Issue |
A&A
Volume 430, Number 1, January IV 2005
|
|
---|---|---|
Page(s) | 287 - 301 | |
Section | Stellar atmospheres | |
DOI | https://doi.org/10.1051/0004-6361:20041525 | |
Published online | 12 January 2005 |
X-ray spectral and timing characteristics of the stars in the young open cluster IC 2391
1
Dipartimento di Scienze Fisiche & Astronomiche, Sezione di Astronomia, Università di Palermo, Piazza del Parlamento 1, 90134 Palermo, Italy e-mail: marino@astropa.unipa.it
2
INAF - Osservatorio Astronomico di Palermo Piazza del Parlamento 1, 90134 Palermo, Italy
Received:
24
June
2004
Accepted:
16
September
2004
We present X-ray spectral and timing analysis of
members of the young open cluster IC 2391 observed with
the XMM-Newton observatory.
We detected 99 X-ray sources by analysing the summed data obtained
from MOS1, MOS2 and pn detectors of the EPIC camera;
24 of them are members, or probable members, of the cluster.
Stars of all spectral types have been detected, from the early-types
to the late-M dwarfs.
Despite the capability of the instrument to recognize up to 3 thermal
components, the X-ray spectra of the G, K and M members of the cluster
are well described with two thermal components
(at –0.5 keV and
–1.2 keV respectively)
while the X-ray spectra of F members require only a softer 1-T model.
The Kolmogorov-Smirnov test applied to the X-ray photon time series shows
that approximately 46% of the members of IC 2391 are variable with a
confidence level >99%.
The comparison of our data with those obtained with ROSAT/PSPC, nine
years earlier, and ROSAT/HRI, seven years earlier, shows that
there is no evidence of significant variability on these time scales,
suggesting that long-term variations due to activity cycles similar to that on the
Sun are not common, if present at all, among these young stars.
Key words: X-ray: stars / stars: coronae / stars: activity / stars: early-type / stars: late-type / Galaxy: open clusters and associations: individual: IC 2391
© ESO, 2005
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