HD 93486

Last updated
HD 93486
RZChaLightCurve.png
A visual band light curve for RZ Chamaeleontis, plotted from data published by Jørgensen & Gyldenkerne (1975) [1]
Observation data
Epoch J2000.0        Equinox J2000.0 (ICRS)
Constellation Chamaeleon
Right ascension 10h 42m 24.10884s [2]
Declination −82° 02 14.1832 [2]
Apparent magnitude  (V)8.1 8.5 [3]
Characteristics
Spectral type F5 IV-V + F5 IV-V [4]
B−V color index +0.45 [5]
Variable type Algol [6]
Astrometry
Radial velocity (Rv)20±0.6 [7] km/s
Proper motion (μ)RA: −13.536 mas/yr [2]
Dec.: −45.153 mas/yr [2]
Parallax (π)5.7404±0.0186  mas [2]
Distance 568 ± 2  ly
(174.2 ± 0.6  pc)
Absolute magnitude  (MV)+1.72 [8] (combined)
Orbit [9]
PrimaryRZ Cha A
CompanionRZ Cha B
Period (P)2.8320896±0.0000013  d
Semi-major axis (a)0.05631 ± 0.00013 AU
Eccentricity (e)0.00
Inclination (i)83.292±0.006°
Semi-amplitude (K1)
(primary)
107.8±0.4 km/s
Semi-amplitude (K2)
(secondary)
108.2±0.4 km/s
Details [9]
RZ Cha A
Mass 1.488±0.011  M
Radius 2.1499±0.0058  R
Luminosity 7.9  L
Surface gravity (log g)3.9458±0.0018  cgs
Temperature 6,596±150  K
Rotational velocity (v sin i)38.41±0.10 km/s
Age 2.3  Gyr
RZ Cha B
Mass 1.482±0.011  M
Radius 2.2708±0.0058  R
Luminosity8.6  L
Surface gravity (log g)3.8967±0.0017  cgs
Temperature 6,564±150  K
Rotational velocity (v sin i)40.57±0.10 km/s
Age 2.3  Gyr
Other designations
RZ Cha, CD−81°391, CPD−81°467, GC 14785, HD 93486, HIP 52381, SAO 258590 [10]
Database references
SIMBAD data

HD 93486, also known as HIP 52381, is a binary star located in the southern circumpolar constellation Chamaeleon near the border with Octans. Its variable star designation is RZ Chamaeleontis (RZ Cha). It has an apparent magnitude ranging from 8.2 to 9.1, [6] which is below the limit for naked eye visibility. Gaia DR3 parallax measurements place the system 568 light years away, [2] and it is currently receding with a heliocentric radial velocity of 20  km/s . [7] At its current distance, HD 93486's average brightness is diminished by 0.53 magnitudes due to interstellar dust. [11] The system has a combined absolute magnitude of +1.72. [8]

In 1964, HD 93486 was discovered to be an eclipsing binary by astronomer W. Strohmeier and colleagues. [12] Four years later, the system was found to be an Algol variable [13] and was given the variable star designation RZ Chamaeleontis in 1974. [14] J. Andersen et al. (1975) calculated a circular orbit of 2.8321 days, [4] which is also its variability period. During this time, RZ Cha drops from photographic magnitude 8.2 to 9.1 when the smaller component is eclipsed, and to 8.8 when the larger one is eclipsed. [6]

Both components have a stellar classification of F5 IV-V, indicating that they are slightly evolved F-type stars with luminosity classes intermediate between a subgiant and a main-sequence star. The primary has 149% the mass of the Sun and 2.15 times the Sun's radius. The secondary has 148% the mass of the Sun and 2.27 times the radius of the Sun. [9] Together, both stars radiate 7.94 times the luminosity of the Sun [15] from their photospheres at an effective temperature of 6,450  K , giving it a combined yellowish-white hue. The system is metal enriched with an iron abundance and is estimated to be 2 to 3 billion years old. [16] Both stars spin modestly, with projected rotational velocities of 38.4  km/s and 40.6 km/s respectively. [9]

References

  1. Jørgensen, H. E.; Gyldenkerne, K. (November 1975). "Four-colour photometry of eclipsing binaries. II. RZ Cha, light curves, photometric elements and determination of helium content". Astronomy and Astrophysics. 44: 343–347. Bibcode:1975A&A....44..343J . Retrieved 16 February 2023.
  2. 1 2 3 4 5 6 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.
  3. Giuricin, G.; Mardirossian, F.; Mezzetti, M.; Predolin, F. (1980). "Revised photometric elements of the detached eclipsing binaries RS Cha, RZ Cha, HS Hya". Astronomy and Astrophysics. 85: 259. Bibcode:1980A&A....85..259G.
  4. 1 2 Andersen, J.; Gjerloff, H.; Imbert, M. (November 1975). "Spectroscopic observations of eclipsing binaries II: Absolute dimensions, evolutionary state, and helium content of RZ Chamaeleontis". Astronomy and Astrophysics. 44: 349-353. Bibcode:1975A&A....44..349A. ISSN   0004-6361.
  5. Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27 –L30. Bibcode:2000A&A...355L..27H. ISSN   0004-6361.
  6. 1 2 3 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. eISSN   1562-6881. ISSN   1063-7729. S2CID   125853869.
  7. 1 2 Pourbaix, D.; Tokovinin, A. A.; Batten, A. H.; Fekel, F. C.; Hartkopf, W. I.; Levato, H.; Morrell, N. I.; Torres, G.; Udry, S. (23 August 2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy & Astrophysics. 424 (2): 727–732. arXiv: astro-ph/0406573 . Bibcode:2004A&A...424..727P. doi: 10.1051/0004-6361:20041213 . eISSN   1432-0746. ISSN   0004-6361.
  8. 1 2 Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv: 1108.4971 . Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. eISSN   1562-6873. ISSN   1063-7737. S2CID   119257644.
  9. 1 2 3 4 Southworth, John (2025-04-23). "Rediscussion of eclipsing binaries. Paper XXIII. The F-type twin system RZ Chamaeleontis". The Observatory. arXiv: 2504.16817 .
  10. "RZ Cha". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved February 13, 2023.
  11. Gontcharov, George A.; Mosenkov, Aleksandr V. (28 September 2017). "Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars". Monthly Notices of the Royal Astronomical Society. 472 (4): 3805–3820. arXiv: 1709.01160 . Bibcode:2017MNRAS.472.3805G. doi: 10.1093/mnras/stx2219 . eISSN   1365-2966. ISSN   0035-8711.
  12. Strohmeier, W.; Knigge, R.; Ott, H. (September 1964). "Bright Southern BV-Stars". Information Bulletin on Variable Stars. 66: 1. Bibcode:1964IBVS...66....1S. ISSN   0374-0676.
  13. Strohmeier, W.; Mauder, H. (1969). "Discovery and study of bright variable stars". Sky and Telescope. 37 (1): 1. Bibcode:1969S&T....37a...1S. ISSN   0037-6604.
  14. Geyer, E. H.; Knigge, R. (October 1974). "Improved Light Elements for the Eclipsing Binaries RZ Cha, YZ Cha and DZ Mus". Information Bulletin on Variable Stars. 941: 1. Bibcode:1974IBVS..941....1G. ISSN   0374-0676.
  15. Malkov, O. Yu. (January 1993). "Catalogue of astrophysical parameters of binary systems". Bulletin d'Information du Centre de Donnees Stellaires. 42: 27. Bibcode:1993BICDS..42...27M. ISSN   1169-8837.
  16. Brown, Timothy M. (4 January 2010). "Radii of Rapidly Rotating Stars, with Application to Transiting-Planet Hosts". The Astrophysical Journal. 709 (1): 535–545. arXiv: 0912.1639 . Bibcode:2010ApJ...709..535B. doi: 10.1088/0004-637X/709/1/535 . eISSN   1538-4357. ISSN   0004-637X.

Further reading