From: Amara Graps (Amara.Graps@mpi-hd.mpg.de)
Date: Tue Jul 16 2002 - 04:49:29 MDT
This was already reported in the popular press some weeks ago. Here's
a scientific paper. (Note: 5.2 AU is distance from Sun to Jupiter)
http://xxx.lanl.gov/abs/astro-ph/0207294
Astrophysics, abstract
astro-ph/0207294
From: Geoffrey W. Marcy <gmarcy@etoile.berkeley.edu>
Date: Sun, 14 Jul 2002 00:40:52 GMT (258kb)
A Planet at 5 AU Around 55 Cancri
Authors: Geoffrey W. Marcy (1 and 2), R. Paul Butler (3), Debra A. Fischer
(1), Greg Laughlin (4), Steven S. Vogt (4), Gregory W. Henry (5), Dimitri
Pourbaix (6) ((1) University of California, Berkeley, (2) San Francisco
State University, (3) Carnegie Institution of Washington, (4) UCO/Lick
Observatory, (5) Tennessee State University, Nashville, (6) Universite Libre
de Bruxelles)
Comments: 47 pages, 4 tables, 12 figures, uses AASTEX
We report precise Doppler shift measurements of 55 Cancri (G8V)
obtained from 1989 to 2002 at Lick Observatory. The velocities
reveal evidence for an outer planetary companion to 55 Cancri
orbiting at 5.5 AU. The velocities also confirm a second, inner
planet at 0.11 AU. The outer planet is the first extrasolar planet
found that orbits near or beyond the orbit of Jupiter. It was
drawn from a sample of ~50 stars observed with sufficient duration
and quality to detect a giant planet at 5 AU, implying that such
planets are not rare. The properties of this jupiter analog may be
compared directly to those of the Jovian planets in our Solar
System. Its eccentricity is modest, e=0.16, compared with e=0.05
for both Jupiter and Saturn. Its mass is at least 4.0 jupiter
masses (M sin i). The two planets do not perturb each other
significantly. Moreover, a third planet of sub-Jupiter mass could
easily survive in between these two known planets. Indeed a third
periodicity remains in the velocity measurements with P = 44.3 d
and a semi-amplitude of 13 m/s. This periodicity is caused either
by a third planet at a=0.24 AU or by inhomogeneities on the
stellar surface that rotates with period 42 d. The planet
interpretation is more likely, as the stellar surface is quiet,
exhibiting log(R'_{HK}) = -5.0 and brightness variations less than
1 millimag, and any hypothetical surface inhomogeneity would have
to persist in longitude for 14 yr. Even with all three planets, an
additional planet of terrestrial--mass could orbit stably at ~1
AU. The star 55 Cancri is apparently a normal, middle-aged main
sequence star with a mass of 0.95 solar masses, rich in heavy
elements ([Fe/H] = +0.27). This high metallicity raises the issue
of the relationship between its age, rotation, and chromosphere.
Paper: PostScript, PDF, or Other formats
--
************************************************************************
Amara Graps, PhD | Max-Planck-Institut fuer Kernphysik
Heidelberg Cosmic Dust Group | Saupfercheckweg 1
+49-6221-516-543 | 69117 Heidelberg, GERMANY
Amara.Graps@mpi-hd.mpg.de * http://www.mpi-hd.mpg.de/dustgroup/~graps
************************************************************************
"Never fight an inanimate object." - P. J. O'Rourke
This archive was generated by hypermail 2.1.5 : Sat Nov 02 2002 - 09:15:29 MST