Omicron Aquilae

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Omicron Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings
Cercle rouge 100%.svg

Location of ο Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 19h 51m 01.64400s[1]
Declination +10° 24′ 56.5992″[1]
Apparent magnitude (V) 5.11[2]
Spectral type F8 V + M3 V[3]
U−B color index 0.07
B−V color index 0.55[4]
R−I color index 0.29
Radial velocity (Rv) –0.2[5] km/s
Proper motion (μ) RA: +242.28[1] mas/yr
Dec.: –136.48[1] mas/yr
Parallax (π) 52.11 ± 0.29[1] mas
Distance 62.6 ± 0.3 ly
(19.2 ± 0.1 pc)
Absolute magnitude (MV) 3.71[5]
ο Aql A
Mass 1.252[6] M
Radius 1.52[6] R
Surface gravity (log g) 4.07[7] cgs
Temperature 6,090[7] K
Metallicity [Fe/H] +0.07[7] dex
Rotational velocity (v sin i) 3[4] km/s
Age 3.3[5] Gyr
ο Aql C
Mass 0.33[8] M
Other designations
54 Aquilae, O Aquilae, BD+10 4073, GJ 768.1, HD 187691, HIP 97675, HR 756, NLTT 48319, LTT 15798, SAO 1053380.[9]
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

Omicron Aquilae (ο Aql, ο Aquilae) is the Bayer designation for a double star in the equatorial constellation of Aquila. The brighter component has an apparent visual magnitude of +5.11,[2] which means it is faintly visible to the naked eye in dark suburban skies. The annual parallax shift of this star is 52.11 mas,[1] which is equivalent to a physical distance of 62.6 light-years (19.2 parsecs) from Earth.

The primary component, Omicron Aquilae A, is an F-type main sequence star with a stellar classification of F8 V.[3] It has about 125% of the mass of the Sun and 152% of the Sun's radius.[6] With an age of roughly 3.3 billion years,[5] it appears to spinning at a leisurely rate with a projected rotational velocity of 3 km/s.[4] The outer atmosphere has an effective temperature of 6,090 K,[7] giving it the yellowish-white hue of an F-type star.

In 1998, Omicron Aquilae was one of nine stars identified as experiencing a superflare. The first flare observed from Omicron Aquilae was in 1979, with a magnitude increase of 0.07 and a duration of less than five days. The second occurred in 1980, with a magnitude change of 0.09 and a duration of fifteen days. The energy released during the second flare is estimated as 9 × 1037 erg.[10]

There is a magnitude 12.67 common proper motion companion located at an angular separation of 22.5 arcseconds along a position angle of 221°. Based upon its matching parallax value, this corresponds to a projected linear separation of 431 astronomical units. (Hence, the companion is located at this separation or greater.) Designated component C, this is a small red dwarf star with a stellar classification of M3 V. Component B is an optical companion that appears near the primary only through a chance alignment.[3]


  1. ^ a b c d e f van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, arXiv:0708.1752, Bibcode:2007A&A...474..653V, doi:10.1051/0004-6361:20078357. 
  2. ^ a b Nicolet, B. (1978), "Photoelectric photometric Catalogue of homogeneous measurements in the UBV System", Astronomy and Astrophysics Supplement Series 34: 1–49, Bibcode:1978A&AS...34....1N. 
  3. ^ a b c Raghavan, Deepak; et al. (September 2010), "A Survey of Stellar Families: Multiplicity of Solar-type Stars", The Astrophysical Journal Supplement 190 (1): 1–42, arXiv:1007.0414, Bibcode:2010ApJS..190....1R, doi:10.1088/0067-0049/190/1/1. 
  4. ^ a b c Takeda, Yoichi; et al. (February 2005), "High-Dispersion Spectra Collection of Nearby F--K Stars at Okayama Astrophysical Observatory: A Basis for Spectroscopic Abundance Standards", Publications of the Astronomical Society of Japan 57 (1): 13–25, Bibcode:2005PASJ...57...13T, doi:10.1093/pasj/57.1.13. 
  5. ^ a b c d Holmberg, J.; Nordström, B.; Andersen, J. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191. 
  6. ^ a b c Takeda, Genya; et al. (February 2007), "Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog", The Astrophysical Journal Supplement Series 168 (2): 297–318, arXiv:astro-ph/0607235, Bibcode:2007ApJS..168..297T, doi:10.1086/509763. 
  7. ^ a b c d Frasca, A.; et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, Bibcode:2009A&A...508.1313F, doi:10.1051/0004-6361/200913327. 
  8. ^ Bonavita, M.; Desidera, S. (June 2007), "The frequency of planets in multiple systems", Astronomy and Astrophysics 468 (2): 721–729, arXiv:astro-ph/0703754, Bibcode:2007A&A...468..721B, doi:10.1051/0004-6361:20066671. 
  9. ^ "LTT 15798 -- High proper-motion Star", SIMBAD Astronomical Database (Centre de Données astronomiques de Strasbourg), retrieved 2012-06-29. 
  10. ^ Schaefer, Bradley E.; King, Jeremy R.; Deliyannis, Constantine P. (February 2000), "Superflares on Ordinary Solar-Type Stars", The Astrophysical Journal 529 (2): 1026–1030, arXiv:astro-ph/9909188, Bibcode:2000ApJ...529.1026S, doi:10.1086/308325 

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