The CARMENES search for exoplanets around M dwarfs

• Published in: Astronomy and astrophysics (Berlin) 2020-12, Vol.644
• Main Authors: Dreizler, S, Crossfield, I J M, Kossakowski, D, Plavchan, P, Kemmer, J, Luque, R, Espinoza, N, Pallé, E, Stassun, K, Matthews, E, Cale, B, Caballero, J A, Schlecker, M, Lillo-Box, J, Zechmeister, M, Lalitha, S, Reiners, A, Soubkiou, A, Bitsch, B, Zapatero Osorio, M R, Hatzes, A P, Ricker, G, Latham, D W, Seager, S, Winn, J, Jenkins, J M, Aceituno, J, Amado, P J, Barkaoui, K, Barbieri, M, Batalha, N M, Bauer, F F, Benneke, B, Benkhaldoun, Z, Beichman, C, Berberian, J, Burt, J, Butler, R P, Chintada, A, Christiansen, J L, Ciardi, D R, Collins, K I, Combs, D, Crane, J D, Daylan, T, Dragomir, D, Esparza-Borges, E, Evans, P, Feng, F, Flowers, E E, Fukui, A, Fulton, B, Furlan, E, Gaidos, E, Geneser, C, Giacalone, S, Gillon, M, Gorjian, V, Howard, A W, Howell, S, Huber, D, Isaacson, H, Jehin, E, Kaminski, A, Kawauchi, K, Kielkopf, J F, Klahr, H, Kreidberg, L, Kürster, M, Lafarga, M, Louie, D, Madrigal-Aguado, A, Matson, R A, Mocnik, T, Muirhead, P S, Murgas, F, Nandakumar, S, Narita, N, Nowak, G, Oshagh, M, Parviainen, H, Passegger, V M, Pollacco, D, Quirrenbach, A, Reefe, M, Ribas, I, Robertson, P, Rodríguez-López, C, Rose, M E, Roy, A, Schweitzer, A, Shectman, S, Tanner, A, Şenavcı, H V, Teske, J, Villasenor, J, Wang, S X, Weiss, L M, Yılmaz, M, Zohrabi, F
• Format: Article
• Language: English
• Subjects: Adaptive optics; Extrasolar planets; Gas giant planets; Observatories; Photometry; Planetary rotation; Red dwarf stars; Spatial resolution; Stellar activity; Stellar rotation; Telescopes; Velocity
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202038016

We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, mb = 30.8 ± 1.5M⊕, Rb = 4.7 ± 0.3 R⊕) 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 TÜBİTAK 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 (Teff = 3950 ± 51 K) with a mass of 0.59 ± 0.02M⊙ and a radius of 0.58 ± 0.02R⊙. 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.