| Issue |
A&A
Volume 399, Number 2, February IV 2003
|
|
|---|---|---|
| Page(s) | 681 - 686 | |
| Section | Stellar structure and evolution | |
| DOI | https://doi.org/10.1051/0004-6361:20021830 | |
| Published online | 07 February 2003 | |
First far–UV observations of KQ Puppis with FUSE *
1
XMM Science Operations Centre, VILSPA, PO Box 50727, 28080 Madrid, Spain
2
Dipartimento di Fisica, Università La Sapienza, Piazzale Aldo Moro 3, 00185 Roma, Italy
3
Istituto di Astrofisica Spaziale e Fisica Cosmica, CNR, Area di Ricerca Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
Corresponding author: R. González-Riestra, rgonzale@xmm.vilspa.esa.es
Received:
29
July
2002
Accepted:
20
November
2002
We report the first far–ultraviolet spectrum of the emission line
spectroscopic binary KQ Pup (M2Iab+B0Ve), obtained with FUSE shortly
after conjunction at orbital phase 
.
The spectrum presents a sharp flux
cutoff at 1040 Å; longwards, it is dominated by a large amount of
resonant and low excitation transitions of neutral and singly ionized
species, probably mostly of circumsystem origin, and by the Lyman
absorption bands of H2, whose strength corresponds to an
interstellar H2 column density of ~
cm-2,
indicating a fraction of molecular hydrogen
2N(H2)/[ N(Hi)+2N(H2)] of ~0.4.
An N(Hi)/EB-V ratio of 
is derived from the
IUE spectra. The long–term UV
monitoring of KQ Pup with IUE, HST and FUSE reveals a large decrease
of the far–UV flux since orbital phase 0.82 and occupying more than
0.3 of the orbital period.
This “shell” episode is attributed to line absorption and to
Lyα Rayleigh scattering due to an extended dense cool envelope
in the line of sight of the B star.
Key words: stars: binaries: spectroscopic / stars: individual: KQ Pup / stars: mass-loss / ultraviolet: stars
Based on observations made with the NASA-CNES-CSA Far Ultraviolet Spectroscopic Explorer. FUSE is operated for NASA by the Johns Hopkins University under NASA contract NAS5-32985. The HST spectrum used in this paper was obtained from the Multimission Archive at the Space Telescope Science Institute (MAST).
© ESO, 2003
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