HD 202908

HD 202908, also known as HIP 105200, is a triple star located in the equatorial constellation Equuleus. It has an apparent magnitude of 7.01, making it readily visible in binoculars but not to the naked eye. When resolved, the components have apparent magnitudes of 7.25 and 8.87 respectively. The system is located relatively close at a distance of 169 light years based on Gaia DR3 parallax measurements but it is receding with a heliocentric radial velocity of $$.

Stellar system


Hierarchy of orbits in the HD 202908 system The system was first observed by astronomer S.W. Burnham.

The "A" component is a double-lined spectroscopic binary that contains two solar-type stars with spectral classifications of F9 V and G0 V respectively. The pair take roughly 4 days to orbit each other.

The tertiary companion designated "B" has a class of G1.5 V, indicating that it is an ordinary G-type main-sequence star like our Sun. HD 202908 A and B both complete an eccentric orbit every 78 years.

Physical characteristics
HD 202908 Aa and Ab have masses 1.08 and 1.14 times that of the Sun and radii 97% and 106% of the Sun respectively. The former radiates 1.41 times the luminosity of the Sun from its photosphere and the latter radiates 1.16 times the Sun's luminosity. The A subsystem has an effective temperature of $$, giving it a whitish-yellow hue.

The B component has 97% the mass of the Sun and 91% of its radius. It radiates 84% of the Sun's luminosity from its photosphere at an effective temperature of 5,703 K. The system is estimated to be 6.4 billion years old.