Optical spectroscopic and polarization properties of 2011 outburst of the recurrent nova T Pyxidis^⋆

¹ Indian Institute of Astrophysics, 560 034 Bangalore, India
e-mail: pavana@iiap.res.in
² Pondicherry University, R.V. Nagar, Kalapet 605014, Puducherry, India
³ Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, 411 007 Pune, India

Received: 28 June 2018
Accepted: 17 December 2018

Abstract

Aims. We aim to study the spectroscopic and ionized structural evolution of T Pyx during its 2011 outburst, and also study the variation in degree of polarization during its early phase.

Methods. Optical spectroscopic data of this system obtained from day 1.28–2415.62 since discovery, and optical, broadband imaging polarimetric observations obtained from day 1.36–29.33 during the early phases of the outburst were used in the study. The physical conditions and the geometry of the ionized structure of the nova ejecta was modelled for a few epochs using the photo-ionization code, CLOUDY in 1D and pyCloudy in 3D.

Results. The spectral evolution of the nova ejecta during its 2011 outburst is similar to that of the previous outbursts. The variation in the line profiles is seen very clearly in the early stages due to good coverage during this period. The line profiles vary from P Cygni (narrower, deeper, and sharper) to emission profiles that are broader and structured, which later become narrower and sharper in the late post-outburst phase. The average ejected mass is estimated to be 7.03 × 10⁻⁶ M_⊙. The ionized structure of the ejecta is found to be a bipolar conical structure with equatorial rings, with a low inclination angle of 14.75 ° ±0.65°.