145 G. Canis Majoris

Stellar properties

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 , resulting in a distance of . Based on this distance, a luminosity 5,250 times that of the Sun () was calculated. From the luminosity and a temperature of , a radius of is obtained,{{efn | name=radius1 | Applying the Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K: :\sqrt{\biggl(\frac{5,772}{3,939}\biggr)^4 \cdot 10^{3.72}} = 155.71\ R_\odot.}} and a mass and age of 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 and a luminosity of 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 , 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 and .

The effective temperature of the star is around 4,000K, 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 . The two stars appear to be unrelated and the close alignment accidental, with HD 56578 being a much closer and less luminous Am star.

Notes

References

| display-authors=1 | last1=Tetzlaff | first1=N.

| display-authors=1 | journal=Astronomy and Astrophysics

References

1. [[K-type star. K]] [[giant star. giant]] or [[supergiant star]] in the southern [[constellation]] of [[Canis Major]]. This star is [[Benjamin Apthorp Gould. Gould]]'s 145th of Canis Major in his ''[[Benjamin Apthorp Gould#Uranography. Uranometria Argentina]]''.Gould, B. A., (2009) ''Uranometria Argentina'', (Reprinted and updated by Pilcher, F.){{usurped
2. [[SIMBAD]] query [https://simbad.u-strasbg.fr/simbad/sim-id?Ident=145%20CMa * 145 CMa – Star]
3. (6 March 2024). "The Colour of Stars".
4. "HD 56577".
5. {{Cite Gaia DR2. 5618016960635836928
6. {{cite Gaia DR3. 5618016960638976896
7. {{Cite Gaia DR2. 5618018438104581888
8. {{cite constellation. HIP 35210
9. (2020). "Distance scale for high-luminosity stars in OB associations and in field with Gaia DR2. Spurious systematic motions". Astrophysics and Space Science.
10. (2024-04-01). "Red supergiant candidates for multimessenger monitoring of the next Galactic supernova". Monthly Notices of the Royal Astronomical Society.
11. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal.
12. Earle Luck, R.. (2014-05-02). "PARAMETERS AND ABUNDANCES IN LUMINOUS STARS". The Astronomical Journal.
13. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.