Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Aquarius [1] |
Right ascension | 22h 34m 42.153s [2] |
Declination | −03° 35′ 58.17″ [2] |
Apparent magnitude (V) | 9.23 [1] Min I: 9.86 Min II: 9.59 [3] |
Characteristics | |
Evolutionary stage | main sequence |
Spectral type | F9 V + G3 V [4] |
U−B color index | 0.029 [5] |
B−V color index | 0.601±0.037 [1] |
Variable type | Algol [3] |
Astrometry | |
Radial velocity (Rv) | −9.59±0.46 [6] km/s |
Proper motion (μ) | RA: 73.192 mas/yr [2] Dec.: −21.545 mas/yr [2] |
Parallax (π) | 7.297±0.0219 mas [2] |
Distance | 447 ± 1 ly (137.0 ± 0.4 pc) |
Absolute magnitude (MV) | 3.95 [1] |
Orbit [4] | |
Period (P) | 20.178321(3) d |
Semi-major axis (a) | 40.744(7) R☉ |
Eccentricity (e) | 0.31654(7) |
Inclination (i) | 89.548(26)° |
Longitude of the node (Ω) | 32.11(14)° |
Periastron epoch (T) | 2,455,100.56106(79) JD |
Argument of periastron (ω) (secondary) | 155.50(4)° |
Semi-amplitude (K1) (primary) | 49.948(13) km/s |
Semi-amplitude (K2) (secondary) | 57.736(14) km/s |
Details [4] | |
Primary | |
Mass | 1.1949(7) M☉ |
Radius | 1.321(6) R☉ |
Luminosity | 2.15(7) L☉ |
Surface gravity (log g) | 4.274(4) cgs |
Temperature | 6,080(45) K |
Metallicity [Fe/H] | 0.02(4) dex |
Rotational velocity (v sin i) | 3.5(5) km/s |
Secondary | |
Mass | 1.0337(7) M☉ |
Radius | 1.002(5) R☉ |
Luminosity | 0.958(35) L☉ |
Surface gravity (log g) | 4.451(4) cgs |
Temperature | 5,703(50) K |
Metallicity [Fe/H] | 0.03(6) dex |
Rotational velocity (v sin i) | 3.6(4) km/s |
Other designations | |
LL Aqr, BD−04°5706, HD 213896, HIP 111454, SAO 146171, PPM 206522 [7] | |
Database references | |
SIMBAD | data |
LL Aquarii is an eclipsing binary star system in the equatorial constellation of Aquarius, abbreviated LL Aqr. At peak brightness it has a combined apparent visual magnitude of 9.23, [1] which is too dim to be visible to the naked eye. Based on parallax measurements, it is located at a distance of approximately 447 light years from the Sun. [2] The system is drifting closer with a heliocentric radial velocity of about −10 km/s. [6]
In 1996, this star was found to be an Algol-type eclipsing binary based on photometric observations made with the Hipparcos space observatory. It was assigned the variable-star designation LL Aqr in 1999. [9] This is a detached system forming a double-lined spectroscopic binary. In 2004, a more extensive light curve showed an eccentric orbit with a period of 20.1784 days. During the primary eclipse, the system dropped to magnitude 9.86, while the secondary eclipse showed a magnitude of 9.59. [10] The first orbital elements were published in 2008, showing an orbital eccentricity of 0.3095 with a mass ratio of 0.86. Stellar models indicated the stars are near the mid point of their main sequence lifetimes. [6]
The more massive member of the system, the primary component, has a stellar classification of F9 V, [4] matching an F-type main-sequence star. It has 19.5% more mass than the Sun and a 32% greater girth. This star is radiating 2.15 times the luminosity of the Sun from its photosphere at an effective temperature of around 6,080 K. It is spinning with a projected rotational velocity of 3.5±0.5 km/s. The metallicity, or abundance of elements with mass greater than helium, is very nearly Sun-like. [4]
The secondary component is considered a solar twin, which means its properties are close to Sun-like. It is a G-type main-sequence star with a class of G3 V. [4] Neither member of the system shows signs of stellar activity, being slowly rotating and not emitting X-rays. Tidal effects between the two stars is negligible; [11] they have an orbital separation of 40.7 times the radius of the Sun. [4]