HD 165189 and HD 165190

HD 165189 and HD 165190 are components of a visual binary star^[10] system located 143 light years away in the southern constellation of Corona Australis. It is visible to the naked eye with the primary having an apparent visual magnitude of 4.929±0.025. The system is a member of the Beta Pictoris Moving Group.^[14]

HD 165189

Observation data Epoch J2000      Equinox J2000
Constellation	Corona Australis
HD 165189
Right ascension	18h 06m 49.89293s[1]
Declination	−43° 25′ 30.8009″[1]
Apparent magnitude (V)	5.62±0.01[2]
HD 165190
Right ascension	18h 06m 49.91494s[3]
Declination	−43° 25′ 29.0976″[3]
Apparent magnitude (V)	5.68±0.01[2]
Characteristics
HD 165189
Spectral type	A6 V[4]
B−V color index	+0.230[5]
HD 165190
Spectral type	A7 V[4]
B−V color index	+0.262[5]
Astrometry
Radial velocity (Rv)	−7.8±0.4[6] km/s
Absolute magnitude (MV)	+1.81[7]
HD 165189
Proper motion (μ)	RA: +10.915 mas/yr[1] Dec.: −105.835 mas/yr[1]
Parallax (π)	22.7417 ± 0.1025 mas[1]
Distance	143.4 ± 0.6 ly (44.0 ± 0.2 pc)
HD 165190
Proper motion (μ)	RA: −1.187 mas/yr[3] Dec.: −101.243 mas/yr[3]
Parallax (π)	22.6753 ± 0.071 mas[3]
Distance	143.8 ± 0.5 ly (44.1 ± 0.1 pc)
Orbit[8][9]
Period (P)	607±245 yr
Semi-major axis (a)	4.63±1.83″
Eccentricity (e)	0.896±0.068
Inclination (i)	104±6°
Longitude of the node (Ω)	84.2±5.5°
Periastron epoch (T)	1854.7
Argument of periastron (ω) (secondary)	282±9°
Details
HD 165189
Mass	1.59[10] M☉
Radius	1.7[1] R☉
Luminosity	8.6[1] L☉
Surface gravity (log g)	4.25[11] cgs
Temperature	7,600[1] K
Metallicity [Fe/H]	−0.25[11] dex
Rotational velocity (v sin i)	130±1[12] km/s
HD 165190
Mass	1.58[10] M☉
Radius	1.7[3] R☉
Luminosity	8.2[3] L☉
Surface gravity (log g)	4.15[11] cgs
Temperature	7,566[3] K
Metallicity [Fe/H]	−0.24[11] dex
Rotational velocity (v sin i)	129±1[12] km/s
Age	813[3] Myr
Other designations
1 G. Coroane Australis, CD−43°12272, GC 24649, HIP 88726, CCDM J18068-4325, WDS J18068-4325[13]
HD 165189: HR 6749
HD 165190: HR 6750
Database references
SIMBAD	data
	HD 165189
	HD 165190

The pair orbit each other with a period of 450 years and a large eccentricity of 0.650.^[9] They have a projected separation of 70.1 AU.^[10] Both components are A-type main-sequence stars; the primary has a stellar classification of A6 V while the secondary is A7 V.^[14] They have similar masses of 1.59 and 1.58 times the mass of the Sun, respectively.^[10]

References

1. 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.
2. 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. S2CID 17128864.
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. Corbally, C. J. (August 1984). "Close visual binaries. I - MK classifications". The Astrophysical Journal Supplement Series. 55: 657. Bibcode:1984ApJS...55..657C. doi:10.1086/190973. eISSN 1538-4365. ISSN 0067-0049.
5. Myers, J. R.; Sande, C. B.; Miller, A. C.; Warren, W. H.; Tracewell, D. A. (2015). "VizieR Online Data Catalog: SKY2000 Master Catalog, Version 5 (Myers+ 2006)". Vizier Online Data Catalog. Bibcode:2015yCat.5145....0M.
6. Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35,495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. eISSN 1562-6873. ISSN 1063-7737. S2CID 119231169.
7. 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.
8. Izmailov, I. S. (January 2019). "The Orbits of 451 Wide Visual Double Stars". Astronomy Letters. 45 (1). Pleiades Publishing Ltd: 30–38. Bibcode:2019AstL...45...30I. doi:10.1134/s106377371901002x. ISSN 1063-7737. S2CID 149618866.
9. Alzner, A.; Argyle, R. (June 2001). "New orbits for WDS 05248-5219, WDS 18068-4325". IAU Commission 26. (Double Stars) Information Circular. 144: 1–2. Bibcode:2001IAUDS.144R...1A. S2CID 228383265.
10. Tokovinin, A.; Kiyaeva, O. (February 2016), "Eccentricity distribution of wide binaries", Monthly Notices of the Royal Astronomical Society, 456 (2): 2070–2079, arXiv:1512.00278, Bibcode:2016MNRAS.456.2070T, doi:10.1093/mnras/stv2825, S2CID 1615080.
11. Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. eISSN 1432-0746. ISSN 0004-6361. S2CID 131780028.
12. Díaz, C. G.; González, J. F.; Levato, H.; Grosso, M. (July 2011). "Accurate stellar rotational velocities using the Fourier transform of the cross correlation maximum". Astronomy & Astrophysics. 531: A143. arXiv:1012.4858. Bibcode:2011A&A...531A.143D. doi:10.1051/0004-6361/201016386. eISSN 1432-0746. ISSN 0004-6361. S2CID 119286673.
13. "CD-43 12272". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-07.
14. Bell, Cameron P. M.; et al. (November 2015), "A self-consistent, absolute isochronal age scale for young moving groups in the solar neighbourhood", Monthly Notices of the Royal Astronomical Society, 454 (1): 593–614, arXiv:1508.05955, Bibcode:2015MNRAS.454..593B, doi:10.1093/mnras/stv1981, S2CID 55297862.