Sun-Like Magnetic Cycles in the Rapidly-Rotating Young Solar Analog HD 30495

TL;DR

This study presents evidence of dual magnetic cycles in the young solar analog HD 30495, revealing solar-like activity patterns in a star with a faster rotation rate, and explores their characteristics and implications for stellar dynamo theories.

Contribution

The paper reports the detection of multiple magnetic cycles in HD 30495, a young, rapidly rotating star, expanding understanding of stellar magnetic variability beyond the Sun.

Findings

HD 30495 exhibits short (~1.7 years) and long (~12 years) magnetic cycles.

Multiple long-term cycles ranging from 9.6 to 15.5 years were observed.

Surface differential rotation measurements remain inconclusive regarding solar equivalence.

Abstract

A growing body of evidence suggests that multiple dynamo mechanisms can drive magnetic variability on different timescales, not only in the Sun but also in other stars. Many solar activity proxies exhibit a quasi-biennial ($\sim$2 year) variation, which is superimposed upon the dominant 11 year cycle. A well-characterized stellar sample suggests at least two different relationships between rotation period and cycle period, with some stars exhibiting long and short cycles simultaneously. Within this sample, the solar cycle periods are typical of a more rapidly rotating star, implying that the Sun might be in a transitional state or that it has an unusual evolutionary history. In this work, we present new and archival observations of dual magnetic cycles in the young solar analog HD 30495, an $\sim$1 Gyr-old G1.5V star with a rotation period near 11 days. This star falls squarely on the relationships established by the broader stellar sample, with short-period variations at $\sim$1.7 years and a long cycle of $\sim$12 years. We measure three individual long-period cycles and find durations ranging from 9.6-15.5 years. We find the short-term variability to be intermittent, but present throughout the majority of the time series, though its occurrence and amplitude are uncorrelated with the longer cycle. These essentially solar-like variations occur in a Sun-like star with more rapid rotation, though surface differential rotation measurements leave open the possibility of a solar equivalence.