ADS 9731 is a star system that consists of six stars, located in the constellation of Corona Borealis. Four of the stars are visually separate in the sky, forming a visual star system, which was resolved using adaptive optics in 1995.[12] Two of these stars were themselves found to be spectroscopic binaries in 1998, resulting in a total of six known stars in the system.[4] It is one of very few multiple star systems known to have at least six members.[4]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Corona Borealis[1] |
| Right ascension | 15h 38m 12.91478s[2] |
| Declination | +36° 14′ 48.5597″[2] |
| Apparent magnitude (V) | 6.9 (total)[3] |
| Characteristics | |
| Spectral type | F4V + F5V + G4V + F3V + F7V + M3V?[4] |
| Astrometry | |
| A | |
| Proper motion (μ) | RA: +73.197[5] mas/yr Dec.: −57.740[5] mas/yr |
| Parallax (π) | 9.0945±0.0175 mas[5] |
| Distance | 358.6 ± 0.7 ly (110.0 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.462[6] |
| B | |
| Proper motion (μ) | RA: +71.824[7] mas/yr Dec.: −54.140[7] mas/yr |
| Parallax (π) | 9.1101±0.0307 mas[7] |
| Distance | 358 ± 1 ly (109.8 ± 0.4 pc) |
| Absolute magnitude (MV) | +4.94[4] |
| C | |
| Proper motion (μ) | RA: +75.165[8] mas/yr Dec.: −59.731[8] mas/yr |
| Parallax (π) | 9.0970±0.0199 mas[8] |
| Distance | 358.5 ± 0.8 ly (109.9 ± 0.2 pc) |
| Absolute magnitude (MV) | +2.72[4] |
| D | |
| Proper motion (μ) | RA: +72.818[9] mas/yr Dec.: −58.281[9] mas/yr |
| Parallax (π) | 9.0870±0.0322 mas[9] |
| Distance | 359 ± 1 ly (110.0 ± 0.4 pc) |
| Absolute magnitude (MV) | +3.82[4] |
| Orbit[3] | |
| Primary | A |
| Name | B |
| Period (P) | 834 yr |
| Semi-major axis (a) | 1.249″ |
| Inclination (i) | 97.0° |
| Orbit[3] | |
| Primary | C |
| Name | D |
| Period (P) | 1,230 yr |
| Semi-major axis (a) | 1.582″ |
| Inclination (i) | 78.4° |
| Orbit[3] | |
| Primary | Aa |
| Name | Ab |
| Period (P) | 3.2732 days |
| Eccentricity (e) | 0.011 |
| Semi-amplitude (K1) (primary) | 85.67 km/s |
| Semi-amplitude (K2) (secondary) | 87.28 km/s |
| Orbit[3] | |
| Primary | Da |
| Name | Db |
| Period (P) | 14.284 days |
| Eccentricity (e) | 0.31 |
| Semi-amplitude (K1) (primary) | 9.92 km/s |
| Details | |
| Aa | |
| Mass | 1.51±0.07[10] M☉ |
| Radius | 2.22+0.99 −0.23[10] R☉ |
| Luminosity | 7.46+0.90 −0.30[10] L☉ |
| Surface gravity (log g) | 3.89+0.77 −0.63[10] cgs |
| Temperature | 6,405+678 −230[10] K |
| Metallicity [Fe/H] | −1.07+0.71 −0.36[10] dex |
| Age | 2.21+0.81 −0.41[10] Gyr |
| Ab | |
| Mass | 1.32[3] M☉ |
| C | |
| Mass | 1.451+0.017 −0.016[11] M☉ |
| Radius | 1.93+0.86 −0.31[11] R☉ |
| Luminosity | 6.10+0.90 −0.80[11] L☉ |
| Surface gravity (log g) | 3.85+0.86 −0.32[11] cgs |
| Temperature | 6,600+800 −600[11] K |
| Metallicity [Fe/H] | −1.18+0.98 −0.03[11] dex |
| Age | 2.15±0.68[11] Gyr |
| Da | |
| Mass | 1.26[3] M☉ |
| Db | |
| Mass | 0.13[3] M☉ |
| Other designations | |
| BD+36°2626, HD 139691, CCDM J15382+3615AB, WDS J15382+3615AB | |
| Database references | |
| SIMBAD | data |
Characteristics
edit| Aa | |||||||||||||||
| Period = 3.27 d | |||||||||||||||
| Ab | |||||||||||||||
| Period = 834 y | |||||||||||||||
| B | |||||||||||||||
| Period > 20,000 y | |||||||||||||||
| C | |||||||||||||||
| Period = 1,230 y | |||||||||||||||
| Da | |||||||||||||||
| Period = 14.28 d | |||||||||||||||
| Db | |||||||||||||||
Hierarchy of orbits
The components are organised thus: Aa and Ab are yellow-white main sequence stars of spectral types F4V and F5V and 1.35 and 1.32 solar masses respectively, which orbit each other every 3.27 days. This pair is in a 834-year orbit with star B, a star of spectral type G4V that has about 66% of the mass of the Sun. Star C is a yellow white star of spectral type F3V around 1.41 times as massive as the sun, which has just started brightening and moving off the main sequence. It is in a 1,230-year orbit with a pair of stars, Da and Db, a yellow-white main sequence star of spectral type F7V and a red dwarf of spectral type M3V respectively. Da and Db take 14.28-days to orbit each other. Finally the system of stars C and Dab, and the system of stars Aab and B, take over 20,000 years to orbit each other.[3][4]
The combined light from the whole system results in an integrated V magnitude of 6.9.[3] Published apparent magnitudes for the components vary greatly and some are certainly in error,[4] but components A, B, C, and D are approximately of visual magnitude 7.8, 10.2, 8.0, and 9.1 respectively.[3] Models of all six components show that Aa and Ab have magnitudes 8.5 and 8.7 respectively while the faint secondary to component D is about 16th magnitude. The CD pair is slightly brighter than the AB pair, although component A is slightly brighter than component C.[4]
Gaia EDR3 catalogues parallaxes for the four resolved stars, all at a distance of 360 light-years (110 pc) with a statistical margin of error of less than a parsec.
The star system has been considered as a possible target for direct imaging searches for exoplanets,[13] but no planets have yet been detected in the system.
References
edit- ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- 1 2 Van Leeuwen, F. (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.
- 1 2 3 4 5 6 7 8 9 10 11 Tokovinin, Andrei (2018). "The Updated Multiple Star Catalog". The Astrophysical Journal Supplement Series. 235 (1): 6. arXiv:1712.04750. Bibcode:2018ApJS..235....6T. doi:10.3847/1538-4365/aaa1a5.
- 1 2 3 4 5 6 7 8 9 Tokovinin, A. A.; Shatskii, N. I.; Magnitskii, A. K. (1998). "ADS 9731: A new sextuple system". Astronomy Letters. 24 (6): 795. Bibcode:1998AstL...24..795T.
- 1 2 3 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- ↑ Freund, S.; Robrade, J.; Schneider, P. C.; Schmitt, J. H. M. M. (2018). "The stellar content of the XMM-Newton slew survey". Astronomy and Astrophysics. 614: A125. arXiv:1712.07410. Bibcode:2018A&A...614A.125F. doi:10.1051/0004-6361/201732009.
- 1 2 3 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- 1 2 3 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- 1 2 3 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics. 649: A1. arXiv:2012.01533. Bibcode:2021A&A...649A...1G. doi:10.1051/0004-6361/202039657. S2CID 227254300. (Erratum: doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
- 1 2 3 4 5 6 7 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.
- 1 2 3 4 5 6 7 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.
- ↑ Drummond, Jack D.; Christou, Julian C.; Fugate, Robert Q. (1995). "Full Adaptive Optics Images of ADS 9731 and MU Cassiopeiae: Orbits and Masses". Astrophysical Journal. 450: 380. Bibcode:1995ApJ...450..380D. doi:10.1086/176148.
- ↑ Janson, M. (2010). "The relevance of prior inclination determination for direct imaging of Earth-like planets". Monthly Notices of the Royal Astronomical Society. 408 (1): 514–521. arXiv:1006.2941. Bibcode:2010MNRAS.408..514J. doi:10.1111/j.1365-2966.2010.17135.x. S2CID 118380508.