Pan-chromatic Observations of the Recurrent Nova LMC 2009a (LMC 1971b)

Journal
Date Issued
2016
Author(s)
Bode, M. F.
•
Darnley, M. J.
•
Beardmore, A. P.
•
Osborne, J. P.
•
Page, K. L.
•
Walter, F. M.
•
Krautter, J.
•
•
Ness, J. -U.
•
O'Brien, T. J.
•
Orio, M.
•
Schwarz, G. J.
•
Shara, M. M.
•
Starrfield, S.
DOI
Abstract
Nova LMC 2009a is confirmed as a recurrent nova (RN) from positional coincidence with nova LMC 1971b. The observational data set is one of the most comprehensive for any Galactic or extragalactic RN: optical and near-IR photometry from outburst until over 6 years later; optical spectra for the first 6 months, and Swift satellite ultraviolet (UV) and X-ray observations from 9 days to almost 1 year post-outburst. We find MV = -8.4 ± 0.8r ± 0.7s and expansion velocities between 1000 and 4000 km s-1. Coronal line emission before day 9 indicates shocks in the ejecta. Strengthening of He IIλ4686 preceded the emergence of the super-soft source (SSS) in X-rays at ∼63-70 days, which was initially very variable. Periodic modulations, P = 1.2 days, most probably orbital in nature, were evident in the UV and optical from day 43. Subsequently, the SSS shows an oscillation with the same period but with a delay of 0.28P. The progenitor system has been identified; the secondary is most likely a sub-giant feeding a luminous accretion disk. Properties of the SSS infer a white dwarf (WD) mass 1.1 M☉ ≲ MWD ≲ 1.3 M☉. If the accretion occurs at a constant rate, {\dot{M}}{{acc}}≃ {3.6}-2.5+4.7× {10}-7 {M}☉ yr-1 is needed, consistent with nova models for an inter-eruption interval of 38 years, low outburst amplitude, progenitor position in the color-magnitude diagram, and spectral energy distribution at quiescence. We note striking similarities between LMC 2009a and the Galactic nova KT Eri, suggesting that KT Eri is a candidate RN.
Volume
818
Issue
2
Start page
145
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...818..145B
Rights
open.access
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