Alpha Monocerotis

α Monocerotis
Location of α Monocerotis (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Monoceros
Right ascension 07h 41m 14.832s[1]
Declination −09° 33′ 04.078″[1]
Apparent magnitude (V) 3.94[2]
Characteristics
Spectral type G9.5 III-IIIb Fe-0.5[3]
B−V color index 1.022[2]
Astrometry
Radial velocity (Rv)+10.50[2] km/s
Proper motion (μ) RA: -74.989 mas/yr[1]
Dec.: -19.838 mas/yr[1]
Parallax (π)22.3839 ± 0.1348 mas[1]
Distance145.7 ± 0.9 ly
(44.7 ± 0.3 pc)[1]
Absolute magnitude (MV)0.71±0.08[4]
Details
Mass1.78±0.11[5] M☉
Radius10.05[5] – 10.42±0.12[6] R☉
Luminosity63.7±1.3[6] L☉
Surface gravity (log g)2.81±0.08[5] cgs
Temperature5049±32[6] K
Metallicity [Fe/H]−0.01±0.03[5] dex
Rotation326 days[7]
Rotational velocity (v sin i)1.9[7] km/s
Age1.824±0.283[5] Gyr
Other designations
α Mon, 26 Monocerotis, BD−09° 2172, HD 61935, HIP 37447, HR 2970, SAO 134986[8]
Database references
SIMBADdata

Alpha Monocerotis, Latinised from α Monocerotis, is the Bayer designation for the brightest star in the equatorial constellation of Monoceros. It can be viewed with the naked eye, having an apparent visual magnitude of 3.94.[2] Based upon an annual parallax shift of 22.4 mas as seen from Earth,[1] it is located 146 light-years away from the Sun. The star is moving away from the Sun with a radial velocity of +10.5 km/s.[2]

The stellar classification of G9.5 III-IIIb Fe-0.5[3] indicates this is an evolved giant star of type G, which means the hydrogen has been depleted at its core and the outer envelope has expanded and cooled. The 'Fe−0.5' notation indicates the spectrum displays a slight underabundance of iron relative to other stars of this temperature. It is a red clump giant, which means it is generating energy through helium fusion at its core.[9] At the age of 1.8 billion years, this yellow-hued star has an estimated two times the mass of the Sun and 10 times the Sun's radius.[5] It is spinning sedately with a rotation period of about 326 days.[7]

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  2. ^ a b c d e Cite error: The named reference aaa454_3_943 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).
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  5. ^ a b c d e f Cite error: The named reference Gomes2021 was invoked but never defined (see the help page).
  6. ^ a b c Cite error: The named reference baines was invoked but never defined (see the help page).
  7. ^ a b c Cite error: The named reference aaa421_241 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ Cite error: The named reference laney2012 was invoked but never defined (see the help page).