gsmith@brahms.BERKELEY.EDU (Gene Ward Smith) (02/28/86)
In article <8602272123.AA08936@s1-b.arpa> REM%IMSSS@SU-SCORE.ARPA writes: >B> A large, space-going cephalopod could come along and eat the whole planet. >B> Get serious (pun intended) Sirius isn't going to blow up. Why don't you >B> learn some Astronomy if you like space so much? It is very interesting >B> stuff. >Why don't you learn some Astronomy. (Sorry, just retaliating; I could >slightly wrong too, so please anyone who knows better please do >correct any errors I make.) Sirius *is* going to blow up, go supernova >probably, in about 10 million years, long before our Sun goes >red-giant. But probably Sirius and the Sun will have drifted far away >by then. More dangerous are Betelguese and Antares, either of which >could go supernova within the next 1000 years, before they drift too far away. Please don't apologize for your sarcasm. I like it, because it is the style I find easiest to use myself. Worry about being polite impedes the flow of thought. Since this has turned into an Astronomy discussion, I am cross-posting it there. I don't know if you or the first poster are talking about a type I or type II supernova to start with. Sirius A is about 2.3 solar masses (all I am saying is off the top of my head, I am hoping the experts will settle this one) and this is too small for iron core collapse, carbon detonation, etc. A type I supernova model exists where a dwarf is forced beyond the Chandresekar limit. Sirius B I recall as 1.05 solar masses, well below the limit. When Sirius is in its giant stage, it will presumably give some matter up to Sirius B. If this becomes a big deal, it looks like the usual nova (not supernova) situation. Once more off the top of the old head, I recall Betelguese and Antares as being both about 400 light years away; hardly close enough to sterilize the planet Earth or whatever. Eta Carinae (?) is even closer to supernova. Sirius right now is firmly on the main sequence. I think its luminosity is about 23 times the Sun (which checks with my figure for its mass) and this would give it one tenth the time of the Sun on the main sequence; i.e., about a billion years. How much has gone? I don't know, but why do you assume most of it? You might think it has picked up some mass from the giant stage of Sirius B, which would mean it was burning slower before, and its time on the main sequence far from nearly over. My sarcasm in the first posting was caused partly by the fact that the author seemed to suggest that Sirius was a kind of ticking bomb, sitting there quietly on the main sequence. What gives with you people making plans 100 or 200 million years in advance, anyway? This is pretty silly, because there is no way you can even guess about 100 million years from now, and no way (despite the "Its urgent to do it in 100 or 200 years! Help!") rant of the article I responded to, to *do* anything sensible in planning for things 100 million years from now. Grow up, folks! ucbvax!brahms!gsmith Gene Ward Smith/UCB Math Dept/Berkeley CA 94720 ucbvax!weyl!gsmith "Are you by any chance from South Africa?" - RR