Ross 248

The Star

This cool and dim, main sequence red dwarf (M5.5 or 4.9 Ve) has almost a fourth of Sol's mass, seven percent of its diameter, but only 11/100,000th of its luminosity. (Another reference, however, suggests seven percent of Sol's mass, 17 percent of its diameter, but the same luminosity). Ross 248 would be only one of many unremarkable stars except that it is one of Sol's closest neighbors. Classified as a flare star, the star also has the variable designation HH Andromedae, and investigators have reported finding possible periods of variability at 4.2 years, 120 or 121 days, and five other periods between 60 and 291 days, which may be caused by an unresolved companion (Edward W. Weiss, 1993, page 1139). Useful catalogue numbers for Ross 248 include: HH And, Gl 905, G 171-10, G 190-42, LHS 549, LTT 16985, and LFT 1816.

Hunt for Substellar Companions

There may have been an unconfirmed detection of a substellar companion around Ross 248 with an orbital period of eight years. In the late 1980s, a search using multiple, precise Doppler shift measurements for weak gravitational perturbations by companion objects as small as 20 times Jupiter's mass that are located within 10 AUs of Ross 248 was negative (Butler and Benitz, 1989). Moreover, a recent search for faint companions using the Hubble Space Telescope found no supporting evidence for a large Jupiter or brown dwarf sized object (Schroeder et al, 2000). In any case, any Earth-type planet must be located very close to red dwarfs to be warmed sufficiently by star light to have liquid water (about 0.01 AU with an orbital period of 1.4 days for Ross 248). However, the light emitted by red dwarfs may be too red in color for Earth-type plant life to perform photosynthesis efficiently.