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arXiv · 0801.2917

The "DODO" survey I: limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa 2)

M. R. Burleigh·F. J. Clarke·E. Hogan·C. S. Brinkworth·P. Bergeron·P. Dufour·P. D. Dobbie·A. J. Levan·S. T. Hodgkin·D. W. Hoard·S. Wachter
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Abstract

We report limits in the planetary-mass regime for companions around the nearest single white dwarf to the Sun, van Maanen's star (vMa 2), from deep J-band imaging with Gemini North and Spitzer IRAC mid-IR photometry. We find no resolved common proper motion companions to vMa 2 at separations from 3" - 45", at a limiting magnitude of J~23. Assuming a total age for the system of 4.1 +/-1 Gyr, and utilising the latest evolutionary models for substellar objects, this limit is equivalent to companion masses >7 +/-1 Mjup (T~300K). Taking into account the likely orbital evolution of very low mass companions in the post-main sequence phase, these J-band observations effectively survey orbits around the white dwarf progenitor from 3 - 50AU. There is no flux excess detected in any of the complimentary Spitzer IRAC mid-IR filters. We fit a DZ white dwarf model atmosphere to the optical BVRI, 2MASS JHK and IRAC photometry. The best solution gives T=6030 +/- 240K, log g=8.10 +/-0.04 and, hence, M= 0.633 +/-0.022Msun. We then place a 3sigma upper limit of 10 +/-2 Mjup on the mass of any unresolved companion in the 4.5 micron band.

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M. R. Burleigh, F. J. Clarke, E. Hogan, C. S. Brinkworth, P. Bergeron, P. Dufour, P. D. Dobbie, A. J. Levan, S. T. Hodgkin, D. W. Hoard, S. Wachter. 2008-01-18. The "DODO" survey I: limits on ultra-cool substellar and planetary-mass companions to van Maanen's star (vMa 2). https://doi.org/10.1111/j.1745-3933.2008.00446.x

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