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Chandra and HST studies of the X-ray sources in the globular cluster NGC 362.

Authors :
Kumawat, Gourav
Heinke, Craig O
Cohn, Haldan N
Lugger, Phyllis M
Source :
Monthly Notices of the Royal Astronomical Society; May2024, Vol. 530 Issue 1, p82-94, 13p
Publication Year :
2024

Abstract

We analyse a Chandra observation of the rich globular cluster NGC 362, finding 33 X-ray sources within 1 arcmin (1.2 half-mass radii) of the cluster centre. Spectral analysis of the brightest source (X1) shows blackbody-like emission, indicating it is likely a quiescent low-mass X-ray binary; we find a possible counterpart that falls in the sub-subgiant region. We use Hubble Space Telescope ultraviolet (UV) Globular Cluster Survey photometry to identify 15 potential optical/UV counterparts to these X-ray sources, including two background active galactic nuclei. We identify no likely cataclysmic variables (CVs), probably due to crowding in optical filters in the core, though we predict of order 8 CVs among the detected X-ray sources. We identify three other sub-subgiants and two red straggler counterparts, which are likely powered by coronal activity, along with five other potential coronally active binary counterparts to three X-ray sources. Finally, we note two unusual counterpart candidates that lie to the red of the red giant branch in V <subscript>606</subscript> − I <subscript>814</subscript>, and shift well to the blue of the red giant branch in ultraviolet colour–magnitude diagrams. These systems seem to contain a red giant with a distorted evolutionary history, plus a bright blue light source, either a blue straggler star (an Algol-like system) or an accreting white dwarf (a long-period CV, or a symbiotic star). [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
00358711
Volume :
530
Issue :
1
Database :
Complementary Index
Journal :
Monthly Notices of the Royal Astronomical Society
Publication Type :
Academic Journal
Accession number :
176725348
Full Text :
https://doi.org/10.1093/mnras/stae865