Astronomy:91 Aquarii

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Short description: Triple star system in the constellation Aquarius
91 Aquarii
Aquarius constellation map.svg
Red circle.svg
Location of ψ1 Aquarii (circled)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Aquarius
Right ascension  23h 15m 53.49482s[1]
Declination –9° 05′ 15.8546″[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)−25.49±0.74[5] km/s
Proper motion (μ) RA: +368.78[1] mas/yr
Dec.: –17.16[1] mas/yr
Parallax (π)21.77 ± 0.29[1] mas
Distance150 ± 2 ly
(45.9 ± 0.6 pc)
Absolute magnitude (MV)0.919[6]
Details
Mass1.38±0.29[3] M☉
Radius10.96±0.21[3] R☉
Luminosity54.3±3.1[3] L☉
Surface gravity (log g)2.6[5] cgs
Temperature4730±68[3] K
Metallicity [Fe/H]–0.14[5] dex
Rotational velocity (v sin i)2.9[5] km/s
Age2.98±1.63[3] 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 the Flamsteed designation for a triple star[7] 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.[1] An extrasolar planet is known to orbit the main star.

Stellar system

91 Aquarii is a triple star system.[7] The primary component, 91 Aqr A, is a giant star with a stellar classification of K1 III.[3] This is an evolved star with 138% of the Sun's mass that has expanded to over 10 times the size of the Sun.[3] It is radiating 54[3] times the Sun's luminosity from its outer envelope at an effective temperature of 4,730 K.[3] This gives it the orange-hued glow of a K-type star.[8]

The primary shares a common proper motion with two others stars, 91 Aqr B and C, suggesting that they are physically connected.[9] The latter pair form a binary system located at an angular separation of 52 arcseconds from the primary.[10] 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.[11] However, it is listed as physically unconnected in the WDS catalogue[12] and the pair have a different proper motion than 91 Aquarii.[9] 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,[13] but its confirmation was not formally published until 2013.[14]

The 91 Aquarii planetary system[14]
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 1.5 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. 
  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 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 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 2009-11-28. 
  5. ↑ 5.0 5.1 5.2 5.3 Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M. 
  6. ↑ 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. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ "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 2012-01-16. 
  9. ↑ 9.0 9.1 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 
  10. ↑ Buscombe, W. (1962), "Spectral classification of Southern fundamental stars", Mount Stromlo Observatory Mimeogram 4: 1, Bibcode: 1962MtSOM...4....1B. 
  11. ↑ "VizieR". http://vizier.u-strasbg.fr/viz-bin/VizieR-S?CCDM%20J23159-0905A. 
  12. ↑ https://web.archive.org/web/20090131051103/http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe4.html
  13. ↑ Mitchell, D. S.; S. Frink; A. Quirrenbach; D. A. Fischer; G. W. Marcy; R. P. Butler (2004-01-05), "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. 
  14. ↑ 14.0 14.1 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. 

External links

Coordinates: Sky map 23h 15m 53.5s, −09° 05′ 16″



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