GD 362 explained

GD 362 is a white dwarf approximately 150 light years from Earth. 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. 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.^[1]

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. 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.^{[2] [3] [4]}

In 2009 it was discovered that this white dwarf has an anomalous high hydrogen content. This could come from the accretion of a water-rich body with a mass between Callisto and Mars.^[5] The origin of the high amount of hydrogen is however still up for debate.^{[6] [7]}

GD 362 has been a white dwarf for approximately 900 million years.^[8]

See also

• List of exoplanets and planetary debris around white dwarfs
• G 29-38 was the first white dwarf for which a disk was discovered

External links

• Universe Today, Dead Star Found Polluted By Earthlike Planet
• Astronomy Now, Doomed planet may have been drenched in water

Notes and References

1. http://adsabs.harvard.edu/abs/2005ApJ...632L.119B A Dusty Disk around GD 362, a White Dwarf with a Uniquely High Photospheric Metal Abundance
2. News: Burned-out star harbors signs of Earthlike planets. 2007-08-16. Reuters. Will. Dunham. 2007-08-17.
3. Zuckerman . etal . The Chemical Composition of an Extrasolar Minor Planet . The Astrophysical Journal . 671 . 1 . 2007 . 872–877 . 10.1086/522223 . 2007ApJ...671..872Z. 0708.0198 . 9631635 .
4. Web site: GD 362 Shows Signs It Had An Earthlike Planet. Scientificblogging.com. 2007-08-17. 2007-08-16. dead. https://archive.today/20130202084814/http://www.scientificblogging.com/news/gd_362_harbors_signs_of_earthlike_planet. 2013-02-02.
5. Jura . M. . Muno . M. P. . Farihi . J. . Zuckerman . B. . 2009-07-01 . X-Ray and Infrared Observations of Two Externally Polluted White Dwarfs . The Astrophysical Journal . 699 . 2 . 1473–1479 . 0905.0117 . 2009ApJ...699.1473J . 10.1088/0004-637X/699/2/1473 . 0004-637X.
6. Wachlin . Felipe . Evidence of water accretion in GD 362? . Vauclair . Gérard . Vauclair . Sylvie . Physics of Oscillating Stars . 2018-09-01 . 16 . 10.5281/zenodo.1492312 . 2018phos.confE..16W.
7. Raddi . R. . Gänsicke . B. T. . Koester . D. . Farihi . J. . Hermes . J. J. . Scaringi . S. . Breedt . E. . Girven . J. . 2015-06-01 . Likely detection of water-rich asteroid debris in a metal-polluted white dwarf . Monthly Notices of the Royal Astronomical Society . 450 . 2 . 2083–2093 . 1503.07864 . 2015MNRAS.450.2083R . 10.1093/mnras/stv701 . free . 0035-8711.
8. Web site: Stars with Exoplanets: GD 362. 2007-08-17.