OWLS I: The Olin Wilson Legacy Survey

TL;DR

This survey studies magnetic activity cycles in low-mass stars using Ca II H & K emission over ten years, revealing activity bifurcation, links to planet hosting, and potential cyclic variability, enhancing understanding of stellar magnetic dynamos.

Contribution

First four-year results from a decade-long survey linking stellar activity cycles, rotation, and magnetic dynamos across FGKM stars, with new insights into activity bifurcation and planet-hosting correlations.

Findings

Data are consistent with historical cycle periods.

Identified bifurcation in activity among late K stars.

M dwarf planet hosts tend to be low activity stars.

Abstract

We present initial results from a planned 10 year survey of Ca II H & K emission, using observations made with the ARC 3.5m Telescope at Apache Point Observatory. The primary goal of the survey is to investigate activity cycles in low mass stars. The sample includes stars chosen from the legacy Mount Wilson survey carried out by Olin Wilson more than 50 years ago, together with newly identified planet-host stars and a select sample of early-mid M dwarfs. This paper presents the first four years of data, comprising 1040 observations of 271 stars, with a specific focus on K and M stars. We identify a subsample of 153 stars for continuing observations over the full 10 year survey. Early results indicate that our data are consistent with the MWO cycle periods over a time span of more than 50 years; that there is a bifurcation in activity in the late K range with separate populations of low and high activity stars at lower masses; and that M dwarf planet hosts tend to be mainly found in the population of low activity stars, even in the unbiased (by activity) TESS sample, potentially indicating a link between activity and planet formation. We have also found indications of possible cyclic variability in some of the lower mass stars in the sample. Our ultimate goal is to link the activity cycle and rotation periods in a robust sample of stars spanning FGKM spectral types and to investigate the implications for the underlying magnetic dynamo.