Rho Cas
Rho Cas (type semiregular) is a hypergiant star and one of the most
luminous stars in our galaxy. Eruptions on these very rare, very massive
stars produce huge mass ejections evidenced by dramatic spectral changes
and optical dimming (an ejection in 2000 amounted to 10,000 Earths worth of
material and caused a ~1.5-magnitude drop in visual brightness). Understanding
hypergiants can help answer fundamental questions related to maximum stellar
mass limits.
Astronomers are anticipating possible major activity in rho Cas over the
next few months. Spectra of rho Cas show that its hydrogen lines have
brightened, which indicates the probable onset of an eruption leading to
mass ejection and consequent optical fading. This pattern was seen in the
last months of 2000, and astronomers feel that the eruption projected for
the coming months may be stronger than the 2000 one.
Charts
Spectra
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| The Rho Cas spectrum was taken by Maurice Gavin with his WPO spectrograph [dispersion = 3.24A/pixel] in 60s exposure via a
30cm Meade LX200 and Starlight Xpress MX9 CCD on 2003 July 7. It covers a 1100A swathe at the red end of
the spectrum from 5900A [left] - 7000A [right] and currently shows no evidence of either emission in lines
like H-alpha or broad absorption bands of TiO etc.
The Rho Cas spectrum closely resembles nearby alpha Cas [type K0] included - the two consecutive exposures
#1,#2 of Rho Cas show a near perfect match. More spectra at http://home.freeuk.com/m.gavin/gensp18.htm |
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| Spectrum by Doug West. Click image to enlarge. |
AAVSO Light Curves
Photoelectric Photometry (PEP) Data
