2020AJ....160..114C

Query : 2020AJ....160..114C

2020AJ....160..114C - Astron. J., 160, 114-114 (2020/September-0)

The multiplanet system TOI-421: a warm Neptune and a super puffy mini-Neptune transiting a G9 V star in a visual binary.

CARLEO I., GANDOLFI D., BARRAGAN O., LIVINGSTON J.H., PERSSON C.M., LAM K.W.F., VIDOTTO A., LUND M.B., VILLARREAL D'ANGELO C., COLLINS K.A., FOSSATI L., HOWARD A.W., KUBYSHKINA D., BRAHM R., OKLOPCIC A., MOLLIERE P., REDFIELD S., SERRANO L.M., DAI F., FRIDLUND M., BORSA F., KORTH J., ESPOSITO M., DIAZ M.R., NIELSEN L.D., HELLIER C., MATHUR S., DEEG H.J., HATZES A.P., BENATTI S., RODLER F., ALARCON J., SPINA L., SANTOS A.R.G., GEORGIEVA I., GARCIA R.A., GONZALEZ-CUESTA L., RICKER G.R., VANDERSPEK R., LATHAM D.W., SEAGER S., WINN J.N., JENKINS J.M., ALBRECHT S., BATALHA N.M., BEARD C., BOYD P.T., BOUCHY F., BURT J.A., BUTLER R.P., CABRERA J., CHONTOS A., CIARDI D.R., COCHRAN W.D., COLLINS K.I., CRANE J.D., CROSSFIELD I., CSIZMADIA S., DRAGOMIR D., DRESSING C., EIGMULLER P., ENDL M., ERIKSON A., ESPINOZA N., FAUSNAUGH M., FENG F., FLOWERS E., FULTON B., GONZALES E.J., GRIEVES N., GRZIWA S., GUENTHER E.W., GUERRERO N.M., HENNING T., HIDALGO D., HIRANO T., HJORTH M., HUBER D., ISAACSON H., JONES M., JORDAN A., KABATH P., KANE S.R., KNUDSTRUP E., LUBIN J., LUQUE R., MIRELES I., NARITA N., NESPRAL D., NIRAULA P., NOWAK G., PALLE E., PATZOLD M., PETIGURA E.A., PRIETO-ARRANZ J., RAUER H., ROBERTSON P., ROSE M.E., ROY A., SARKIS P., SCHLIEDER J.E., SEGRANSAN D., SHECTMAN S., SKARKA M., SMITH A.M.S., SMITH J.C., STASSUN K., TESKE J., TWICKEN J.D., VAN EYLEN V., WANG S., WEISS L.M. and WYTTENBACH A.

Abstract (from CDS):

We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations-comprised of Las Cumbres Observatory Global Telescope transit photometry, NIRC2 adaptive optics imaging, and FIbre-fed Echelle Spectrograph, CORALIE, High Accuracy Radial velocity Planet Searcher, High Resolution Echelle Spectrometer, and Planet Finder Spectrograph high-precision Doppler measurements-and confirmed the planetary nature of the 16 day transiting candidate announced by the TESS team. We discovered an additional radial velocity signal with a period of five days induced by the presence of a second planet in the system, which we also found to transit its host star. We found that the inner mini-Neptune, TOI-421 b, has an orbital period of Pb = 5.19672 ± 0.00049 days, a mass of Mb = 7.17 ± 0.66 M⊕, and a radius of Rb = 2.68–0.18+0.19R⊕, whereas the outer warm Neptune, TOI-421 c, has a period of Pc = 16.06819 ± 0.00035 days, a mass of Mc = 16.42–1.04+1.06M⊕, a radius of Rc = 5.09–0.15+0.16R⊕, and a density of ρc = 0.685–0.072+0.080 g cm–3. With its characteristics, the outer planet (ρc = 0.685–0.072+0.080 g cm–3) is placed in the intriguing class of the super-puffy mini-Neptunes. TOI-421 b and TOI-421 c are found to be well-suited for atmospheric characterization. Our atmospheric simulations predict significant Lyα transit absorption, due to strong hydrogen escape in both planets, as well as the presence of detectable CH4 in the atmosphere of TOI-421 c if equilibrium chemistry is assumed.

Abstract Copyright: © 2020. The American Astronomical Society. All rights reserved.

Journal keyword(s): Exoplanet astronomy - Exoplanet systems - Exoplanets - Mini Neptunes - Hot Neptunes - Fundamental parameters of stars - High resolution spectroscopy - Transit photometry - Radial velocity

VizieR on-line data: <Available at CDS (J/AJ/160/114): table2.dat table3.dat table4.dat table5.dat>

Simbad objects: 17

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Number of rows : 17
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 BD-14 1137B PM* 05 27 23.7421270704 -14 16 12.212667840       15.466   ~ 4 0
2 BD-14 1137c Pl 05 27 24.8258862552 -14 16 37.046186364           ~ 26 0
3 BD-14 1137b Pl 05 27 24.8258862552 -14 16 37.046186364           ~ 39 0
4 BD-14 1137 PM* 05 27 24.8258862552 -14 16 37.046186364   10.73 9.93     G9V 44 0
5 CoRoT-24b Pl 06 47 41.4118109352 -03 43 09.483840696           ~ 24 0
6 NAME LP 424-4b Pl 07 59 05.8395356736 +15 23 29.236065000           ~ 387 1
7 * rho01 Cnc e Pl 08 52 35.8111044043 +28 19 50.954994470           ~ 682 1
8 NAME L 320-124b Pl 10 14 51.7786855411 -47 09 24.192778106           ~ 223 0
9 K2-18b Pl 11 30 14.5177445592 +07 35 18.255348492           ~ 303 0
10 Ross 905b Pl 11 42 11.0933350978 +26 42 23.650782778           ~ 913 1
11 K2-137b Pl 12 27 28.9846732536 -06 11 42.831206628           ~ 31 0
12 * ksi Boo A PM* 14 51 23.3884659504 +19 06 01.619801424   5.40 4.675     G7Ve 564 0
13 NAME G 139-21b Pl 17 15 18.9339850845 +04 57 50.066612336           ~ 845 1
14 Kepler-42c Pl 19 28 52.5688740811 +44 37 08.989819665           ~ 55 1
15 TRAPPIST-1b Pl 23 06 29.3684948589 -05 02 29.037301866           ~ 380 0
16 HD 219134b Pl 23 13 16.9749603608 +57 10 06.083823619           ~ 129 0
17 BD-02 5958b Pl 23 27 04.8376907739 -01 17 10.582653030           ~ 78 0

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