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GD 362

Star in the constellation Hercules

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1349221590 · 2026-04-16T08:42:22Z
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spectroscopy5 uses in this article atmosphere3 uses in this article white4 uses in this article abundance3 uses in this article hydrogen3 uses in this article material3 uses in this article however3 uses in this article dwarf3 uses in this article probe3 uses in this article different2 uses in this article telescope2 uses in this article emission2 uses in this article infrared2 uses in this article silicate2 uses in this article olivine2 uses in this article Optical2 uses in this article stellar2 uses in this article amount2 uses in this article carbon2 uses in this article debris2 uses in this article

Overview

GD 362 is a white dwarf approximately 183 light-years from Earth. 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. GD 362 has an exceptionally strong infrared excess. 2.4% of the star light is re-processed into the mid-infrared. Optical spectroscopy can only probe material that did already fall into the atmosphere. Infrared spectroscopy can however directly probe the material of the disk. James Webb Space Telescope spectroscopy did find strong silicate emission between 9 and 11 μm. This feature can be explained by a combination of olivine and pyroxene silicate minerals.

Dust modelling showed that the minerals ferrosilite (28.3%), amorphous olivine (24.1%) and forsterite (12.6%) have the highest mass fraction. Additionally the emission in the near-infrared requires grains such as carbon. The carbon and silicates reside inside a disk located within 140 to 1400 stellar radii from the white dwarf and the disk has a scale height greater than half the stellar radius. This is just outside the Roche limit and requires hot debris with a temperature of close to the star. The element abundance matches with the abundance from optical spectroscopy, except for hydrogen. The elemental abundance of the disk also matches that of CI chondrites, with aluminium elevated and oxygen slightly depleted. The mineral composition is however different to CI chondrites, as the disk does not contain any phyllosilicates.

The origin of the high amount of hydrogen is however still up for debate. JWST spectroscopy did probe the material of the disk and found it to be very dry. No H-bearing minerals and no water is detected inside the disk. The large amount of hydrogen in the atmosphere could be explained by a past accretion of an ice-rich body, different to the body that formed the disk currently present.

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

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