Magnetic activity variability from Hα line intensive monitoring of two F-type stars with a hot Jupiter, τ Bootis A and υ Andromedae A. (11th March 2023)

• Record Type: Journal Article
• Authors: Lee, Sanghee; Notsu, Yuta; Sato, Bun'ei
• Is Part Of: Publications of the Astronomical Society of Japan. Volume 75:Number 2(2023)
• Page Start: 446
• Page End: 461
• Publication Date: 2023-03-11
• Subjects: planet–star interactions -- stars: activity -- stars: chromospheres -- stars: individual (τ Bootis, υ Andromedae); Astronomy -- Periodicals; 520.5
• DOI: 10.1093/pasj/psad010
• Languages: English
• ISSNs: 0004-6264

Abstract

Abstract: We report the results of intensive monitoring of the variability in the Hα line for two F-type stars, τ Boo and υ And, over the last four years 2019–2022, in order to investigate their stellar magnetic activity. The 4 yr Hα line intensity data taken with the 1.88 m reflector at the Okayama Branch Office, Subaru Telescope, shows the existence of a possible ∼123 d magnetic activity cycle for τ Boo. The result of the Hα variability as another tracer of the magnetic activity on the chromosphere is consistent with previous studies of the Ca ii H&K line and suggests that the magnetic activity cycle persists in τ Boo. For υ And, we suggest a quadratic long-term trend in the Hα variability. Meanwhile, the short-term monitoring shows no significant period corresponding to specific variations likely induced by their hot Jupiter in both cases (≈3.31 and 4.62 d, respectively). In this Hα observation, we could not find any signature of the star–planet magnetic interaction. It is speculated that the detected magnetic activity variability of the two F-type stars is related to the stellar intrinsic dynamo.