91 Aquarii
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91 Aquarii, also known as Psi1 Aquarii (ψ1 Aqr, ψ1 Aquarii), is the brightest star in a triple star system approximately 148 light-years away in the constellation of Aquarius. The system comprises three stars of which a fainter binary component is known under the name HD 219430. The primary star 91 Aqr is an orange giant star, around which an extrasolar planet is known to orbit with a mean distance from the central star slightly shorter than from Mercury to our Sun.
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[edit] Star system
The primary star, 91 Aquarii, is an orange giant star with an apparent magnitude of +4.22. At a separation of 49.6 arcseconds from the primary is a binary companion composed of two 10th magnitude stars (HD 219430 B and C). They are 0.3 arcseconds from each other.
| NAME | Apparent magnitude (V) | Spectral type |
|---|---|---|
| 91 Aqr (ψ¹ Aqr, HD 219449, Gliese 893.2) | 4.22 | K0III |
| HD 219430B | 9.62 | K3V |
| HD 219430C | 10.10 | D |
Another nearby binary system CCDM J23159-0905DE was listed to belong to the system according to the CCDM catalogue, but is listed as physically unconnected by the WDS catalogue. 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.
[edit] Planetary system
In 2003, the discovery of an extrasolar planet orbiting 91 Aquarii was announced. Despite controversy, the exoplanet was confirmed again on Jan 03, 2011 by the Conference " Planetary Systems Beyond the Main Sequence", Bamberg 2010 (Quirrenbach et al)[citation needed].
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | >2.9[3] MJ | 0.3[4][dubious ] | 182[3] | 0 |
[edit] See also
[edit] Citations
- ^ a b c d e f g h i Simbad result for GJ 893.2 A
- ^ a b c d e f Vizier
- ^ a b 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. http://adsabs.harvard.edu/cgi-bin/bib_query?2003AAS...203.1703M. Retrieved 2009-11-28.
- ^ Two Suns in The Sky: Stellar Multiplicity in Exoplanet Systems Raghavan, Henry, Mason, Subasavage, Jao, Beaulieu and Hambly 2006
[edit] References
- "VizieR Detailed Page for HR 8841". http://webviz.u-strasbg.fr/viz-bin/VizieR-S?HR%208841. Retrieved 2009-11-28.
- "Simbad query result for GJ 893.2 A". http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=GJ+893.2+A&submit=SIMBAD+search. Retrieved 2009-11-28.
- "Simbad query result for GJ 893.2 B". http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%401325076&Name=GJ%20%20%20893.2%20B. Retrieved 2009-11-28.
[edit] External links
- SIMBAD: HD 219449 -- High proper-motion Star
- Extrasolar Planets Encyclopaedia: 91 Aqr
- Extrasolar Visions: 91 Aquarii
- Orbit simulation
- Image Psi Aquarii
- sky-map.org/
- planetquest.jpl.nasa.gov
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Coordinates: 
23h 15m 53.5s, −09° 05′ 16″
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