The CARMENES search for exoplanets around M dwarfs: LP 714-47 b (TOI 442.01): populating the Neptune desert

Dreizler, S.; Crossfield, I. J. M.; Kossakowski, D.; Plavchan, P.; Jeffers, S., V; Kemmer, J.; Luque, R.; Espinoza, N.; Palle, 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.; Osorio, M. R. Zapatero; Chaturvedi, P.; Hatzes, A. P.; Ricker, G.; Vanderspek, R.; 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.; Caldwell, D. A.; Chintada, A.; Chontos, A.; Christiansen, J. L.; Ciardi, D. R.; Cifuentes, C.; Collins, K. A.; Collins, K., I; Combs, D.; Cortes-Contreras, M.; 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.; Gonzales, E.; Gorjian, V; Hellier, C.; Hidalgo, D.; Howard, A. W.; Howell, S.; Huber, D.; Isaacson, H.; Jehin, E.; Jensen, E. L. N.; Kaminski, A.; Kane, S. R.; Kawauchi, K.; Kielkopf, J. F.; Klahr, H.; Kosiarek, M. R.; Kreidberg, L.; Kurster, M.; Lafarga, M.; Livingston, J.; Louie, D.; Mann, A.; Madrigal-Aguado, A.; Matson, R. A.; Mocnik, T.; Morales, J. C.; Muirhead, P. S.; Murgas, F.; Nandakumar, S.; Narita, N.; Nowak, G.; Oshagh, M.; Parviainen, H.; Passegger, V. M.; Pollacco, D.; Pozuelos, F. J.; Quirrenbach, A.; Reefe, M.; Ribas, I; Robertson, P.; Rodriguez-Lopez, C.; Rose, M. E.; Roy, A.; Schweitzer, A.; Schlieder, J.; Shectman, S.; Tanner, A.; Senavci, H., V; Teske, J.; Twicken, J. D.; Villasenor, J.; Wang, S. X.; Weiss, L. M.; Wittrock, J.; Yilmaz, M.; Zohrabi, F.
2020
ASTRONOMY & ASTROPHYSICS
DOI
10.1051/0004-6361/202038016
We report the discovery of a Neptune-like planet (LP 714-47 b, P = 4.05204 d, m(b) = 30.8 +/- 1.5M(circle plus), R-b = 4.7 +/- 0.3 R-circle plus) 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 TuBTAK 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 +/- 0.02M(circle dot) and a radius of 0.58 +/- 0.02R(circle dot). 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.