ASASSN-15th (M33N 2015-12a): Additional Spectroscopic Observations
ATel #8396; M. J. Darnley (LJMU), S. C. Williams (LJMU)
on 10 Dec 2015; 22:19 UT
Credential Certification: Matt Darnley (M.J.Darnley@ljmu.ac.uk)
Subjects: Optical, Nova, Transient
We report additional spectroscopic observations of the developing M33 nova eruption ASASSN-15th (M33N 2015-12a; see ATel #8349, #8352). The low resolution, high throughput, SPRAT instrument on the 2m fully-robotic Liverpool Telescope obtained three 600s spectra of ASASSN-15th at 2015 Dec. 10.9 UT.
These spectra show significant evolution from that reported in ATel #8352, in that the deep P Cygni profiles seen in the few days after discovery have now almost completely disappeared, with the emission component of these lines growing in strength.
Balmer, Fe II (multiplets 42, 49 and 74), and Na I D lines are all still present (ATel #8352), with all except Fe II (49 & 74) still clearly displaying shallow absorption components. We also tentatively detect emission from O I (7773), Si II (multiplets 2 and 4) and possibly a number of He I lines.
We measure the FWHM of the Hα emission peak to be 2500 km/s.