Theta Aquilae

Theta Aquilae
Location of θ Aquilae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Aquila
Right ascension 20h 11m 18.28528s[1]
Declination –00° 49′ 17.2626″[1]
Apparent magnitude (V) 3.26[2]
Characteristics
Spectral type B9.5 III + B9.5 III[3]
U−B color index –0.15[2]
B−V color index –0.07[2]
Astrometry
Radial velocity (Rv)–27.3[4] km/s
Proper motion (μ) RA: +35.26[1] mas/yr
Dec.: +5.71[1] mas/yr
Parallax (π)11.39 ± 0.24 mas[1]
Distance286 ± 6 ly
(88 ± 2 pc)
Absolute magnitude (MV)–1.39/0.14[5]
Orbit[6]
Period (P)17.124281 ± 0.000038 days
Semi-major axis (a)3.148 ± 0.002 mas″
Eccentricity (e)0.6040 ± 0.0009
Inclination (i)144.10 ± 0.18°
Longitude of the node (Ω)96.92 ± 0.19°
Periastron epoch (T)JD 2458624.154 ± 0.004
Argument of periastron (ω)
(primary)		33.73 ± 0.22°
Semi-amplitude (K1)
(primary)		48.78 ± 0.09 km/s
Semi-amplitude (K2)
(secondary)		63.48 ± 0.11 km/s
Details
θ Aql A
Mass3.564 ± 0.049[6] M☉
Radius4.76 ± 0.14[6] R☉
Luminosity229.8 ± 22.5[6] L☉
Surface gravity (log g)3.64 ± 0.02[6] cgs
Temperature10300 ± 200[6] K
Metallicity [Fe/H]+0.20[7] dex
Rotational velocity (v sin i)36.3 ± 0.4[6] km/s
Age20.9[5] Myr
θ Aql B
Mass2.739 ± 0.037[6] M☉
Radius2.34 ± 0.07[6] R☉
Luminosity54.0 ± 5.8[6] L☉
Surface gravity (log g)4.14 ± 0.02[6] cgs
Temperature10230 ± 220[6] K
Rotational velocity (v sin i)13.6 ± 0.9[6] km/s
Other designations
Tseen Foo, 65 Aql, BD–01 3911, FK5 756, HD 191692, HIP 99473, HR 7710, SAO 144150.
Database references
SIMBADdata

Theta Aquilae (θ Aql, θ Aquilae) is a binary star in the constellation Aquila. The combined apparent visual magnitude of the pair is 3.26,[2] making it the fourth-brightest member of the constellation. In Chinese, it has the traditional name Tseen Foo /ˌsiːn ˈfuː/, from the Chinese 天桴 (Mandarin pronunciation tiānfú), which could mean "heavenly raft" or "heavenly ridgepole"; it might also mean "heavenly drumsticks", with Altair, Beta Aquilae and Gamma Aquilae being the drum. This distance to this star can be determined through the parallax technique, yielding an estimate of roughly 286 light-years (88 parsecs) from Earth.[1]

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