Abstract
We discuss the interpretation of the distortions to the stellar spectral lines, with particular attention to line bisectors in the presence of an orbiting planetary companion. We present a simple model whereby light reflected by the companion can cause temporal variations to the observed line profiles. These distortions have a characteristic signature that depends on the inclination angle of the system. For the known close-in extrasolar giant planets, the expected amplitude of the effect might not be far from current detection capabilities. This method could be used to detect the presence of the companion directly, yielding the orbital inclination and hence the planetary mass. Futhermore, a detection would measure a combination of the planetary radius and albedo, from which a minimum radius may be deduced.
Highlights
The interpretation of low-amplitude, periodic radial velocity variations in solar-type stars as being induced by orbiting lowmass companions was recently put into question. Gray (1997) and Gray & Hatzes (1997) claimed to detect distortions to the line profile bisector in one spectral line (Fe i l6253) of the star 51 Pegasi at the well-known 4.23 day radial velocity period (Mayor & Queloz 1995; Marcy et al 1997)
Is it a given that the planet explanation is immediately excluded should intrinsic variations in the line profiles of 51 Peg be detected at the claimed orbital period? Our purpose in this Letter is twofold: (1) to provide a simple model whereby a close-in orbiting companion produces periodic distortions to the line profiles and (2) to explore the observational consequences of this effect, the amplitude of which might be close to current observational limits, and the specific signature of which is set by the orbital inclination of the system and the radius and albedo of the companion
We have shown that the presence of a close-in extrasolar giant planet can distort the observed spectral line profiles of
Summary
The interpretation of low-amplitude, periodic radial velocity variations in solar-type stars as being induced by orbiting lowmass companions was recently put into question. Gray (1997) and Gray & Hatzes (1997) claimed to detect distortions to the line profile bisector (the locus of midpoints of a stellar absorption line from the core up to the continuum) in one spectral line (Fe i l6253) of the star 51 Pegasi at the well-known 4.23 day radial velocity period (Mayor & Queloz 1995; Marcy et al 1997). Gray (1997) and Gray & Hatzes (1997) claimed to detect distortions to the line profile bisector (the locus of midpoints of a stellar absorption line from the core up to the continuum) in one spectral line (Fe i l6253) of the star 51 Pegasi at the well-known 4.23 day radial velocity period (Mayor & Queloz 1995; Marcy et al 1997) They stated that the planet hypothesis could not account for variations in the line profiles and proposed the alternative explanation that 51 Peg was undergoing nonradial pulsations. Is it a given that the planet explanation is immediately excluded should intrinsic variations in the line profiles of 51 Peg be detected at the claimed orbital period? Our purpose in this Letter is twofold: (1) to provide a simple model whereby a close-in orbiting companion produces periodic distortions to the line profiles and (2) to explore the observational consequences of this effect, the amplitude of which might be close to current observational limits, and the specific signature of which is set by the orbital inclination of the system and the radius and albedo of the companion
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
