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145 G. Canis Majoris
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145 G. Canis Majoris
145 G. Canis Majoris (HD 56577) is a single K giant or supergiant star in the southern constellation of Canis Major. This star is Gould's 145th of Canis Major in his Uranometria Argentina. SIMBAD erroneously lists the star in its object query result as "* 145 CMa – Star".
The spectral type of 145 G. Canis Majoris has been given as K4III in 1978, with the luminosity class "III" corresponding to a giant star. In 1989, the spectral type was revised to K3Ib, with a luminosity class Ib suggesting the star is at the lower luminosity range of supergiant stars.
Measurement of stellar properties such as radius, luminosity and mass depend on the star's distance, which is not well-known. The Hipparcos mission measured a parallax of 2.30±0.52 mas, resulting in a distance of 1,400±300 ly. Based on this distance, a luminosity 5,250 times that of the Sun (L☉) was calculated. From the luminosity and a temperature of 3,937±141 K, a radius of 156 ± 11 R☉ is obtained, and a mass and age of 1.90 M☉ and 1.05 Gyr have been obtained using the stellar parameters and isochrones. Those values are consistent with the star being a giant. However, parallax measurements by the Gaia spacecraft suggest the star is more distant than previously thought, hence has higher luminosity, radius and mass. A radius of 315 R☉ and a luminosity of 23,660 L☉ have been derived using the Gaia DR3 distance, suggesting the star is indeed a supergiant. At the Gaia DR2 parallax, the star should have a luminosity of 14,000 L☉, also rather high for a giant. Values for the mass and age at the Gaia distance have not been computed yet, but a 2012 study give 7.8±0.5 M☉ and 35.4±2.0 Myr.
The effective temperature of the star is around 4,000 K, which gives it an orange hue typical of K-type stars.
The star is one component of a close double, the other being HD 56578 which on its own would be a faint naked-eye star. The two are separated by 27″. The two stars appear to be unrelated and the close alignment accidental, with HD 56578 being a much closer and less luminous Am star.
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145 G. Canis Majoris
145 G. Canis Majoris (HD 56577) is a single K giant or supergiant star in the southern constellation of Canis Major. This star is Gould's 145th of Canis Major in his Uranometria Argentina. SIMBAD erroneously lists the star in its object query result as "* 145 CMa – Star".
The spectral type of 145 G. Canis Majoris has been given as K4III in 1978, with the luminosity class "III" corresponding to a giant star. In 1989, the spectral type was revised to K3Ib, with a luminosity class Ib suggesting the star is at the lower luminosity range of supergiant stars.
Measurement of stellar properties such as radius, luminosity and mass depend on the star's distance, which is not well-known. The Hipparcos mission measured a parallax of 2.30±0.52 mas, resulting in a distance of 1,400±300 ly. Based on this distance, a luminosity 5,250 times that of the Sun (L☉) was calculated. From the luminosity and a temperature of 3,937±141 K, a radius of 156 ± 11 R☉ is obtained, and a mass and age of 1.90 M☉ and 1.05 Gyr have been obtained using the stellar parameters and isochrones. Those values are consistent with the star being a giant. However, parallax measurements by the Gaia spacecraft suggest the star is more distant than previously thought, hence has higher luminosity, radius and mass. A radius of 315 R☉ and a luminosity of 23,660 L☉ have been derived using the Gaia DR3 distance, suggesting the star is indeed a supergiant. At the Gaia DR2 parallax, the star should have a luminosity of 14,000 L☉, also rather high for a giant. Values for the mass and age at the Gaia distance have not been computed yet, but a 2012 study give 7.8±0.5 M☉ and 35.4±2.0 Myr.
The effective temperature of the star is around 4,000 K, which gives it an orange hue typical of K-type stars.
The star is one component of a close double, the other being HD 56578 which on its own would be a faint naked-eye star. The two are separated by 27″. The two stars appear to be unrelated and the close alignment accidental, with HD 56578 being a much closer and less luminous Am star.