Context. Classical novae are the product of thermonuclear runaway-initiated explosions occurring on accreting white dwarfs. Aims. V339 Del (Nova Delphinus 2013) was one of the brightest classical novae of the last hundred years. Spectroscopy and photometry are available from γ-rays through infrared at stages that have frequently not been observed well. The complete data set is intended to provide a benchmark for comparison with modeling and for understanding more sparsely monitored historical classical and recurrent novae. This paper is the first in the series of reports on the development of the nova. We report here on the early stages of the outburst, through the X-ray active stage. Methods. A time sequence of optical, flux calibrated high resolution spectra was obtained with the Nordic Optical Telescope (NOT) using FIES simultaneously, or contemporaneously, with the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope during the early stages of the outburst. These were supplemented with Mercator/HERMES optical spectra. High resolution IUE ultraviolet spectra of OS And 1986, taken during the Fe curtain phase, served as a template for the distance determination. We used standard plasma diagnostics (e.g., [O III] and [N II] line ratios, and the Hβ line flux) to constrain electron densities and temperatures of the ejecta. Using Monte Carlo modeling of the ejecta, we derived the structure, filling factor, and mass from comparisons of the optical and ultraviolet line profiles. Results. We derive an extinction of E(B - V) = 0.23 ± 0.05 from the spectral energy distribution, the interstellar absorption, and H I emission lines. The distance, about 4-4.5 kpc, is in agreement with the inferred distance from near infrared interferometry. The maximum velocity was about 2500 km s-1, measured from the UV resonance and optical profiles. The ejecta showed considerable fine structure in all transitions, much of which persisted as emission knots. The line profiles were modeled using a bipolar conical structure for the ejecta within a relatively restricted range of parameters. For V339 Del, we find that an inclination to the line of sight of about 35°-55°, an opening angle of 60°-80°, and an inner radius ΔR/R(t) ≈ 0.3 based on vrad,max matches the permitted and intercombination lines. The filling factor is f ≈ 0.1, and the derived range in the ejecta mass is (2-3) × 10-5M⊙.
Bibliographical noteFunding Information:
Based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 312430 (OPTICON). Sumner Starrfield acknowledges partial support from NASA and NSF grants to ASU. C.E.W. acknowledges partial support from NASA Swift grant NNX14AC54G. Simone Scaringi acknowledges funding from the Alexander von Humboldt Foundation. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained [from the Data Archive] at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program # 13828. Support for program #13828 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. We thank our collaborators in the ARAS group for their remarkable diligence, skill, and persistence in obtaining spectroscopy of this and other novae and for the resulting archival treasures. The program described here was planned during a workshop in Pisa in July 2013, fortuitously just before the announcement of V339 Del, and we thank the participants or their insights, especially A. Caleo, C.-C. Cheung, J. Jos?, J.-U. Ness, and B. Warner. We also thank D. Gies, P. Hauschildt, D. Korcakova, P. Kuin, P. Selvelli, F. Walter, and P. Woudt for discussions and exchanges.
© ESO, 2016.
- line: profiles
- novae, cataclysmic variables
- stars: individual: V339 Del (Nova Del 2013)