Two Saturn-mass planets around M dwarfs

DOI

The CARMENES radial-velocity survey is currently searching for planets in a sample of 387 M dwarfs. Here we report on two Saturn-mass planets orbiting TYC 2187-512-1 (Mstar=0.50M_{sun}) and TZ Ari (Mstar=0.15M{sun}), respectively. We obtained supplementary photometric time series, which we use along with spectroscopic information to determine the rotation periods of the two stars. In both cases, the radial velocities also show strong modulations at the respective rotation period. We thus modeled the radial velocities as a Keplerian orbit plus a Gaussian process representing the stellar variability. TYC 2187-512-1 is found to harbor a planet with a minimum mass of 0.33M_Jup in a near-circular 692-day orbit. The companion of TZ Ari has a minimum mass of 0.21M_Jup_, orbital period of 771d, and orbital eccentricity of 0.46. We provide an overview of all known giant planets in the CARMENES sample, from which we infer an occurrence rate of giant planets orbiting M dwarfs with periods up to 2 years in the range between 2% to 6%. TZ Ari b is only the second giant planet discovered orbiting a host with mass less than 0.3M_{sun}_. These objects occupy an extreme location in the planet mass versus host mass plane. It is difficult to explain their formation in core-accretion scenarios, so they may possibly have been formed through a disk fragmentation process.

Identifier
DOI http://doi.org/10.26093/cds/vizier.36630048
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/A+A/663/A48
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/663/A48
Related Identifier https://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/663/A48
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/A+A/663/A48
Provenance
Creator Quirrenbach A.; Passegger V.M.; Trifonov T.; Amado P.J.; Caballero J.A.,Reiners A.; Ribas I.; Aceituno J.; Bejar V.J.S.; Chaturvedi P.,Gonzalez-Cuesta L.; Henning T.; Herrero E.; Kaminski A.; Kuerster M.,Lalitha S.; Lodieu N.; Lopez-Gonzalez M.J.; Montes D.; Palle E.; Perger M.,Pollacco D.; Reffert S.; Rodriguez E.; Rodriguez Lopez C.; Shan Y.,Tal-Or L.; Zapatero Osorio M.R.; Zechmeister M.
Publisher CDS
Publication Year 2022
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Exoplanet Astronomy; Natural Sciences; Observational Astronomy; Physics; Stellar Astronomy