From: Amara Graps (amara@amara.com)
Date: Fri Jan 04 2002 - 14:31:27 MST
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Astrophysics, abstract
astro-ph/0107313
From: Giovanna Tinetti <tinetti@to.infn.it>
Date: Tue, 17 Jul 2001 17:18:27 GMT (37kb)
Available Energy for Life on a Planet, with or without Stellar Radiation
Authors: L. Sertorio, G. Tinetti (University of Torino and INFN, Torino)
Comments: 30 pages, 10 figures, to be published in Nuovo Cimento C
Report-no: DFTT 33/00
Subj-class: Astrophysics; Biological Physics
The quest for life in the Universe is often affected by the free
use of extrapolations of our phenomenological geocentric
knowledge. We point out that the existence of a living organism,
and a population of organisms, requires the existence of available
energy or, more precisely, available power per unit volume (Sect.
1). This is not a geocentric concept, but a principle that belongs
to the foundations of thermodynamics. A quest about availability
in the Universe is justified. We discuss the case in which power
comes from mining (Sect. 2), and from thermal disequilibrium
(Sect. 3). Thermal disequilibrium may show up in two ways: on
planets without a star (Sect. 4), and on planets where the surface
thermal disequilibrium is dominated by the incoming photon flux
from the nearest star (Sect. 6). In the first case we study the
availability by simulating the structure of the planet with a
simple model that contains the general features of the problem.
For the first case we show that the availability is in general
very small (Sect. 5). In the second case we show that the
availability is in general large; the order of magnitude depends
first of all on the star's temperature and the planet's orbit, but
is also controlled by the greenhouse gases present on the planet.
Paper: Source (37kb), PostScript, or Other formats
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Amara Graps | Max-Planck-Institut fuer Kernphysik
Interplanetary Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://galileo.mpi-hd.mpg.de/~graps
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"Never fight an inanimate object." - P. J. O'Rourke
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