Issue |
A&A
Volume 409, Number 3, October III 2003
|
|
---|---|---|
Page(s) | 1007 - 1015 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20031160 | |
Published online | 17 November 2003 |
The enigmatic outburst of V445 Puppis – A possible helium nova?
Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India e-mail: orion@prl.ernet.in
Corresponding author: N. M. Ashok, ashok@prl.ernet.in
Received:
22
January
2003
Accepted:
16
July
2003
JHK spectroscopic and photometric observations are reported for the
enigmatic, nova-like, variable V445 Puppis which erupted at the end of
2000.
The near-IR spectra are hydrogen-deficient and unusually rich in CI lines. The
important CI lines are found to be positioned at 1.133, 1.166, 1.175,
1.189, 1.26 and 1.689 μm.
Model calculations for the CI lines are done to make the identification
of the lines secure. Photometric data, taken on January 2.90 UT, 2001
shortly after
the outburst, show the formation of an optically thin dust shell around V445
Puppis. The temperature and upper limit for the mass of the dust
shell are estimated to be 1800 K and
respectively. A subsequent episode of massive dust formation
– indicated by the observed, deep visual dimming – is also seen
in JHK images of early November 2001. V445 Puppis has shown two unusual
properties for a nova: (i) the hydrogen-deficiency and He/C enrichment of the object as seen from
optical and IR data and (ii) synchrotron radio emission which was detected
nearly a year after its outburst by other workers. The strange nature of the
object is discussed and it is shown that it is difficult to place it in the
known categories of eruptive variables viz. novae (classical, recurrent or
symbiotic); born-again AGB stars; the new class of eruptive variables like
V838 Mon; and RCB/HdC stars. Tentative evidence for an accretion disk and
binarity of the V445 Puppis system is presented. It is debated whether
V445 Puppis is a rare helium nova or a unique object.
Key words: stars: individual: V445 Puppis / infrared: stars / stars: novae, cataclysmic variables / techniques: spectroscopic
© ESO, 2003
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