The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades

Nunez, A.; Kraus, A. L.; Covey, K. R.; Drake, J. J.; Law, N. M.; Rampalli, R.; Douglas, Stephanie; Agueros, M. A.; Cargile, P. A.; Bowsher, E. C.

The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades

Abstract

X-ray observations of low-mass stars in open clusters are critical to understanding the dependence of magnetic activity on stellar properties and their evolution. Praesepe and the Hyades, two of the nearest, most-studied open clusters, are among the best available laboratories for examining the dependence of magnetic activity on rotation for stars with masses less than or similar to 1 M (circle dot). We present an updated study of the rotation-X-ray activity relation in the two clusters. We updated membership catalogs that combine pre-Gaia catalogs with new catalogs based on Gaia Data Release 2. The resulting catalogs are the most inclusive ones for both clusters: 1739 Praesepe and 1315 Hyades stars. We collected X-ray detections for cluster members, for which we analyzed, re-analyzed, or collated data from ROSAT, the Chandra X-ray Observatory, the Neil Gehrels Swift Observatory, and XMM-Newton. We have detections for 326 Praesepe and 462 Hyades members, of which 273 and 164, respectively, have rotation periods-an increase of 6x relative to what was previously available. We find that at approximate to 700 Myr, only M dwarfs remain saturated in X-rays, with only tentative evidence for supersaturation. We also find a tight relation between the Rossby number and fractional X-ray luminosity L (X)/L (bol) in unsaturated single members, suggesting a power-law index between -3.2 and -3.9. Lastly, we find no difference in the coronal parameters between binary and single members. These results provide essential insight into the relative efficiency of magnetic heating of the stars' atmospheres, thereby informing the development of robust age-rotation-activity relations.

Title	The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades
Creator	Nunez, A.
	Kraus, A. L.
	Covey, K. R.
	Drake, J. J.
	Law, N. M.
	Rampalli, R.
	Douglas, Stephanie
	Agueros, M. A.
	Cargile, P. A.
	Bowsher, E. C.
Publisher	Astrophysical Journal
Academic Department	Physics
Division	Natural Sciences
Organization	Lafayette College
Date Issued	May 24, 2022
Date Available	2022-06-09
Type	Article
Language	English
Bibliographic Citation	Nunez, A., et al. (2022 May 24) "The Factory and the Beehive. IV. A Comprehensive Study of the Rotation X-Ray Activity Relation in Praesepe and the Hyades." Astrophysical Journal 931 (1): 45.
Standard Identifier	DOI 10.3847/1538-4357/ac6517
Standard Identifier	Handle 10385/02870x05w
Permalink	http://hdl.handle.net/10385/02870x05w
Rights Statement	Creative Commons - Attribution
Rights Holders	Cargile, P. A.
	Covey, K. R.
	Drake, J. J.
	Bowsher, E. C.
	Rampalli, R.
	Agueros, M. A.
	Kraus, A. L.
	Law, N. M.
	Nunez, A.
	Douglas, Stephanie