CG Andromedae ( lat. CG Andromedae ) is a variable star of the type α² Hounds of Dogs in the constellation Andromeda . The star is located at a distance of about 188 pc (610 light years), the apparent magnitude varies from 6.32 to 6.42 with a period of about 3.74 days.
| CG Andromeda | |||
|---|---|---|---|
| Star | |||
| Observational data ( Age J2000.0 ) | |||
| Right ascension | |||
| Declination | |||
| Distance | 614 St. years (188 pc ) | ||
| Visible magnitude ( V ) | 6.32 - 6.42 [2] | ||
| Constellation | Andromeda | ||
| Astrometry | |||
| Radial velocity ( R v ) | −1.00 ± 2.2 [3] km / s | ||
| Own movement (μ) | RA: 17.683 ± 0.099 [1] Dec: 0.919 ± 0.065 [1] | ||
| Parallax (π) | 5.3162 ± 0.0768 [1] mas | ||
| Characteristics | |||
| Spectral class | A0IIspSiSrHg [5] | ||
| Color Index ( B - V ) | -0.0425 [6] | ||
| Color Index ( U - B ) | -0.35 [7] | ||
| Variability | α² CVn [8] | ||
| physical characteristics | |||
| Temperature | 11000 [5] K | ||
| Metallicity | |||
| Rotation | 30 km / s [7] | ||
| |||
| Database Information | |||
| SIMBAD | data | ||
Spectrum
CG Andromeda is a chemically peculiar star with a strong magnetic field, or an Ap star of spectral class A0IIspSiSrHg. This means that the star is a bright giant with narrow absorption lines and unusually strong lines of silicon, strontium and mercury. The calcium and magnesium lines are weaker than expected. [5] Other sources report that the lines of silicon and europium are quite strong, so the star can be attributed to the class B9pSiEu, which has a slightly different temperature in addition to other spectral lines. [2]
Variability
Like other variables such as α² Hounds Dogs, CG Andromeda exhibits variability in luminosity and power of spectral lines with the same period of 3.74 days. [8] It is believed that the reason for this is the uneven distribution of elements on the surface of the star, which gives an uneven surface brightness .
A shorter period, slightly more than 2 hours, with an amplitude of about 0.011 magnitude, is observed on the CG Andromeda light curve; however, at a temperature of 11000 K, it lies outside the instability band of the Hertzsprung-Russell diagram , where rapidly oscillating Ap stars are located . Magnetohydrodynamic waves propagating in a star can explain the observed variability. [5]
Notes
- ↑ 1 2 3 4 5 vizier.u-strasbg.fr .
- ↑ 1 2 CG And , database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), NN Samus, OV Durlevich, et al., CDS ID II / 250 Accessed on line 2018-10-17.
- ↑ Gontcharov, GA Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system (Eng.) // Astronomy Letters: journal. - 2006 .-- November ( vol. 32 , no. 11 ). - P. 759-771 . - DOI : 10.1134 / S1063773706110065 . - . - arXiv : 1606.08053 .
- ↑ 1 2 3 4 Collaboration G. Gaia DR2 - 2018 .-- Vol. 1345.
- ↑ 1 2 3 4 Abt, HA; Morrell, NA The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars (Eng.) // Astrophysical Journal Supplement: journal. - 1995. - Vol. 99 . - P. 135 . - DOI : 10.1086 / 192182 . - .
- ↑ Høg, E .; Fabricius, C .; Makarov, VV & Urban, S. (2000), "The Tycho-2 catalog of the 2.5 million brightest stars", Astronomy & Astrophysics T. 355: L27-L30
- ↑ 1 2 Renson, P .; Manfroid, J. Catalog of Ap, HgMn and Am stars (Eng.) // Astronomy and Astrophysics. - 2009. - Vol. 498 , no. 3 . - P. 961-966 . - .
- ↑ 1 2 VSX. CG Andromedae . AAVSO Website . American Association of Variable Star Observers (January 4, 2010). Date of treatment October 9, 2014.
- ↑ M. Koleva, A. Vazdekis Stellar population models in the UV // Astron. Astrophys. - EDP Sciences , 2012. - Vol. 538.- P. A143. - ISSN 0004-6361 ; 0365-0138 ; 1432-0746 ; 1286-4846 - doi: 10.1051 / 0004-6361 / 201118065