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Astron. Astrophys. 349, L34-L36 (1999)


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Letter to the Editor

HD 30187 B and HD 39927 B: two suspected nearby hot subdwarfs in resolved binaries *

Valeri V. Makarov and Claus Fabricius

Copenhagen University Observatory, Juliane Maries Vej 30, DK-2100 Copenhagen O, Denmark

Received 25 June 1999 / Accepted 13 July 1999

Abstract

In doing a [FORMULA], [FORMULA] photometric solution for close Hipparcos double stars, based on the observations with the Tycho instrument of the Hipparcos satellite, we discovered two very blue subluminous components of HD 30187 and HD 39927. The position of the components on an observational HR diagram implies their being sdO or sdB hot subdwarfs. The only previously known sdO component of a visual binary, HD 113001 B, is also confirmed by our photometric data. The two new candidate hot subdwarfs have parallaxes 8.25 and 10.17 mas, respectively, and with angular separations of about 0.35 arcsec, the orbital periods must be of the order of 100 years. This should make it possible to determine their masses from observation.

Key words: stars: individual: HD 30187 B – stars: individual: HD 39927 B – stars: white dwarfs – stars: binaries: visual

* Based on observations made with the ESA Hipparcos satellite.

Send offprint requests to: makarov@astro.ku.dk

© European Southern Observatory (ESO) 1999

Online publication: August 25, 1999

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