Aliasing in the Radial Velocities of YZ Ceti: An Ultra-Short Period for YZ Ceti c?

Abstract

Mid-late M stars are opportunistic targets for the study of low-mass exoplanets in transit because of the high planet-to-star radius ratios of their planets. Recent studies of such stars have shown that, like their early-M counterparts, they often host multi-resonant networks of small planets. Here, we reanalyze radial velocity measurements of YZ Ceti, an active M4 dwarf for which the HARPS exoplanet survey recently discovered three exoplanets on short-period (P = 4.66, 3.06, 1.97 days) orbits. Our analysis finds that the orbital periods of the inner two planets cannot be uniquely determined using the published HARPS velocities. In particular, it appears likely that the 3.06-day period of YZ Ceti c is an alias, and that its true period is 0.75 days. If so, the revised minimum mass of this planet is less than 0.6 Earth masses, and its geometric transit probability increases to 10%. We encourage additional observations to determine the true periods of YZ Ceti b and c, and suggest a search for transits at the 0.75-day period in TESS lightcurves.

Accepted for publication in ApJ Letters

References in corpus (13)

• The Transiting Exoplanet Survey Satellite
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• RadVel: The Radial Velocity Modeling Toolkit
• Assessing statistical significance of periodogram peaks
• Radial velocity planets de-aliased. A new, short period for Super-Earth 55 Cnc e
• Accounting for velocity jitter in planet search surveys
• Towards Space-like Photometric Precision from the Ground with Beam-Shaping Diffusers
• Radial Velocity Data Analysis with Compressed Sensing Techniques
• The HARPS search for southern extra-solar planets XLII. A system of Earth-mass planets around the nearby M dwarf YZ Ceti

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• The CARMENES search for exoplanets around M dwarfs. Characterization of the nearby ultra-compact multiplanetary system YZ Ceti
• Improving exoplanet detection capabilities with the false inclusion probability. Comparison with other detection criteria in the context of radial velocities
• The Habitable-zone Planet Finder Detects a Terrestrial-mass Planet Candidate Closely Orbiting Gliese 1151: The Likely Source of Coherent Low-frequency Radio Emission from an Inactive Star
• Simulations for Planning Next-Generation Exoplanet Radial Velocity Surveys