145 G. Canis Majoris

145 G. Canis Majoris
Observation data
Epoch J2000      Equinox J2000
Constellation Canis Major
Right ascension 07h 16m 36.83456s[1]
Declination −23° 18′ 56.1383″[1]
Apparent magnitude (V) 4.79[2]
Characteristics
Spectral type K3Ib-[3] or K4III[4]
B−V color index 1.710[2]
Astrometry
Radial velocity (Rv)+28.05±0.42[5] km/s
Proper motion (μ) RA: −3.816[1] mas/yr
Dec.: +3.896[1] mas/yr
Parallax (π)1.2155 ± 0.0998 mas[1]
Distance2,700 ± 200 ly
(820 ± 70 pc)
Details
If a giant star
Mass1.90[2] M☉
Radius156 ± 11[2][a] R☉
Luminosity5,250[2] L☉
Surface gravity (log g)0.70[2] cgs
Temperature3,937±141[2] K
Metallicity [Fe/H]0.03[2] dex
Age1.05[2] Gyr
If a supergiant
Mass7.8±0.5[6] M☉
Radius315[7] R☉
Luminosity23,660[7] L☉
Temperature3,986[7] K
Rotational velocity (v sin i)7.4±1.0[8] km/s
Age35.4±2.0[6] Myr
Other designations
145 G. CMa, NSV 3503, CD−23°5189, HD 56577, HIP 35210, HR 2764, SAO 173349, WDS J07166-2319A[9]
Database references
SIMBADdata

145 G. Canis Majoris (HD 56577) is a single[10] 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. [11] Kostjuk erroneously lists it as simply "145 CMa". SIMBAD follows this error in its object query result as "* 145 CMa – Star".[12]

The properties and evolutionary state of 145 G. CMa are disputed, it being classed either as a young massive supergiant or a somewhat older and less massive giant. It has been given two MK spectral classifications: K3Ib[3] (corresponding to a supergiant) and K4III[4] (corresponding to a giant). Tezzlaff et al. gives a large mass of 7.8 M☉ and a young age of 35 million years,[6] while Earle Luck gives a smaller mass of 1.9 M☉ and a higher age of 1.05 billion years.[2] The effective temperature of the star is of 3,980 K,[7] which gives it a orange hue typical of K-type stars.[13]

Based on the assumption that it is a supergiant, 145 CMa has been given a large radius of 315 R☉ and a luminosity of 23,660 L☉.[7] Assuming it is a giant, Earle Luck give a much lower luminosity of 5,250 L☉ with a corresponding radius of 156 R☉.[a][2] By the distance implied by its Gaia DR2 parallax, it would have a luminosity of 14,000 L☉, rather high for a giant.[5] An older measurement based on the Hipparcos distance of 435 parsecs (1,420 ly) give a lower luminosity of 5,960 L☉.[14]

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″.[15] The two stars appear to be unrelated and the close alignment accidental, with HD 56578 being a much closer and less luminous Am star.[16]

  1. ^ a b c d e Cite error: The named reference dr3 was invoked but never defined (see the help page).
  2. ^ a b c d e f g h i j k Cite error: The named reference luck2015 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference perkins1989 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference houk1978 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference Tetzlaff2011 was invoked but never defined (see the help page).
  7. ^ a b c d e Cite error: The named reference healy2023 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference DeMedeiros2002 was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Gould, B. A., (2009) Uranometria Argentina, (Reprinted and updated by Pilcher, F.)[1] Archived 2016-03-05 at the Wayback Machine
  12. ^ SIMBAD query * 145 CMa – Star
  13. ^ "The Colour of Stars". Australia National Telescope Facility. 6 March 2024. Retrieved 2024-05-27.
  14. ^ Cite error: The named reference mcdonald was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference wds was invoked but never defined (see the help page).
  16. ^ Cite error: The named reference dr3b was invoked but never defined (see the help page).


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