26 Aquilae (abbreviated 26 Aql) is a binary star system in the equatorial constellation of Aquila. 26 Aquilae is its Flamsteed designation though it also bears the Bayer designation f Aquilae. It has an apparent visual magnitude of 5.00,[2] which means it is faintly visible to the naked eye. As the Earth orbits the Sun, this star system undergoes a parallax shift of 21.15 mas.[1] This means it is located at a distance of approximately 154 light-years (47 parsecs) from Earth, give or take a three-light-year margin of error.
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Aquila |
| Right ascension | 19h 20m 32.90437s[1] |
| Declination | –05° 24′ 56.7440″[1] |
| Apparent magnitude (V) | 5.00[2] |
| Characteristics | |
| Spectral type | G8 III-IV[3] |
| U−B color index | +0.634[2] |
| B−V color index | +0.936[2] |
| R−I color index | 0.5 |
| Astrometry | |
| Radial velocity (Rv) | −16.91±1.93[4] km/s |
| Proper motion (μ) | RA: +113.13[1] mas/yr Dec.: +46.20 [1] mas/yr |
| Parallax (π) | 21.15 ± 0.39 mas[1] |
| Distance | 154 ± 3 ly (47.3 ± 0.9 pc) |
| Orbit[4] | |
| Period (P) | 266.544 days |
| Eccentricity (e) | 0.833 |
| Semi-amplitude (K1) (primary) | 29.86 km/s |
| Details | |
| 26 Aquilae A | |
| Mass | 3.2+0.2 −0.2[5] M☉ |
| Radius | 6[4] R☉ |
| Luminosity | 21[4] L☉ |
| Surface gravity (log g) | 3.2[4] cgs |
| Temperature | 4940[5] K |
| Metallicity [Fe/H] | –0.21[4] dex |
| Rotational velocity (v sin i) | 1.3[4] km/s |
| 26 Aquilae B | |
| Mass | 1.4±0.05[5] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
This is a single-lined spectroscopic binary system, meaning that the presence of an orbiting companion is revealed through shifts in the spectrum of the primary star. The pair orbit each other with a period of 266.544 days at a high eccentricity of 0.833.[4] Little is known about this companion, although its mass can be estimated as 140% of the Sun's.
The primary component has a stellar classification of G8 III-IV.[3] The luminosity class of III-IV indicates the spectrum resembles that of a star part way between the subgiant and giant stages of its evolution. It has more than three[5] times the mass of the Sun and six[4] times the Sun's radius. It is radiating 21[4] times as much luminosity as the Sun from this enlarged outer envelope at an effective temperature of 4,940 K.[5] At this heat, the star glows with the characteristic yellow hue of a G-type star.[7]
References
edit- ^ 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, S2CID 18759600.
- ^ a b c d 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, Bibcode:1975MNRAS.172..667J, doi:10.1093/mnras/172.3.667.
- ^ a b 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, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
- ^ a b c d e f g h i j 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, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209.
- ^ a b c d e Pourbaix, D.; Boffin, H. M. J. (February 2003), "Reprocessing the Hipparcos Intermediate Astrometric Data of spectroscopic binaries. II. Systems with a giant component", Astronomy and Astrophysics, 398 (3): 1163–1177, arXiv:astro-ph/0211483, Bibcode:2003A&A...398.1163P, doi:10.1051/0004-6361:20021736, S2CID 12361870.
- ^ "f Aql". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2012-07-22.
- ^ "The Colour of Stars", Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organisation, December 21, 2004, archived from the original on February 22, 2012, retrieved 2012-01-16