Astronomy:HD 224801

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Short description: Alpha2 Canum Venaticorum variable star in the constellation of Andromeda
HD 224801
Observation data
Equinox J2000.0]] (ICRS)
Constellation Andromeda
Right ascension  00h 00m 43.6345s[1]
Declination +45° 15′ 12.007″[1]
Apparent magnitude (V) 6.32 – 6.42[2]
Characteristics
Spectral type A0IIspSiSrHg[3]
Apparent magnitude (B) 6.299[4]
Apparent magnitude (V) 6.347[4]
Apparent magnitude (G) 6.333[1]
Apparent magnitude (J) 6.407[5]
Apparent magnitude (H) 6.506[5]
Apparent magnitude (K) 6.511[5]
U−B color index -0.35[6]
B−V color index -0.0425[4]
Variable type Alpha² CVn[7]
Astrometry
Radial velocity (Rv)−1.00±2.2[8] km/s
Proper motion (μ) RA: +17.745[1] mas/yr
Dec.: +0.607[1] mas/yr
Parallax (π)5.5784 ± 0.0405[1] mas
Distance585 ± 4 ly
(179 ± 1 pc)
Absolute magnitude (MV)0.0[9]
Details
Mass3.4[1] M☉
Radius2.8[1] R☉
Luminosity170[1] L☉
Surface gravity (log g)4.12[1] cgs
Temperature11,900[10] K
Metallicity [Fe/H]0.98[9] dex
Rotation3.74[10] days
Rotational velocity (v sin i)30[6] km/s
Age239[11] Myr
Other designations
CG Andromedae, BD+44° 4538, HD 224801, HIP 63, HR 9080, SAO 53568, PPM 42458, TYC 3246-2388-1.
Database references
SIMBADdata

HD 224801, also known as CG Andromedae, is an Alpha2 Canum Venaticorum variable star in the constellation Andromeda. Located approximately 188 parsecs (610 ly) away, the star varies between apparent magnitudes 6.32 and 6.42 over a period of approximately 3.74 days.

Spectrum

CG Andromedae is also a chemically peculiar star with a strong magnetic field, or Ap star, with a spectral type A0IIspSiSrHg. This means that it's a bright giant star that shows narrow absorption lines and unusual strong lines of silicium, strontium and mercury. Calcium and manganese lines are weaker than expected instead.[3] Other sources report that the stronger lines are of silicium and europium, thus giving a spectral classification B9pSiEu, which has just a slightly different temperature for the blackbody emission in addition to the different lines.[2]

Variability

Like in Alpha2 Canum Venaticorum variable stars, CG Andromedae shows a variation of luminosity and one in the strength of spectral lines with the same period of approximately 3.74 days.[7] It is thought that this is caused by an inhomogeneous distribution of elements on the surface of the star, which cause an inhomogeneous surface brightness.

A shorter period, slightly longer than 2 hours, with an amplitude of 0.011 magnitudes has been observed in the light curve of CG Andromedae; however, with a temperature of 11,000 K, it lies outside the instability strip of the HR diagram where rapidly oscillating Ap stars are located. Magnetohydrodynamic waves propagating in the star could explain the observed variability.[3]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 CG 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.
  3. ↑ 3.0 3.1 3.2 Abt, H. A.; Morrell, N. A. (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. 
  4. ↑ 4.0 4.1 4.2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy & Astrophysics 355: L27–L30. Bibcode: 2000A&A...355L..27H. 
  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. ↑ 6.0 6.1 Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HgMn and Am stars". Astronomy and Astrophysics 498 (3): 961–966. doi:10.1051/0004-6361/200810788. Bibcode: 2009A&A...498..961R. 
  7. ↑ 7.0 7.1 VSX (4 January 2010). "CG Andromedae". AAVSO Website. American Association of Variable Star Observers. http://www.aavso.org/vsx/index.php?view=detail.top&oid=108. 
  8. ↑ 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. 
  9. ↑ 9.0 9.1 Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters 38 (5): 331. doi:10.1134/S1063773712050015. Bibcode: 2012AstL...38..331A. 
  10. ↑ 10.0 10.1 Shultz, M. E.; Owocki, S. P.; Ud-Doula, A.; Biswas, A.; Bohlender, D.; Chandra, P.; Das, B.; David-Uraz, A. et al. (2022). "MOBSTER - VI. The crucial influence of rotation on the radio magnetospheres of hot stars". Monthly Notices of the Royal Astronomical Society 513 (1): 1429. doi:10.1093/mnras/stac136. Bibcode: 2022MNRAS.513.1429S. 
  11. ↑ Gontcharov, G. A. (December 2012). "Dependence of kinematics on the age of stars in the solar neighborhood". Astronomy Letters 38 (12): 771–782. doi:10.1134/S1063773712120031. ISSN 0320-0108. Bibcode: 2012AstL...38..771G. 



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