Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-01-05
Astron.J.131:2105-2113,2006
Astronomy and Astrophysics
Astrophysics
26 pages, 6 figures
Scientific paper
10.1086/500811
Variable A in M33 is a member of a rare class of highly luminous, evolved stars near the upper luminosity boundary that show sudden and dramatic shifts in apparent temperature due to the formation of optically thick winds in high mass loss episodes. Recent optical and infrared spectroscopy and imaging reveal that its ``eruption'' begun in $\sim$1950 has ended, {\it lasting $\approx$ 45 yrs}. Our current observations show major changes in its wind from a cool, dense envelope to a much warmer state surrounded by low density gas with rare emission lines of Ca II, [Ca II] and K I. Its spectral energy distribution has unexpectedly changed, especially at the long wavelengths, with a significant decrease in its apparent flux, while the star remains optically obscured. We conclude that much of its radiation is now escaping out of our line of sight. We attribute this to the changing structure and distribution of its circumstellar ejecta corresponding to the altered state of its wind as the star recovers from a high mass loss event.
Gehrz Robert D.
Gordon Karl
Helton Andrew
Hinz Joannah
Humphreys Roberta M.
No associations
LandOfFree
M33's Variable A -- A Hypergiant Star More Than 35 Years in Eruption 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 M33's Variable A -- A Hypergiant Star More Than 35 Years in Eruption, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and M33's Variable A -- A Hypergiant Star More Than 35 Years in Eruption will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-109898