Exoplanets & Exomoons

Wolf 327b: A New Member Of The Pack Of Ultra-short-period Super-Earths Around M Dwarfs

By Keith Cowing
Status Report
January 24, 2024
Filed under , , , , , , ,
Wolf 327b: A New Member Of The Pack Of Ultra-short-period Super-Earths Around M Dwarfs
Tpfplotter (Aller et al. 2020) target pixel file (TPF) images of Wolf 327 for sectors 21 and 48. The red squares correspond to the TESS aperture used to compute the photometry, the size of the red circles represent the Gaia DR3 (Gaia Collaboration et al. 2023) magnitudes of the stars, and the gray arrows shows the Gaia DR3 proper motion directions of each star inside the field of view. Wolf 327b is positioned at the center (star 1), star 7 (TIC 4918919) is a known eclipsing binary. — astro-ph.EP

Planets with orbital periods shorter than 1 day are rare and have formation histories that are not completely understood. Small (Rp<2R⊕) ultra-short-period (USP) planets are highly irradiated, probably have rocky compositions with high bulk densities, and are often found in multi-planet systems.

Additionally, USP planets found around small stars are excellent candidates for characterization using present-day instrumentation. Of the current full sample of approximately 5500 confirmed exoplanets, only 130 are USP planets and around 40 have mass and radius measurements. Wolf 327 (TOI-5747) is an M dwarf (R⋆=0.406±0.015R⊙, M⋆=0.405±0.019M⊙, Teff=3542±70 K, and V=13 mag) located at a distance d=28.5 pc. NASA’s planet hunter satellite, TESS, detected transits in this star with a period of 0.573 d (13.7 h) and with a transit depth of 818 ppm. Ground-based follow-up photometry, high resolution imaging, and radial velocity (RV) measurements taken with the CARMENES spectrograph confirm the presence of this new USP planet.

Wolf 327b is a super-Earth with a radius of Rp=1.24±0.06R⊕ and a mass of Mp=2.53±0.46M⊕, yielding a bulk density of 7.24±1.66\,g cm−3 and thus suggesting a rocky composition. Owing to its close proximity to its host star (a=0.01 au), Wolf 327b has an equilibrium temperature of 996±22 K. This planet has a mass and radius similar to K2-229b, a planet with an inferred Mercury-like internal composition. Planet interior models suggest that Wolf 327b has a large iron core, a small rocky mantle, and a negligible (if any) H/He atmosphere.

F. Murgas, E. Pallé, J. Orell-Miquel, I. Carleo, L. Peña-Moñino, M. Pérez-Torres, C. N. Watkins, S. V. Jeffers, M. Azzaro, K. Barkaoui, A. A. Belinski, J. A. Caballero, D. Charbonneau, D. V. Cheryasov, D. R. Ciardi, K. A. Collins, M. Cortés-Contreras, J. de Leon, C. Duque-Arribas, G. Enoc, E. Esparza-Borges, A. Fukui, S. Geraldía-González, E. A. Gilbert, A. P. Hatzes, Y. Hayashi, Th. Henning, E. Herrero, J. M. Jenkins, J. Lillo-Box, N. Lodieu, M. B. Lund, R. Luque, D. Montes, E. Nagel, N. Narita, H. Parviainen, A. S. Polanski, S. Reffert, M. Schlecker, P. Schöfer, R. P. Schwarz, A. Schweitzer, S. Seager, K. G. Stassun, H. M. Tabernero, Y. Terada, J. D. Twicken, S. Vanaverbeke, J. N. Winn, R. Zambelli, P. J. Amado, A. Quirrenbach, A. Reiners, I. Ribas

Comments: 26 pages, 19 figures. Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2401.12150 [astro-ph.EP] (or arXiv:2401.12150v1 [astro-ph.EP] for this version)
Focus to learn more
Submission history
From: Felipe Murgas
[v1] Mon, 22 Jan 2024 17:37:42 UTC (4,178 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻