2000.0 (ICRS) |
|
|---|---|
| Constellation (pronunciation) |
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[4] pc) |
| Details | |
| Mass | 0.73±0.02[5] M☉ |
| Surface gravity (log g) | 8.24±0.04[5] |
| Temperature | 10540±200[5] K |
| Other designations | |
|
G 204-14, NLTT 44986, WD 1729+371, EGGR 545, 2MASS J17313433+3705209, PG 1729+371[6]
|
|
GD 362 is a white dwarf star 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.[7]
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.[5] 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][8][5]
GD 362 has been a white dwarf for approximately 900 million years.[9]
[edit] References
- ^ Constellation boundaries, CDS. Accessed on line October 4, 2007.
- ^ a b c d e 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.
- ^ a b 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.
- ^ a b c d Dunham, Will. "Burned-out star harbors signs of Earthlike planets", Reuters, Aug 16, 2007. Retrieved on 2007-08-17.
- ^ a b c d e The Chemical Composition of an Extrasolar Minor Planet, B. Zuckerman, D. Koester, C. Melis, and B. Hansen, arXiv:0708.0198v1, August 1, 2007. Accessed on line October 4, 2007.
- ^ SIMBAD. Entry for GD 362. Accessed on line October 4, 2007.
- ^ 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.
- ^ GD 362 Shows Signs It Had An Earthlike Planet. Scientificblogging.com (16 August 2007). Retrieved on 2007-08-17.
- ^ Stars with Exoplanets: GD 362. Retrieved on 2007-08-17.
