Sirius (Alpha Canis Majoris) is a blue multiple star system that can be located in the constellation of Canis Major. The description is based on the spectral class. Sirius is a main star of the constellation.
Sirius is the brightest star in the night sky and the brightest star in Canis Major based on the Hipparcos 2007 apparent magnitude. The star can be seen with the naked eye, that is, you don't need a telescope/binoculars to see it.
Sirius is also known as the Dog star, after all it is in the Big Dog constellation of Canis Major. It is widely known in part as it is the brightest star in the night sky, it is almost twice as bright as the next brightest star, Canopus. It is also one of our nearest neighbour stars, not as close as Rigil Kentaurus (Alpha Centauri) but still close. The only thing that is brighter excluding the moon is the planet Venus. It is moving closer towards us but won't for a long time, longer than you and I will be on this planet so nothing to worry. 1. Sirius is a Double Star System with the smaller star being a white dwarf star having used up all its hydrogen.
Being the brightest and one of the most well known, it has become of interest by science fiction writers, for example, the lizard Visitors from V come from a planet orbiting this star. JK Rowling, author of the Harry Potter books has a character Sirius Black who name is inspired from this star. There are also other stars that have been the inspiration for characters such as Regulus Black. Sirius isn't just limited to being mentioned in these fictions, the star is mentioned elsewhere. Sirius gets mentioned in Star Trek but there's no real stories based in the Sirius Solar System excluding the cartoon series and extended universe. ref:Memory Alpha.
Sirius is currently moving towards us but don't fear a solar apocalypse, it will never collide with our Sun. It is moving at a very slow speed of 5.5 km/s and the closest it will ever get to us is 7.8 Light years, down from 8.6 that it is now. It will continue to be the brightest star in the night sky for at least another 90000 year after which point Delta Scuti will then take on that title. ref:StackExchange
Alpha Canis Majoris (Alf Cma) is the Bayer Classification for the star. The Id of the star in the Yale Bright Star Catalogue is HR2491. HIP32349 is the reference name for the star in the Hipparcos Star Catalogue. The Id of the star in the Henry Draper catalogue is HD48915. The Gliese ID of the star is GL 244A. The star was part of the original catalogue devised by German Astronomer Wilheim Gliese of stars located within 20 parsecs of Earth. Star Names
Flamsteed designations are named after the creator, Sir John Flamsteed. Sir John numbered the stars in the constellation with a number and the latin name, this star's Flamsteed designation is 9 Canis Majoris with it shortened to 9 CMa.
BD number is the number that the star was filed under in the Durchmusterung or Bonner Durchmusterung, a star catalogue that was put together by the Bonn Observatory between 1859 to 1903. The star's BD Number is BD-16 1591.
More details on star alternative names can be found at Star Names .
The location of the star in the night sky is determined by the Right Ascension (R.A.) and Declination (Dec.), these are equivalent to the Longitude and Latitude on the Earth. The Right Ascension is how far expressed in time (hh:mm:ss) the star is along the celestial equator. If the R.A. is positive then its eastwards. The Declination is how far north or south the star is compared to the celestial equator and is expressed in degrees. For Sirius, the location is 06h 45m 09.25 and -16° 42` 47.3 .
All stars like planets orbit round a central spot, in the case of planets, its the central star such as the Sun. In the case of a star, its the galactic centre. The constellations that we see today will be different than they were 50,000 years ago or 50,000 years from now. Proper Motion details the movements of these stars and are measured in milliarcseconds. The star is moving -1,223.07 ± 1.04 miliarcseconds/year towards the north and -546.01 ± 1.58 miliarcseconds/year east if we saw them in the horizon.
The Radial Velocity, that is the speed at which the star is moving away/towards the Sun is -5.50 km/s with an error of about 0.40 km/s . When the value is negative then the star and the Sun are getting closer to one another, likewise, a positive number means that two stars are moving away. Its nothing to fear as the stars are so far apart, they won't collide in our life-time, if ever.
Luminosity is the amount of energy that a star pumps out and its relative to the amount that our star, the Sun gives out. The figure of 25.84 that I have given is based on the value in the Simbad Hipparcos Extended Catalogue at the University of Strasbourg from 2012.
Sirius has a spectral type of A0m.... This means the star is a blue multiple star system. The star is 7,402.00 Parsecs from the Galactic Centre or terms of Light Years is 24,142.61 s. The star has a B-V Colour Index of -0.03 which means the star's temperature has been calculated using information from Morgans @ Uni.edu at being 11,122 Kelvin.
Sirius Radius has been calculated as being 1.29 times bigger than the Sun.The Sun's radius is 695,800km, therefore the star's radius is an estimated 897,444.94.km. If you need the diameter of the star, you just need to multiple the radius by 2. The figure is derived at by using the formula from SDSS and has been known to produce widely incorrect figures. The star's Iron Abundance is 0.36 with an error value of 9.99 Fe/H with the Sun has a value of 1 to put it into context.
Sirius has an apparent magnitude of -1.44 which is how bright we see the star from Earth. Apparent Magnitude is also known as Visual Magnitude. Using the supplied Parallax value, you would get an absolute magnitude of 1.45 Magnitude, whether it be apparent/visual or absolute magnitude is measured by a number, the smaller the number, the brighter the Star is. Our own Sun is the brightest star and therefore has the lowest of all magnitudes, -26.74. A faint star will have a high number.
Using the original Hipparcos data that was released in 1997, the parallax to the star was given as 379.21 which gave the calculated distance to Sirius as 8.60 light years away from Earth or 2.64 parsecs. It would take a spaceship travelling at the speed of light, 8.60 years to get there. We don't have the technology or spaceship that can carry people over that distance yet.
The star's Galacto-Centric Distance is 7,402.00 Parsecs or 24,142.61 Light Years. The Galacto-Centric Distance is the distance from the star to the Centre of the Galaxy which is Sagittarius A*.
The source of the information if it has a Hip I.D. is from Simbad, the Hipparcos data library based at the University at Strasbourg, France. Hipparcos was a E.S.A. satellite operation launched in 1989 for four years. The items in red are values that I've calculated so they could well be wrong. Information regarding Metallicity and/or Mass is from the E.U. Exoplanets. The information was obtained as of 12th Feb 2017.
|Primary / Proper / Traditional Name||Sirius|
|Alternative Names||Alpha Canis Majoris, Alf Cma, HD 48915, HIP 32349, HR 2491, 9 Canis Majoris, 9 CMa, BD-16 1591, Gliese 244A|
|Constellation's Main Star||Yes|
|Multiple Star System||Yes|
|Star Type||Multiple Star System|
|Visual / Apparent Magnitude||-1.44|
|Naked Eye Visible||Yes - Magnitudes|
|Right Ascension (R.A.)||06h 45m 09.25|
|Declination (Dec.)||-16° 42` 47.3|
|Galactic Latitude||-8.89 degrees|
|Galactic Longitude||227.23 degrees|
|Distance from Earth||379.21 Parallax (milliarcseconds)|
|8.60 Light Years|
|544,535.29 Astronomical Units|
|Galacto-Centric Distance||24,142.61 Light Years / 7,402.00 Parsecs|
|Proper Motion Dec.||-1223.07 ± 1.04 milliarcseconds/year|
|Proper Motion RA.||-546.01 ± 1.58 milliarcseconds/year|
|Radial Velocity||-5.50 ± 0.40 km/s|
|Iron Abundance||0.36 ± 9.99 Fe/H|
|Stellar Luminosity (Lsun)||25.84|
|Orbital Period (Days)||18295.40|
|Argument Of Periastron||327.27|
|Brightest in Night Sky||1st|
|Associated / Clustered Stars||Sirius B|
|Calculated Effective Temperature||11,122 Kelvin|
The star has been identified as being a multi-star system, one in which there is at least one star in close orbit to another star or two or more stars orbiting a central point. The stars may be of equal mass, unequal mass where one star is stronger than the other or be in groups orbiting a central point which doesn't necessarily have to be a star. More information can be found on my dedicated multiple star systems page. The source of the info is Simbad. The file is dated 2000 so any differences between this and any other source will be down to the actual source from where the information came from.
|Proper Motion mas/yr|
|H.D. Id||B.D. Id||Star Code||Magnitude||R.A.||Dec.||Spectrum||Colour||Year|