2003/03/28 by Abraham Loeb, B. Scott Gaudi · 3 citations
Engineering · Physics and Astronomy · #Astrophysics and Star Formation Studies #CCD and CMOS Imaging Sensors #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/375551
4 pages, 2 figures. Revised version, minor changes. Accepted to ApJL, to appear in the May 10, 2003 issue
arxiv created 2003/03/28 · openalex publication_date 2003/04/08 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Upcoming space-based photometric satellites offer the possibility of detecting continuum flux variability at the micromagnitude (μmag) level. We show that the Doppler flux variability induced by the reflex motion of stars due to planetary companions has an amplitude of (3 - α) K / c , where K is the reflex radial velocity amplitude and α ≈ is the logarithmic slope of the source spectral flux in the observed frequency band. For many of the known close-in planetary systems with periods P ≲ 0.2 yr, the periodic Doppler variability, (μmag), is significant relative to the variability caused by reflected light from the planetary companion. For companions with P ≳ 0.2 yr, the Doppler signal is larger than the reflected light signal. We show that the future photometric satellites should reach the sensitivity to detect this Doppler variability. In particular, the Kepler satellite should have the photon noise sensitivity to detect at a signal-to-noise ratio ≳5 all planets with minimum mass M p sin i ≳ 5 M J and P ≲ 0.1 yr around the ~10 4 main-sequence stars with spectral types A-K and apparent magnitude V < 12 in its field of view.