Astronomer's Paul Butler and Geoffrey Marcy at San Francisco State University recently announced their detection of yet another planet beyond our solar system, this time orbiting the star Rho^1 Cancri ( 55 Cancri) about 45 light years from the Sun. The planet is about the mass of Jupiter and orbits about 10 million miles from the star. There also seem to be hints in the data that another planet further out may exist.
This is the second planet discovered in what are called 'blowtorch orbits'. Astronomers are surprised that planets in these orbits are so common. It wasn't previously thought that large planets could form so close to their parent star, because the parent star at these distances would compete with the planet in accumulating the orbiting material leaving little left over for the planet to use as building material. One possibility is that planets in these orbits were originally much further out, and experienced some kind of gravitational perturbation by other planets in their system which inserted them into these close-in orbits. The fact that Blowtorch Orbits are so common ( 2 out of 4 stars with planets have them) is very troubling.
The star is located at RA(2000) = 8h 52m 35.8s and Dec(2000) = +28d 19' 51" and has an apparent magnitude of +5.98 making it just at the limit of being a naked eye star. It is a G8 V Main Sequence star with a surface temperature of about 5200 K, a little cooler than the Sun. It also goes by the catalog name HR 3522. The "Yale Bright Star Catalog" lists it as member of a binary star system which includes the M3 III giant star 53 Cancri at a distance of about 85 arcseconds. Some listings identify Rho^1 as 53 Cancri, Rho^2 as 55 Cancri and Rho^3 as HR 3540.
The star is surrounded by a dust disk extending at least a 40 AU, with an inclination of ~ 25o. If the planets are in the same plane than the disc, this gives to the first planet a mas of 1.9+1.1 -0.4 MJ (Trilling & Brown 1998, Trilling et al 2000).
Copyright 1997 Dr. Sten Odenwald
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