Extremely fast spectral evolution of SLSN 2019neq
ATel #13184; B. P. Thomas (UT Austin), R. Konyves-Toth (Konkoly Obs.), J. Vinko (Konkoly Obs., U Szeged, UT Austin), J. C. Wheeler (UT Austin)
on 11 Oct 2019; 19:21 UT
Credential Certification: Jozsef Vinko (vinko@astro.as.utexas.edu)
Subjects: Optical, Supernovae
We report post-maximum spectroscopic observations of the Type I SLSN SN2019neq that augment the pre-maximum spectroscopic observations of the same SLSN-I reported in ATel #13085 and AstroNote-2019-79 .
Two additional spectra (range 360-1000 nm) were obtained with the "Low Resolution Spectrograph-2" (LRS2) on the 10m Hobby-Eberly Telescope at McDonald Observatory on 2019-09-10 UT by Matthew Shetrone and 2019-10-05/07 UT by Sergey Rostopchin and Steven Janowiecki.
The spectroscopic evolution of SN 2019neq is fast relative to other SLSNe-I. We measure the Fe II \lambda 5169\AA absorption feature to be 15900 km/s on 2019-09-11 UT (+5 rest-frame days post-peak), and 14450 km/s on 2019-10-06 UT (+26 rest-frame days post-peak). The absorption velocity is both unusually high and evolves more quickly when compared with other SLSNe-I from the literature (e.g. Quimby et al., 2018, Inserra et al., 2018). Synthetic spectral models from SYN++ also suggest a fast velocity evolution.
The photospheric temperature as derived from the slope of the spectroscopic continuum declines from 20,000K at 4 rest-frame days pre-peak to 12,000K at five rest-frame days post-peak, and finally to 6,000K at 26 rest-frame days post-peak, comparable to the fastest evolving SLSNe-I from the literature
(e.g. Lunnan et al. 2018).
To the author's knowledge this is the fastest-evolving SLSN-I to be discovered so far, as measured from the Fe II \lambda 5169 \AA absorption minima and its time derivative, and from SYN++ spectroscopic modelling of the photospheric velocity.
