The vulcan photometer: A dedicated photometer for extrasolar planet searches

Citation
Wj. Borucki et al., The vulcan photometer: A dedicated photometer for extrasolar planet searches, PUB AST S P, 113(782), 2001, pp. 439-451
Citations number
23
Categorie Soggetti
Space Sciences
Journal title
PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC
ISSN journal
00046280 → ACNP
Volume
113
Issue
782
Year of publication
2001
Pages
439 - 451
Database
ISI
SICI code
0004-6280(200104)113:782<439:TVPADP>2.0.ZU;2-1
Abstract
A small CCD photometer dedicated to the detection of extrasolar planets has been developed and put into operation at Mount Hamilton, California. It si multaneously monitors 6000 stars brighter than 13th magnitude in its 49 deg (2) field of view. Observations are conducted all night every clear night o f the year. A single field is monitored at a cadence of eight images per ho ur for a period of about 3 months. When the data are folded for the purpose of discovering low-amplitude transits, transit amplitudes of 1% are readil y detected. This precision is sufficient to find Jovian-size planets orbiti ng solar-like stars, which have signal amplitudes from 1% to 2% depending o n the inflation of the planet's atmosphere and the size of the star. An inv estigation of possible noise sources indicates that neither star field crow ding, scintillation noise, nor photon shot noise are the major noise source s for stars brighter than visual magnitude 11.6. Over one hundred variable stars have been found in each star field. About 5 0 of these stars are eclipsing binary stars, several with transit amplitude s of only a few percent. Three stars that showed only primary transits were examined with high-precision spectroscopy. Two were found to be nearly ide ntical stars in binary pairs orbiting at double the photometric period. Spe ctroscopic observations showed the third star to be a high mass ratio singl e-lined binary. On 1999 November 22 the transit of a planet orbiting HD 209 458 was observed and the predicted amplitude and immersion times were confi rmed. These observations show that the photometer and the data reduction an d analysis algorithms have the necessary precision to find companions with the expected area ratio for Jovian-size planets orbiting solar-like stars.