Astronomy:74 Aquarii

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Short description: Triple star system in the constellation Aquarius
74 Aquarii
250px
A light curve for HI Aquarii, plotted from TESS data[1]
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  22h 53m 28.70492s[2]
Declination −11° 36′ 59.4532″[2]
Apparent magnitude (V) 5.8[3]
Characteristics
Spectral type B8IV/V[4] (B9pHgMn)[3])
U−B color index −0.245[5]
B−V color index −0.082[5]
Variable type a2 CVn[3]
Astrometry
Proper motion (μ) RA: +21.539[2] mas/yr
Dec.: +2.282[2] mas/yr
Parallax (π)5.5008 ± 0.6556[2] mas
Distanceapprox. 590 ly
(approx. 180 pc)
Absolute magnitude (MV)−1.19[6]
Orbit[7]
Primary74 Aquarii A
Companion74 Aquarii B
Period (P)9.479±0.044 yr
Semi-major axis (a)0.0460±0.0061″
Eccentricity (e)0.862±0.029
Inclination (i)29.8±17.4°
Longitude of the node (Ω)40.9±20.3°
Periastron epoch (T)2010.039±0.134
Argument of periastron (ω)
(secondary)		70.7±16.1°
Orbit[8]
Primary74 Aquarii Aa
Companion74 Aquarii Ab
Period (P)3.429616±0.000004 d
Eccentricity (e)0.05±0.02
Periastron epoch (T)2452909.150±0.007 JD
Argument of periastron (ω)
(secondary)		86.5±0.8°
Semi-amplitude (K1)
(primary)		95±2 km/s
Semi-amplitude (K2)
(secondary)		113±2 km/s
Details
Aa
Mass2.72[9] M☉
Rotational velocity (v sin i)20[10] km/s
Ab
Mass2.53[9] M☉
B
Mass3.11[9] M☉
Other designations
HI Aqr, BD−12 6371, HD 216494, HIP 113031, HR 8704, SAO 165359[11]
Database references
SIMBADdata

74 Aquarii (abbreviated 74 Aqr) is a triple star[12] system in the constellation of Aquarius. 74 Aquarii is its Flamsteed designation and it also bears the variable star designation HI Aquarii. The combined apparent visual magnitude is 5.8,[5] although it is very slightly variable,[3] and it is located at a distance of 590 light-years (180 parsecs) from Earth.

Jean Manfroid and Gautier Mathys reported that 74 Aquarii is a variable star in 1985.[13] Based on that result it was given its variable star designation in 1987.[14]

Visual binary

74 Aquarii is a double star with the two components separated by about 0.1″.[15] The two components are referred to as A and B or AB and C in different publications.[7][8] The pair form a binary with a period of 9.5 years at a typical angular separation of 0.046″, but the orbit is highly eccentric.[7] In 2010, this component was at an angular separation of 0.069 arcseconds along a position angle of 285.9°. This is equivalent to a projected separation of 13.9±2.4 astronomical unit|AU.[12]

Spectroscopic binary

The primary star of the visual pair is a double-lined spectroscopic binary, where the presence of both components is revealed from the Doppler shift of their spectral lines, meaning 74 Aquarii is a triple system. The spectroscopic binary was discovered and the orbit calculated by Richard J. Wolff of the University of Hawaii in 1974.[16] A refined orbit was calculated in 2004 by Italian astronomers Giovanni Catanzaro and Paolo Leto. The orbital period is 3.4 days and the orbit is nearly circular.[8]

Components

The three stars have a combined spectral type of B8 or B9 and all three are thought to be similar. It is unclear whether the stars are on the main sequence, subgiants, or giant stars.[9][17][4] The two visual components are both chemically peculiar stars, the brighter of the two being a mercury-manganese star and the fainter an Ap/Bp star with an excess of mercury.[15] 74 Aquarii is an α2 CVn variable star, with a total amplitude of just 0.01 magnitudes,[3] and a period of 3.5892 days.[18]

References

  1. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  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. ↑ 3.0 3.1 3.2 3.3 3.4 Samus, N. N. 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: B/GCVS, Bibcode: 2009yCat....102025S. 
  4. ↑ 4.0 4.1 Houk, Nancy (1978), Michigan catalogue of two-dimensional spectral types for the HD stars, 4, Ann Arbor: Dept. of Astronomy, University of Michigan, Bibcode: 1988mcts.book.....H. 
  5. ↑ 5.0 5.1 5.2 Gutierrez-Moreno, Adelina et al. (1966), "A System of photometric standards", Publications of the Department of Astronomy University of Chile (Publicaciones Universidad de Chile, Department de Astronomy) 1: 1–17, Bibcode: 1966PDAUC...1....1G. 
  6. ↑ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  7. ↑ 7.0 7.1 7.2 Tokovinin, Andrei (2017), "New Orbits Based on Speckle Interferometry at SOAR. II", The Astronomical Journal 154 (3): 110, doi:10.3847/1538-3881/aa8459, Bibcode: 2017AJ....154..110T. 
  8. ↑ 8.0 8.1 8.2 Catanzaro, G.; Leto, P. (2004), "Orbital solutions for SB2 systems with a HgMn component", Astronomy and Astrophysics 416 (2): 661–668, doi:10.1051/0004-6361:20034445, Bibcode: 2004A&A...416..661C. 
  9. ↑ 9.0 9.1 9.2 9.3 Tokovinin, Andrei (2018-03-01), "The Updated Multiple Star Catalog", The Astrophysical Journal Supplement Series 235 (1): 6, doi:10.3847/1538-4365/aaa1a5, ISSN 0067-0049, Bibcode: 2018ApJS..235....6T. 
  10. ↑ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, doi:10.1086/340590, Bibcode: 2002ApJ...573..359A. 
  11. ↑ "* 74 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=%2A+74+Aqr. 
  12. ↑ 12.0 12.1 Schöller, M. et al. (November 2010), "Multiplicity of late-type B stars with HgMn peculiarity", Astronomy and Astrophysics 522: A85, doi:10.1051/0004-6361/201014246, Bibcode: 2010A&A...522A..85S. 
  13. ↑ Manfroid, J.; Mathys, G. (March 1985). "New period determinations for variable CP stars". Astronomy and Astrophysics Supplement Series 59: 429–432. Bibcode: 1985A&AS...59..429M. https://articles.adsabs.harvard.edu/pdf/1985A%26AS...59..429M. Retrieved 19 November 2024. 
  14. ↑ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Kireeva, N.N. (August 1987). "The 68th Name-List of Variable Stars". Information Bulletin on Variable Stars 3058: 1–30. Bibcode: 1987IBVS.3058....1K. https://ibvs.konkoly.hu/pub/ibvs/3001/3058.pdf. Retrieved 19 November 2024. 
  15. ↑ 15.0 15.1 Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics 498 (3): 961–966, doi:10.1051/0004-6361/200810788, Bibcode: 2009A&A...498..961R. 
  16. ↑ Wolff, Richard J (1974), "Orbit of the Manganese Star HR 8704", Publications of the Astronomical Society of the Pacific 86 (510): 173–175, doi:10.1086/129576, Bibcode: 1974PASP...86..173W. 
  17. ↑ Skiff, B. A. (2014), "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009- )", VizieR On-line Data Catalog, Bibcode: 2014yCat....1.2023S. 
  18. ↑ "HI Aqr". AAVSO. https://www.aavso.org/vsx/index.php?view=detail.top&oid=1055. 



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