[vsnet-chat 3677] What about T Cas?

[Thorsten Lange <tl@thola.de>]

Hallo,
I just went through the last periods of Mira star T Cas.
The brightness of both maximum and minimum of the last five
periods have been falling slowly.
	max	min
1994	8.0	11.3
1995 	7.7	11.4	note: AFOEV shows a max of 8.1mag
1996	8.0	11.3
1997	8.0	11.5
1998	8.4	11.8
1999/00	8.5	<11.9 (this days 11.9)

A similar behaviour can be seen in the lightcurve of the 1980s:
1981	7.8	12.5 	note: this maximum does not fit 
1982	8.3	12.3
1983	8.0	11.8
1984/5	7.7	11.5
1985/6	7.7	11.6
1987	8.3	11.8
1988	8.3	11.9

Is there anything known about a doubleperiod?

Another question: Did anyone check for a correlation in the
pre-maximum phase (the star often shows a premaximum and then
falls again up to 0.5mag before reaching the real maximum)
and the max-min-difference? What I mean is a correlation
between the length&depth of the premaximum to the difference
between the following maximum and minimum.
Maybe I check this next week...

Thorsten Lange

-- 
Thorsten Lange               
EMail tl@thola.de
http://thola.de/

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