The Early Infrared Temporal Development of Nova Delphini 2013 (V339 Del) Observed With the Stratospheric Observatory for Infrared Astronomy (Sofia) and From the Ground

Abstract

We present ground-based infrared photometry, JHK spectroscopy, and 5-28 μm SOFIA FORCAST spectroscopy documenting the early temporal development of Nova Delphini 2013 (V339 Del). We derive a distance of ∼4.5 kpc using data available from the early expansion of the fireball. This distance gives an outburst luminosity of ∼8.3 × 10 5 L ☉ making V339 Del the most luminous CO nova on record. Our data provide new constraints on the ejected gas mass and the dust yield in fast CO novae. The ejected gas mass as estimated by the cutoff wavelength during the free-free emission phase is ∼7.5 × 10 −5 M. ☉ There is evidence for the formation of ∼1.2 (±0.4) × 10 −7 M ☉ of dust about 102 days after outburst. The gas to dust ratio of ∼470/1-940/1 implies that dust production was much less efficient in V339 Del than is the case for most CO novae.

Rise and fall of the dust shell of the classical nova V339 Delphini

“…IR photometric observations of V339 Del were reported by Cass et al (2013a,b), Shenavrin, Taranova & Tatarnikov (2013), Taranova et al (2014) and Gehrz et al (2015). Taranova et al (2014) detected an IR excess due to dust formation approximately 1 month after maximum.…”

“…They estimated a dust temperature and mass of ∼1500 K and ∼1.6 × 10 24 g (∼8 × 10 −10 M ), respectively, on 2013 September 21 (day 38.9) and ∼1200 K and ∼10 25 g (∼5 × 10 −6 M ) on 2013 October 11 (day 58.8). The presence of dust is confirmed by the IR photometry by Cass et al (2013a) and Gehrz et al (2015). Gehrz et al estimated the amount of dust to be ∼1.3 × 10 −9 M 78.66 d after outburst and ∼1.2 [ ± 0.4] × 10 −7 M 102 d after outburst.…”

“…They further detected an ellipticity in the light distribution, suggesting a prolate or bipolar structure that may have developed as early as day 2. On the basis of photometry of the expanding fireball following outburst, Gehrz et al (2015) determined that the distance of V339 Del is 4.5 ± 0.8 kpc, and that the eruption occurred on 2013 August 13.9 UT (JD 245 6518.4); in this paper, we adopt this as t = 0 and D = 4.5 kpc.…”

“…It would have been detected had it been present to the extent seen in other novae; its weakness in V339 Del may be connected with this nova's inability to form a copious amount of dust. Gehrz et al (2015) have described IR observations of V339 Del using SOFIA and, using their fireball-derived distance, deduced an outburst luminosity of ∼8.3 × 10 5 L : V339 Del seems to have been the most luminous CO nova on record. They determined the mass of ejected gas to be ∼7.5 × 10 −5 M , and that the gas-todust ratio in V339 Del was in the range of ∼470-940.…”

“…Gehrz et al (2015), which also gives full details of the observing and data reduction procedures; the photometric data and these details are not repeated here. The spectra are shown in Fig.…”