Ross 248

Ross 248 (Gliese 905 / HH Andromedae) is a star in the Andromeda constellation. It was discovered by Frank Elmore Ross in 1925. Of apparent magnitude +12.29, it is not observable with the naked eye, and is located south of λ Andromedae, near κ Andromedae and ι Andromedae.

Distance

Ross 248 is one of the closest stars to the solar system – currently the ninth –, 10.30 light years away. However, in 37,100 years it will be just 3.03 light years from Earth, when it will be the closest star to the Sun.

The Voyager 2 space probe will pass within 1.76 light years of Ross 248 in about 40,200 years.

Features

Ross 248 is a red dwarf of spectral type M6.0V with an effective temperature of 3058 K. At only 13.6% of the Sun's mass and 17 percent of its diameter, its luminosity is equivalent to one ten-thousandth of the Sun's luminosity. It exhibits a metallicity – relative abundance of elements heavier than helium – higher than the solar one by 38% ([M/H] = +0.14) but, unlike the Sun, it is considered a thick disk star.

Ross 248 is a variable star of the type BY Draconis, which is why it is called, as a variable, HH Andromedae. The variation in its brightness is 0.13 magnitudes. It was the first star where small variations in brightness were attributed to spots in its photosphere (1950). Possible periods of 4.2 and 120 years have been reported—as well as five other periods between 60 and 91 days—which may be caused by the presence of an as-yet undetected stellar companion.