Periodic Flux Variability of Stars due to the Reflex Doppler Effect Induced by Planetary Companions
By Abraham Loeb, B. Gaudi. 2003
180 citations recorded by the source corpus.
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, 𝒪(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 Mp sin i ≳ 5MJ and P ≲ 0.1 yr around the ~104 main-sequence stars with spectral types A-K and apparent magnitude V < 12 in its field of view.
Subfields: Astronomy and Astrophysics, Electrical and Electronic Engineering
View Paper: https://www.semanticscholar.org/paper/aa519e0a82b7e5b8b0968bced708783e9780c4b7
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Citations in the corpus
- PHYSICS OF ECLIPSING BINARIES. II. TOWARD THE INCREASED MODEL FIDELITY (2016, background): “Loeb & Gaudi (2003) showed that the boosting signal in exoplanet-hosting stars is larger than variability due to reflected light from the planet; Zucker et al. (2007) did a similar study for binary stars and showed that ellipsoidal variability, reflection, and boosting are the same…”
- KEPLER-413B: A SLIGHTLY MISALIGNED, NEPTUNE-SIZE TRANSITING CIRCUMBINARY PLANET (2014, unknown): “Using Equations 2 and 3 from Loeb and Gaudi (2003), we estimate the boost factor 3−α = 5.13.”
- THERMAL PHASE VARIATIONS OF WASP-12b: DEFYING PREDICTIONS (2011, unknown): “24 It is tempting to attribute the early peak of the 3.6 μ m phase curve to Doppler beaming, which would produce a peak in flux when the star is moving toward us, a quarter period before superior conjunction (Loeb & Gaudi 2003).”
- Magnetic activity in the photosphere of CoRoT-Exo-2a. Active longitudes and short-term spot cycle in (2008, background): “The flux variation associated with the Doppler shift produced by the star’s reflex motion has a relative amplitude of only 8.0 × 10−6 (Loeb & Gaudi 2003).”
- Global Climate and Atmospheric Composition of the Ultra-hot Jupiter WASP-103b from HST and Spitzer Phase Curve Observations (2018, methodology): “Using the analytic expression from Loeb & Gaudi (2003), we estimated the effect of Doppler beaming and found that it contributes less than 10 ppm to the measured flux.”