Astronomy:Z Chamaeleontis

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Short description: Variable star in the constellation Chamaeleon
Not to be confused with Zeta Chamaeleontis.
Z Chamaeleontis
250px
A light curve for Z Chamaeleontis, adapted from Wood et al. (1986)[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Chamaeleon
Right ascension  08h 07m 27.7518s[2]
Declination −76° 32′ 00.665″[2]
Apparent magnitude (V) 11.5 - 16.2[3]
Characteristics
Spectral type DA? + M5.5e[4]
Variable type SU UMa + Algol[5]
Astrometry
Radial velocity (Rv)−20[6] km/s
Proper motion (μ) RA: −33.650[2] mas/yr
Dec.: +56.883[2] mas/yr
Parallax (π)8.2805 ± 0.074[2] mas
Distance394 ± 4 ly
(121 ± 1 pc)
Orbit[7]
Primarywhite dwarf
Companionred dwarf
Period (P)0.0744992631(3) days
(1.79 h)
Semi-major axis (a)0.734±0.005 R☉
Eccentricity (e)0[8]
Inclination (i)80.44±0.11°
Semi-amplitude (K1)
(primary)		78.4+1.1
−1.8 km/s
Semi-amplitude (K2)
(secondary)		413.2+2.5
−2.0 km/s
Details[7]
white dwarf
Mass0.803±0.014 M☉
Radius0.01046±0.00017 R☉
Surface gravity (log g)8.304±0.016 cgs
Temperature16,300±1,400 K
red dwarf
Mass0.152±0.005 M☉
Radius0.1820±0.0020 R☉
Other designations
Z Cha, 2E 1942, SBC9 505, CSV 1244, 2MASS J08072774-7632006, SON 4893, 2E 0808.8-7622, 1RXS J080728.8-763157, AAVSO 0809-76
Database references
SIMBADdata

Z Chamaeleontis (abbreviated Z Cha) is a dwarf nova variable star system approximately 394 light-years[2] away from the Sun, where two stars orbit each other every 1.78 hours. The system comprises an eclipsing white dwarf and red dwarf and possibly a yet unconfirmed third low-mass substellar companion.[9]

Z Chamaeleontis was discovered in 1904, during the work required to produce the Astrographic Catalogue. By 1905 a period of variability had been derived.[10] in 1969, George S. Mumford discovered that in addition to being a dwarf nova, the star is an eclipsing variable.[11]

Substellar companion

Dai et al. (2009) invoke the presence of a third object to explain orbital period variations with an apparent periodicity of roughly 28 years. The third body could yield a minimum mass 20 times greater than Jupiter and be located 9.9 Astronomical Units away from the dwarf nova, being likely a low-mass brown dwarf.

Possible makeup of the Z Chamaeleontis Star system.
The Z Chamaeleontis planetary system[9]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b (unconfirmed) ≥20 MJ 9.9 28 ≤0.2 — —

See also

References

  1. ↑ Wood, Janet; Horne, Keith; Berriman, Graham; Wade, R.; O'Donoghue, D.; Warner, B. (April 1986). "High-speed photometry of the dwarf nova Z Cha in quiescence". Monthly Notices of the Royal Astronomical Society 219 (3): 629–655. doi:10.1093/mnras/219.3.629. Bibcode: 1986MNRAS.219..629W. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 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.
  3. ↑ Watson, C. L.; Henden, A. A.; Price, A. (May 2006). "The International Variable Star Index (VSX)". Society for Astronomical Sciences Annual Symposium 25: 47. Bibcode: 2006SASS...25...47W. 
  4. ↑ Wade, Richard A.; Horne, Keith (January 1988). "The radial velocity curve and peculiar TiO distribution of the red secondary star in Z Chamaeleontis". The Astrophysical Journal 324: 411. doi:10.1086/165905. ISSN 0004-637X. Bibcode: 1988ApJ...324..411W. 
  5. ↑ Samus’, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (January 2017). "General catalogue of variable stars: Version GCVS 5.1". Astronomy Reports 61 (1): 80–88. doi:10.1134/S1063772917010085. ISSN 1063-7729. Bibcode: 2017ARep...61...80S. 
  6. ↑ Duflot, M.; Figon, P.; Meyssonnier, N. (December 1995). "Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.". Astronomy and Astrophysics Supplement Series 114: 269. ISSN 0365-0138. Bibcode: 1995A&AS..114..269D. 
  7. ↑ 7.0 7.1 McAllister, M; Littlefair, S P; Parsons, S G; Dhillon, V S; Marsh, T R; Gänsicke, B T; Breedt, E; Copperwheat, C et al. (2019-07-11). "The evolutionary status of Cataclysmic Variables: eclipse modelling of 15 systems" (in en). Monthly Notices of the Royal Astronomical Society 486 (4): 5535–5551. doi:10.1093/mnras/stz976. ISSN 0035-8711. 
  8. ↑ Marsh, T. R.; Horne, Keith; Shipman, H. L. (April 1987). "A spectrophotometric study of the emission lines in the quiescent dwarf nova Z Chamaeleontis". Monthly Notices of the Royal Astronomical Society 225 (3): 551–580. doi:10.1093/mnras/225.3.551. ISSN 0035-8711. Bibcode: 1988ApJ...324..411W. 
  9. ↑ 9.0 9.1 Dai; Qian, Shengbang; Lajús, Eduardo FernáNdez (26 August 2009). "Evidence of a Brown Dwarf in the Eclipsing Dwarf Nova Z Chamaeleonis". The Astrophysical Journal 703 (1): 109–113. doi:10.1088/0004-637X/703/1/109. Bibcode: 2009ApJ...703..109D. http://sedici.unlp.edu.ar/handle/10915/82785. 
  10. ↑ Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory 55: 1–94. Bibcode: 1907AnHar..55....1C. https://articles.adsabs.harvard.edu/pdf/1907AnHar..55....1C. Retrieved 26 January 2025. 
  11. ↑ Mumford, G. S. (March 1969). "Z Chameleontis". Information Bulletin on Variable Stars 337: 1. Bibcode: 1969IBVS..337....1M. https://ibvs.konkoly.hu/pub/ibvs/0301/0337.pdf. Retrieved 26 January 2025. 

Coordinates: Sky map 08h 07m 27.75s, −76° 32′ 00.7″




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