Size comparison: Sirius A vs Sirius B

Size comparison between the two stars making up the binary star Sirius. Sirius is the brightest star in the night sky. Its name means "ablaze" in Greek. Sirius is getting closer and closer to the sun. Its brightness is expected to continue to increase over the next 60,000 years. The mass of Sirius is twice that of the sun, it is 25 times brighter than our star, it is much younger.

Sirius B has already consumed its main resources; she became a red supergiant, then a white dwarf; it has been collapsing on itself for 120 million years.

Object	Sirius A	Sirius B
Type	Star, main sequence	Star, white dwarf
Age	242 million years	228 million years
Diameter	2,382,882 km	11,698 km
Mean radius	1,191,441 km	5,849 km
Mass	3.96 × 1030 kg	2 × 1030 kg
Surface temperature (average)	9,940 K 9,666 °C 17,432 °F	25,000 K 24,726 °C 44,540 °F
Surface gravity	213.8 m/s²	3715352.3 m/s²
Atmosphere composition	hydrogen, helium	hydrogen
Sun distance	8.6 light years	8.6 light years
Luminosity	9.7 × 1027 W	2.1 × 1025 W
Spectral classification	A0mA1 Va	DA2
Absolute magnitude	1.42	11.18
Right ascension	06h 45m 08.917s	06h 45m 09.0s
Declination	−16° 42′ 58.02″	−16° 43′ 06″

Note: if one of the objects is not visible, it just means that it is too tiny to be displayed compared to the other one.