Spectroscopic observation of LBV outburst (TCP J12355222+2755559)
ATel #14638; A. F. Valeev; A. Vinokurov; Yu. Solovyeva; E. S. Shablovinskaya (SAO RAS)
on 18 May 2021; 12:17 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Azamat Valeev (azamat@sao.ru)
Subjects: Optical, Transient, Variables
Referred to by ATel #: 15808
With the aim of characterization of the spectral evolution of current outburst of the LBV (TCP J12355222+2755559, AT 2016blu) in NGC 4559C galaxy on May 13 (13-05-2021, MJD=59347.91) we obtained the next epoch spectrum. We used the VPHG1200@540 grism on SCORPIO-2 multi-mode spectrograph which covers 3650-7300 ÅÅ waverange with the spectral resolution about 4.0 Å.
On our spectrum we clearly see the lines of Balmer series with complex P Cyg profiles. The emission lines have the narrow components and broad components. The absorption components of the Hβ and Hγ lines have double-peaked shape. Our spectrum revealed also the weak lines of the He I and ionized iron. By the comparison of our previous spectrum (Atel #14460) we detected only the slight changes, described below.
The red wings of the emission components are broader. The blue wings of the absorption feature extend up to velocity 4700 km/s, which gives the terminal velocity about 3700 km/s. These are about 1000 km/s lower than the epoch one (two months ago) values. However the difference between the velocities of two absorption peaks shows the same value ~2800 km/s.
