NOVA V2362 CYGNI (NOVA CYGNI 2006):SPITZER,SWIFT, AND GROUND-BASED SPECTRAL EVOLUTION

Abstract

Nova V2362 Cygni has undergone a number of very unusual changes. Ground-based spectroscopy initially revealed a normal sequence of events: the object faded and its near-infrared emission lines gradually shifted to higher excitation conditions until about day 100 when the optical fading reversed and the object slowly brightened. This was accompanied by a rise in the Swift X-ray telescope flux and a sudden shift in excitation of the visible and IR spectrum back to low levels. The new lower excitation spectrum revealed broad line widths and many P-Cygni profiles, all indicative of the ejection of a second shell. Eventually, dust formed, the X-ray brightnessapparently unaffected by dust formation-peaked and then declined, and the object faded at all wavelengths. The Spitzer dust spectra revealed a number of solid-state emission features that, at this time, are not identified.

The peculiar dust shell of Nova DZ Cru (2003)

“…The Spitzer-derived values are broadly in agreement with the velocities reported by Rushton et al (2008) on the basis of linewidths in the 1-2.5 μm range. The presence of [Ne III] 15.5-μm and [O IV] 25.9-μm emission is common in mature novae (Lynch et al 2008;Schwarz et al 2008); this, together with the inferred expansion velocities, appears to reinforce the conclusion of Rushton et al (2008) that DZ Cru is a classical nova.…”

“…There are superficial similarities between the dust shell of DZ Cru and those of V2361 Cyg (Helton et al, in preparation) and V2362 Cyg (Lynch et al 2008;Helton et al, in preparation). The latter displayed features at 6.37, 8.05, 11.32 and a broad 'plateau' centred at ∼18 μm; Lynch et al 2008 were unable to securely identify any of the dust features in V2362 Cyg.…”

“…2, in which the features are indicated by vertical ticks. The wavelengths and FWHM of the features are given in Table 2, together with an indication of their presence (possibly at slightly different wavelengths) or absence in V705 Cas (Evans et al 2005) and V2362 Cyg (Lynch et al 2008), and in evolved stars. In addition, there may be a 'plateau' of emission that extends from ∼14 to ∼34 μm (cf.…”

The Distance and Morphology of V723 Cassiopeiae (Nova Cassiopeia 1995)

“…Lynch et al (2008) explain the pronounced second brightening of the recent nova V2362 Cyg as a separate TNR ejection event and Evans et al (2003) suggested that the multiple peaks in the visual light curve of V723 Cas may be the result of multiple mass ejection events. If so, multiple mass ejection events may be common because many novae have had multiple peaks in the visual light curves during their early evolution.…”

Infrared laboratory absorbance spectra of olivine: using classical dispersion analysis to extract peak parameters

“…A spectral attribution of Fe-rich olivine dust particles around a Vega-like star could imply the existence of a surrounding asteroid belt or a series of planetesimals (Honda et al 2004). In addition, there are various IR features that remain unidentified (λ ∼ 13, 20, 28 μm, Sloan et al 2003; ∼8 μm feature in Spitzer data of novae ejecta, Lynch et al 2008). Given that there will be more observation cycles to come from Spitzer and Stratospheric Observatory for Infrared Astronomy (SOFIA) that may show Fe-rich or unidentified silicate signatures in astronomical objects, there is a need for absorption data on and an understanding of the transitions from Fe-to Mg-rich olivine compositions for a complete suite of olivine compositions at mid-to far-IR wavelengths to interpret observed spectra and test dust formation hypotheses.…”