Short description: Star in the constellation Aquarius
7 Aquarii, abbreviated 7 Aqr, is a binary star[3] system in the zodiac constellation of Aquarius. 7 Aquarii is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 5.5;[2] the brighter component is baseline magnitude 5.62 while the faint secondary is magnitude 11.4.[3] As of 2002, the pair had an angular separation of 2.10″ along a position angle of 165°.[10] The distance to this system, based upon an annual parallax shift of 4.9 mas,[1] is around 660 light years. It is moving closer to the Earth with a heliocentric radial velocity of −32 km/s.[7]
The primary component is an aging giant star with a stellar classification of K4 III.[4] It is a suspected variable star of unknown type with a maximum magnitude of 5.48.[6] The interferometry-measured angular diameter of this star, after correcting for limb darkening, is 2.14±0.02 mas,[11] which, at its estimated distance, equates to a physical radius of about 46 times the radius of the Sun.[8] The star is radiating 404[5] times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,990 K.[2]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.
- ↑ 2.0 2.1 2.2 2.3 2.4 2.5 McWilliam, Andrew (December 1990), "High-resolution spectroscopic survey of 671 GK giants. I. Stellar atmosphere parameters and abundances", Astrophysical Journal Supplement Series 74: 1075–1128, doi:10.1086/191527, Bibcode: 1990ApJS...74.1075M.
- ↑ 3.0 3.1 3.2 Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society 389 (2): 869–879, doi:10.1111/j.1365-2966.2008.13596.x, Bibcode: 2008MNRAS.389..869E.
- ↑ 4.0 4.1 Houk, Nancy; Smith-Moore, M. (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.
- ↑ 5.0 5.1 5.2 5.3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A.
- ↑ 6.0 6.1 Samus, N. N.; Kazarovets, E. V.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (2017), "General Catalogue of Variable Stars", Astronomy Reports, GCVS 5.1 61 (1): 80–88, doi:10.1134/S1063772917010085, Bibcode: 2017ARep...61...80S.
- ↑ 7.0 7.1 Gontcharov, G. A. (2006), "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system", Astronomy Letters 32 (11): 759–771, doi:10.1134/S1063773706110065, Bibcode: 2006AstL...32..759G.
- ↑ 8.0 8.1 Lang, Kenneth R. (2006), Astrophysical formulae, Astronomy and astrophysics library, 1 (3rd ed.), Birkhäuser, ISBN 3-540-29692-1, https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41. The radius (R*) is given by:
- [math]\displaystyle{ \begin{align} 2\cdot R_*
& = \frac{(10^{-3}\cdot 202\cdot 2.14)\ \text{AU}}{0.0046491\ \text{AU}/R_{\bigodot}} \\
& \approx 93\cdot R_{\bigodot}
\end{align} }[/math]
- ↑ "7 Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=7+Aqr.
- ↑ Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M.
- ↑ Richichi, A. et al. (February 2005), "CHARM2: An updated Catalog of High Angular Resolution Measurements", Astronomy and Astrophysics 431 (2): 773–777, doi:10.1051/0004-6361:20042039, Bibcode: 2005A&A...431..773R.
External links
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