| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Aquarius |
| Right ascension | 22 34 42.153 |
| Declination | −03° 35′ 58.17″ |
| Apparent magnitude (V) | 9.23 Min I: 9.86 Min II: 9.59 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | F9 V + G3 V |
| U−B color index | 0.029 |
| B−V color index | 0.601±0.037 |
| Variable type | Algol |
| Astrometry | |
| Radial velocity (Rv) | −9.59±0.46 km/s |
| Proper motion (μ) | RA: 73.192 mas/yr Dec.: −21.545 mas/yr |
| Parallax (π) | 7.297 ± 0.0219 mas |
| Distance | 447 ± 1 ly (137.0 ± 0.4 pc) |
| Absolute magnitude (MV) | 3.95 |
| Orbit | |
| 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 | |
| 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 | 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 | 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 | |
| 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, 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. The system is drifting closer with a heliocentric radial velocity of about −10 km/s.
Observations
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. 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. 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.
The more massive member of the system, the primary component, has a stellar classification of F9 V, 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.
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. 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; they have an orbital separation of 40.7 times the radius of the Sun.
References
- ^ Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
- ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- ^ Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
- ^ Graczyk, D.; et al. (October 2016), "A solar twin in the eclipsing binary LL Aquarii", Astronomy & Astrophysics, 594, id. A92, arXiv:1608.01000, Bibcode:2016A&A...594A..92G, doi:10.1051/0004-6361/201628918.
- Saputra, M. B. (April 2020), "Atmospheric model and synthetic spectrum of LL Aquarii using Kurucz model", Journal of Physics: Conference Series, 1523 (1), id. 012021, Bibcode:2020JPhCS1523a2021S, doi:10.1088/1742-6596/1523/1/012021.
- ^ Ibanoǧlu, C.; et al. (November 2008), "Spectroscopic and photometric observations of the selected Algol-type binaries - III. LL Aquarii, MP Delphini and NSV 20913", Monthly Notices of the Royal Astronomical Society, 390 (3): 958–968, Bibcode:2008MNRAS.390..958I, doi:10.1111/j.1365-2966.2008.13585.x.
- "LL Aqr", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2024-12-29.
- MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 29 December 2024.
- Kazarovets, E. V.; et al. (1999), "The 74th Special Name-list of Variable Stars", Information Bulletin on Variable Stars, 4659: 1, Bibcode:1999IBVS.4659....1K.
- Otero, Sebastian A.; Dubovsky, Pavol A. (August 2004), "New Elements for 80 Eclipsing Binaries IV", Information Bulletin on Variable Stars, 5557: 1, Bibcode:2004IBVS.5557....1O.
- Southworth, J. (September 2013), "The solar-type eclipsing binary system LL Aquarii*", Astronomy & Astrophysics, 557: 557, arXiv:1308.1320, Bibcode:2013A&A...557A.119S, doi:10.1051/0004-6361/201322195, A119.
Further reading
- Griffin, R. F. (June 2013), "Spectroscopic binary orbits from photoelectric radial velocities - Paper 230: Five Short-Period Double-Lined Binaries: HD 25788, HD 32704, HD 45191 (V455 Aur), and HD 213896 (LL Aqr)", The Observatory, 133: 156–184, Bibcode:2013Obs...133..156G.
- Solonovich, A. P.; et al. (2003), "Searches of the periods and variability type definition of new variable stars AL Ari, FM Leo, LL Aqr, V1125 Tau, V1366 Ori.", Odessa Astronomical Publications, 16: 66, Bibcode:2003OAP....16...66S.
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