Stars between 8.2 and 9.5 l.y.

Number of stars: 5

SIRIUS 8.58 LIGHT YEARS 

MASS
A : 2.35
B : 0.98

LUMINOSITY
24 : A
0.0080 : B


This young, 300-million-year-old binary system has an orbital period of 50.09 years, with an average distance between the two stars of about 3 billion kilometres. Sirius A, a pure white coloured star (spectral type A1), has a radius of approximately one million kilometres, and Sirius B is a small white dwarf of radius close to 5,000 kilometres (spectral type DA).

This small white companion is an ageing star which has used up its main sources of energy and now shines feebly as it loses heat to its outer layers. It is believed among astronomers that the small white dwarf was once the more massive of the two. Any native life developing on an unseen planet in this system would be very primitive indeed.



UV CETI or LUYTEN 726-8 8.73 LIGHT YEARS 

MASS
A : 0.44
B : 0.35

LUMINOSITY
0.00006 : A
0.00004 : B


A red dwarf binary system separated by a distance of 1.65 billion kilometres, of which Luyten 726-8 A (spectral type M5) is of the 'flare-up' variety. Two dark companions, possibly planets, seem to orbit one or both of these stars although the period of orbit for each has not been determined.



ROSS 154 9.67 LIGHT YEARS 

MASS
0.31

LUMINOSITY
0.00041


This is another uninteresting red dwarf 'flare-type' star (spectral type M5), probably younger than our Sun. It is emitting harmful, sporadic bursts of radiation; and its dim red colour may not be of a suitable wavelength to support primitive photosynthesizing microorganisms, if life were in fact trying to emerge on some unseen rocky terrestrial world in this part of the stellar neighbourhood.