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A descriptive title

ATel #10502; John C. Martin (University of Illinois Springfield, IL, USA) Steven C. Williams (Lancaster University, Lancaster, UK), Matt Darnley (Liverpool John Moores University, Liverpool, UK), Roberta M. Humphreys (University of Minnesota, MN, USA)
on 17 Jun 2017; 17:30 UT
Credential Certification: John Martin (jmart5@uis.edu)

Subjects: Optical, Star, Variables

In ATEL 10383 we reported the classical Luminous Blue Variable (Humphreys & Davidson, 1994) AF And = J004333.08+411210.3 = Var 19 in M31 (Hubble & Sandage, 1953) has brightened and grown redder over the last 800 days, indicating the start of a possible S Dor outburst. A low-res spectrum (R~350) taken by S. Williams and M. Darnely on 2017 May 20.23 UT with SPRAT on the Liverpool Telescope shows the He I emission present in 2010, 2013, and 2015 has disappeared and the O I 777nm triplet is possibly in absorption. These indicate a change in spectrum to a lower temperature, consistent with an S Doradus eruption. See link for plot of spectra.

Plots of those spectra compared with earlier spectra of AF And taken with the LBV in 2010 and 2015