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HD 4778

From Wikipedia, the free encyclopedia
Star in the constellation Andromeda
HD 4778

Alight curve for GO Andromedae, plotted fromTESS data[1]
Observation data
Epoch J2000      Equinox J2000
ConstellationAndromeda
Right ascension00h 50m 18.26563s[2]
Declination+45° 00′ 08.1439″[2]
Apparent magnitude (V)6.13[3]
Characteristics
Spectral typeA3VpSiSrCrEuKsn[4]
B−Vcolor index0.043±0.004[3]
Variable typeα2 CVn[5]
Astrometry
Radial velocity (Rv)1.60[6] km/s
Proper motion (μ)RA: 65.353[2]mas/yr
Dec.: 4.133[2]mas/yr
Parallax (π)9.3224±0.0916 mas[2]
Distance350 ± 3 ly
(107 ± 1 pc)
Absolute magnitude (MV)1.18[7]
Details
Mass2.24±0.09[7] M☉
Radius2.36±0.12[8] R☉
Luminosity34.9±4.3[8] L☉
Surface gravity (log g)4.12±0.09[7] cgs
Temperature9,135±400[8] K
Rotation2.5616[7] days
Rotational velocity (v sin i)33[4] km/s
Age77[9] Myr
Other designations
GO Andromedae,BD+44° 176,FK5 2055,HD 4778,HIP 3919,HR 234,SAO 36702,PPM 43369[10]
Database references
SIMBADdata

HD 4778, also known asHR 234 andGO Andromedae, is avariable star in the constellationAndromeda. Its magnitude varies by 0.04 magnitudes from the median of 6.12 with a period of approximately 2.55 days.[11] The star is located 350 light years away, as determined from its annualparallax shift of9.32 mas.[2]

This is anAp star with astellar classification of A3VpSiSrCrEuKsn,[4] showingchemical peculiarities in itsspectrum from strontium, chromium, and europium.[12] It is anAlpha2 Canum Venaticorum variable[5] with amagnetic field that varies across the range+1,400 to −1,100 G.[13] This rotation-modulated variability allows direct determination of the rotation rate of 2.5616 days.[7]

HD 4778 has 2.24[7] times themass of the Sun and 2.36[8] times theSun's radius. The star is radiating 35[8] times theSun's luminosity from itsphotosphere at aneffective temperature of 9,375 K.[7] It is about 77[9] million years old.

References

[edit]
  1. ^"MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved8 December 2021.
  2. ^abcdefBrown, A. G. A.; et al. (Gaia collaboration) (August 2018)."Gaia Data Release 2: Summary of the contents and survey properties".Astronomy & Astrophysics.616. A1.arXiv:1804.09365.Bibcode:2018A&A...616A...1G.doi:10.1051/0004-6361/201833051.
  3. ^abAnderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation",Astronomy Letters,38 (5): 331,arXiv:1108.4971,Bibcode:2012AstL...38..331A,doi:10.1134/S1063773712050015,S2CID 119257644.
  4. ^abcAbt, 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.
  5. ^abSamus, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017). "General Catalogue of Variable Stars".Astronomy Reports. GCVS 5.1.61 (1):80–88.Bibcode:2017ARep...61...80S.doi:10.1134/S1063772917010085.S2CID 125853869.
  6. ^Kharchenko, N. V.; et al. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations".Astronomische Nachrichten.328 (9): 889.arXiv:0705.0878.Bibcode:2007AN....328..889K.doi:10.1002/asna.200710776.S2CID 119323941.
  7. ^abcdefgNorth, P. (June 1998), "Do SI stars undergo any rotational braking?",Astronomy and Astrophysics,334:181–187,arXiv:astro-ph/9802286,Bibcode:1998A&A...334..181N
  8. ^abcdePerraut, K.; et al. (October 2020), "Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements",Astronomy & Astrophysics,642: 13,Bibcode:2020A&A...642A.101P,doi:10.1051/0004-6361/202038753, A101.
  9. ^abDavid, 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.
  10. ^"HD 3167".SIMBAD.Centre de données astronomiques de Strasbourg. RetrievedOctober 6, 2018.
  11. ^VSX (4 January 2010)."GO Andromedae".AAVSO Website.American Association of Variable Star Observers. Retrieved25 May 2014.
  12. ^Panek, R. J. (October 1980). "Periodic spectral variability of the AP star HR 234".Astronomy and Astrophysics.90 (3):341–343.Bibcode:1980A&A....90..341P.
  13. ^Bohlender, D. A. (August 1989). "The magnetic field and rotation period of the AP star HD 4778".Astronomy and Astrophysics.220:215–217.Bibcode:1989A&A...220..215B.
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