74 Aquarii
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22h 53m 28.70347s[1] |
| Declination | –11° 36′ 59.4532″[1] |
| Apparent magnitude (V) | 5.791[2] |
| Characteristics | |
| Spectral type | B8IV/V[3] |
| U−B color index | –0.245[2] |
| B−V color index | –0.082[2] |
| Variable type | a2 CVn[4] |
| Astrometry | |
| Proper motion (μ) | RA: +20.81[1] mas/yr Dec.: +1.69[1] mas/yr |
| Parallax (π) | 4.96 ± 0.84[1] mas |
| Distance | approx. 700 ly (approx. 200 pc) |
| Details | |
| Rotational velocity (v sin i) | 20[5] km/s |
| Other designations | |
74 Aquarii (abbreviated 74 Aqr) is a triple star[6] 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[2] and it is located at a distance of 700 light-years (210 parsecs) from Earth.[1]
The inner pair of stars form a double-lined spectroscopic binary, where the presence of both components is revealed from the Doppler shift of their spectral lines. They have an orbital period of 3.4298 days. A third component is orbiting the inner pair with an 18 year period at a typical angular separation of 0.078 arcseconds. 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 AU.[6]
References
- 1 2 3 4 5 6 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv:0708.1752
, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. - 1 2 3 4 Gutierrez-Moreno, Adelina; et al. (1966), A System of photometric standards, 1, Publicaciones Universidad de Chile, Department de Astronomy, pp. 1–17, Bibcode:1966PDAUC...1....1G.
- ↑ 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.
- 1 2 "HI Aqr -- Variable Star of alpha2 CVn type", SIMBAD Astronomical Object Database, Centre de Données astronomiques de Strasbourg, retrieved 2012-07-01.
- ↑ Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal, 573 (1): 359–365, Bibcode:2002ApJ...573..359A, doi:10.1086/340590.
- 1 2 Schöller, M.; et al. (November 2010), "Multiplicity of late-type B stars with HgMn peculiarity", Astronomy and Astrophysics, 522: A85, arXiv:1010.3643, Bibcode:2010A&A...522A..85S, doi:10.1051/0004-6361/201014246.