A Planet for VB10
VB10 is the designation for one of the smallest known stars located in the constellation Aquila, The Eagle. It is a nearby star just over 19 light-years away, but extremely faint bringing no more than 17 magnitudes on the visual brightness scale.

Field: 6 x 4 arc min. The STScI Digitized Sky Survey


VB10 is the smallest star known to harbour a planet, but there maybe more. Provided Einstein is correct, it would take a board time of approximately 6 years to travel one way to VB10 at 1g acceleration.

Chinen, Okinawa, May 30th, 2009
An artist's concept of VB10b. Courtesy NASA/JPL-Caltech


VB10 is a dim, red class M8 flare star with only one-tenth the size, and one-twelfth the mass of our sun. On May 28, 2009, NASA reported detection of a planet (using a technique, called astrometry) with 6.4 masses of Jupiter in a mean distance of 0.36 AU which is near the distance of Mercury to our sun. Yet, it is a "cold Jupiter" lying far outside the mathematical habitable zone* of VB10 with a cloud or surface temperature of less than -250°C. Both, the planet and its sun may be of approximately equal size.

Class M stars are near the end of their life span barely radiating energy. For this reason, the habitable zone is closer to VB10 than Mercury is to our sun, say some 0.0025 AU. Possibly there are further, smaller planets within the habitable zone between the one just found and the star.

The planet's orbit appears to be highly eccentric (0.98!) bringing it as close as 0.0072AU and as far as 0.7128AU (roughly the distance of Venus in our solar system) to VB10. If that should prove correct, then the planet is subjected to extreme temperature changes and orbit velocities.

Further reading
NASA Report
The Extrasolar Planets Encyclopaedia

NOTE: The Habitable Zone, HZ, is the belt around a star within which liquid water can exist. The distance from the star and its width depend on the energy flux of the star. It does not imply evidence for existence of lifeforms due to various uncertainties.