Article (Scientific journals)
A Detailed X-Ray Investigation of ζ Puppis. II. The Variability on Short and Long Timescales
Nazé, Yaël; Oskinova, Lidia M.; Gosset, Eric
2013In Astrophysical Journal, 763, p. 143
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Keywords :
stars: early-type; stars: individual: zeta Pup; X-rays: stars
Abstract :
[en] Stellar winds are a crucial component of massive stars, but their exact properties still remain uncertain. To shed some light on this subject, we have analyzed an exceptional set of X-ray observations of ζ Puppis, one of the closest and brightest massive stars. The sensitive light curves that were derived reveal two major results. On the one hand, a slow modulation of the X-ray flux (with a relative amplitude of up to 15% over 16 hr in the 0.3-4.0 keV band) is detected. Its characteristic timescale cannot be determined with precision, but amounts from one to several days. It could be related to corotating interaction regions, known to exist in ζ Puppis from UV observations. Hour-long changes, linked to flares or to the pulsation activity, are not observed in the last decade covered by the XMM observations; the 17 hr tentative period, previously reported in a ROSAT analysis, is not confirmed either and is thus transient, at best. On the other hand, short-term changes are surprisingly small (<1% relative amplitude for the total energy band). In fact, they are compatible solely with the presence of Poisson noise in the data. This surprisingly low level of short-term variability, in view of the embedded wind-shock origin, requires a very high fragmentation of the stellar wind, for both absorbing and emitting features (>10[SUP]5[/SUP] parcels, comparing with a two-dimensional wind model). This is the first time that constraints have been placed on the number of clumps in an O-type star wind and from X-ray observations. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Nazé, Yaël  ;  Université de Liège - ULiège > GAPHE : Astrophysique observationnelle (sol et espace)
Oskinova, Lidia M.;  Institute for Physics and Astronomy, University of Potsdam, D-14476 Potsdam, Germany
Gosset, Eric ;  Université de Liège - ULiège > GAPHE : Astrophysique observationnelle (sol et espace)
Language :
English
Title :
A Detailed X-Ray Investigation of ζ Puppis. II. The Variability on Short and Long Timescales
Publication date :
01 February 2013
Journal title :
Astrophysical Journal
ISSN :
0004-637X
eISSN :
1538-4357
Publisher :
University of Chicago Press, United States - Illinois
Volume :
763
Pages :
143
Peer reviewed :
Peer Reviewed verified by ORBi
Available on ORBi :
since 22 March 2013

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