A sub-Neptune and a non-transiting Neptune-mass companion unveiled by ESPRESSO around the bright late-F dwarf HD 5278 (TOI-130)

Sozzetti, A.; Damasso, M.; Bonomo, A. S.; Alibert, Y.; Sousa, S. G.; Adibekyan, V.; Zapatero Osorio, M. R.; González Hernández, J. I.; Barros, S. C. C.; Lillo-Box, J.; Stassun, K. G.; Winn, J.; Cristiani, S.; Pepe, F.; Rebolo, R.; Santos, N. C.; Allart, R.; Barclay, T.; Bouchy, F.; Cabral, A.; ... (2021). A sub-Neptune and a non-transiting Neptune-mass companion unveiled by ESPRESSO around the bright late-F dwarf HD 5278 (TOI-130). Astronomy and astrophysics, 648, A75. EDP Sciences 10.1051/0004-6361/202040034

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[Abridged] We exploit the extreme radial velocity (RV) precision of the ultra-stable echelle spectrograph ESPRESSO on the VLT to unveil the physical properties of the transiting sub-Neptune TOI-130 b, uncovered by TESS orbiting the nearby, bright, late F-type star HD 5278 (TOI-130) with a period Pb=14.3. We use 43 ESPRESSO high-resolution spectra and broad-band photometry information to derive accurate stellar atmospheric and physical parameters of HD 5278. We exploit the TESS light curve (LC) and spectroscopic diagnostics to gauge the impact of stellar activity on the ESPRESSO RVs. We perform a joint ESPRESSO RVs + TESS LC analysis using fully Bayesian frameworks to determine the system parameters. The updated stellar parameters of HD 5278 are Teff=6203±64 K, logg=4.50±0.11 dex, [Fe/H]=−0.12±0.04 dex, M⋆=1.126+0.036−0.035 M⊙ and R⋆=1.194+0.017−0.016 R⊙. We determine HD 5278 b's mass and radius to be Mb=7.8+1.5−1.4 M⊕ and Rb=2.45±0.05 R⊕. The derived mean density, ϱb=2.9+0.6−0.5 g cm−3, is consistent with a bulk composition with a substantial (∼30%) water mass fraction and a gas envelope comprising ∼17% of the measured radius. Given the host brightness and irradiation levels, HD 5278 b is one of the best targets orbiting G-F primaries for follow-up atmospheric characterization measurements with HST and JWST. We discover a second, non-transiting companion in the system, with a period Pc=40.87+0.18−0.17 days and a minimum mass Mcsinic=18.4+1.8−1.9 M⊕. We study emerging trends in the growing population of transiting sub-Neptunes, and provide statistical evidence for a low occurrence of close-in, 10−15 M⊕ companions around G-F primaries with Teff≳5500 K.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences > Theoretical Astrophysics and Planetary Science (TAPS)
08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
08 Faculty of Science > Physics Institute
08 Faculty of Science > Physics Institute > NCCR PlanetS

UniBE Contributor:

Alibert, Yann Daniel Pierre, Haldemann, Jonas

Subjects:

500 Science
500 Science > 520 Astronomy
500 Science > 530 Physics
600 Technology > 620 Engineering

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Janine Jungo

Date Deposited:

28 Mar 2022 14:51

Last Modified:

05 Dec 2022 16:12

Publisher DOI:

10.1051/0004-6361/202040034

BORIS DOI:

10.48350/166497

URI:

https://boris.unibe.ch/id/eprint/166497

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