SALT spectroscopic follow up of V1047 Cen

ATel #12885; E. Aydi (MSU), D. A. H. Buckley (SAAO), P. Mroz (Warsaw U. Observatory), M. Orio (National Institute of Astrophysics Padova, Italy and University of Wisconsin at Madison), P. Woudt (UCT), D. P. K. Banerjee (Physical Research Laboratory, Ahmedabad), N. Evans (Keele University, UK), S. Starrfield (ASU), K. Sokolovsky (MSU), M. Gromadzki (Warsaw U. Observatory)
on 25 Jun 2019; 15:32 UT
Credential Certification: Elias Aydi (eaydi@saao.ac.za)

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We report on high-resolution optical spectroscopy of the recent re-brightening of V1047 Cen (ATel #12876).

On 2019-06-19.86UT, we obtained a 2000 s spectrum using the High Resolution Spectrograph (HRS; Crause et al. 2014, Proc. SPIE, 91476) mounted on the 11m Southern African Large Telescope under the SALT Large Science Program on Transients. The observations were taken in the LR mode of HRS which covers the spectral range of 3800-8900 A at a resolution of R=14000. The data were reduced with the SALT HRS MIDAS pipeline (Kniazev et al. 2016, MNRAS 459, 3068).

The spectrum is dominated by relatively broad emission lines of [O III] (FWZI > 1100 km/s), H I (FWZI > 2500 km/s), C IV, and He II (see below a list of line identifications). These broad lines probably originate from the remnant of the 2005 outburst. We also identify relatively narrow He I emission lines (FWHM < 300 km/s), as well as similar narrow emission features superimposed on top of the broad Hbeta and Halpha. These features indicate that the recent re-brightening is possibly a slow dwarf nova outburst, similar to the long outbursts displayed by long-orbital-period novae GK Per (Evans et al. 2009, MNRAS 399, 1167) and V1017 Sgr (Salazar et al. 2017, MNRAS 469, 4116). However, the unusual ongoing brightness increase of the system for more than 2 months leaves other possibilities on the table. Follow up observations are strongly encouraged in all bands.

The EWs of the Na D interstellar absorptions indicate high reddening towards the system, E(B-V) ~ 4.8, consistent with the high extinction implied by the Galactic reddening maps (Schlafly & Finkbeiner 2011, ApJ, 737, 103).

 
Line identifications: 
Broad: 
H I : 4861, 6563, 8502, 8595, 8665, 8750 A (FWZI > 2500 km/s). 
[O III]: 4959 and 5007 A (FWZI > 1100 km/s). 
[O II]: 7320/30 A. 
C IV: 4658 and 5805 A (FWZI > 2500 km/s). 
He II: 4686 (FWZI > 2500 km/s) and weak 5412 A. 
N III: 4638 A. 
[N II]: 5755 A. 
Narrow: 
He I: 4922, 5876, 6678, 7068, and 7282 A (FWZI ~ 550  km/s).