SOPHIE velocimetry of Kepler transit candidates. I. Detection of the low-mass white dwarf KOI 74b

D. EHRENREICH; A. M. LAGRANGE; F. BOUCHY; C. PERRIER; G. HÉBRARD; I. BOISSE; X. BONFILS; L. ARNOLD; X. DELFOSSE; M. DESORT; R. F. DÍAZ; A. EGGENBERGER; T. FORVEILLE; C. LOVIS; C. MOUTOU; F. PEPE; F. PONT; N. C. SANTOS; A. SANTERNE; D. SÉGRANSAN; S. UDRY; A. VIDAL-MADJAR

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2011 vol. 525 p. 1 - 8

0004-6361

The Kepler mission has detected transits and occultations of a hot compact object around an early-type star, the Kepler Object of Interest KOI 74. The mass of this transiting object was photometrically assessed in a previous study using the presence of the relativistic beaming effect (so-called ?Doppler boosting?) in the light curve. Our aim was to provide a spectroscopic validation of this pioneering approach. We measured the radial velocity variations of the A1V star KOI 74 with the SOPHIE spectrograph at the 1.93-m telescope of the Observatoire de Haute-Provence (France). Radial velocity measurements of this star are challenging because of the high level of stellar pulsations and the few available spectral lines. Using a technique dedicated to early-type main-sequence stars, we measured radial velocity variations compatible with a companion of mass 0.252 ± 0.025 {M_sun}, in good agreement with the value derived from the Kepler light curve. This work strengthens the scenario suggesting that KOI 74 is a blue straggler orbited by a stellar core despoiled of its envelope, the low-mass white dwarf KOI 74b.