Here is an important study of high relevance to our interest in the link between planetary orbits and solar activity.
H/T Gerry Pease:
The Astrophysical Journal, 683: L63–L66, 2008 August 10
THE JUPITER TWIN HD 154345b
J. T. Wright, G. W. Marcy, R. P. Butler, S. S. Vogt, G. W. Henry, H. Isaacson, and A. W. Howard
Received 2008 January 8; accepted 2008 February 12; published 2008 July 23
ABSTRACT
We announce the discovery of a twin of Jupiter orbiting the slightly metal-poor ( ) nearby [Fe/H] p 0.1
( pc) G8 dwarf HD 154345. This planet has a minimum mass of 0.95Mjup and a 9.2 year, circular orbit
with radius 4.2 AU. There is currently little or no evidence for other planets in the system, but smaller or exterior
planets cannot yet be ruled out. We also detect a ∼ 9 year activity cycle in this star photometrically and in
chromospheric emission. We rule out activity cycles as the source of the radial velocity variations by comparison
with other cycling late G dwarfs.
Subject headings: planetary systems — techniques: radial velocities
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