KIC 9970396

KIC 9970396

Location of KIC 9970396 (circled)
Observation data Epoch J2000.0       Equinox J2000.0
Constellation	Cygnus [1]
Right ascension	19h 54m 50.35534s [2]
Declination	+46° 49′ 58.9104″ [2]
Apparent magnitude  (V)	11.447 [3]
Characteristics
Evolutionary stage	Red-giant branch + main sequence [3]
Spectral type	G6V [4] or G9III-IV [5]
J−H color index	0.562 [6]
J−K color index	0.661 [6]
Variable type	Eclipsing binary [3]
Astrometry
Radial velocity (Rv)	−13.05±4.32 [2] km/s
Proper motion (μ)	RA: 2.097 [2] mas/yr Dec.: −8.260 [2] mas/yr
Parallax (π)	0.991±0.0192  mas [2]
Distance	3,290 ± 60  ly (1,010 ± 20  pc)
Orbit [3]
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 [3]
KIC 9970396A
Mass	1.178±0.015  M☉
Radius	8.035±0.074  R☉
Surface gravity (log g)	2.852±0.199 [7]   cgs
Temperature	4868±143 [7]   K
Metallicity [Fe/H]	−0.244±0.156 [7]   dex
Age	6.13±0.19 [8]   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
Gaia DR3 2085557916175822336, KOI-7606, KIC 9970396, TIC 268059376, TYC 6466-1769-1, 2MASS J19545035+4649589 [6]
Database references
SIMBAD	data

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.

The system was given the Kepler Object of Interest designation KOI-7606 as a planetary candidate, but has been marked a false positive ^[9] since the dips in the light curve are caused by an eclipsing stellar companion rather than a transiting exoplanet.

Stellar components

KIC 9970396A

KIC 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_☉. ^[7] Its age is estimated at 6.13±0.19 billion years, ^[8] about 1.5 billion years older than the Solar System (4.568 Gyr). ^[10]

KIC 9970396B

KIC 9970396B is a late F-type star ^[11] 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. ^[11]

Its stellar parameters, alongside those of the red giant, were precisely measured using a combination of Kepler photometry and spectroscopic observations. ^[3]

References

1. 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.
2. 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.
3. 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.
4. Frasca, A.; Molenda-Żakowicz, J.; De Cat, P.; Catanzaro, G.; Fu, J. N.; Ren, A. B.; Luo, A. L.; Shi, J. R.; Wu, Y.; Zhang, H. T. (2016). "Activity indicators and stellar parameters of the Kepler targets. An application of the ROTFIT pipeline to LAMOST-Kepler stellar spectra". Astronomy and Astrophysics. 594. arXiv: 1606.09149 . Bibcode:2016A&A...594A..39F. doi:10.1051/0004-6361/201628337.
5. Gray, R. O.; Corbally, C. J.; De Cat, P.; Fu, J. N.; Ren, A. B.; Shi, J. R.; Luo, A. L.; Zhang, H. T.; Wu, Y.; Cao, Z.; Li, G.; Zhang, Y.; Hou, Y.; Wang, Y. (2016). "LAMOST Observations in the Kepler Field: Spectral Classification with the MKCLASS Code". The Astronomical Journal. 151 (1): 13. Bibcode:2016AJ....151...13G. doi: 10.3847/0004-6256/151/1/13 .
6. "KOI-7606". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 23 October 2024.
7. 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.
8. 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. Bibcode:2022ApJ...931...64Z. doi: 10.3847/1538-4357/ac695b . ISSN   0004-637X.
9. "Kepler Objects of Interest". NASA Exoplanet Archive . NASA Exoplanet Science Institute . Retrieved 23 October 2024.
10. 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.
11. Gaulme, P.; McKeever, J.; Rawls, M. L.; Jackiewicz, J.; Mosser, B.; Guzik, J. A. (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): 82. arXiv: 1303.1197 . Bibcode:2013ApJ...767...82G. doi:10.1088/0004-637X/767/1/82.