XMMSL1 J060636.2-694933: an XMM-Newton slew discovery and Swift/Magellan follow up of a new classical nova in the LMC

¹ Dept. of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK e-mail: amr30@star.le.ac.uk
² XMM-Newton SOC, ESAC, Apartado 78, 28691 Villanueva de la Cañada, Madrid, Spain
³ SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht, The Netherlands
⁴ Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
⁵ Warsaw University Observatory, A1. Ujazdowskie 4, 00-478, Warsaw, Poland
⁶ Max-Planck-Institut für extraterrestrische Physik, 85748 Garching, Germany
⁷ University of California, 601 Campbell Hall, Berkeley, CA 94720, USA

Received: 16 March 2009
Accepted: 24 August 2009

Abstract

Aims. In order to discover new X-ray transients, the data taken by XMM-Newton as it slews between targets are being processed and cross-correlated with other X-ray observations.

Methods. A bright source, XMMSL1 J060636.2-694933, was detected on 18 July 2006 at a position where no previous X-ray source had been seen. The XMM-Newton slew data, plus follow-up dedicated XMM-Newton and Swift observations, plus optical data acquired with the Magellan Clay telescope, and archival All-Sky Automated Survey (ASAS) data were used to classify the new object, and to investigate its properties.

Results. No XMM-Newton slew X-ray counts are detected above 1 keV and the source is seen to be over five hundred times brighter than the ROSAT All-Sky Survey upper limit at that position. The line-rich optical spectrum acquired with the Magellan telescope allows the object to be classified as an A₀ auroral phase nova, and the soft X-ray spectrum indicates that the nova was in a super-soft source state in the X-ray decline seen in the follow-up X-ray observations. The archival ASAS data suggests that the nova at onset (Oct 2005) was a “very fast” nova, and an estimate of its distance is consistent with the nova being situated within the LMC.

Conclusions. With the discovery presented here of a new classical nova in the LMC, it is clear that XMM-Newton slew data are continuing to offer a powerful opportunity to find new X-ray transient objects.