Volume 454, Number 3, August II 2006
|Page(s)||1047 - 1063|
|Section||Online catalogs and data|
|Published online||17 July 2006|
An XMM-Newton view of the young open cluster NGC 6231
I. The catalogue
Institut d'Astrophysique et de Géophysique, University of Liège, Allée du 6 Août 17, Bât. B5c, 4000 Liège, Belgium e-mail: [sana;gosset;rauw;vreux]@astro.ulg.ac.be
2 Department of Astronomy and Space Science, Sejong University, Kunja-dong 98, Kwangjin-gu, Seoul 143-747, Korea e-mail: firstname.lastname@example.org
Accepted: 22 March 2006
This paper is the first of a series dedicated to the X-ray properties of the young open cluster NGC 6231. Our data set relies on an XMM-Newton campaign of a nominal duration of 180 ks and reveals that NGC 6231 is very rich in the X-ray domain too. Indeed, 610 X-ray sources are detected in the present field of view, centered on the cluster core. The limiting sensitivity of our survey is approximately 6 10-15 erg cm-2 s-1 but clearly depends on the location in the field of view and on the source spectrum. Using different existing catalogues, over 85% of the X-ray sources could be associated with at least one optical and/or infrared counterpart within a limited cross-correlation radius of 3´´ at maximum. The surface density distribution of the X-ray sources presents a slight N-S elongation. Once corrected for the spatial sensitivity variation of the EPIC instruments, the radial profile of the source surface density is well described by a King profile with a central density of about 8 sources per arcmin2 and a core radius close to 3.1 arcmin. The distribution of the X-ray sources seems closely related to the optical source distribution. The expected number of foreground and background sources should represent about 9% of the detected sources, thus strongly suggesting that most of the observed X-ray emitters are physically belonging to NGC 6231. Finally, beside a few bright but soft objects – corresponding to the early-type stars of the cluster – most of the sources are relatively faint (~5 10-15 erg cm-2 s-1) with an energy distribution peaked around 1.0–2.0 keV.
Key words: open clusters and associations: individual: NGC 6231 / X-rays: individuals: NGC 6231 / X-rays: stars / stars: early-type / catalogues
© ESO, 2006
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.