Planet B
Further information: Epsilon Eridani bReferred to as Epsilon Eridani b, this planet was announced in 2000, but the discovery has remained controversial. A comprehensive study in 2008 called the detection "tentative" and described the proposed planet as "long suspected but still unconfirmed." However, many astronomers believe the evidence is sufficiently compelling that they regard the discovery as confirmed.
Published sources remain in disagreement as to the proposed planet's basic parameters. Values for its orbital period range from 6.85 to 7.2 years. Estimates of the maximum radius of its elliptical orbit—the semimajor axis—range from 3.38 AU to 3.50 AU and approximations of its orbital eccentricity range from 0.25 ± 0.23 to 0.702 ± 0.039.
The true mass of this planet remains unknown, but it can be estimated based on the displacement effect of the planet's gravity upon the star. Only the component of the displacement along the line of sight to the Earth is known, which yields a value for the formula m sin i, where m is the mass of the planet and i is the orbital inclination. Estimates for the value of m sin i range from 0.60 Jupiter masses to 1.06 Jupiter masses, which sets the lower limit for the mass of the planet (since the sine function has a maximum value of 1). By choosing a mass of 0.78 and an estimated inclination of 30°, this yields the frequently cited value of 1.55 ± 0.24 Jupiter masses for the planet's mass.
Of all the measured parameters for this planet, the value for orbital eccentricity is the most uncertain. The frequently cited value of 0.7 for Epsilon Eridani b's eccentricity is inconsistent with the presence of the proposed asteroid belt at a distance of 3 AU from the star. If the eccentricity was actually this high, the planet would pass through the asteroid belt and clear it out within about ten thousand years. If the belt has existed for longer than this period, which appears likely, it imposes an upper limit on Epsilon Eridani b's eccentricity of about 0.10–0.15. If the dust disk is instead being generated from the outer debris disk, rather than from collisions in an asteroid belt, then no constraints on the planet's orbital eccentricity are needed to explain the dust distribution.
Read more about this topic: Epsilon Eridani, Planetary System, Possible Planets
Famous quotes related to planet b:
“After the planet becomes theirs, many millions of years will have to pass before a beetle particularly loved by God, at the end of its calculations will find written on a sheet of paper in letters of fire that energy is equal to the mass multiplied by the square of the velocity of light. The new kings of the world will live tranquilly for a long time, confining themselves to devouring each other and being parasites among each other on a cottage industry scale.”
—Primo Levi (1919–1987)