AN ALUMINUM/CALCIUM-RICH, IRON-POOR, WHITE DWARF STAR: EVIDENCE FOR AN EXTRASOLAR PLANETARY LITHOSPHERE?
- Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
- Institut fur Theoretische Physik und Astrophysik, University of Kiel, 24098 Kiel (Germany)
- Departement de Physique, Universite de Montreal, Montreal, QC H3C 3J7 (Canada)
- Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093-0424 (United States)
The presence of elements heavier than helium in white dwarf atmospheres is often a signpost for the existence of rocky objects that currently or previously orbited these stars. We have measured the abundances of various elements in the hydrogen-atmosphere white dwarfs G149-28 and NLTT 43806. In comparison with other white dwarfs with atmospheres polluted by heavy elements, NLTT 43806 is substantially enriched in aluminum but relatively poor in iron. We compare the relative abundances of Al and eight other heavy elements seen in NLTT 43806 with the elemental composition of bulk Earth, with simulated extrasolar rocky planets, with solar system meteorites, with the atmospheric compositions of other polluted white dwarfs, and with the outer layers of the Moon and Earth. The best agreement is found with a model that involves accretion of a mixture of terrestrial crust and upper mantle material onto NLTT 43806. The implication is that NLTT 43806 is orbited by a differentiated rocky planet, perhaps quite similar to Earth, that has suffered a collision that stripped away some of its outer layers.
- OSTI ID:
- 21587450
- Journal Information:
- Astrophysical Journal, Vol. 739, Issue 2; Other Information: DOI: 10.1088/0004-637X/739/2/101; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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