Gamma Persei

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Gamma Persei
Diagram showing star positions and boundaries of the Perseus constellation and its surroundings
Cercle rouge 100%.svg

Location of γ Pegasi (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Perseus
Right ascension 03h 04m 47.79074s[1]
Declination +53° 30′ 23.1687″[1]
Apparent magnitude (V) 2.93[2]
Characteristics
Spectral type G9 III + A2–A3[3][4]
U−B color index +0.45[2]
B−V color index +0.70[2]
Astrometry
Radial velocity (Rv) +2.5[5] km/s
Proper motion (μ) RA: +0.51[1] mas/yr
Dec.: –5.92[1] mas/yr
Parallax (π) 13.41 ± 0.51[1] mas
Distance 243 ± 9 ly
(75 ± 3 pc)
Absolute magnitude (MV) –1.50[6] (–1.23/0.01)[4]
Orbit[4]
Period (P) 14.6 yr
Semi-major axis (a) 0.144"
Eccentricity (e) 0.785
Inclination (i) 90.9°
Longitude of the node (Ω) 244.1°
Periastron epoch (T) 1991.08 Besselian
Argument of periastron (ω)
(secondary)
170.0°
Details
γ Per A
Mass 2.7[4] M
Surface gravity (log g) 2.83[7] cgs
Temperature 5,170[7] K
Metallicity [Fe/H] –0.19[7] dex
Rotation 5,350 days[6]
Rotational velocity (v sin i) 50.0[6] km/s
γ Per B
Mass 1.65[4] M
Temperature 7,895[4] K
Other designations
γ Persei, γ Per, Gamma Per, 23 Persei, BD+52 654, CCDM J03048+5331AP, FK5 108, GC 3664, HD 18925, HIP 14328, HR 915, IDS 02576+5307 AP, PPM 28201, SAO 23789, WDS J03048+5330Aa,Ab.

Gamma Persei (Gamma Per, γ Persei, γ Per) is a binary star system in the constellation Perseus. The combined apparent visual magnitude of the pair is +2.9,[2] making it the fourth brightest member of the constellation. The distance to this system has been measured using the parallax technique, giving an estimate of roughly 243 light-years (75 parsecs) with a 4% margin of error.[1] About 4° to the north of Gamma Persei is the radiance point for the annual Perseid meteor shower.[8]

This is a wide eclipsing binary system with an orbital period of 5,329.8 days (14.6 years).[9] This eclipse was first observed in 1990 and lasted for two weeks.[10] During an eclipse, the primary passes in front of the secondary, causing the magnitude of the system to decrease by 0.55.[11] The primary component of this system is a giant star with a stellar classification of G9 III.[3] It has a projected rotational velocity of 50.0 km s−1 and a lengthy estimated rotation period of 14.6 years.[6] The classification of the secondary remains tentative, with assignments of A3 V[4] and A2(III).[3]

Mass estimates for the two stars remain disparate. Using speckle interferometery, McAlister (1982) obtained mass estimates of 4.73 M for the primary and 2.75 M for the secondary, where M is the mass of the Sun. He noted that the mass estimate was too high for the given classification of the primary.[12] Martin and Mignard (1998) determined masses for both components based on data from the Hipparcos mission: 5.036 ± 0.951 M for the primary and 2.295 ± 0.453 M for the secondary. They admit that the high inclination of the orbit resulted in a large margin of error.[13] Prieto and Lambert (1999) came up with a mass estimate of 3.81 M for the primary,[14] while Pizzolato and Maggio (2000) obtained 4.34 M.[6] Ling et al. (2001) obtained estimates of 2.7 M for the primary and 1.65 M for the secondary,[4] while Kaler (2001) obtained 2.5 and 1.9, respectively.[10]

Name and etymology[edit]

References[edit]

  1. ^ a b c d e f van Leeuwen, F. (November 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 
  2. ^ a b c d 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 
  3. ^ a b c Ginestet, N.; Carquillat, J. M. (December 2002), "Spectral Classification of the Hot Components of a Large Sample of Stars with Composite Spectra, and Implication for the Absolute Magnitudes of the Cool Supergiant Components", The Astrophysical Journal Supplement Series 143 (2): 513–537, Bibcode:2002ApJS..143..513G, doi:10.1086/342942 
  4. ^ a b c d e f g h Ling, J. F.; Magdalena, P.; Prieto, C. (October 2001), "Perturbations by Mass Loss in the Orbital Elements of γ Persei and α Centauri", Revista Mexicana de Astronomia y Astrofisica 37: 179–186, Bibcode:2001RMxAA..37..179L 
  5. ^ Wilson, Ralph Elmer (1953), General Catalogue of Stellar Radial Velocities, Washington: Carnegie Institution of Washington, Bibcode:1953QB901.W495..... 
  6. ^ a b c d e Pizzolato, N.; Maggio, A.; Sciortino, S. (September 2000), "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases", Astronomy and Astrophysics 361: 614–628, Bibcode:2000A&A...361..614P 
  7. ^ a b c McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants", Astrophysical Journal Supplement Series 74: 1075–1128, Bibcode:1990ApJS...74.1075M, doi:10.1086/191527 
  8. ^ Burnham, Robert (1978), Burnham's celestial handbook: an observer's guide to the universe beyond the solar system, Dover books explaining science 3 (2nd ed.), Courier Dover Publications, p. 420, ISBN 0486236730 
  9. ^ Pourbaix, D.; Boffin, H. M. J. (February 2003), "Reprocessing the Hipparcos Intermediate Astrometric Data of spectroscopic binaries. II. Systems with a giant component", Astronomy and Astrophysics 398: 1163–1177, arXiv:astro-ph/0211483, Bibcode:2003A&A...398.1163P, doi:10.1051/0004-6361:20021736 
  10. ^ a b Kaler, James B. (January 5, 2001), "GAMMA PER (Gamma Persei)", Stars (University of Illinois), retrieved 2012-02-25 
  11. ^ Malkov, O. Yu. et al. (February 2006), "A catalogue of eclipsing variables", Astronomy and Astrophysics 446 (2): 785–789, Bibcode:2006A&A...446..785M, doi:10.1051/0004-6361:20053137 
  12. ^ McAlister, H. A. (March 1982), "Masses and luminosities for the giant spectroscopic/speckle interferometric binaries gamma Persei and phi Cygni", Astronomical Journal 87: 563–569, Bibcode:1982AJ.....87..563M, doi:10.1086/113130 
  13. ^ Martin, C.; Mignard, F. (February 1998), "Mass determination of astrometric binaries with Hipparcos. II. Selection of candidates and results", Astronomy and Astrophysics 330: 585–599, Bibcode:1998A&A...330..585M 
  14. ^ Allende Prieto, C.; Lambert, D. L. (1999), "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: masses, radii and effective temperatures", Astronomy and Astrophysics 352: 555–562, arXiv:0809.0359, Bibcode:1999A&A...352..555A 
  15. ^ Allen, R. H. (1963). Star Names: Their Lore and Meaning (Reprint ed.). New York: Dover Publications Inc. p. 331. ISBN 0-486-21079-0. Retrieved 2012-09-04. 
  16. ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 11 日

External links[edit]