Stellar X-ray activity across the Hertzsprung-Russell diagram. I. Catalogs

TL;DR

This paper presents a comprehensive catalog of X-ray activity for around 6000 stars, derived from Chandra and Gaia data, enabling detailed studies of stellar magnetic activity across different star types and evolutionary stages.

Contribution

The study provides the first large-scale catalog of stellar X-ray activity with classifications, facilitating new insights into activity-rotation relations and stellar magnetic phenomena.

Findings

Young stellar objects, dwarfs, and giants follow a common activity-rotation sequence.

Giants do not follow the dwarf activity-rotation relation based on P_rot.

The catalog enables investigations into activity indicators and stellar evolution.

Abstract

Stellar magnetic activity provides substantial information on the magnetic dynamo and the coronal heating process. We present a catalog of X-ray activity for about 6000 stars, based on the $Chandra$ and $Gaia$ DR2 data. We also classified more than 3000 stars as young stellar objects, dwarf stars, or giant stars. By using the stars with valid stellar parameters and classifications, we studied the distribution of X-ray luminosity ($L_X$) and the ratio of X-ray-to-bolometric luminosities ($R_X$), the positive relation between $L_X$, $R_X$, and hardness ratio, and the long-term X-ray variation. This catalog can be used to investigate some important scientific topics, including the activity-rotation relation, the comparison between different activity indicators, and the activities of interesting objects (e.g., A-type stars and giants). As an example, we use the catalog to study the activity-rotation relation, and find that the young stellar objects, dwarfs, and giants fall on a single sequence in the relation $R_X$ versus Rossby number, while the giants do not follow the relation $R_X$ versus $P_{\rm rot}^{-2}R^{-4}$ valid for dwarfs.