A Recent Spectrum of PSN J09132750+7627410
ATel #7172; Roberta M. Humphreys, Michael S. Gordon (Univ Minn.)
on 3 Mar 2015; 19:19 UT
Credential Certification: Roberta Humphreys (roberta@umn.edu)
Subjects: Optical, Supernovae, Transient
Blue and red spectra of the likely supernova impostor PSN J09132750+7627410in NGC 2748 (ATEL #7051) were obtained on February 16, 2015 with the MODS1 spectrograph on the Large Binocular Telescope (LBT) on Mt Graham, Arizona.
The Balmer lines are in emission with very asymmetric profiles and broad Thomson scattering wings to the red. The higher Balmer lines have deep narrow P Cygni absorption profiles which indicate expansion velocities of 450 - 600 km/s measured relative to the emission peak. But there are also at least two additional blue shifted and broad absorption components in Halpha, Hbeta and Hgamma which may be formed in circumstellar ejecta moving outwards at higher velocities perhaps from this eruption or previous events. Fe II emission is present and the Fe II multiplet 42 lines also have deep P Cygni profiles. O I 7774A and Ca II K are present in absorption.
PSN J09132750+7627410 does not show the F supergiant absorption line spectrum common in several
impostors and LBVs at maximum light due to the formation of a cool dense wind. It may develop later as the ejecta expands. The broad absorption components in the Balmer lines may also weaken with time. Therefore spectroscopic and photometric monitoring are needed over the next few months.
