HD 49933

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HD 49933
Observation data
Epoch J2000      Equinox J2000
Constellation Monoceros
Right ascension 06h 50m 49.83180s[1]
Declination –00° 32′ 27.1701″[1]
Apparent magnitude (V) 5.781[2]
Spectral type F2 V[3]
U−B color index –0.07[4]
B−V color index +0.39[4]
Radial velocity (Rv) –14.7[5] km/s
Proper motion (μ) RA: +22.09[1] mas/yr
Dec.: –186.51[1] mas/yr
Parallax (π) 33.69 ± 0.42[1] mas
Distance 97 ± 1 ly
(29.7 ± 0.4 pc)
Absolute magnitude (MV) 3.42[2]
Mass 1.079 ± 0.073[6] M
Radius 1.385 ± 0.031[6] R
Luminosity 3.47 ± 0.18[6] L
Surface gravity (log g) 4.08[7] cgs
Temperature 6,598[7] K
Metallicity [Fe/H] –0.29[7] dex
Rotational velocity (v sin i) 10[8] km/s
Age 2.4[2] Gyr
Other designations
BD−00 1462, HD 49933, HIP 32851, HR 2530, SAO 133760.[9]
Database references

HD 49933 (HR 2530) is a Sun-like[6] star in the equatorial constellation of Monoceros, the unicorn. The HD designation indicates the identifier of the star found in the Henry Draper catalogue. At an apparent magnitude of 5.8,[2] this star can just be seen with the naked eye under suitably dark conditions. Based upon parallax measurements from the Hipparcos mission,[10] the distance to HD 49933 is about 97 light-years (30 parsecs) with a 1% margin of error. It has an 11.3 magnitude common proper motion companion at an angular separation of 5.9 arcseconds, which may make this a binary star system if the pair are gravitationally bound.[11]

This is an F-type main sequence star with a stellar classification of F2 V,[3] where the luminosity class V indicates that it is generating energy through the nuclear fusion of hydrogen at its core. It is slightly larger than the Sun, with 108% of the Sun's mass and 139% of the Sun's radius. HD 49933 emits 3.47 times as much energy as the Sun from its outer atmosphere at a higher effective temperature of about 6,598 K,[6] giving it the yellow-white hue of an F-type star.[12] It is estimated to be 2.4 billion years old.[2]

The surface magnetic activity on this star is similar to what is observed on the Sun. Magnetic features on the surface have been detected using asteroseismology that appear to be starspots (the stellar equivalent to sunspots on the Sun).[13]


  1. ^ a b c d e van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752Freely accessible, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357 
  2. ^ a b c d e Holmberg, J.; Nordström, B.; Andersen, J. (July 2009). "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics". Astronomy and Astrophysics Supplement Series. 501 (3): 941–947. arXiv:0811.3982Freely accessible. Bibcode:2009A&A...501..941H. doi:10.1051/0004-6361/200811191.  Note: see VizieR catalogue V/130.
  3. ^ a b Malaroda, S. (August 1975). "Study of the F-type stars. I. MK spectral types". Astronomical Journal. 80: 637–641. Bibcode:1975AJ.....80..637M. doi:10.1086/111786. 
  4. ^ a b Johnson, H. L.; et al. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J. 
  5. ^ Wilson, Ralph Elmer (1953). General catalogue of stellar radial velocities. Carnegie Institution of Washington. Bibcode:1953GCRV..C......0W. 
  6. ^ a b c d e Bruntt, H. (October 2009). "Accurate fundamental parameters of CoRoT asteroseismic targets. The solar-like stars HD 49933, HD 175726, HD 181420, and HD 181906". Astronomy and Astrophysics. 506 (1): 235–244. arXiv:0907.1198Freely accessible. Bibcode:2009A&A...506..235B. doi:10.1051/0004-6361/200911925. 
  7. ^ a b c Cenarro, A. J.; et al. (January 2007). "Medium-resolution Isaac Newton Telescope library of empirical spectra - II. The stellar atmospheric parameters". Monthly Notices of the Royal Astronomical Society. 374 (2): 664–690. arXiv:astro-ph/0611618Freely accessible. Bibcode:2007MNRAS.374..664C. doi:10.1111/j.1365-2966.2006.11196.x. 
  8. ^ Bernacca, P. L.; Perinotto, M. (1970). "A catalogue of stellar rotational velocities". Contributi Osservatorio Astronomico di Padova in Asiago. 239 (1). Bibcode:1970CoAsi.239....1B. 
  9. ^ "HR 2530 -- Star in double system". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-08-27. 
  10. ^ Perryman, M. A. C.; et al. (1997). "The Hipparcos Catalogue". Astronomy and Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P. 
  11. ^ Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878Freely accessible. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. 
  12. ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, retrieved 2012-01-16 
  13. ^ National Center for Atmospheric Research (August 26, 2010). "Distant star's sound waves reveal cycle similar to the Sun's". PhysOrg.com. Retrieved 2010-08-27.