X-ray Activity from Different Types of Stars

Abstract

X-ray emission is an important indicator of stellar activity. In this paper, we study stellar X-ray activity using the XMM-Newton and LAMOST data for different types of stars. We provide a sample including 1259 X-ray emitting stars, of which 1090 have accurate stellar parameter estimations. Our sample size is much larger than those in previous works. We find a bimodal distribution of X-ray to optical flux ratio (log(fX/fV)) for G and K stars. We interpret that this bimodality is due to two subpopulations with different coronal heating rates. Furthermore, using the full widths at half maxima calculated from Hα and H\b{eta} lines, we show that these stars in the inactive peaks have smaller rotational velocities. This is consistent with the magnetic dynamo theory that stars with low rotational velocities have low levels of stellar activity. We also examine the correlation between log(fX/fV) and luminosity of the excess emission in the Hα line, and find a tight relation between the coronal and chromospheric activity indicators.

25 pages, 19 figures, 3 tables. Accepted for publication in RAA

References in corpus (7)

• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• Generalized investigation of the rotation-activity relation: Favouring rotation period instead of Rossby number
• The XMM-Newton wide-field survey in the COSMOS field: III. optical identification and multiwavelength properties of a large sample of X-ray selected sources
• X-ray Emission from T Tauri Stars and the Role of Accretion: Inferences from the XMM-Newton Extended Survey of the Taurus Molecular Cloud
• The Magnetic Fields at the Surface of Active Single G-K Giants
• Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis
• X-Ray-Emitting Stars Identified from the ROSAT All-Sky Survey and the Sloan Digital Sky Survey