2020A&A...640A..66F


C.D.S. - SIMBAD4 rel 1.7 - 2020.10.26CET14:42:37

2020A&A...640A..66F - Astronomy and Astrophysics, volume 640A, 66-66 (2020/8-1)

Updated X-ray view of the Hyades cluster.

FREUND S., ROBRADE J., SCHNEIDER P.C. and SCHMITT J.H.M.M.

Abstract (from CDS):


Aims. We revisit the X-ray properties of the main sequence Hyades members and the relation between X-ray emission and stellar rotation.
Methods. As an input catalog for Hyades members, we combined three recent Hyades membership lists derived from Gaia DR2 data that include the Hyades core and its tidal tails. We searched for X-ray detections of the main sequence Hyades members in the ROSAT all-sky survey, and pointings from ROSAT, the Chandra X-Ray Observatory, and XMM-Newton. Furthermore, we adopted rotation periods derived from Kepler's K2 mission and other resources.
Results. We find an X-ray detection for 281 of 1066 bona fide main sequence Hyades members and provide statistical upper limits for the undetected sources. The majority of the X-ray detected stars are located in the Hyades core because of its generally smaller distance to the Sun. F- and G-type stars have the highest detection fraction (72%), while K- and M-type dwarfs have lower detection rates (22%). The X-ray luminosities of the detected members range from ∼2x1027erg/s for late M-type dwarfs to ∼2x1030erg/s for active binaries. The X-ray luminosity distribution functions formally differ for the members in the core and tidal tails, which is likely caused by a larger fraction of field stars in our Hyades tails sample. Compared to previous studies, our sample is slightly fainter in X-rays due to differences in the Hyades membership list used; furthermore, we extend the X-ray luminosity distribution to fainter luminosities. The X-ray activity of F- and G-type stars is well defined at FX/Fbol≃10–5. The fractional X-ray luminosity and its spread increases to later spectral types reaching the saturation limit (FX/Fbol≃10–3) for members later than spectral type M3. Confirming previous results, the X-ray flux varies by less than a factor of three between epochs for the 104 Hyades members with multiple epoch data, significantly less than expected from solar-like activity cycles. Rotation periods are found for 204 Hyades members, with about half of them being detected in X-rays. The activity-rotation relation derived for the coeval Hyades members has properties very similar to those obtained by other authors investigating stars of different ages.

Abstract Copyright: © ESO 2020

Journal keyword(s): open clusters and associations: individual: Hyades - X-rays: stars - stars: activity - stars: rotation - stars: coronae - stars: late-type

VizieR on-line data: <Available at CDS (J/A+A/640/A66): hyades.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Per Region reg 03 37 00.0 +31 15 00           ~ 232 0
2 Cl Melotte 22 OpC 03 47 00 +24 07.0           ~ 3024 0
3 UCAC3 157-11984 PM* 04 15 07.1520193088 -11 32 15.581118050   12.99 11.61 11.24 9.83 M0 5 0
4 Cl Melotte 25 OpC 04 26 54.00 +15 52 00.0           ~ 2695 0
5 NAME Tau-Aur Complex SFR 04 30 +25.0           ~ 1227 0
6 HD 28977 PM* 04 34 32.1823964098 +15 49 39.205949205   10.565 9.644 9.139 8.702 K0 97 0
7 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11760 0
8 NAME Hyades Moving Group MGr ~ ~           ~ 240 0

    Equat.    Gal    SGal    Ecl

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2020.10.26-14:42:37

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