Astronomy:GR Andromedae

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Short description: Variable star in the constellation Andromeda
GR Andromedae
GRAndLightCurve.png
The visual band light curve of GR Andromedae, showing variation about the mean brightness. Adapted from Pyper et al. (2017)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 28m 28.5694s[2]
Declination +32° 26′ 15.8791″[2]
Apparent magnitude (V) 6.87 – 6.95 variable[3]
Characteristics
Spectral type A2pSrCrEu[3]
Apparent magnitude (B) 6.99[4]
Apparent magnitude (V) 6.91[4]
Apparent magnitude (G) 6.8449[2]
Apparent magnitude (J) 6.708[5]
Apparent magnitude (H) 6.765[5]
Apparent magnitude (K) 6.739[5]
Variable type α2 CVn[3]
Astrometry
Radial velocity (Rv)−18.2±0.7[6] km/s
Proper motion (μ) RA: −28.861±0.093 [2] mas/yr
Dec.: −20.308±0.070[2] mas/yr
Parallax (π)5.3516 ± 0.0704[2] mas
Distance609 ± 8 ly
(187 ± 2 pc)
Absolute magnitude (MV)+0.88[7]
Details
Mass2.24[7] M☉
Radius2.24[8] R☉
Luminosity37[7] L☉
Surface gravity (log g)3[9] cgs
Temperature8,542[9] K
Metallicity [Fe/H]1[9] dex
Rotation518.2 days[1]
Rotational velocity (v sin i)< 6[8] km/s
Age525[7] Myr
Other designations
2MASS J00282858+3226159, BD+31 59, HD 2453, HIP 2243, SAO 53921, TYC 2266-725-1
Database references
SIMBADdata

GR Andromedae (often abbreviated to GR And) is a variable star in the constellation Andromeda. Its apparent visual magnitude varies between 6.87 and 6.95 in a cycle of 518.2 days.[1] It is classified as an α2 Canum Venaticorum variable.[3]

Spectrum

The radiation emitted by GP Andromedae is a typical stellar blackbody with absorption lines from various elements, which gives to the star a spectral type A2pSrCrEu, meaning that unusually strong lines of strontium, chromium and europium can be observed.[3] GP Andromedae is thus classified as an Ap star. The intensity and profile of the spectral lines varies within a cycle with the same period as the brightness variations.[8]

Variability

Photometric and spectral variability of GR Andromedae is typical of a star with a strong and variable magnetic field. This way, the 518.2 days periodicity can be identified as the rotation period of the star.[8] It's among the slowest rotators in the category of magnetic chemically peculiar stars, with a calculated equatorial rotation rate of only 0.2 km/s.[1]

References

  1. ↑ 1.0 1.1 1.2 1.3 Pyper, D. M.; Adelman, S. J. (October 2017). "On the Photometric Variability of Very Sharp-lined Cool mCP Stars". Publications of the Astronomical Society of the Pacific 129 (980): 104203. doi:10.1088/1538-3873/aa7c9e. Bibcode: 2017PASP..129j4203P. 
  2. ↑ 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.  Gaia DR2 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 GR And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2018-10-17.
  4. ↑ 4.0 4.1 "GR And". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GR+And. 
  5. ↑ 5.0 5.1 5.2 Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E. et al. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues 2246: II/246. Bibcode: 2003yCat.2246....0C. http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=II/246. 
  6. ↑ Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  7. ↑ 7.0 7.1 7.2 7.3 Kochukhov, O.; Bagnulo, S. (2006). "Evolutionary state of magnetic chemically peculiar stars". Astronomy and Astrophysics 450 (2): 763. doi:10.1051/0004-6361:20054596. Bibcode: 2006A&A...450..763K. 
  8. ↑ 8.0 8.1 8.2 8.3 Catalano, F. A.; Leone, F. (June 1990). "Photoelectric photometry of chemically peculiar stars at the Catania astrophysical observatory. Observatory of HD 2453, HD 71866, HD 72968 and HD 126515.". Astronomy and Astrophysics Supplement Series 83: 491. Bibcode: 1990A&AS...83..491C. 
  9. ↑ 9.0 9.1 9.2 Soubiran, Caroline et al. (2016), "The PASTEL catalogue: 2016 version", Astronomy & Astrophysics 591: A118, doi:10.1051/0004-6361/201628497, Bibcode: 2016A&A...591A.118S. 



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