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Title: X-ray source populations in the region of the open clusters NGC 6633 and IC 4756
Authors: Briggs, K. R.
Pye, John Patrick
Jeffries, R. D.
Totten, E. J.
First Published: 12-Dec-2000
Publisher: Wiley-Blackwell
Citation: Monthly Notices of the Royal Astronomical Society, 2000, 319 (3), pp. 826-836
Abstract: 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.
DOI Link: 10.1046/j.1365-8711.2000.03903.x
ISSN: 0035-8711
eISSN: 1365-2966
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2000, RAS. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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