On the Binary Nature of Dust-encircled BD+20 307

Abstract

Three epochs of high resolution spectra of the star BD+20 307 show that it is a short period (~3.5 day) spectroscopic binary of two nearly identical stars. Surprisingly, the two stars, though differing in effective temperature by only ~250 K and having a mass ratio of 0.91, show very different Li line equivalent widths. A Li 6707 Angstrom line is only detected from the primary star, and it is weak. This star is therefore likely to be older than 1 Gyr. If so, the large amount of hot circumbinary dust must be from a very large and recent, but very late evolutionarily, collision of planetesimals.

Accepted to ApJ Letters, with corrected typos and added info on Li equivalent widths

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• The Absence of Cold Dust and the Mineralogy and Origin of the Warm Dust Encircling BD +20 307
• Planetary systems around close binary stars: the case of the very dusty, Sun-like, spectroscopic binary BD+20 307
• A new sample of warm extreme debris disks from the ALLWISE catalog
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• Project Hephaistos - II. Dyson sphere candidates from Gaia DR3, 2MASS, and WISE
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• Studying the Evolution of Warm Dust Encircling BD +20 307 Using SOFIA
• Collisions of Terrestrial Worlds: The Occurrence of Extreme Mid-Infrared Excesses around Low-Mass Field Stars
• Close Binaries with Infrared Excess: Destroyers of Worlds?
• Prospect for UV observations from the Moon
• One of Everything: The Breakthrough Listen Exotica Catalog
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