KIC 9970396 is an eclipsing binary system located in the northern constellation of Cygnus about 3,290 light-years (1,010 parsecs) distant. The system consists of a red-giant branch star and an F-type main-sequence star. The two stars orbit each other every 235 days (0.64 years) at a mean distance of 207.92±0.73 R☉ (0.9669±0.0034 AU), almost the same as Earth's distance from the Sun.
  | |
| Observation data Epoch J2000.0[1] Equinox J2000.0[1] | |
|---|---|
| Constellation | Cygnus |
| Right ascension | 19h 54m 50.35534s |
| Declination | +46° 49′ 58.9104″ |
| Apparent magnitude (V) | 11.447[2] |
| Characteristics | |
| Evolutionary stage | Red-giant branch star |
| J−H color index | 0.562[3] |
| J−K color index | 0.661[3] |
| Variable type | Eclipsing binary |
| Astrometry | |
| Radial velocity (Rv) | −2.34±8.65[4] km/s |
| Proper motion (μ) | RA: 2.097[1] mas/yr Dec.: −8.260[1] mas/yr |
| Parallax (π) | 0.991 ± 0.0192 mas[1] |
| Distance | 3,290 ± 60 ly (1,010 ± 20 pc) |
| Orbit[2] | |
| Primary | KIC 9970396A |
| Companion | KIC 9970396B |
| Period (P) | 235.29861±0.00024 d |
| Semi-major axis (a) | 0.9669±0.0034 AU |
| Eccentricity (e) | 0.1942±0.0053 |
| Inclination (i) | 89.437±0.046° |
| Details[2] | |
| KIC 9970396A | |
| Mass | 1.178±0.015 M☉ |
| Radius | 8.035±0.074 R☉ |
| Surface gravity (log g) | 2.852±0.199[5] cgs |
| Temperature | 4868±143[5] K |
| Metallicity [Fe/H] | −0.244±0.156[5] dex |
| Age | 6.13±0.19[6] Gyr |
| KIC 9970396B | |
| Mass | 1.0030±0.0085 M☉ |
| Radius | 1.1089±0.0052 R☉ |
| Surface gravity (log g) | 4.3493±0.0054 cgs |
| Temperature | 6221±125 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
The system was given the Kepler Object of Interest designation KOI-7606 as a planetary candidate, but has been marked a false positive[7] since the dips in the light curve are caused by an eclipsing stellar companion rather than a transiting exoplanet.
Stellar components
editKIC 9970396A
editKIC 9970396A is a pulsating red giant currently in the red-giant branch, past the first dredge-up event and approaching the red giant bump. The star displays solar-like oscillations caused by turbulent convection near the surface. Since the star has used up all of its hydrogen within its core, the core now consists mostly of helium, with a mass of 0.229 M☉, that is 19% of the star's entire mass, and a radius of 0.03055 R☉.[5] Its age is estimated at 6.13±0.19 billion years,[6] about 1.5 billion years older than the Solar System (4.568 Gyr[8]).
KIC 9970396B
editKIC 9970396B is a late F-type star[9] almost identical in mass to the Sun but slightly larger and hotter. Its mass is slightly smaller than the red giant primary, thus a possible scenario for the system is that the two stars formed together and the more massive primary star evolved past the main sequence first.[9]
Its stellar parameters, alongside those of the red giant, were precisely measured using a combination of Kepler photometry and spectroscopic observations.[2]
References
edit- ^ a b c d 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.
- ^ a b c d Brogaard, K; et al. (1 February 2018). "Establishing the accuracy of asteroseismic mass and radius estimates of giant stars – I. Three eclipsing systems at [Fe/H] ∼ −0.3 and the need for a large high-precision sample". Monthly Notices of the Royal Astronomical Society. 476 (3). Oxford University Press (OUP): 3729–3743. arXiv:1801.08167. doi:10.1093/mnras/sty268. ISSN 0035-8711.
- ^ a b c "KOI-7606". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 23 October 2024.
- ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d Zhang, Xinyi; et al. (2 April 2020). "Determining the size of the helium core of KIC 9970396 using asteroseismology: a red giant approaching the red giant bump". Monthly Notices of the Royal Astronomical Society. 494 (1). Oxford University Press (OUP): 511–528. doi:10.1093/mnras/staa667. ISSN 0035-8711.
- ^ a b Zhang, Xinyi; et al. (1 May 2022). "Determining the Age for the Red Giants KIC 9145955 and KIC 9970396 by Gravity-dominated Mixed Modes". The Astrophysical Journal. 931 (1). American Astronomical Society: 64. doi:10.3847/1538-4357/ac695b. ISSN 0004-637X.
- ^ "Kepler Objects of Interest". NASA Exoplanet Archive. NASA Exoplanet Science Institute. Retrieved 23 October 2024.
- ^ Bouvier, A.; Wadhwa, M. (2010). "The age of the Solar System redefined by the oldest Pb–Pb age of a meteoritic inclusion". Nature Geoscience. 3 (9): 637–641. Bibcode:2010NatGe...3..637B. doi:10.1038/NGEO941. S2CID 56092512.
- ^ a b Gaulme, P.; et al. (26 March 2013). "RED GIANTS IN ECLIPSING BINARY AND MULTIPLE-STAR SYSTEMS: MODELING AND ASTEROSEISMIC ANALYSIS OF 70 CANDIDATES FROM KEPLER DATA". The Astrophysical Journal. 767 (1). American Astronomical Society: 82. arXiv:1303.1197. doi:10.1088/0004-637x/767/1/82. ISSN 0004-637X.