Possible new LBV eruption of an Ofpe/WN9 star in M33
ATel #14790; Andrew Sevrinsky, Nathan Smith (U. Arizona), Jennifer Andrews (Gemini Obs.), Tom Matheson (NOIR Lab), Monika Soraisam (NCSA/UIUC)
on 16 Jul 2021; 01:18 UT
Credential Certification: Nathan Smith (nathans@as.arizona.edu)
Subjects: Optical, Star, Transient, Variables
Photometry from ZTF over the past three years shows that the luminous blue variable (LBV)
candidate star LGGS J013416.07+303642.1 is brightening slowly,
possibly indicating the start of a new LBV-like eruption. If this is
an LBV eruption, it would shift this star from a candidate LBV to be
the sixth confirmed LBV in M33 (after Var B, Var C, Var 83, Var 2, and
MCA-1B).
Prior to 2019, this star had a relatively constant apparent R
magnitude of around 17.6-17.8 mag, and like many LBV candidates, was
previously classified with a spectral type of Ofpe/WN9 (Neugent &
Massey 2011). Available ZTF photometry shows that it has brightened
slowly but continuously, by about 0.4 mag in recent years at red
wavelengths, from r=17.9 mag in late 2018 to r=17.5 mag in early 2021.
This was flagged automatically as a possible transient/variable
source (i.e. ZTF20abduida, AT2020aafy) but the transient had not yet
been classified or identified as a potential LBV eruption.
M33 is now observable again from the northern hemisphere and we
encourage spectroscopic and multicolor photometric observations.
