Evidence for a spectroscopic direct detection of reflected light from 51 Peg b

Abstract

The detection of reflected light from an exoplanet is a difficult technical challenge at optical wavelengths. Even though this signal is expected to replicate the stellar signal, not only is it several orders of magnitude fainter, but it is also hidden among the stellar noise. We apply a variant of the cross-correlation technique to HARPS observations of 51 Peg to detect the reflected signal from planet 51 Peg b. Our method makes use of the cross-correlation function of a binary mask with high-resolution spectra to amplify the minute planetary signal that is present in the spectra by a factor proportional to the number of spectral lines when performing the cross correlation. The resulting cross-correlation functions are then normalized by a stellar template to remove the stellar signal. Carefully selected sections of the resulting normalized CCFs are stacked to increase the planetary signal further. The recovered signal allows probing several of the planetary properties, including its real mass and albedo. We detect evidence for the reflected signal from planet 51 Peg b at a significance of 3σ_noise. The detection of the signal permits us to infer a real mass of 0.46^+0.06_-0.01 M_Jup (assuming a stellar mass of 1.04\;M_Sun) for the planet and an orbital inclination of 80^+10_-19 degrees. The analysis of the data also allows us to infer a tentative value for the (radius-dependent) geometric albedo of the planet. The results suggest that 51Peg b may be an inflated hot Jupiter with a high albedo (e.g., an albedo of 0.5 yields a radius of 1.9 \pm 0.3 R_Jup for a signal amplitude of 6.0\pm0.4 x 10^-5). We confirm that the method we perfected can be used to retrieve an exoplanet's reflected signal, even with current observing facilities. The advent of next generation of observing facilities will yield new opportunities for this type of technique to probe deeper into exoplanets.

9 pages, 6 figures

References in corpus (13)

• The Occurrence and Mass Distribution of Close-in Super-Earths, Neptunes, and Jupiters
• Sodium Absorption From the Exoplanetary Atmosphere of HD189733b Detected in the Optical Transmission Spectrum
• The fast spin-rotation of a young extrasolar planet
• Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy
• Kepler-62: A five-planet system with planets of 1.4 and 1.6 Earth radii in the Habitable Zone
• Hubble Space Telescope Near-IR Transmission Spectroscopy of the Super-Earth HD 97658b
• Carbon monoxide and water vapor in the atmosphere of the non-transiting exoplanet HD 179949 b
• Weighing The Non-Transiting Hot Jupiter Tau BOO b
• H2O abundances in the atmospheres of three hot Jupiters
• Impact of occultations of stellar active regions on transmission spectra: Can occultation of a plage mimic the signature of a blue sky?
• Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
• Clouds on the hot Jupiter HD189733b: constraints from the reflection spectrum
• The Albedos of Kepler's Close-in super-Earths

Cited by in corpus (17)

• ESPRESSO@VLT -- On-sky performance and first results
• Discovery of water at high spectral resolution in the atmosphere of 51 Peg b
• Evidence for a spectroscopic direct detection of reflected light from 51 Peg b
• Evidence for the Direct Detection of the Thermal Spectrum of the Non-Transiting Hot Gas Giant HD 88133 b
• Detection of Water Vapor in the Thermal Spectrum of the Non-Transiting Hot Jupiter upsilon Andromedae b
• Black Mirror: The impact of rotational broadening on the search for reflected light from 51 Pegasi b with high resolution spectroscopy
• Exoplanet Interior Retrievals: core masses and metallicities from atmospheric abundances
• The GAPS Programme at TNG. XXIX. No detection of reflected light from 51 Peg b using optical high-resolution spectroscopy
• Polarization of hot Jupiter systems: a likely detection of stellar activity and a possible detection of planetary polarization
• Reflected Light Phase Curves in the TESS Era
• Dark Matter (H)eats Young Planets
• How eclipse time variations, eclipse duration variations, and radial velocities can reveal S-type planets in close eclipsing binaries
• ROME III. The Arecibo Search for Star-Planet Interactions at 5 GHz
• Planet Earth in reflected and polarized light: II. Refining contrast estimates for rocky exoplanets with ELT and HWO
• No TiO detected in the hot Neptune-desert planet LTT-9779 b in reflected light at high spectral resolution
• Quantum-inspired exoplanet detection in the presence of experimental imperfections
• How does the shape of the stellar spectrum affect the Raman scattering features in the albedo of exoplanets?