Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-01-26
Astrophys.J.660:301-310,2007
Astronomy and Astrophysics
Astrophysics
Accepted by the Astrophysical Journal
Scientific paper
10.1086/513182
We call attention to the fact that one of the brightest red supergiants in the SMC has recently changed its spectral type from K0-1 I (December 2004) to M4 I (December 2005) and back to K0-1 I (September 2006). An archival spectrum from the Very Large Telescope reveals that the star was even cooler (M4.5-M5 I) in December 2001. By contrast, the star was observed to be an M0 I in both October 1978 and October 1979. The M4-5 I spectral types is by far the latest type seen for an SMC supergiant, and its temperature in that state places it well beyond the Hayashi limit into a region of the H-R diagram where the star should not be in hydrostatic equilibrium. The star is variable by nearly 2 mag in V, but essentially constant in K. Our modeling of its spectral energy distribution shows that the visual extinction has varied during this time, but that the star has remained essentially constant in bolometric luminosity. We suggest that the star is currently undergoing a period of intense instability, with its effective temperature changing from 4300 K to 3300 K on the time-scale of months. It has one of the highest 12-micron fluxes of any RSG in the SMC, and we suggest that the variability at V is due primarily to changes in effective temperature, and secondly, due to changes in the local extinction due to creation and dissipation of circumstellar dust. We speculate that the star may be nearing the end of its life.
Levesque Emily M.
Massey Philip
Olsen Knut A. G.
Plez Bertrand
Skiff Brian A.
No associations
LandOfFree
HV 11423: The Coolest Supergiant in the SMC does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with HV 11423: The Coolest Supergiant in the SMC, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and HV 11423: The Coolest Supergiant in the SMC will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-567935