* Astronomy

Title: Possible Signs of Water and Differentiation in a Rocky Exoplanetary Body
Authors: J. Farihi, C. Brinkworth, B. T. Gaensicke, T. R. Marsh, J. Girven, D. W. Hoard, B. Klein, D. Koester

Spitzer observations reveal the presence of warm debris from a tidally destroyed rocky and possibly icy planetary body orbiting the white dwarf GD61. Ultraviolet and optical spectroscopy of the metal-contaminated stellar photosphere reveal traces of hydrogen, oxygen, magnesium, silicon, iron, and calcium. The nominal ratios of these elements indicate an excess of oxygen relative to that expected from rock-forming metal oxides, and thus it is possible that water was accreted together with the terrestrial-like debris. Iron is found to be deficient relative to magnesium and silicon, suggesting the material may have originated as the outer layers of a differentiated parent body, as is widely accepted for the Moon.

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