Astronomy:91 Aquarii

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Short description: Triple star system in the constellation Aquarius
This star is about ψ1 Aquarii. For other stars with this Bayer designation, see ψ Aquarii.

91 Aquarii
Location of ψ1 Aquarii (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  23h 15m 53.49405s[1]
Declination −09° 05′ 15.8450″[1]
Apparent magnitude (V) +4.248[2]
Characteristics
Spectral type K1 III[3]
U−B color index +1.035[2]
B−V color index +1.104[2]
R−I color index 0.56[4]
Astrometry
Radial velocity (Rv)−26.07±0.13[1] km/s
Proper motion (μ) RA: +369.477[1] mas/yr
Dec.: −16.981[1] mas/yr
Parallax (π)22.0924 ± 0.1302[1] mas
Distance147.6 ± 0.9 ly
(45.3 ± 0.3 pc)
Absolute magnitude (MV)0.919[5]
Details[6]
Mass0.774±0.150[6] M☉
1.004±0.175[6] M☉
1.4±0.1[7] M☉
1.76±0.21[8] M☉
Radius10.8±0.2 R☉
Luminosity48±3 L☉
Surface gravity (log g)2.32±0.11 cgs
Temperature4,631±69 K
Metallicity [Fe/H]−0.03±0.01 dex
Rotational velocity (v sin i)1.49±0.45[8] km/s
Age1.54±0.46[8] Gyr
3.56±0.63[7] Gyr
9.2±5.1[9] Gyr
Other designations
Psi1 Aquarii, ADS 16633, Gl 893.2, WDS J23159-0905
A: BD−09 6156, FK5 1608, HD 219449, HIP 114855, HR 8841, LTT 9437, SAO 146598
BC: BD−09 6155, HD 219430, LTT 9434, SAO 146596
Database references
SIMBADA
BC

91 Aquarii is a triple star[10] system in the equatorial constellation of Aquarius. It also bears the Bayer designation Psi1 Aquarii (Template:Bayer-blank, Template:Bayer-blank). It is visible to the naked eye with an apparent visual magnitude of +4.248.[2] Parallax measurements yield an estimated distance of around 150 light-years (46 parsecs) from Earth.[11] An extrasolar planet is known to orbit the main star.

Stellar system

91 Aquarii is a triple star system.[10] The primary component, 91 Aqr A, is a giant star with a stellar classification of K1 III.[3] 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 0.77 M☉[6] to 1.8 M☉,[8] while age ranges from 1.5[8] to 9 billion years.[9] It is radiating 48 times the Sun's luminosity from its outer envelope at an effective temperature of 4,630 K.[6] This gives it the orange-hued glow of a K-type star.[12]

The primary shares a common proper motion with two others stars, 91 Aqr B and C, suggesting that they are physically connected.[13] The latter pair form a binary system located at an angular separation of 52 arcseconds from the primary.[14] They are 10th magnitude stars separated by 0.3 arcseconds from each other.

Component Apparent magnitude (V) Spectral type
A 4.22 K0 III
B 9.62 K3 V
C 10.10

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.[15] However, it is listed as physically unconnected in the WDS catalogue[16] and the pair have a different proper motion than 91 Aquarii.[13] 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,[17] but its confirmation was not formally published until 2013.[7]

The 91 Aquarii planetary system[7]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b >3.2 MJ 0.70 181.4±0.1 0.027±0.026 — —

See also

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 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.
  2. ↑ 2.0 2.1 2.2 2.3 Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.", Monthly Notices of the Royal Astronomical Society 172 (3): 667–679, doi:10.1093/mnras/172.3.667, Bibcode: 1975MNRAS.172..667J. 
  3. ↑ 3.0 3.1 Baines, Ellyn K. et al. (2018), "Fundamental Parameters of 87 Stars from the Navy Precision Optical Interferometer", The Astronomical Journal 155 (1): 30, doi:10.3847/1538-3881/aa9d8b, Bibcode: 2018AJ....155...30B. 
  4. ↑ VizieR Detailed Page for HR 8841, http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%208841, retrieved November 28, 2009. 
  5. ↑ Liu, Y. J. et al. (2007), "The abundances of nearby red clump giants", Monthly Notices of the Royal Astronomical Society 382 (2): 553–66, doi:10.1111/j.1365-2966.2007.11852.x, Bibcode: 2007MNRAS.382..553L. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Soubiran, C.; Creevey, O. L.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera-Gómez, C. et al. (February 1, 2024), "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version", Astronomy and Astrophysics 682: A145, doi:10.1051/0004-6361/202347136, ISSN 0004-6361, Bibcode: 2024A&A...682A.145S  91 Aquarii's database entry at VizieR.
  7. ↑ 7.0 7.1 7.2 7.3 Mitchell, David S. et al. (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 555: A87, doi:10.1051/0004-6361/201321714, Bibcode: 2013A&A...555A..87M. 
  8. ↑ 8.0 8.1 8.2 8.3 8.4 Jofré, E.; Petrucci, R.; Saffe, C.; Saker, L.; Artur de la Villarmois, E.; Chavero, C.; Gómez, M.; Mauas, P. J. D. (February 1, 2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy and Astrophysics 574: A50, doi:10.1051/0004-6361/201424474, ISSN 0004-6361, Bibcode: 2015A&A...574A..50J 
  9. ↑ 9.0 9.1 Silva, J. Gomes da; Santos, N. C.; Adibekyan, V.; Sousa, S. G.; Campante, T. L.; Figueira, P.; Bossini, D.; Delgado-Mena, E. et al. (February 1, 2021). "Stellar chromospheric activity of 1674 FGK stars from the AMBRE-HARPS sample - I. A catalogue of homogeneous chromospheric activity" (in en). Astronomy & Astrophysics 646: A77. doi:10.1051/0004-6361/202039765. ISSN 0004-6361.  91 Aquarii's database entry at VizieR.
  10. ↑ 10.0 10.1 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. 
  11. ↑ van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V. 
  12. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved January 16, 2012. 
  13. ↑ 13.0 13.1 Roell, T.; Neuhäuser, R.; Seifahrt, A.; Mugrauer, M. (June 2012), "Extrasolar planets in stellar multiple systems", Astronomy & Astrophysics 542: A92, doi:10.1051/0004-6361/201118051, Bibcode: 2012A&A...542A..92R 
  14. ↑ Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram 4: 1, Bibcode: 1962MtSOM...4....1B. 
  15. ↑ "VizieR". http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J23159-0905A. 
  16. ↑ "WDS Identifier". January 31, 2009. http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe4.html. 
  17. ↑ Mitchell, D. S.; S. Frink; A. Quirrenbach; D. A. Fischer; G. W. Marcy; R. P. Butler (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 203: 17.03, Bibcode: 2003AAS...203.1703M. 

Coordinates: Sky map 23h 15m 53.49s, −09° 05′ 15.8″



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