Volume 396, Number 3, December IV 2002
|Page(s)||877 - 884|
|Section||Interstellar and circumstellar matter|
|Published online||05 December 2002|
A 2.4–12 μm spectrophotometric study with ISO of Cygnus X-3 in quiescence*
DAPNIA/Service d'Astrophysique, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
2 Konkoly Observatory, PO Box 67, 1525 Budapest, Hungary
3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
4 Université Paris VII, France
Corresponding author: L. Koch-Miramond, firstname.lastname@example.org
Accepted: 28 June 2002
We present mid-infrared spectrophotometric results obtained with the ISO on the peculiar X-ray binary Cygnus X-3 in quiescence, at orbital phases 0.83 to 1.04. The 2.4–12 μm continuum radiation observed with ISOPHOT-S can be explained by thermal free-free emission in an expanding wind with, above 6.5 μm, a possible additional black-body component with temperature K and radius at 10 kpc, likely due to thermal emission by circumstellar dust. The observed brightness and continuum spectrum closely match that of the Wolf-Rayet star WR 147, a WN8+B0.5 binary system, when rescaled at the same 10 kpc distance as Cygnus X-3. A rough mass loss estimate assuming a WN wind gives ~ yr-1. A line at ~4.3 μm with a more than 4.3 σ detection level, and with a dereddened flux of 126 mJy, is interpreted as the expected He I 3p–3s line at 4.295 μm, a prominent line in the WR 147 spectrum. These results are consistent with a Wolf-Rayet-like companion to the compact object in Cyg X-3 of WN8 type, a later type than suggested by earlier works.
Key words: stars: binaries: close / stars: individual: Cyg X-3 / stars: Wolf-Rayet / stars: mass-loss / infrared: stars
© ESO, 2002
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.