Spectroscopic observations of Nova Lup 2016
ATel #9587; L. Izzo, Z. Cano, A. de Ugarte Postigo, C. Thoene (IAA-CSIC), L. Vanzi, A. Zapata, N. Espinoza, D. Fernandez (PUC-Chile), J. L. Prieto (UDP/MAS), P. Bonifacio (GEPI-Obs. Paris), M. Della Valle (INAF-OAC), P. Molaro (INAF-OATs)
on 3 Oct 2016; 17:17 UT
Credential Certification: Luca Izzo (firstname.lastname@example.org)
We report spectroscopic observations of the Nova Lup 2016 (ATel #9538, #9539, #9550, #9564; CBET #4322), also known as ASASSN-16kt and PNV J15290182-4449409. A series (6x10 min exposures) of optical spectra were obtained with the 0.5 m telescope at the Pontificia Universidad Catolica de Chile Observatory at Santa Martina, Lo Barnechea (Santiago, Chile), equipped with the PUCHEROS echelle spectrograph on 2016 September 29.0. The observations cover the spectral range between 4250 and 6900 Angstrom at a resolution of \sim 0.25 Ang/pix at 5000 Ang.
A preliminary analysis of the combined spectrum shows a bright Halpha P-Cygni profiles with blue shifted velocities centred at v $\sim$ -2250 and -3650 km/s. The emission line is characterised by a measured FWHM = 3700 km/s and FWZI = 7700 km/s. Similar results for the Hbeta line, for which we measure a larger FWZI = 9400 km/s, likely due to the presence of an underlying emission line on the red wing of the Hbeta line, probably due to Fe II 4924. We have also identified the other two lines of the Fe II multiplet 42, Fe II 5018, 5169, which do not show blue shifted velocities.
We also report the presence of the He I 5876 and N II 5679 lines from their corresponding blue-shifted absorption centred at the velocity of v = -3650 km/s, that corresponds to the higher velocity component observed in Balmer lines. The low-ionisation transitions of Na I 5890 and 5686 also show a P-Cygni profile but centred at the velocity of v = -2250 km/s, that is the slower velocity component observed on the Halpha blue wing.
Both Halpha and Hbeta lines show an asymmetric profile, that hints at the existence of multiple components. This will be clarified in the spectral evolution in the next few days. Given the rapid photometric evolution of Nova Lup 2016 (t3 $\approx$ 5 days), follow-up is strongly encouraged