A transmission spectrum of the planet candidate WD 1856+534 b and a lower limit to its mass

Abstract

The cool white dwarf WD 1856+534 was found to be transited by a Jupiter-sized object with a mass at or below 14 M${}_{\mathrm{Jup}}$. We used the GTC telescope to obtain and analyse photometry and low resolution spectroscopy of six transits of WD 1856+534 b, with the intention to derive the slope of the transmission spectrum, towards an eventual detection of Rayleigh scattering of the particles in its atmosphere. Such a slope, assuming a cloud-free atmosphere dominated by Rayleigh scattering, could be translated into an estimation of the mass of WD 1856+534 b. However, the resultant transmission spectrum is essentially flat, and therefore permits only the determination of lower mass limits of 2.4 M${}_{\mathrm{Jup}}$ at the 2-$\sigma$ level, or 1.6 M${}_{\mathrm{Jup}}$ at 3-$\sigma$. These limits have implications for some of the proposed formation scenarios for the object. We elaborate on the potential effects of clouds and hazes in our estimations, based on previous studies of Jupiter and Titan. In addition, we detected an H$\alpha$ absorption feature in the combined spectrum of the host white dwarf, that leads to the assignation of a DA classification and allows derivation of an independent set of atmospheric parameters. Furthermore, the epochs of five transits were measured with sub-second precision, which demonstrates that additional objects more massive than $\approx$5 M${}_{\mathrm{Jup}}$ and with periods longer than $O(100)$ days could be detected through the light travel time effect

14 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (17)

• The Gaia mission
• The Transiting Exoplanet Survey Satellite
• The frequency of planetary debris around young white dwarfs
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• A Giant Planet Candidate Transiting a White Dwarf
• A planetesimal orbiting within the debris disc around a white dwarf star
• Accretion of a giant planet onto a white dwarf
• Transit surveys for Earths in the habitable zones of white dwarfs
• Theoretical Transit Spectra for GJ 1214b and Other "Super-Earths"
• Titan solar occultation observations reveal transit spectra of a hazy world
• Limits to the planet candidate GJ 436c
• WD 1145+017 Photometric Observations During 8 Months of High Activity
• WD 1856 b: a close giant planet around a white dwarf that could have survived a common-envelope phase
• Enhanced Lidov-Kozai migration and the formation of the transiting giant planet WD1856+534b
• Kozai Migration Naturally Explains the White Dwarf Planet WD1856b
• Jupiter as an exoplanet: UV to NIR transmission spectrum reveals hazes, a Na layer and possibly stratospheric H2O-ice clouds
• Do instabilities in high-multiplicity systems explain the existence of close-in white dwarf planets?

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• Gemini/GMOS Transmission Spectroscopy of the Grazing Planet Candidate WD 1856+534 b
• MIRI-LRS spectrum of a cold exoplanet around a white dwarf: water, ammonia, and methane measurements
• TTV Constraints on Additional Planets in the WD 1856+534 system
• Common envelope evolution and triple dynamics as potential pathways to form the inner white dwarf + brown dwarf binary of the triple star system Gaia 0007-1605
• Aerosols and hydrocarbons in the atmosphere of a white dwarf planet
• Second-generation planet formation after tidal disruption from common envelope evolution
• Synthetic X-ray emission from white dwarf accreting planetary material