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arXiv · 2302.02135

Magnetic activity variability from H$α$ line intensive monitoring for two F-type stars having a hot-Jupiter, $τ$ Bootis A and $\upsilon$ Andromedae A

Sanghee Lee·Yuta Notsu·Bun'ei Sato
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Abstract

We report the results of intensive monitoring of the variability in the H$α$ line for two F-type stars, $τ$ Boo and $\upsilon$ And, during the last four years 2019-2022, in order to investigate their stellar magnetic activity. The 4-year H$α$ line intensity data taken with the 1.88-m reflector at Okayama Branch Office, Subaru Telescope, shows the existence of a possible $\sim$ 123-day magnetic activity cycle of $τ$ Boo. The result of the H$α$ 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 is persisted in $τ$ Boo. For $\upsilon$ And, we suggest a quadratic long-term trend in the H$α$ variability. Meanwhile, the short-term monitoring shows no significant period corresponding to specific variations likely induced by their hot-Jupiter in both cases ($\approx$ 3.31 and 4.62 days, respectively). In this H$α$ 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.

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Sanghee Lee, Yuta Notsu, Bun'ei Sato. 2023-02-04. Magnetic activity variability from H$α$ line intensive monitoring for two F-type stars having a hot-Jupiter, $τ$ Bootis A and $\upsilon$ Andromedae A. https://doi.org/10.1093/pasj%2Fpsad010

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