Transient Heavy Element Absorption Systems in Novae: Episodic Mass Ejection from the Secondary Star

TL;DR

This study uses high-resolution spectroscopy to identify and analyze short-lived heavy element absorption systems in novae, suggesting they originate from episodic mass ejection from the secondary star, with implications for understanding nova outbursts and supernova progenitors.

Contribution

It provides the first detailed characterization of heavy element absorption systems in novae and links them to episodic mass ejection from the secondary star.

Findings

Heavy element absorption systems are common near nova maximum light.

These systems show velocities of 400-1000 km/s and weaken over weeks.

Episodic mass ejection from the secondary star likely causes these absorption features.

Abstract

A high-resolution spectroscopic survey of postoutburst novae reveals short-lived heavy element absorption systems in a majority of novae near maximum light, having expansion velocities of 400-1000 km/s and velocity dispersions between 35-350 km/s. A majority of systems are accelerated outwardly, and they all progressively weaken and disappear over timescales of weeks. A few of the systems having narrow, deeper absorption reveal a rich spectrum of singly ionized Sc, Ti, V, Cr, Fe, Sr, Y, Zr, and Ba lines. Analysis of the richest such system, in Nova LMC 2005, shows the excitation temperature to be 104 K and elements lighter than Fe to have abundance enhancements over solar values by up to an order of magnitude. The gas causing the absorption systems must be circumbinary and its origin is most likely mass ejection from the secondary star. The absorbing gas pre-exists the outburst and may represent episodic mass transfer events from the secondary star that initiate the nova outburst(s). If SNe Ia originate in single degenerate binaries, such absorption systems could be detectable before maximum light