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θ Geminorum
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Gemini
Right ascension 06h 52m 47.33887s [1]
Declination +33° 57′ 40.5175″ [1]
Apparent magnitude (V) 3.59 [2]
Characteristics
Spectral type A2 IV [3]
U−B color index +0.13 [2]
B−V color index +0.10 [2]
Astrometry
Radial velocity (Rv)+21 [4] km/s
Proper motion (μ) RA: −1.66 [1]  mas/ yr
Dec.: −47.31 [1]  mas/ yr
Parallax (π)17.25 ± 0.19  mas [1]
Distance189 ± 2  ly
(58.0 ± 0.6  pc)
Absolute magnitude (MV)−0.18 [5]
Details
Mass1.80 [6]  M☉
Radius5.1 [7]  R☉
Luminosity93 [8]  L☉
Surface gravity (log g)3.40±0.14 [6]  cgs
Temperature8,502±289 [6]  K
Rotational velocity (v sin i)133 [9] km/s
Age252 [6]  Myr
Other designations
θ Gem, 34 Gem, BD+34°1481, FK5 261, HD 50019, HIP 33018, HR 2540, SAO 59570. [10]
Database references
SIMBAD data

Theta Geminorum (θ Gem, θ Geminorum) is a single [11] star in the northern zodiac constellation of Gemini. It is visual to the naked eye with an apparent visual magnitude of 3.59. [2] Based upon an annual parallax shift of 17.25  mas, [1] it is about 189  light years distant from the Sun.

This is an evolving A-type subgiant star with a stellar classification of A2 IV. [3] It has 1.80 [6] times the mass of the Sun and radiates 93 [8] times the solar luminosity. The measured angular diameter is 0.82±0.03  mas. [12] At an estimated distance of this star, this yields a physical size of about 5.1 times the radius of the Sun. [7] It is around 252 million years old and has a projected rotational velocity of 133 [9] km/s. This rotation rate is giving the star an oblate shape, with an equatorial bulge that is 11% larger than the polar radius. [13]

The Washington Visual Double Star Catalog lists five visual companions within 100 ″; the closest and brightest such companion is the magnitude 8.6 θ Geminorum E at an angular separation of 2.4″ along a position angle of 295°, as of 2010. [14]

References

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752, Bibcode: 2007A&A...474..653V, doi: 10.1051/0004-6361:20078357, S2CID  18759600.
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode: 1986EgUBV........0M.
  3. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode: 1995ApJS...99..135A, doi: 10.1086/192182.
  4. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode: 1967IAUS...30...57E.
  5. ^ Huang, W.; et al. (2012), "A catalogue of Paschen-line profiles in standard stars", Astronomy & Astrophysics, 547: A62, arXiv: 1210.7893, Bibcode: 2012A&A...547A..62H, doi: 10.1051/0004-6361/201219804, S2CID  119286159.
  6. ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv: 1501.03154, Bibcode: 2015ApJ...804..146D, doi: 10.1088/0004-637X/804/2/146, S2CID  33401607.
  7. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN  3-540-29692-1. The radius (R*) is given by:
  8. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv: 1208.2037, Bibcode: 2012MNRAS.427..343M, doi: 10.1111/j.1365-2966.2012.21873.x, S2CID  118665352.
  9. ^ a b Royer, F.; et al. (October 2012), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv: astro-ph/0205255, Bibcode: 2002A&A...393..897R, doi: 10.1051/0004-6361:20020943, S2CID  14070763.
  10. ^ "tet Gem". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-12-02.{{ cite web}}: CS1 maint: postscript ( link)
  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: 0806.2878, Bibcode: 2008MNRAS.389..869E, doi: 10.1111/j.1365-2966.2008.13596.x, S2CID  14878976.
  12. ^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode: 2005A&A...431..773R, doi: 10.1051/0004-6361:20042039.
  13. ^ van Belle, Gerard T., Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv: 1204.2572, Bibcode: 2012A&ARv..20...51V, doi: 10.1007/s00159-012-0051-2, S2CID  119273474.
  14. ^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode: 2001AJ....122.3466M, doi: 10.1086/323920.
Retrieved from " https://en.wikipedia.org/?title=Theta_Geminorum&oldid=1170017544"
From Wikipedia, the free encyclopedia
θ Geminorum
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
Constellation Gemini
Right ascension 06h 52m 47.33887s [1]
Declination +33° 57′ 40.5175″ [1]
Apparent magnitude (V) 3.59 [2]
Characteristics
Spectral type A2 IV [3]
U−B color index +0.13 [2]
B−V color index +0.10 [2]
Astrometry
Radial velocity (Rv)+21 [4] km/s
Proper motion (μ) RA: −1.66 [1]  mas/ yr
Dec.: −47.31 [1]  mas/ yr
Parallax (π)17.25 ± 0.19  mas [1]
Distance189 ± 2  ly
(58.0 ± 0.6  pc)
Absolute magnitude (MV)−0.18 [5]
Details
Mass1.80 [6]  M☉
Radius5.1 [7]  R☉
Luminosity93 [8]  L☉
Surface gravity (log g)3.40±0.14 [6]  cgs
Temperature8,502±289 [6]  K
Rotational velocity (v sin i)133 [9] km/s
Age252 [6]  Myr
Other designations
θ Gem, 34 Gem, BD+34°1481, FK5 261, HD 50019, HIP 33018, HR 2540, SAO 59570. [10]
Database references
SIMBAD data

Theta Geminorum (θ Gem, θ Geminorum) is a single [11] star in the northern zodiac constellation of Gemini. It is visual to the naked eye with an apparent visual magnitude of 3.59. [2] Based upon an annual parallax shift of 17.25  mas, [1] it is about 189  light years distant from the Sun.

This is an evolving A-type subgiant star with a stellar classification of A2 IV. [3] It has 1.80 [6] times the mass of the Sun and radiates 93 [8] times the solar luminosity. The measured angular diameter is 0.82±0.03  mas. [12] At an estimated distance of this star, this yields a physical size of about 5.1 times the radius of the Sun. [7] It is around 252 million years old and has a projected rotational velocity of 133 [9] km/s. This rotation rate is giving the star an oblate shape, with an equatorial bulge that is 11% larger than the polar radius. [13]

The Washington Visual Double Star Catalog lists five visual companions within 100 ″; the closest and brightest such companion is the magnitude 8.6 θ Geminorum E at an angular separation of 2.4″ along a position angle of 295°, as of 2010. [14]

References

  1. ^ a b c d e f van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752, Bibcode: 2007A&A...474..653V, doi: 10.1051/0004-6361:20078357, S2CID  18759600.
  2. ^ a b c d Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data, SIMBAD, Bibcode: 1986EgUBV........0M.
  3. ^ a b Abt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars", Astrophysical Journal Supplement, 99: 135, Bibcode: 1995ApJS...99..135A, doi: 10.1086/192182.
  4. ^ Evans, D. S. (June 20–24, 1966), "The Revision of the General Catalogue of Radial Velocities", in Batten, Alan Henry; Heard, John Frederick (eds.), Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30, vol. 30, University of Toronto: International Astronomical Union, p. 57, Bibcode: 1967IAUS...30...57E.
  5. ^ Huang, W.; et al. (2012), "A catalogue of Paschen-line profiles in standard stars", Astronomy & Astrophysics, 547: A62, arXiv: 1210.7893, Bibcode: 2012A&A...547A..62H, doi: 10.1051/0004-6361/201219804, S2CID  119286159.
  6. ^ a b c d e David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv: 1501.03154, Bibcode: 2015ApJ...804..146D, doi: 10.1088/0004-637X/804/2/146, S2CID  33401607.
  7. ^ a b Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, vol. 1 (3rd ed.), Birkhäuser, ISBN  3-540-29692-1. The radius (R*) is given by:
  8. ^ a b McDonald, I.; et al. (2012), "Fundamental Parameters and Infrared Excesses of Hipparcos Stars", Monthly Notices of the Royal Astronomical Society, 427 (1): 343–57, arXiv: 1208.2037, Bibcode: 2012MNRAS.427..343M, doi: 10.1111/j.1365-2966.2012.21873.x, S2CID  118665352.
  9. ^ a b Royer, F.; et al. (October 2012), "Rotational velocities of A-type stars in the northern hemisphere. II. Measurement of v sin i", Astronomy and Astrophysics, 393: 897–911, arXiv: astro-ph/0205255, Bibcode: 2002A&A...393..897R, doi: 10.1051/0004-6361:20020943, S2CID  14070763.
  10. ^ "tet Gem". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2016-12-02.{{ cite web}}: CS1 maint: postscript ( link)
  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: 0806.2878, Bibcode: 2008MNRAS.389..869E, doi: 10.1111/j.1365-2966.2008.13596.x, S2CID  14878976.
  12. ^ Richichi, A.; et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics, 431 (2): 773–777, Bibcode: 2005A&A...431..773R, doi: 10.1051/0004-6361:20042039.
  13. ^ van Belle, Gerard T., Gerard T. (March 2012), "Interferometric observations of rapidly rotating stars", The Astronomy and Astrophysics Review, 20 (1): 51, arXiv: 1204.2572, Bibcode: 2012A&ARv..20...51V, doi: 10.1007/s00159-012-0051-2, S2CID  119273474.
  14. ^ Mason, B. D.; et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal, 122 (6): 3466–3471, Bibcode: 2001AJ....122.3466M, doi: 10.1086/323920.
Retrieved from " https://en.wikipedia.org/?title=Theta_Geminorum&oldid=1170017544"

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