2009A&A...503..505C


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.03CET18:36:34

2009A&A...503..505C - Astronomy and Astrophysics, volume 503, 505-509 (2009/8-4)

Hard X-ray flux from low-mass stars in the Cygnus OB2 association.

CARAMAZZA M., DRAKE J.J., MICELA G. and FLACCOMIO E.

Abstract (from CDS):

The Cygnus OB2 association, the central engine of the Cygnus X star-forming region, is the subject of an extensive INTEGRAL Key Project that will accumulate 6Ms of observations. Analysis of 2Ms of observations by De Becker and co-workers provides the most sensitive limit yet obtained on hard X-ray emission from the cluster. We investigate the X-ray emission in the 20-40 keV band expected from the flaring low-mass stellar population in Cygnus OB2. We discuss whether such emission needs to be considered in the interpretation of existing and future X-ray observations of the region, and whether such observations might provide insight into the high-energy processes on low-mass pre-main sequence stars. The total hard X-ray flux from low-mass stars is estimated by assuming the observed soft X-ray emission stems from a superposition of flares. We further assume the ratio of hard X-ray to soft X-ray emission is described by a scaling found for solar flares by Isola and co-workers. We estimate the low-mass stellar hard X-ray flux in the 20-40keV band to lie in the range ∼2x1031-6x1032erg/s and discuss some potential biases that might affect this result. Hard X-ray emission could lie at a level not much below the current observed flux upper limits for Cygnus OB2. If this emission could be detected, it would provide insight into the hard X-ray production of large flares on pre-main sequence stars. We highlight the penetrating power of hard X-rays from low-mass stellar populations as a possible pointer to our Galaxy's hidden star-forming clusters and super-clusters using more sensitive observations from future missions.

Abstract Copyright:

Journal keyword(s): stars: coronae - stars: flare - Galaxy: open clusters and associations: individual: Cygnus OB2

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 * bet Per EB* 03 08 10.1324535 +40 57 20.328013 1.70 2.07 2.12 2.08 2.11 B8V 1154 2
2 V* UX Ari RS* 03 26 35.3764089427 +28 42 54.211100955 7.76 7.28 6.37     K0IV 666 0
3 V* AB Dor TT* 05 28 44.8916324761 -65 26 55.289846904 8.259 7.856 6.999 6.496 5.993 K0V 939 0
4 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2021 1
5 NAME Northern Coalsack DNe 20 21 +37.0           ~ 103 0
6 NAME Cyg X Cld 20 28 41 +41 10.2           ~ 635 1
7 TeV J2032+4130 gam 20 32.1 +41 34           ~ 122 0
8 [MT91] 213 Be* 20 32 13.1248987067 +41 27 24.343749507 13.12 13.08 11.266     B0Vp 221 0
9 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 810 0
10 HD 224085 RS* 23 55 04.0516465022 +28 38 01.248194500 8.88 8.20   6.9   K2+IVeFe-1 686 0

    Equat.    Gal    SGal    Ecl

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2020.12.03-18:36:34

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