Early Infrared Spectral Development of V1187 Scorpii (Nova Scorpii 2004 No. 2)

Abstract

We report on an unprecedented infrared time series of spectra of V1187 Sco, a very fast ONeMg nova. The observations covered a 56 day period (2004 August 6-September 30) starting 2 days after the nova's peak brightness. Time evolution of the spectra revealed changing line strengths and profiles on timescales of less than a day to weeks as the nova evolved from early postmaximum to early coronal phases. When our ground-based optical and Spitzer Space Telescope data were combined, the wavelength coverage of 0.38-36 m allowed an accurate spectral energy distribution to be derived when it was about 6 weeks after outburst. Developing double structure in the He i lines showed them changing from narrow to broad in only a few days. Using the O i lines in combination with the optical spectra, we derived a reddening of E(B À V ) ¼ 1:56 AE 0:08 and a distance of 4:9 AE 0:5 kpc. Modeling of the ejected material strongly suggested that it was geometrically thick with ÁR/R ¼ 0:8 0:9 (more of a wind than a shell) and a low filling factor of order a few percent. The line shapes were consistent with a cylindrical jet, bipolar, or spherical Hubble flow expansion with a maximum speed of about À3000 km s À1 . The central peak appeared to be more associated with the spherical component, while the two peaks (especially in H ) suggested a ring with either a lower velocity component or with its axis inclined to the line of sight.

How peculiar is the ‘peculiar variable’ DZ Crucis (Nova Cru 2003)?

“…The spectra presented here leave us in no doubt DZ Cru is a nova, for H i , He i , [N i ] and O i lines appear in their near‐IR spectra (e.g. Evans et al 2003b; Rudy et al 2003; Lynch et al 2004; Venturini et al 2004; Lynch et al 2006), and extensive dust shells are known to have formed around some novae (Evans & Rawlings 2008). Furthermore, the outflow velocities in DZ Cru are within the range shown by novae (Warner 2008).…”

The Early Spectrophotometric Evolution of V1186 Scorpii (Nova Scorpii 2004 No. 1)

“…The light curve behavior, the low expansion velocities, and the similarity of the early spectra of V1186 Sco (Fujii 2004, and §2.2) to those of V723 Cas (Evans et al 2003) and PW Vul Evans et al 1990; Williams et al 1996) implies that the outburst occurred on a low mass CO-type WD. The behavior of V1186 Sco contrasts markedly with that of the other nova discovered in the constellation Scorpius in 2004, the fast ONeMg nova V1187 Sco (Lynch et al 2006). In particular, the development of infrared coronal lines detected with Spitzer was significantly more rapid in V1187 Sco (cf., §4).…”

“…The emergence of this line is typically taken as a sign that the outburst occurred on the surface of an ONeMg WD (Gehrz et al 1998) although Greenhouse et al (1988) and Gehrz et al (1988) and others have argued that strong continuum emission from condensing dust in the ejecta may mask the presence of [Ne II] lines, especially if observations are obtained at low spectral resolution. Previous [Ne II] detections discussed in the literature, V1974 Cyg (Hayward et al 1992), V1187 Sco (Lynch et al 2006), QU Vul (Gehrz et al 2007b;Greenhouse et al 1988;Gehrz, Grasdalen, & Hackwell 1985), and CP Cru , occurred on ONeMg nova with high ejection velocities (≥ 1000 km s −1 ). However, it is unlikely that the progenitor is a ONeMg WD in the V1186 Sco system as the speed class (slow) and expansion velocities from the line widths are more similar to that observed in CO WD outbursts.…”

“…To emphasize the slow evolution in V1186 Sco, Fig. 6 compares the Spitzer observations of V1186 Sco with the faster ONeMg nova V1187 Sco (Lynch et al 2006). V1187 Sco reached visual maximum on 03 August 2003 UT, or approximately one month after V1186 Sco.…”

An Expanding Shell and Synchrotron Jet in RS Ophiuchi

“…2 of that paper shows that the difference between FWHM and HWZI results from the shape of the line profile: a strong, narrow, roughly Gaussian peak, surrounded by a faint, broad plateau. The narrow component suggests an expanding wind or outflow, while the broad plateau is more characteristic of a thin shell (e.g., Lynch et al 2006;Bertout & Magnan 1987;Gill & O'Brien 1999). The consistent ratio of the FWHMs and HWZIs, and the roughly constant ratio of the peak flux density in the two components, shows they remain closely associated for at least the first 40 days after the explosion.…”