Asteroseismology and Spectropolarimetry of the Exoplanet Host Star λ Serpentis

Travis S. Metcalfe*, Derek Buzasi, Daniel Huber, Marc H. Pinsonneault, Jennifer L. van Saders, Thomas R. Ayres, Sarbani Basu, Jeremy J. Drake, Ricky Egeland, Oleg Kochukhov, Pascal Petit, Steven H. Saar, Victor See, Keivan G. Stassun, Yaguang Li, Timothy R. Bedding, Sylvain N. Breton, Adam J. Finley, Rafael A. García, Hans KjeldsenMartin B. Nielsen, J. M.Joel Ong, Jakob L. Rørsted, Amalie Stokholm, Mark L. Winther, Catherine A. Clark, Diego Godoy-Rivera, Ilya V. Ilyin, Klaus G. Strassmeier, Sandra V. Jeffers, Stephen C. Marsden, Aline A. Vidotto, Sallie Baliunas, Willie Soon

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Abstract

The bright star λ Ser hosts a hot Neptune with a minimum mass of 13.6 M and a 15.5 day orbit. It also appears to be a solar analog, with a mean rotation period of 25.8 days and surface differential rotation very similar to the Sun. We aim to characterize the fundamental properties of this system and constrain the evolutionary pathway that led to its present configuration. We detect solar-like oscillations in time series photometry from the Transiting Exoplanet Survey Satellite, and we derive precise asteroseismic properties from detailed modeling. We obtain new spectropolarimetric data, and we use them to reconstruct the large-scale magnetic field morphology. We reanalyze the complete time series of chromospheric activity measurements from the Mount Wilson Observatory, and we present new X-ray and ultraviolet observations from the Chandra and Hubble space telescopes. Finally, we use the updated observational constraints to assess the rotational history of the star and estimate the wind braking torque. We conclude that the remaining uncertainty on the stellar age currently prevents an unambiguous interpretation of the properties of λ Ser, and that the rate of angular momentum loss appears to be higher than for other stars with a similar Rossby number. Future asteroseismic observations may help to improve the precision of the stellar age.

Original languageEnglish
Article number167
JournalAstronomical Journal
Volume166
Issue4
Number of pages15
ISSN0004-6256
DOIs
Publication statusPublished - Oct 2023

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