The CARMENES Search For Exoplanets Around M dwarfs -- LP 714-47b (TOI 442.01): Populating The Neptune desert

TESS Target Pixel File (TPF) of TOI 442 (created with tpfplotter1 , Aller et al. 2020). The pipeline aperture mask is shown as a red shaded region. Objects in the Gaia DR2 catalogue are overplotted with red circles (size depending on brightness as indicated in the legend). TOI 442 is marked with a white cross.

We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, m_b = 30.8 +/- 1.5 M_earth , R_b = 4.7 +/- 0.3 R_earth ) located in the 'hot Neptune desert'.

Confirmation of the TESS Object of Interest (TOI 442.01) was achieved with radial-velocity follow-up using CARMENES, ESPRESSO, HIRES, iSHELL, and PFS, as well as from photometric data using TESS, Spitzer, and ground-based photometry from MuSCAT2, TRAPPIST- South, MONET-South, the George Mason University telescope, the Las Cumbres Observatory Global Telescope network, the El Sauce telescope, the TUBITAK National Observatory, the University of Louisville Manner Telescope, and WASP-South. We also present high-spatial resolution adaptive optics imaging with the Gemini Near-Infrared Imager.

The low uncertainties in the mass and radius determination place LP 714-47 b among physically well-characterised planets, allowing for a meaningful comparison with planet structure models. The host star LP 714-47 is a slowly rotating early M dwarf (T_eff = 3950 +/- 51 K) with a mass of 0.59 +/- 0.02 M_sun and a radius of 0.58 +/- 0.02 R_sun. From long-term photometric monitoring and spectroscopic activity indicators, we determine a stellar rotation period of about 33 d. The stellar activity is also manifested as correlated noise in the radial-velocity data. In the power spectrum of the radial-velocity data, we detect a second signal with a period of 16 days in addition to the four-day signal of the planet. This could be shown to be a harmonic of the stellar rotation period or the signal of a second planet. It may be possible to tell the difference once more TESS data and radial-velocity data are obtained.

S. Dreizler, I., J., M. Crossfield, D. Kossakowski, P. Plavchan, S., V. Jeffers, J. Kemmer, R. Luque, N. Espinoza, E. Pallé, K. Stassun, E. Matthews, B. Cale, J., A. Caballero, M. Schlecker, J. Lillo-Box, M. Zechmeister, S. Lalitha, A. Reiners, A. Soubkiou, B. Bitsch, M., R. Zapatero Osorio, P. Chaturvedi, A., P. Hatzes, G. Ricker, R. Vanderspek, D., W. Latham, S. Seager, J. Winn, J. M. Jenkins, J. Aceituno, P., J. Amado, K. Barkaoui, M. Barbieri, N., M. Batalha, F., F. Bauer, B. Benneke, Z. Benkhaldoun, C, Beichman, J. Berberian, J. Burt, R., P. Butler, D., A. Caldwell, A. Chintada, A. Chontos, J., L. Christiansen, D. R. Ciardi, C. Cifuentes, K., A. Collins, K., I. Collins, D. Combs, M. Cortés-Contreras, J., D. Crane, T. Daylan, D. Dragomir, E. Esparza-Borges, P. Evans, F. Feng, E., E. Flowers, A. Fukui, B. Fulton, E. Furlan, E. Gaidos, C. Geneser, S. Giacalone, M. Gillon, E. Gonzales, V. Gorjian, C. Hellier, D. Hidalgo, A., W. Howard, S. Howell, D. Huber, H. Isaacson, E. Jehin, E., L., N. Jensen, A. Kaminski, S., R. Kane, K. Kawauchi, J., F. Kielkopf, H. Klahr, M., R. Kosiarek, L. Kreidberg, M., Kürster, M. Lafarga, J. Livingston, D. Louie, A. Mann, A. Madrigal-Aguado, R., A. Matson, T. Mocnik, J., C. Morales, P., S. Muirhead, F. Murgas, S. Nandakumar, N. Narita, G. Nowak, M. Oshagh, H. Parviainen, V., M. Passegger, D. Pollacco et al. (21 additional authors not shown)

Comments: Accepted for publication in A&A. 24 pages, 21 figures, 5 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2011.01716 [astro-ph.EP] (or arXiv:2011.01716v1 [astro-ph.EP] for this version)
Submission history
From: Stefan Dreizler
[v1] Tue, 3 Nov 2020 14:10:12 UTC (15,710 KB)

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