太陽に70年間黒点がなかった理由を、近傍の星が説明できるかもしれない(Nearby star could help explain why our sun didn’t have sunspots for 70 years)

2022-03-22 ペンシルベニア州立大学（PennState）

＜関連情報＞

• https://www.psu.edu/news/eberly-college-science/story/nearby-star-could-help-explain-why-our-sun-didnt-have-sunspots-70/
• https://iopscience.iop.org/article/10.3847/1538-3881/ac5683

太陽型星59個における50年にわたる色球活動、および新しいマウンダー極小期候補星HD166620 Five Decades of Chromospheric Activity in 59 Sun-like Stars and New Maunder Minimum Candidate HD 166620

Anna C. Baum^1,2, Jason T. Wright^1,3,4, Jacob K. Luhn^1,3,5, and Howard Isaacson^6,7
Published 2022 March 22

Abstract：

We present five decades of chromospheric activity measurements in 59 Sun-like stars as time series. These include and extend the 35 yr of stellar chromospheric activity observations by the Mount Wilson Survey (1966–2001), and continued observations at Keck by the California Planet Search (1996–). The Mount Wilson Survey was studied closely in 1995, and revealed periodic activity cycles similar to the Sun’s 11 yr cycle. The California Planet Search provides more than five decades of measurements, significantly improving our understanding of these stars’ activity behavior. We have curated the activity measurements in order to create contiguous time series, and have classified the stellar sample according to a predetermined system. We have analyzed 29 stars with periodic cycles using the Lomb–Scargle periodogram, and present best-fit sinusoids to their activity time series. We report the best-fit periods for each cycling star, along with stellar parameters (T_eff, log(g), vsin(i), etc.) for the entire sample. As a first application of these data, we offer a possible Maunder minimum candidate, HD 166620.