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From: gsmith@brahms.BERKELEY.EDU (Gene Ward Smith)
Newsgroups: net.astro,net.space
Subject: Re: Was Sirius red after all?
Message-ID: <12364@ucbvax.BERKELEY.EDU>
Date: Fri, 14-Mar-86 00:43:20 EST
Article-I.D.: ucbvax.12364
Posted: Fri Mar 14 00:43:20 1986
Date-Received: Sat, 15-Mar-86 19:31:43 EST
References: <8603020306.AA00249@s1-b.arpa> <8603061510.AA04282@infinet.UUCP> <1146@lsuc.UUCP>
Sender: usenet@ucbvax.BERKELEY.EDU
Reply-To: gsmith@brahms.UUCP (Gene Ward Smith)
Organization: University of California, Berkeley
Lines: 23
Keywords: Sirius, red
Xref: watmath net.astro:1471 net.space:6442

In article <1146@lsuc.UUCP> msb@lsuc.UUCP (Mark Brader) writes:

>> > By the way, in latest Sky&Telescope there's a note on Sirius being
>> > reddish in recorded history (in fact about 600 AD), because at that
>> > time its white-dwarf companion was in the red giant stage. It's hard

>> I recently (two months ago?) read an article in the Boston Globe
>> that said roughly the same thing - Sirius was reddish within recorded
>> history.  I posted the same question to net.astro.  The general response

>   Ancient Babylonian, Greek, and Roman texts were known to consistently
>   refer to Sirius as red.  But now there is medieval evidence for this as
>   well.  Wolfhard Schlosser and Werner Bergmann of the Ruhr University

    One other problem with the Sirius B as red giant theory: Sirius B has 
about the same temperature as Sirius A: about 12000 K if I remember right.
This is *much cooler* than some other white dwarves, and seems to indicate
a considerable cooling-off period. Also, where is there any sign of a left-
over planetary nebula?

ucbvax!brahms!gsmith    Gene Ward Smith/UCB Math Dept/Berkeley CA 94720
          "There are no differences but differences of degree 
            between degrees of difference and no difference"