Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/5/84; site v1.UUCP Path: utzoo!watmath!clyde!bonnie!akgua!sdcsvax!sdcrdcf!hplabs!hao!seismo!cmcl2!philabs!v1!josh From: josh@v1.UUCP (Josh Knight) Newsgroups: net.sci Subject: Re: Re: VB-8B: First Planet Outside Solar System Discovered Message-ID: <116@v1.UUCP> Date: Sun, 23-Dec-84 23:00:45 EST Article-I.D.: v1.116 Posted: Sun Dec 23 23:00:45 1984 Date-Received: Thu, 27-Dec-84 03:09:31 EST References:, <1279@dciem.UUCP> <170@dmcnh.UUCP> Organization: IBM Research, Yorktown Heights, N.Y. Lines: 23 > "Igniting" is a continuum. Jupiter radiates more energy than > it absorbs due to the fusion occuring in its core from the intense > pressure. Larger planets would radiate more and more energy from > more complete fusing until it could be considered a star (red- > dwarf status). Igniting isn't continuous if one means conversion of hydrogen nuclei to helium nuclei plus some energy (with or without catalysts like carbon, oxygen and nitrogen). If the central temperature and density get high enough, hydrogen "burning" starts and the star stays basically in the same condition while some fraction of the hydrogen is converted into helium...called the "main sequence". Jupiter hasn't ever "burned" hydogen (may have consumed it's primordial deuterium, but I'm not sure about the numbers). It does indeed radiate more energy than it receives from the sun, but that is because it is slowly contracting...converting gravitational potential energy to thermal energy and then radiating it away. This is what things that aren't big enough to become stars do. Below some mass, they don't burn hydrogen at their cores and so don't have a main sequence phase. See net.astro for more (better?) info. Josh Knight, IBM T.J. Watson Research josh at YKTVMX on BITNET, josh.yktvmx.ibm on CSnet, ...!philabs!v1!josh