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

A Sozzetti; M Damasso; J Fernández Fernández; A Mortier; A Anna John; P E Cubillos; T G Wilson; M Pinamonti; L Nielsen; A S Bonomo; A V Freckelton; A Collier Cameron; D Armstrong; A Vanderburg; D Bayliss; X Dumusque; A Ghedina; M A F Keniger; D W Latham; M López Morales; L Malavolta; A Osborn; F Pepe; R Rabino; P A Strøm; S Udry; P Wheatley

doi:10.1093/mnras/stae2323

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

A Sozzetti^*
, M Damasso
, J Fernández Fernández
, A Mortier
, A Anna John
, P E Cubillos
, T G Wilson
, M Pinamonti
, L Nielsen
, A S Bonomo
, A V Freckelton
, A Collier Cameron
, D Armstrong
, A Vanderburg
, D Bayliss
, X Dumusque
, A Ghedina
, M A F Keniger
, D W Latham
, M López Morales

L Malavolta, A Osborn, F Pepe, R Rabino, P A Strøm, S Udry, P Wheatley

^*Corresponding author for this work

Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

22 Downloads (Pure)

Abstract

We report on the detailed characterisation of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 (𝑇_eff = 5662 ± 44 K, < log 𝑅′_𝐻𝐾 >= −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 ± 0.05 d and measure the planetary RV signal with semi-amplitude 𝐾_𝑏 = 5.6 ± 0.7 m s⁻¹. We find that K2-370 b has a radius of 2.67 ± 0.05 𝑅_⊕ and a mass of 11.1 ± 1.4 𝑀_⊕. With an estimated equilibrium temperature 𝑇_eq ∼ 1480 K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with 𝑇_eff > 5500 K. The resulting density of 3.2±0.4 g cm⁻³ implies that K2-370 b either retains a significant (∼ 2 per cent by mass) H-rich atmosphere or its interior contains a high (∼ 40 per cent) water-mass fraction.

Original language	English
Pages (from-to)	531-550
Number of pages	20
Journal	Monthly Notices of the Royal Astronomical Society
Volume	535
Issue number	1
Early online date	11 Oct 2024
DOIs	https://doi.org/10.1093/mnras/stae2323
Publication status	Published - Nov 2024

Bibliographical note

Corrected and typeset: 30 October 2024.

Keywords

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

Access to Document

10.1093/mnras/stae2323Licence: Creative Commons: Attribution (CC BY)

SozzettiA2024K2-370bFinal published version, 3.25 MBLicence: Creative Commons: Attribution (CC BY)

Cite this

Sozzetti, A., Damasso, M., Fernández, J. F., 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., ... Wheatley, P. (2024). K2-370 b: a strongly irradiated sub-Neptune transiting a very active solar-type star. Monthly Notices of the Royal Astronomical Society, 535(1), 531-550. https://doi.org/10.1093/mnras/stae2323

@article{078d5f93584243b699d82d4f9f211808,

title = "K2-370 b: a strongly irradiated sub-Neptune transiting a very active solar-type star",

abstract = "We report on the detailed characterisation of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 (𝑇eff = 5662 ± 44 K, < log 𝑅′𝐻𝐾 >= −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 ± 0.05 d and measure the planetary RV signal with semi-amplitude 𝐾𝑏 = 5.6 ± 0.7 m s−1. We find that K2-370 b has a radius of 2.67 ± 0.05 𝑅⊕ and a mass of 11.1 ± 1.4 𝑀⊕. With an estimated equilibrium temperature 𝑇eq ∼ 1480 K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with 𝑇eff > 5500 K. The resulting density of 3.2±0.4 g cm−3 implies that K2-370 b either retains a significant (∼ 2 per cent by mass) H-rich atmosphere or its interior contains a high (∼ 40 per cent) water-mass fraction.",

keywords = "methods: miscellaneous, planets and satellites: composition, stars: individual: HD 284521 (K2-370), techniques: radial velocities, techniques: photometric",

author = "A Sozzetti and M Damasso and Fern{\'a}ndez, \{J Fern{\'a}ndez\} and A Mortier and John, \{A Anna\} and Cubillos, \{P E\} and Wilson, \{T G\} and M Pinamonti and L Nielsen and Bonomo, \{A S\} and Freckelton, \{A V\} and Cameron, \{A Collier\} and D Armstrong and A Vanderburg and D Bayliss and X Dumusque and A Ghedina and Keniger, \{M A F\} and Latham, \{D W\} and Morales, \{M L{\'o}pez\} and L Malavolta and A Osborn and F Pepe and R Rabino and Str{\o}m, \{P A\} and S Udry and P Wheatley",

note = "Corrected and typeset: 30 October 2024. ",

year = "2024",

month = nov,

doi = "10.1093/mnras/stae2323",

language = "English",

volume = "535",

pages = "531--550",

journal = "Monthly Notices of the Royal Astronomical Society",

issn = "0035-8711",

publisher = "SIPRI/Oxford University Press",

number = "1",

}

Sozzetti, A, Damasso, M, Fernández, JF, Mortier, A , John, AA, Cubillos, PE, Wilson, TG, Pinamonti, M, Nielsen, L, Bonomo, AS, Freckelton, AV, Cameron, AC, Armstrong, D, Vanderburg, A, Bayliss, D, Dumusque, X, Ghedina, A, Keniger, MAF, Latham, DW, Morales, ML, Malavolta, L, Osborn, A, Pepe, F, Rabino, R, Strøm, PA, Udry, S & Wheatley, P 2024, 'K2-370 b: a strongly irradiated sub-Neptune transiting a very active solar-type star', Monthly Notices of the Royal Astronomical Society, vol. 535, no. 1, pp. 531-550. https://doi.org/10.1093/mnras/stae2323

TY - JOUR

T1 - K2-370 b

T2 - a strongly irradiated sub-Neptune transiting a very active solar-type star

AU - Sozzetti, A

AU - Damasso, M

AU - Fernández, J Fernández

AU - Mortier, A

AU - John, A Anna

AU - Cubillos, P E

AU - Wilson, T G

AU - Pinamonti, M

AU - Nielsen, L

AU - Bonomo, A S

AU - Freckelton, A V

AU - Cameron, A Collier

AU - Armstrong, D

AU - Vanderburg, A

AU - Bayliss, D

AU - Dumusque, X

AU - Ghedina, A

AU - Keniger, M A F

AU - Latham, D W

AU - Morales, M López

AU - Malavolta, L

AU - Osborn, A

AU - Pepe, F

AU - Rabino, R

AU - Strøm, P A

AU - Udry, S

AU - Wheatley, P

N1 - Corrected and typeset: 30 October 2024.

PY - 2024/11

Y1 - 2024/11

N2 - We report on the detailed characterisation of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 (𝑇eff = 5662 ± 44 K, < log 𝑅′𝐻𝐾 >= −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 ± 0.05 d and measure the planetary RV signal with semi-amplitude 𝐾𝑏 = 5.6 ± 0.7 m s−1. We find that K2-370 b has a radius of 2.67 ± 0.05 𝑅⊕ and a mass of 11.1 ± 1.4 𝑀⊕. With an estimated equilibrium temperature 𝑇eq ∼ 1480 K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with 𝑇eff > 5500 K. The resulting density of 3.2±0.4 g cm−3 implies that K2-370 b either retains a significant (∼ 2 per cent by mass) H-rich atmosphere or its interior contains a high (∼ 40 per cent) water-mass fraction.

AB - We report on the detailed characterisation of K2-370 b, a transiting sub-Neptune on a 2.14-d orbit around the chromospherically active G-type dwarf HD 284521 (𝑇eff = 5662 ± 44 K, < log 𝑅′𝐻𝐾 >= −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 ± 0.05 d and measure the planetary RV signal with semi-amplitude 𝐾𝑏 = 5.6 ± 0.7 m s−1. We find that K2-370 b has a radius of 2.67 ± 0.05 𝑅⊕ and a mass of 11.1 ± 1.4 𝑀⊕. With an estimated equilibrium temperature 𝑇eq ∼ 1480 K, K2-370 b is the second-hottest sub-Neptune with a highly precise mass determination around primaries with 𝑇eff > 5500 K. The resulting density of 3.2±0.4 g cm−3 implies that K2-370 b either retains a significant (∼ 2 per cent by mass) H-rich atmosphere or its interior contains a high (∼ 40 per cent) water-mass fraction.

KW - methods: miscellaneous

KW - planets and satellites: composition

KW - stars: individual: HD 284521 (K2-370)

KW - techniques: radial velocities

KW - techniques: photometric

UR - https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/stae2323/7819156

U2 - 10.1093/mnras/stae2323

DO - 10.1093/mnras/stae2323

M3 - Article

SN - 0035-8711

VL - 535

SP - 531

EP - 550

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 1

ER -

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

Abstract

Bibliographical note

Keywords

Access to Document

Fingerprint

Cite this