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CH Cygni

Not to be confused with Chi Cygni.
CH Cygni
Location of CH Cygni (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 24m 33.06773s[1]
Declination +50° 14′ 29.1263″[1]
Apparent magnitude (V) 5.60 – 8.49[2]
Characteristics
Spectral type M7IIIab + Be[3]
Variable type Z And and SR[2]
Astrometry
Radial velocity (Rv)−59.74[4] km/s
Proper motion (μ) RA: −7.09[1] mas/yr
Dec.: −59.74[1] mas/yr
Parallax (π)5.4642 ± 0.2172 mas[5]
Distance600 ± 20 ly
(183 ± 7 pc)
Orbit[6]
Period (P)15.58±0.13 yr
Semi-major axis (a)8.5 AU
Eccentricity (e)0.122±0.024
Inclination (i)84°
Semi-amplitude (K1)
(primary)		4.45±0.12 km/s
Details[6]
Red giant
Mass2 M☉
Radius280 R☉
Luminosity5012 L☉
Temperature3,100 K
White dwarf
Mass0.7 M☉
Luminosity0.25 L☉
Other designations
HD 182917, BD+49°2999, HIP 95413, SAO 31632
Database references
SIMBADdata

CH Cygni (CH Cyg / HIP 95413 / BD +49 2999) is a red giant, variable, symbiotic binary in the constellation Cygnus. It is the nearest symbiotic star to Earth, and one of the brightest, making it an ideal candidate for study.

Properties

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CH Cygni has a mass of 2 M☉ and a radius of 280 R☉. Its white-dwarf companion has a mass of 0.75 M☉, and the orbital period of the two stars is 5689 days.[6] CH Cygni is classified as M7IIIab + Be.[3]

Observation history

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A blue band light curve for CH Cygni, adapted from Wallerstein et al. (2010)[7]

The earliest observations of CH Cygni were made in 1890 by Pickering and Wendel using wedge photometer, and was classified as a M6III variable star in 1924.[8] In 1963 strong H I emissions were observed, indicating CH Cygni was likely in a symbiotic relationship with a white dwarf. Similar emissions were observed in 1965, 1967, 1977, 1992, and 1998.[9] The system was briefly thought to contain a third star[10] but this was later disproved.[6]

In 1984 bipolar jets were detected coming from CH Cygni, which were suspected to be due to accretion from its companion star.[9][8] The luminosity of the system decreased significantly in 1986, likely owing to dust thrown out of the system by the jets or a concurrent helium flash. This dust had dissipated by 2002, with subsequent luminosities returning to pre-1985 levels.[3]

References

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  1. ^ a b c d van Leeuwen, F. (13 August 2007). "Validation of the new Hipparcos reduction". Astronomy & Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ a b Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ a b c Shenavrin, V. I; Taranova, O. G; Nadzhip, A. E (2011). "Search for and study of hot circumstellar dust envelopes". Astronomy Reports. 55 (1): 31–81. Bibcode:2011ARep...55...31S. doi:10.1134/S1063772911010070. S2CID 122700080.
  4. ^ Famaey, B.; Pourbaix, D.; Frankowski, A.; Van Eck, S.; Mayor, M.; Udry, S.; Jorissen, A. (18 February 2009). "Spectroscopic binaries among Hipparcos M giants". Astronomy & Astrophysics. 498 (2): 627–640. arXiv:0901.0934. Bibcode:2009A&A...498..627F. doi:10.1051/0004-6361/200810698. S2CID 18739721.
  5. ^ 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.
  6. ^ a b c d Hinkle, Kenneth H; Fekel, Francis C; Joyce, Richard R (2009). "Infrared Spectroscopy of Symbiotic Stars. Vii. Binary Orbit and Long Secondary Period Variability of Ch Cygni". The Astrophysical Journal. 692 (2): 1360. arXiv:0811.0631. Bibcode:2009ApJ...692.1360H. doi:10.1088/0004-637X/692/2/1360. S2CID 14500048.
  7. ^ Wallerstein, George; Munari, U.; Siviero, A.; Dallaporta, S.; Dalmeri, I. (January 2010). "The Spectrum and Light Curve of CH Cygni during its Recent Broad Minimum". Publications of the Astronomical Society of the Pacific. 122 (887): 12–16. Bibcode:2010PASP..122...12W. doi:10.1086/648563. S2CID 120765815.
  8. ^ a b Mikołajewski, M.; Mikołajewska, J.; Khudiakova, T.N. (August 1990). "A long-period symbiotic binary CH Cygni. I - A hundred years' history of variability". Astronomy and Astrophysics. 235 (1–2): 219–233. Bibcode:1990A&A...235..219M. ISSN 0004-6361.
  9. ^ a b Burmeister, M.; Leedjärv, L. (9 July 2009). "Spectroscopy of the symbiotic binary CH Cygni from 1996 to 2007". Astronomy & Astrophysics. 504 (1): 171–180. arXiv:0907.2017. Bibcode:2009A&A...504..171B. doi:10.1051/0004-6361/200911686. S2CID 2498584.
  10. ^ Hinkle, Kenneth H.; Fekel, Francis C.; Johnson, Diana S.; Scharlach, Werner W. G. (March 1993). "The triple symbiotic system CH Cygni". The Astronomical Journal. 105: 1074. Bibcode:1993AJ....105.1074H. doi:10.1086/116494.