학술논문
Two Warm Neptunes transiting HIP 9618 revealed by TESS & Cheops
Document Type
Working Paper
Author
Osborn, Hugh P.; Nowak, Grzegorz; Hébrard, Guillaume; Masseron, Thomas; Lillo-Box, J.; Pallé, Enric; Bekkelien, Anja; Florén, Hans-Gustav; Guterman, Pascal; Simon, Attila E.; Adibekyan, V.; Bieryla, Allyson; Borsato, Luca; Brandeker, Alexis; Ciardi, David R.; Cameron, Andrew Collier; Collins, Karen A.; Egger, Jo A.; Gandolfi, Davide; Hooton, Matthew J.; Latham, David W.; Lendl, Monika; Matthews, Elisabeth C.; Tuson, Amy; Ulmer-Moll, Solène; Vanderburg, Andrew; Wilson, Thomas G.; Ziegler, Carl; Alibert, Yann; Alonso, Roi; Anglada, Guillem; Arnold, Luc; Asquier, Joel; Navascues, David Barrado y; Baumjohann, Wolfgang; Beck, Thomas; Belinski, Alexandr A.; Benz, Willy; Biondi, Federico; Boisse, Isabelle; Bonfils, Xavier; Broeg, Christopher; Buchhave, Lars A.; Bárczy, Tamas; Barros, S. C. C.; Cabrera, Juan; Guillen, Carlos Cardona; Carleo, Ilaria; Castro-González, Amadeo; Charnoz, Sébastien; Christiansen, Jessie; Cortes-Zuleta, Pia; Csizmadia, Szilard; Dalal, Shweta; Davies, Melvyn B.; Deleuil, Magali; Delfosse, Xavier; Delrez, Laetitia; Demory, Brice-Olivier; Dunlavey, Ava B.; Ehrenreich, David; Erikson, Anders; Fernandes, Rachel B.; Fortier, Andrea; Forveille, Thierry; Fossati, Luca; Fridlund, Malcolm; Gillon, Michaël; Goeke, Robert F.; Goliguzova, Maria V.; Gonzales, Erica J.; Günther, M. N.; Güdel, Manuel; Heidari, Neda; Henze, Christopher E.; Howell, Steve; Hoyer, Sergio; Frey, Jonas Immanuel; Isaak, Kate G.; Jenkins, Jon M.; Kiefer, Flavien; Kiss, Laszlo; Korth, Judith; Maxted, Pierre F. L.; Laskar, Jacques; Etangs, Alain Lecavelier des; Lovis, Christophe; Lund, Michael B.; Luque, Rafa; Magrin, Demetrio; Almenara, Jose Manuel; Martioli, Eder; Mecina, Marko; Medina, Jennifer V.; Moldovan, Daniel; Morales-Calderón, María; Morello, Giuseppe; Moutou, Claire; Murgas, Felipe; Jensen, Eric L. N.; Nascimbeni, Valerio; Olofsson, Göran; Ottensamer, Roland; Pagano, Isabella; Peter, Gisbert; Piotto, Giampaolo; Pollacco, Don; Queloz, Didier; Ragazzoni, Roberto; Rando, Nicola; Rauer, Heike; Ribas, Ignasi; Ricker, George; Demangeon, Olivier D. S.; Smith, Alexis M. S.; Santos, Nuno; Scandariato, Gaetano; Seager, Sara; Sousa, Sergio G.; Steller, Manfred; Szabó, Gyula M.; Ségransan, Damien; Thomas, Nicolas; Udry, Stéphane; Ulmer, Bernd; Van Grootel, Valerie; Vanderspek, Roland; Walton, Nicholas; Winn, Joshua N.
Source
MNRAS, Vol. 523, 2023, issue 2, pp 3069-3089
Subject
Language
Abstract
HIP 9618 (HD 12572, TOI-1471, TIC 306263608) is a bright ($G=9.0$ mag) solar analogue. TESS photometry revealed the star to have two candidate planets with radii of $3.9 \pm 0.044$ $R_\oplus$ (HIP 9618 b) and $3.343 \pm 0.039$ $R_\oplus$ (HIP 9618 c). While the 20.77291 day period of HIP 9618 b was measured unambiguously, HIP 9618 c showed only two transits separated by a 680-day gap in the time series, leaving many possibilities for the period. To solve this issue, CHEOPS performed targeted photometry of period aliases to attempt to recover the true period of planet c, and successfully determined the true period to be 52.56349 d. High-resolution spectroscopy with HARPS-N, SOPHIE and CAFE revealed a mass of $10.0 \pm 3.1 M_\oplus$ for HIP 9618 b, which, according to our interior structure models, corresponds to a $6.8\pm1.4\%$ gas fraction. HIP 9618 c appears to have a lower mass than HIP 9618 b, with a 3-sigma upper limit of $< 18M_\oplus$. Follow-up and archival RV measurements also reveal a clear long-term trend which, when combined with imaging and astrometric information, reveal a low-mass companion ($0.08^{+0.12}_{-0.05} M_\odot$) orbiting at $26^{+19}_{-11}$ au. This detection makes HIP 9618 one of only five bright ($K<8$ mag) transiting multi-planet systems known to host a planet with $P>50$ d, opening the door for the atmospheric characterisation of warm ($T_{\rm eq}<750$ K) sub-Neptunes.
Comment: 19 pages, 16 figures, 9 tables. Accepted at MNRAS. CHEOPS, RV and ground-based photometric data is available on CDS at https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/523/3069
Comment: 19 pages, 16 figures, 9 tables. Accepted at MNRAS. CHEOPS, RV and ground-based photometric data is available on CDS at https://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/523/3069