SETI New ultra-cool sub-stellar objects found


Larry Klaes (lklaes@bbn.com)
Thu, 03 Jun 1999 10:29:39 -0400


>Date: Wed, 2 Jun 1999 14:36:21 -0700 (PDT) >From: Bill Wheaton <waw@ipac.caltech.edu> >X-Sender: >X-Sender: waw@clarke >To: Larry Klaes <lklaes@bbn.com> >cc: acc-list@clarke.lac.usp.br >Subject: New ultra-cool sub-stellar objects found > >Larry & all, > >The two sky survey projects, the 2 Micron All-sky survey here and IPAC and >the SLOAN Digital sky Survey (in the optical) have just reported at the >Chicago AAS Mtg discovery of several (two for SLOAN & four for 2MASS, if I >recall) sub-stellar objects even smaller and cooler than the previously >recognized stellar class L, recently added to extend the spectral sequence >(O,B,A,F,G,K,M,...) to cooler objects. (The guess here is that the next >letter may be "T"; only 2 or 3 choices are available that do not conflict >or interfere confusingly with previous conventions.) Until now Gl 229B (T >~ 900-1000 K, a binary companion of Gl 229A) was the record holder for low >mass and low temperature, but some of the new objects appear to be even >cooler. All are "field" (ie, non-binary) objects, which makes them easier >to study. > >Anyhow, it does appear that there are probably more such objects than >there are normal (ABAFGKM) stars, (even though the total mass in stars is >greater), which has implications for the probability of the Earth being >affected by a passing object; and second, if such objects can harbor >Europa-like bodies, then the number of possible abodes for life might be >much larger than previously assumed, and some of these could be quite >nearby. We guess 2MASS will ultimately find several hundred such objects; >the ones found to date seem to be about 10 pc (~30 lt-yrs) away. > >Cheers > >Bill W. > >___________________________________________________________ >Wm. A. Wheaton >Infrared Processing & Analysis Center >California Institute of Technology >M/S 100-22 >770 So. Wilson Ave. >Pasadena CA 91125 > >626/397-7104 fax 626/397-9600 > >waw@ipac.caltech.edu >http://spider.ipac.caltech.edu/staff/waw > > > >On Wed, 2 Jun 1999, Larry Klaes wrote: > >> >Date: Tue, 1 Jun 1999 16:24:02 GMT >> >From: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov> >> >Subject: [ASTRO] Scientists Calculate Odd Of Doomday Scenarios For Solar >> System >> > >> >The University of Michigan >> >News and Information Services >> >412 Maynard >> >Ann Arbor, Michigan 48109-1399 >> > >> >Contact: Sally Pobojewski >> >Phone: (734) 647-1844 >> >E-mail: pobo@umich.edu >> >Web: http://www.umich.edu/~newsinfo/ >> > >> >News Release: May 27, 1999 (15) > >... > >> >Adams and Laughlin's detailed models for a frozen Earth have interesting >> >implications for extra-terrestrial life. Adams maintains that liquid >> >oceans could exist beneath thick ice sheets on many planets or moons >> >of giant planets in the galaxy, especially planets that develop past the >> >"snowline" in the planetary formation disk. "The snowline indicates the >> >temperature where water ice can form in disk material," Adams said. >> >"The easiest places to get a large volume of water onto a rocky planet >> >or moon are places where it's cold enough to form ice. >> > >> >"Since water is vital to the existence of life as we understand it, many >> >people have suggested Jupiter's moon, Europa, as a good candidate for >> >supporting life," Adams added. "Our work suggests that the most likely >> >places for extra-terrestrial life to develop would be in liquid oceans >> >under ice. In other words, life on frozen icy bodies like Europa may be >> >much more common in the galaxy than life on planets with liquid water >> >on the surface like Earth. If true, this shift would greatly affect the >> >possible branches of biological evolution in these extra-terrestrial >> >environments." > >.... >



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