Open AccessA new upper limit on the reflected starlight from τ Bootis b
Author(s) -
Leigh Christopher,
Cameron Andrew Collier,
Horne Keith,
Penny Alan,
James David
Publication year - 2003
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2003.06901.x
Subject(s) - physics , starlight , geometric albedo , astrophysics , planet , radius , albedo (alchemy) , astronomy , giant planet , amplitude , spectral line , venus , stars , planetary system , photometry (optics) , optics , astrobiology , art , computer security , performance art , computer science , art history
ABSTRACT Using improved Doppler tomographic signal‐analysis techniques, we have carried out a deep search for starlight reflected from the giant planet orbiting the star τ Bootis. We combined echelle spectra secured at the 4.2‐m William Herschel telescope in 1998 and 1999 (which yielded a tentative detection of a reflected starlight component from the orbiting companion) with new data obtained in 2000 (which failed to confirm the detection). The combined data set comprises 893 high‐resolution spectra with a total integration time of 75 h 32 m spanning 17 nights. We establish an upper limit on the planet's geometric albedo p < 0.39 (at the 99.9 per cent significance level) at the most probable orbital inclination i ≃ 36° , assuming a grey albedo, a Venus‐like phase function and a planetary radius R p = 1.2 R Jup . We are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks. Although a weak candidate signal appears near to the most probable radial velocity amplitude, its statistical significance is insufficient for us to claim a detection with any confidence.