The Emergence of the Infrared transient VVV-WIT-06
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Author
Minniti, Dante
Saito, Roberto K.
Forster, F.
Pignata, G.
Ivanov, Valentin D.
Lucas, Philip
Beamin, J.C.
Borissova, Jura
Catelan, Marcio
Gonzalez, Oscar A.
Hempel, Maren
Hsiao, E
Kurtev, Radostin
Majaess, Daniel
Masetti, N.
Morrell, N.I.
Phillips, M.M.
Pullen, J. B.
Rejkuba, M.
Smith, L.C.
Surot, F.
Valenti, Elena
Zoccali, Manuela
Attention
2299/20635
Abstract
We report the discovery of an enigmatic large-amplitude (ΔKs> 10.5 mag) transient event in near-IR data obtained by the VISTA Variables in the Via Lactea (VVV) ESO Public Survey. The object (designated VVV-WIT-06) is located at R.A. = 17:07:18.917, decl. = -39:06:26.45 (J2000), corresponding to Galactic coordinates l = 347.14539, b = 0.88522. It exhibits a clear eruption, peaking at Ks = 9 mag during 2013 July and fading to Ks ~ 16.5 in 2017. Our late near-IR spectra show post-outburst emission lines, including some broad emission lines (upward of {FWHM} ~ 3000 k/s). We estimate a total extinction of A_V=10--15 mag in the surrounding field, and no progenitor was observed in ZYJHKs images obtained during 2010-2012 (down to Ks> 18.5 mag). Subsequent deep near-IR imaging and spectroscopy, in concert with the available multiband photometry, indicate that VVV-WIT-06 may be either: (I) the closest Type I SN observed in about 400 years, (II) an exotic high-amplitude nova that would extend the known realm of such objects, or (III) a stellar merger. In all of these cases, VVV-WIT-06 is a fascinating and curious astrophysical target under any of the scenarios considered.