Optical and near-infrared spectroscopy of No v a V2891 Cygni: evidence for shock-induced dust formation

Vipin Kumar, Mudit K. Srivastava, Dipankar P.K. Banerjee, C. E. Woodward, Ulisse Munari, Aneurin Evans, Vishal Joshi, Sergio Dallaporta, Kim L. Page

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Abstract

We present multi-epoch optical and near-infrared observations of the highly reddened, Fe II class slow Nova V2891 Cygni. The observations span 15 months since its disco v ery. The initial rapid brightening from quiescence, and the presence of an ∼35-d long pre-maximum halt, is well documented. The evidence that the current outburst of V2891 Cyg has undergone several distinct episodes of mass ejection is seen through time-varying P Cygni profiles of the O I 7773 Åline. A highlight is the occurrence of a dust formation event centred around approximately + 273 d, which coincides with a phase of coronal line emission. The dust mass is found to be ∼0 . 83 -1 . 25 ×10 -10 M ⊙. There is strong evidence to suggest that the coronal lines are created by shock heating rather than by photoionization. The simultaneous occurrence of the dust and coronal lines (with varying velocity shifts) supports the possibility that dust formation is shock induced. Such a route for dust formation has not previously been seen in a nova, although the mechanism has been proposed for dust formation in some core-collapse supernovae. Analysis of the coronal lines indicates a gas mass and temperature of 8.35-8.42 ×10 -7 M ⊙and ∼(4.8-9.1) ×10 5 K, respectively, and an o v erabundance of aluminium and silicon. A Case B analysis of the hydrogen lines yields a mass of the ionized gas of (8.60 ±1.73) ×10 -5 M ⊙. The reddening and distance to the nova are estimated to be E ( B -V ) = 2.21 ±0.15 and d = 5.50 kpc, respectively.

Original languageEnglish (US)
Pages (from-to)4265-4283
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Volume510
Issue number3
DOIs
StatePublished - 2022

Bibliographical note

Funding Information:
We are grateful to the anonymous reviewer for several useful suggestions. The research work at the Physical Research Laboratory (PRL) is funded by the Department of Space, Government of India. VK thanks PRL for his PhD research fellowship. DPKB is supported by a CSIR Emeritus Scientist grant. CEW acknowledges partial support from NASA grant 80NSSC19K0868. KLP acknowledges the support of the UK Space Agency. We thank the staff of 3.6-m DOT, which is a National Facility run and managed by Aryabhatta Research Institute of Observational Sciences (ARIES), an autonomous Institute under Department of Science and Technology, Government of India, for service observations with TANSPEC instrument. We ac-

Publisher Copyright:
© 2021 The Author(s) .

Keywords

  • cataclysmic variables
  • infrared: spectra
  • line: identification
  • spectroscopic
  • stars: individual V2891 Cyg
  • stars: novae
  • techniques: photometric

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