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X-ray source populations in the region of the open clusters NGC 6633 and IC 4756

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posted on 2016-02-09, 14:52 authored by K. R. Briggs, John Patrick Pye, R. D. Jeffries, E. J. Totten
Using deep exposures (∼105 s) with the ROSAT High Resolution Imager, we have performed flux-limited surveys for X-ray sources in the vicinity of the Hyades-age open stellar clusters NGC 6633 and IC 4756, detecting 31 and 13 sources, respectively. Our primary aim is to search for so-far unrecognized cluster members. We propose identifications or classifications (cluster member, field star, extragalactic field object) for the X-ray sources, based on published membership lists, and on X-ray:optical flux ratios and optical colour-magnitude diagrams. Results of simulating the expected X-ray-emitting source populations are compared with the ROSAT measurements and with the expected capabilities of the XMM mission. The simulations provide a novel method of comparing the activity levels of NGC 6633 and IC 4756 with that of the Hyades. The measurements and simulations confirm that cluster members are the major class of X-ray emitter in these fields at flux levels Graphic (0.1–2.4 keV), contributing ∼40 per cent of the total X-ray sources. We find six possible new members in NGC 6633 and four candidates in IC 4756; all require further observation to establish membership probability.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2000, 319 (3), pp. 826-836

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

  • VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Wiley-Blackwell

issn

0035-8711

eissn

1365-2966

Acceptance date

2000-07-21

Copyright date

2000

Available date

2016-02-09

Publisher version

http://mnras.oxfordjournals.org/content/319/3/826.short

Language

en

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