91 Aquarii

Stellar system

91 Aquarii is a triple star system. The primary component, 91 Aqr A, is a giant star with a stellar classification of K1 III. This is an evolved star that has expanded to over 10 times the size of the Sun's size. Is mass and age are uncertain, mass estimates range from to , while age ranges from 1.5 to 9 billion years. It is radiating 48 times the Sun's luminosity from its outer envelope at an effective temperature of 4,630 K. This gives it the orange-hued glow of a K-type star.

The primary shares a common proper motion with two others stars, 91 Aqr B and C, suggesting that they are physically connected. The latter pair form a binary system located at an angular separation of 52 arcseconds from the primary. They are 10th magnitude stars separated by 0.3 arcseconds from each other.

Because it lies near the same line of sight, the binary star system CCDM J23159-0905DE was listed to belong to the 91 Aquarii system according to the CCDM catalogue. However, it is listed as physically unconnected in the WDS catalogue and the pair have a different proper motion than 91 Aquarii. CCDM J23159-0905DE has two components, the 13th magnitude CCDM J23159-0905D 80.4 arcseconds from 91 Aquarii, and the 14th magnitude CCDM J23159-0905E 19.7 arcseconds from 91 Aquarii.

Planetary system

In 2003, the discovery of an extrasolar planet orbiting 91 Aquarii A was announced, but its confirmation was not formally published until 2013.

References

References

1. "VizieR".
2. (January 31, 2009). "WDS Identifier".
3. {{cite DR3. 2630155547353593216
4. Silva, J. Gomes da. (February 1, 2021). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample - I. A catalogue of homogeneous chromospheric activity". [[Astronomy & Astrophysics]].
5. Jofré, E.. (February 1, 2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". [[Astronomy and Astrophysics]].
6. Soubiran, C.. (February 1, 2024). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version". [[Astronomy and Astrophysics]].
7. Mitchell, D. S.. (January 5, 2004). "Four Substellar Companions Found Around K Giant Stars". Bulletin of the American Astronomical Society, 35#5; AAS 203rd Meeting; Session 17 Extra Solar Planets.
8. van Leeuwen, F.. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics.
9. Buscombe, W.. (1962). "Spectral classification of Southern fundamental stars". Mount Stromlo Observatory Mimeogram.
10. (September 1975). "A new photometric metal abundance and luminosity calibration for field G and K giants.". [[Monthly Notices of the Royal Astronomical Society]].
11. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society.
12. (June 2012). "Extrasolar planets in stellar multiple systems". Astronomy & Astrophysics.
13. "VizieR Detailed Page for HR 8841".
14. (December 21, 2004). "The Colour of Stars". [[Commonwealth Scientific and Industrial Research Organisation]].
15. (2018). "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer". The Astronomical Journal.
16. (2013). "Precise radial velocities of giant stars. V. A brown dwarf and a planet orbiting the K giant stars τ Geminorum and 91 Aquarii". Astronomy and Astrophysics.