Letter to the Editor

U Scorpii 2010 outburst: observational evidence of an underlying ONeMg white dwarf^⋆

E. Mason

Space Telescope Science Institute (STScI), 3700 S. Martin Dr., Baltimore, MD 21218, USA
e-mail: emason@stsci.edu

Received: 8 June 2011
Accepted: 18 July 2011

Abstract

This paper presents U Sco nebular spectra collected in the period March–May 2010 after the binary outburst on Jan. 28, 2010. The spectra display strong [Nev] and [Neiii] lines that can be used to compute the relative abundance of [Ne/O]. The value obtained ([Ne/O] = 1.69) is higher than the typical [Ne/O] abundance found in classical novae from CO progenitors and suggests that U Sco has a ONeMg white-dwarf progenitor. It follows that U Sco will not explode as a SN Ia but rather collapse to become a neutron star or a millisecond pulsar.