Astronomy:HD 4778
Observation data Equinox J2000.0]] (ICRS) | |
---|---|
Constellation | Andromeda |
Right ascension | 00h 50m 18.26563s[2] |
Declination | +45° 00′ 08.1439″[2] |
Apparent magnitude (V) | 6.13[3] |
Characteristics | |
Spectral type | A3VpSiSrCrEuKsn[4] |
B−V color index | 0.043±0.004[3] |
Variable type | α2 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[2] mas |
Distance | 350 ± 3 ly (107 ± 1 pc) |
Absolute magnitude (MV) | 1.18[7] |
Details | |
Mass | 2.24±0.09[7] M☉ |
Radius | 2.36±0.12[8] R☉ |
Luminosity | 34.9±4.3[8] L☉ |
Surface gravity (log g) | 4.12±0.09[7] cgs |
Temperature | 9,135±400[8] K |
Rotation | 2.5616[7] days |
Rotational velocity (v sin i) | 33[4] km/s |
Age | 77[9] Myr |
Other designations | |
Database references | |
SIMBAD | data |
HD 4778, also known as HR 234 and GO Andromedae, is a variable star in the constellation Andromeda. 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 annual parallax shift of 9.32 mas.[2]
This is an Ap star with a stellar classification of A3VpSiSrCrEuKsn,[4] showing chemical peculiarities in its spectrum from strontium, chromium, and europium.[12] It is an Alpha2 Canum Venaticorum variable[5] with a magnetic 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 the mass of the Sun and 2.36[8] times the Sun's radius. The star is radiating 35[8] times the Sun's luminosity from its photosphere at an effective temperature of 9,375 K.[7] It is about 77[9] million years old.
References
- ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.
- ↑ 3.0 3.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 4.0 4.1 4.2 Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". Astrophysical Journal Supplement 99: 135. doi:10.1086/192182. Bibcode: 1995ApJS...99..135A.
- ↑ 5.0 5.1 Samus, 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. doi:10.1134/S1063772917010085. Bibcode: 2017ARep...61...80S.
- ↑ 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. doi:10.1002/asna.200710776. Bibcode: 2007AN....328..889K.
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 North, P. (June 1998), "Do SI stars undergo any rotational braking?", Astronomy and Astrophysics 334: 181–187, Bibcode: 1998A&A...334..181N
- ↑ 8.0 8.1 8.2 8.3 8.4 Perraut, K. et al. (October 2020), "Benchmarking the fundamental parameters of Ap stars with optical long-baseline interferometric measurements", Astronomy & Astrophysics 642: 13, doi:10.1051/0004-6361/202038753, A101, Bibcode: 2020A&A...642A.101P.
- ↑ 9.0 9.1 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. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D.
- ↑ "HD 3167". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+3167.
- ↑ VSX (4 January 2010). "GO Andromedae". AAVSO Website. American Association of Variable Star Observers. http://www.aavso.org/vsx/index.php?view=detail.top&oid=197.
- ↑ 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.
- ↑ 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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