The helium nova V445 Puppis

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The helium nova V445 Puppis
Patrick Woudt (UCT), Danny Steeghs, Paul Groot,
Tom Marsh Gijs Nelemans, Gijs Roelofs, Tim
OBrien, Derck Smits, Brian Warner

• V445 Pup (Nova Puppis 2000) the first observed
  helium nova
• The nature of the (presumed) underlying binary
  and determining the distance
• of V445 Pup
• The secular evolution of the nova at
• near-infrared wavelength
• Optical spectroscopy an asymmetric
• expanding nova shell?
• Imaging at high angular resolution
• with the VLT/NACO

Combined J, H, Ks colour image of V445 Pup taken
with the IRSF (2003 March 22)
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V445 Pup (Nova Puppis 2000) the first observed
helium nova

• Last nova of the previous millenium
• Reported 2000 Dec 30 (Kato Kanatsu 2000), but
  first outburst
• measurement 2000 Nov 23
• Proposed as the first observed helium nova (Kato
  Hachisu 2003 Ashok Banerjee 2003). Various
  unique aspects
• Hydrogen-deficient (Wagner et al. 2001)
• Enriched in carbon and helium (e.g. Ashok
  Banerjee 2003)
• The initially formed optically thin dust shell
  has developed in an optically thick shell
  (Henden et al. 2001)
• Shell still obscures the nova (4-5 years later)
• One of a kind!
• From modelling of the optical light curve, Kato
  Hachisu (2003) deduced the following
  (model-dependent) parameters
• Mass of the primary (M1) gt 1.33 Msun
• dM/dt is several times 10-7 Msun/yr
• nova recurrence time (tr) is 70 yr
• M1 and tr in their models depend sensitively on
  the assumed distance
• d 640 pc (1.33 Msun and 61 yr) d 700 pc
  (1.35 Msun and 84 yr)

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V445 Pup (Nova Puppis 2000), the first observed
helium nova

• Short recurrence time between nova outbursts and
  weak photospheric wind ? white dwarf continuously
  growing in mass ? either progenitor of SN Ia, or
  end up via accretion-induced collapse as a
  neutron star.
• Nature of the underlying binary still unknown
• AM CVn at short Porb (high dM/dt) MV 5 9
  mag
• CV with a helium donor (Iben Tutukov 1991) Mv
  -1 mag
• Hydrogen accretor with very high dM/dt Mv -2
  to 3 mag
• ?

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V445 Pup in outburst (optical). Figure from Ashok
Banerjee (2003).
V445 Pup monitoring campaign on the Japanese
1.4-m InfraRed Survey Telescope 22 March 2002 -
present
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The optical spectrum of V445 Pup
Taken with the 6.5-m Magellan telescope and the
imaging spectrograph (IMACS) on 2003 December 17
(3 years after outburst).
Spectral lines HeI, OI, OII and OIII High
temperatures 20000 K (OIII 4363Å, OII
7320/7330Å) High reddening! I(3727Å) vs.
I(7320/7330Å)
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The optical spectrum of V445 Pup (line
diagnostics)
The main velocity-components -1570 km/s, -850
km/s and 750 km/s
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The optical spectrum of V445 Pup (line
diagnostics)
Is there any evidence of hydrogen?
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V445 Pup spatially resolved
Taken with the VLT and the NAOS/CONICA adaptive
optics camera (in the Ks band) on 2005 March 25.
Second epoch due 2005 September. Scale
0.027/pixel, FWHM 0.1
Distance upper limit diameter 2.1 ? D lt
1.5 kpc ? mV MV lt 10.9 mag (combined with AV
lt 0.7 mag) ? MV gt 3.3 mag
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Detailed dynamical modelling of the nova
shell Necessary for accurate expansion
parallax measurement. Integral Field Unit
Spectroscopy 2006 January 2 nights on Magellan
IFU Follow-up adaptive optics observations
with SINFONI
HR Del (in OIII).
VLT (NAOS/CONICA) Ks band image of V445 Pup.
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• V445 Puppis (current observational overview)
• Adaptive optics imaging clear estimate of the
  size of the shell
• Integral Field Unit spectroscopy (2 nights in
  2006 January)
• Detailed dynamical modelling
• Current (conservative) distance
• constraint d lt 1.5 kpc
• MV fainter than 3.3 mag (a very
• conservative estimate)

• Nature of the underlying binary still unknown
• AM CVn at short Porb (high dM/dt) MV 5 9
  mag
• CV with a helium donor Mv -1 mag
• Hydrogen accretor with very high dM/dt Mv -2
  to 3 mag
• ?
• Scheduled observations with ULTRACAM (2005
  November) to search for periodicities.