Sirius

asterisms

Sirius is also part of a large asterism, the Winter Triangle, the other two stars of which are Betelgeuse in Orion and Procyon in the smaller dog, Canis Minor.
Winter Triangle

binary star

Sirius is a binary star system consisting of two white stars orbiting each other with a separation of about 20 AU (roughly the distance between the Sun and Uranus) and a period of 50.1 years.

cause of brightness

The star, a white class A (A1) hydrogen-fusing dwarf with a temperature of 9880 Kelvin, is bright in part because it is indeed rather luminous, 26 times more so than the Sun, but mostly because it is nearby, a mere 8.6 light years away, just double that of the closest star to the Earth (Alpha Centauri) and the fifth closest star system.

charts

NGC 2506 - Open Cluster (freestarcharts.com)

classification

Sirius A is classed as a type Am star, because the spectrum shows deep metallic absorption lines, indicating an enhancement of its surface layers in elements heavier than helium, such as iron.

common name

Sirius is the luminary of the constellation Canis Major, the Greater Dog, which represents Orion’s larger hunting dog, and as such is commonly referred to as the “Dog Star.”

distance

The Hipparcos parallax for Sirius is only accurate to about ±0.04 light years, giving a distance of 8.6 light years. Sirius B is generally assumed to be at the same distance.

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iron content

Sirius is “metal rich,” its iron content perhaps double that of the Sun, most likely from some sort of elemental diffusion.

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meaning

Its name [Sirius] comes from the Greek word for “searing” or “scorching,” certainly appropriate for a star that shines at the bright end of the “minus-first” (-1.47) magnitude.

random

Luke 11

rising of the Nile

Famed from times long past, the first glimpse of Sirius in dawn announced the rising of the Nile in ancient Egypt. (It no longer does because of precession, the 26,000-year wobble of the Earth’s axis.)

rotation speed

With a radius of 1.75 solar (in agreement with the measured angular diameter) and a minimum equatorial rotation speed of 16 kilometers per second, Sirius rotates in under 5.5 days.

star of

STARS by Jim Kaler

Sirius (stars.astro.illinois.edu) SIRIUS (Alpha Canis Majoris). From Orion, look south and to the east to find brilliant Sirius, as if one really needs directions to find the brightest star in the sky.

tags

Wikidata

https://www.wikidata.org/wiki/Q3409

Wikipedia

Sirius (Wikipedia) Sirius is the brightest star in the night sky. Its name is derived from the Greek word Σείριος (Latin script: Seirios), meaning lit. ‘glowing’ or ‘scorching’. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated α CMa or Alpha CMa. With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as Canopus, the next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1, termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5 astronomical units as they orbit every 50 years.