CN Andromedae

CN Andromedae (CN And) is an eclipsing binary star in the constellation Andromeda. Its maximum apparent visual magnitude is 9.62 and drops down to a minimum of 10.2 during the main eclipse. It's classified as a Beta Lyrae variable with a period roughly of 0.4628 days.[2]

CN Andromedae

Observation data Epoch J2000      Equinox J2000
Constellation	Andromeda
Right ascension	00^h 20^m 30.54209^s[1]
Declination	+40° 13′ 33.80342″[1]
Apparent magnitude (V)	9.62 – 10.21 variable [2]
Characteristics
Spectral type	F5V[2]
Apparent magnitude (B)	10.24[3]
Apparent magnitude (V)	9.706[3]
Apparent magnitude (G)	9.6637[1]
Apparent magnitude (J)	8.670[4]
Apparent magnitude (H)	8.452[4]
Apparent magnitude (K)	8.427[4]
B−V color index	0.49725[3]
Variable type	EB[2]
Astrometry
Radial velocity (Rv)	−24.2±1.0[5] km/s
Proper motion (μ)	RA: −8.549±0.054 [1] mas/yr Dec.: −35.291±0.024[1] mas/yr
Parallax (π)	4.9670 ± 0.0425[1] mas
Distance	657 ± 6 ly (201 ± 2 pc)
Orbit[5]
Period (P)	0.4627952±0.000035 days
Semi-major axis (a)	3.066±0.035
Inclination (i)	68.51±0.17°
Periastron epoch (T)	HJD 2445231.51710±0.00059
Details
Primary
Mass	1.433±0.030[6] M☉
Radius	1.48±0.03[6] R☉
Luminosity	3.40[6] L☉
Surface gravity (log g)	4.24[5] cgs
Temperature	6,450[6] K
Secondary
Mass	0.552±0.020[6] M☉
Radius	0.95[6] R☉
Luminosity	0.40[6] L☉
Surface gravity (log g)	4.22[5] cgs
Temperature	4,726[6] K
Other designations
2MASS J00203054+4013337, BD+39 59, TYC 2787-1815-1
Database references
SIMBAD	data

System

The two stars in this system orbit very close to each other; their spectrum cannot be separated and as a whole they have a spectrum of an F5V star. They are in marginal contact,[6] and there is a mass flow from the primary star to the secondary at a rate of 1.4 × 10⁻⁷ M_☉ yr⁻¹.[5] The binary orbit is slowly decaying at rate 1.5*10^-7 days/year. The third suspected component of the system is the red dwarf star with mass about 0.11 M_☉, at 38±4 years obit around binary. [7]

Variability

The light curve of CN Andromedae shows a primary eclipse, with its brightness dropping down to 10.21 magnitude, and a secondary one down to a magnitude of 9.9.[2] This phenomenon repeats with a cycle of approximately 11.1 hours, with period decreasing in time due to the mass transfer from one star to the another.[5]

References

1. Brown, 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. Gaia DR2 record for this source at VizieR.
2. CN 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. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy & Astrophysics, 355: L27–L30, Bibcode:2000A&A...355L..27H.
4. Cutri, R. M.; Skrutskie, M. F.; Van Dyk, S.; et al. (June 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.
5. Van Hamme, W.; Samec, R. G.; Gothard, N. W.; Wilson, R. E.; Faulkner, D. R.; Branly, R. M. (2001). "CN Andromedae: A Broken-Contact Binary?". The Astronomical Journal. 122 (6): 3436–3446. Bibcode:2001AJ....122.3436V. doi:10.1086/324110.
6. Siwak, M.; Zola, S.; Koziel-Wierzbowska, D. (2010). "A Study of Contact Binaries with Large Temperature Differences between Components". Acta Astronomica. 60 (4): 305–336. arXiv:1011.5682. Bibcode:2010AcA....60..305S.
7. Yildirim, Muhammed (2019). "CN Andromedae: a shallow contact binary with a possible tertiary component". National Astronomical Observatories. 19 (1): 10-1–10-10. doi:10.1088/1674-4527/19/1/10. Retrieved 17 December 2020.