Sirius (star)

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Sirius A
Spectral	A1V
Type	Main Sequence
Multiple	binary
Luminosity	25.4
Absolute magnitude	1.42
Mag Terra	−1.47
Temperature	9,940 K
Mass	2.02
Companion	Sirius B, white dwarf, 0.978 solar masses, 25,200 K, 20AU orbit about primary.

Sirius (Alpha Canis Majoris) is the brightest star in the night-time sky of Terra with a visual apparent magnitude of −1.47. This owes more to its proximity (2.6 parsecs) than its brightness, its absolute magnitude is a unremarkable 1.42.

Sirius is a binary star the primary is an A1-V and the companion a white dwarf (DA) at about 20AU. Sirius A has a mass about 2.0 times that of Sol. A typical white dwarf has a mass equal to 0.5–0.6 solar masses. With a mass nearly equal to the Sun's, Sirius B is one of the more massive white dwarfs known. The original star had an estimated 5 solar masses and was a B-type star (roughly B4-5) when it still was on the main sequence.

While it passed through the red giant stage, Sirius B may have enriched the metallicity of its companion. For this reason Sirius A now has a higher than normal abundance of elements heavier than helium, such as iron. The Sirius star system also emits a higher than expected level of infrared radiation. This may be an indication of dust in the system, and is considered somewhat unusual for a binary star.

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This page uses content from Wikipedia. The original article was at Sirius. The list of authors can be seen in the page history. As with Traveller, the text of Wikipedia is available under the GNU Free Documentation License.