Discovery of Metastable Helium Absorption Lines in V1280 Scorpii

TL;DR

This paper reports the discovery of metastable helium absorption lines in V1280 Scorpii, revealing complex ejecta structures and providing estimates of the ejected mass through high-resolution spectral analysis.

Contribution

It is the first detection of metastable He I* absorption lines in V1280 Scorpii, offering new insights into the ejecta composition and dynamics of this nova.

Findings

Detection of blue-shifted metastable He I* lines at 3188 A and 3889 A.

Observation of time variation in absorption line depths and velocities.

Estimated ejected mass of approximately 10^{-4} solar masses.

Abstract

We report the discovery of blue-shifted metastable He I* absorption lines at 3188 A and 3889 A with multiple components on high-resolution spectra (R ~ 60,000) of V1280 Scorpii. Similar multiple absorption lines associated with Na I D doublet and Ca II H and K are observed. Na I D doublet absorption lines have been observed since 2009, while the metastable He I* absorption lines were absent in 2009 and were detected in 2011 (four years after the burst). We find different time variations in depths and velocities of blue-shifted absorption components among He I*, Na I, and Ca II. The complex time evolutions of these lines can be explained by assuming changes in density and recombination/ionization rate when the ejecta expand and the photosphere contracts to become hotter. The multiple absorption lines originate in the ejected materials consisting of clumpy components, which obscure a significant part of the continuum emitting region. We estimate the total mass of the ejected material to be on the order of ~ 10^{-4} Mo, using metastable He I* 3188 and 3889 absorption lines.