EDP Sciences
Free access
Issue A&A
Volume 408, Number 2, September III 2003
Page(s) 715 - 727
Section Formation and evolution of planetary systems
DOI http://dx.doi.org/10.1051/0004-6361:20031007

A&A 408, 715-727 (2003)
DOI: 10.1051/0004-6361:20031007

Radio and submillimetre observations of wind structure in  $\zeta$ Puppis

R. Blomme1, G. C. van de Steene1, R. K. Prinja2, M. C. Runacres1 and J. S. Clark2

1  Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium
2  Department of Physics & Astronomy, University College London, Gower Street, London WC1E 6BT, UK

(Received 17 April 2003 / Accepted 24 June 2003)

We present radio and submillimetre observations of the O4I(n)f star $\zeta$ Pup, and discuss structure in the outer region of its wind (~ 10-100 R*). The properties of bremsstrahlung, the dominant emission process at these wavelengths, make it sensitive to structure and allow us to study how the amount of structure changes in the wind by comparing the fluxes at different wavelengths. Possible forms of structure at these distances include Corotating Interaction Regions (CIRs), stochastic clumping, a disk or a polar enhancement. As the CIRs are azimuthally asymmetric, they should result in variability at submillimetre or radio wavelengths. To look for this variability, we acquired 3.6 and 6 cm observations with the Australia Telescope Compact Array (ATCA), covering about two rotational periods of the star. We supplemented these with archive observations from the NRAO Very Large Array (VLA), which cover a much longer time scale. We did not find variability at more than the $\pm$ 20% level. The long integration time does allow an accurate determination of the fluxes at 3.6 and 6 cm. Converting these fluxes into a mass loss rate, we find $\dot{M} = 3.5 \times 10^{-6}~M_{\odot}/{\rm yr}$. This value confirms the significant discrepancy with the mass loss rate derived from the H $\alpha$ profile, making $\zeta$ Pup an exception to the usually good agreement between the H $\alpha$ and radio mass loss rates. To study the run of structure as a function of distance, we supplemented the ATCA data by observing  $\zeta$ Pup at 850  $\mu$m with the James Clerk Maxwell Telescope (JCMT) and at 20 cm with the VLA. A smooth wind model shows that the millimetre fluxes are too high compared to the radio fluxes. While recombination of helium in the outer wind cannot be discounted as an explanation, the wealth of evidence for structure strongly suggests this as the explanation for the discrepancy. Model calculations show that the structure needs to be present in the inner ~ 70 R* of the wind, but that it decays significantly, or maybe even disappears, beyond that radius.

Key words: stars: early-type -- stars: individual: $\zeta$ Pup -- stars: mass loss -- stars: winds, outflows -- radio continuum: stars

Offprint request: R. Blomme, Ronny.Blomme@oma.be

SIMBAD Objects

© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.
  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.

Editor-in-Chief: T. Forveille
Letters Editor-in-Chief: J. Alves
Managing Editor: C. Bertout

ISSN: 0004-6361 ; e-ISSN: 1432-0746
Frequency: 12 volumes per year
Published by: EDP Sciences

Mirror sites: CDS | EDP Sciences
  RSS feeds
© The European Southern Observatory (ESO)