2024MNRAS.535..531S

Query : 2024MNRAS.535..531S

2024MNRAS.535..531S - Mon. Not. R. Astron. Soc., 535, 531-550 (2024/November-3)

K2-370 b: a strongly irradiated sub-Neptune transiting a very active solar-type star.

SOZZETTI A., DAMASSO M., FERNANDEZ FERNANDEZ J., MORTIER A., JOHN A.A., CUBILLOS P.E., WILSON T.G., PINAMONTI M., NIELSEN L., BONOMO A.S., FRECKELTON A.V., CAMERON A.C., ARMSTRONG D., VANDERBURG A., BAYLISS D., DUMUSQUE X., GHEDINA A., KENIGER M.A.F., LATHAM D.W., LOPEZ MORALES M., MALAVOLTA L., OSBORN A., PEPE F., RABINO R., STROM P.A., UDRY S. and WHEATLEY P.

Abstract (from CDS):

We report on the detailed characterization of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 ($T_\mathrm{eff} = 5662\pm 44$ K, $\lt \log R^\prime _{\rm HK}\gt =-4.49$). The system parameters are derived based on a global fit to K2, TESS and CHEOPS photometry, and HARPS-N and HARPS radial velocities (RVs). A Gaussian process regression analysis is performed simultaneously to the orbital fit of the RVs of K2-370 to effectively model the strong stellar rotation signal with a period of $13.5\pm 0.05$ d and measure the planetary RV signal with semi-amplitude $K_{\rm b}=5.6\pm 0.7$ m s$^{-1}$. We find that K2-370 b has a radius of $2.67\pm 0.05$ ${\rm R}_{\rm{\oplus }}$ and a mass of $11.1\pm 1.4$ ${\rm M}_{\rm{\oplus }}$. With an estimated equilibrium temperature $T_\mathrm{eq}\sim 1480$ K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with $T_\mathrm{eff}\gt 5500$ K. The resulting density of $3.2\pm 0.4$ g cm$^{-3}$ implies that K2-370 b either retains a significant ($\sim 2~{{\ \rm per\ cent}}$ by mass) H-rich atmosphere or its interior contains a high ($\sim 40~{{\ \rm per\ cent}}$) water-mass fraction.

Abstract Copyright: © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society.

Journal keyword(s): methods: miscellaneous - techniques: photometric - techniques: radial velocities - planets and satellites: composition - stars: individual: HD 284521 (K2-370)

Simbad objects: 5

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Number of rows : 5
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 HD 284521 * 04 31 16.9643265552 +19 49 54.504732324   11.72 11.11     G5 11 0
2 HD 284521b Pl 04 31 16.9643265552 +19 49 54.504732324           ~ 5 0
3 K2-18b Pl 11 30 14.5177445592 +07 35 18.255348492           ~ 303 0
4 NAME G 139-21b Pl 17 15 18.9339850845 +04 57 50.066612336           ~ 845 1
5 BD+72 969c Pl 20 54 02.6103662208 +72 34 49.878396228           ~ 6 0

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