Z Chamaeleontis

Not to be confused with Zeta Chamaeleontis.

Z Chamaeleontis

A light curve for Z Chamaeleontis, adapted from Wood et al. (1986)[1]
Observation data Epoch J2000      Equinox ICRS
Constellation	Chamaeleon
Right ascension	08^h 07^m 27.7518^s[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 mas/yr[2] Dec.: +56.883 mas/yr[2]
Parallax (π)	8.2805±0.074 mas[2]
Distance	394 ± 4 ly (121 ± 1 pc)
Orbit[7]
Primary	white dwarf
Name	red 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
Mass	0.803±0.014 M☉
Radius	0.01046±0.00017 R☉
Surface gravity (log g)	8.304±0.016 cgs
Temperature	16,300±1,400 K
red dwarf
Mass	0.152±0.005 M☉
Radius	0.1820±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
SIMBAD	data

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

• HW Virginis
• NN Serpentis
• OY Carinae

References

1. Otulakowska-Hypka, Magdalena; Olech, Arkadiusz; Patterson, Joseph (12 May 2016). "Statistical analysis of properties of dwarf novae outbursts". Monthly Notices of the Royal Astronomical Society. 460 (3): 2526–2541. arXiv:1605.02937. Bibcode:2016MNRAS.460.2526O. doi:10.1093/mnras/stw1120. eISSN 1365-2966. ISSN 0035-8711. Cite error: A list-defined reference named "OH2016" is not used in the content (see the help page).
2. 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. Bibcode:1986MNRAS.219..629W. doi:10.1093/mnras/219.3.629.
3. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
4. 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.
5. 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. Bibcode:1988ApJ...324..411W. doi:10.1086/165905. eISSN 1538-4357. ISSN 0004-637X.
6. 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. Bibcode:2017ARep...61...80S. doi:10.1134/S1063772917010085. ISSN 1063-7729. S2CID 255195566.
7. 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. Bibcode:1995A&AS..114..269D. ISSN 0365-0138.
8. McAllister, M; Littlefair, S P; Parsons, S G; Dhillon, V S; Marsh, T R; Gänsicke, B T; Breedt, E; Copperwheat, C; Green, M J; Knigge, C; Sahman, D I; Dyer, Martin J; Kerry, P; Ashley, R P; Irawati, P (2019-07-11). "The evolutionary status of Cataclysmic Variables: eclipse modelling of 15 systems". Monthly Notices of the Royal Astronomical Society. 486 (4): 5535–5551. arXiv:1904.01888. doi:10.1093/mnras/stz976. ISSN 0035-8711.
9. 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. Bibcode:1988ApJ...324..411W. doi:10.1093/mnras/225.3.551. eISSN 1365-2966. ISSN 0035-8711.
10. 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. Bibcode:2009ApJ...703..109D. doi:10.1088/0004-637X/703/1/109.
11. Cannon, Annie J. (1907). "Second catalogue of variable stars". Annals of Harvard College Observatory. 55: 1–94. Bibcode:1907AnHar..55....1C. Retrieved 26 January 2025.
12. Mumford, G. S. (March 1969). "Z Chameleontis" (PDF). Information Bulletin on Variable Stars. 337: 1. Bibcode:1969IBVS..337....1M. Retrieved 26 January 2025.