26 Aquilae

26 Aquilae
Diagram showing star positions and boundaries of the Aquila constellation and its surroundings
Location of 26 Aquilae (circled)
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]
Distance154 ± 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
Mass3.2+0.2
−0.2[5] M☉
Radius6[4] R☉
Luminosity21[4] L☉
Surface gravity (log g)3.2[4] cgs
Temperature4940[5] K
Metallicity [Fe/H]–0.21[4] dex
Rotational velocity (v sin i)1.3[4] km/s
26 Aquilae B
Mass1.4±0.05[5] M☉
Other designations
f Aquilae, BD–05° 4936, FK5 3544, HD 181391, HIP 95066, HR 7333, SAO 143286.[6]
Database references
SIMBADdata

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.

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]

  1. ^ a b c d e f Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference mnras172_667 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j Cite error: The named reference aj135_1_209 was invoked but never defined (see the help page).
  5. ^ a b c d e Cite error: The named reference aaa398_1163 was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference csiro was invoked but never defined (see the help page).