KIC 9832227

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KIC 9832227

KIC 9832227 (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cygnus
Right ascension 19h 29m 15.950s[1]
Declination +46° 37′ 19.86″[1]
Apparent magnitude (V) 12.27 – 12.46[2]
Spectral type K2III/IV[3]
Variable type Eclipsing[4]
Proper motion (μ) RA: −9.505[1] mas/yr
Dec.: −5.718[1] mas/yr
Parallax (π)1.5798 ± 0.0134 mas[1]
Distance2,060 ± 20 ly
(633 ± 5 pc)
Period (P)0.4282579 days
Semi-major axis (a)2.992 R
Inclination (i)53.2°
Periastron epoch (T)2455688.49913
Mass1.395 M
Radius1.581 R
Luminosity2.609 L
Surface gravity (log g)4.19 cgs
Temperature5800 K
Rotational velocity (v sin i)149.7 km/s
Mass0.318 M
Radius0.830 R
Luminosity0.789 L
Surface gravity (log g)4.10 cgs
Temperature5920 K
Rotational velocity (v sin i)84.7 km/s
Other designations
2MASS J19291594+4637198, KIC 9832227, ASAS J192916+4637.3, GSC 03543-01211
Database references

KIC 9832227 is a contact binary star system in the constellation Cygnus, located about 2,060 light-years away. It is also identified as an eclipsing binary with an orbital period of almost 11 hours.[4]

Incorrect 2022 Merger Prediction[edit]

A light curve for KIC 9832227, plotted from TESS data[6]

In 2017, the system was predicted to result in a merger in 2022.2 (± 0.6 years), producing a luminous red nova (LRN) reaching an apparent magnitude of 2,[7] or about the brightness of Polaris, the North Star. The LRN would remain visible to the naked eye for roughly a month. The merger of the two stellar cores was predicted to give birth to a new, hotter, more massive main-sequence star. However, a reanalysis of the data in September 2018 revealed that the prediction had been based on a wrongly timed observation, negating the predicted merger.[8][9][10]

The period of the variations in KIC 9832227 has been observed to be growing shorter since 2013, leading to the prediction of the merger in or around 2022.[11] In September 2018, it was announced that the original prediction was based on a dataset which timing had been erroneously offset by 12 hours—and error which appeared to exaggerate the decay rate of the orbital period. Correcting for the error shows that the period had actually been increasing up to about 2008. The cause for the period variation is still unknown, but it is unlikely that the system will end in a merger at the predicted time.[8][9][12]

See also[edit]


  1. ^ a b c d e 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.
  2. ^ "ASAS J192916+4637.3". AAVSO. Retrieved 7 January 2017.
  3. ^ 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. S2CID 119283349.
  4. ^ a b Kinemuchi, Karen (2013-10-01). "To Pulsate or to Eclipse? Status of KIC 9832227 Variable Star". arXiv:1310.0544 [astro-ph.SR].
  5. ^ a b Molnar, Lawrence A.; Van Noord, Daniel M.; Steenwyk, Steven D.; Spedden, Chris J.; Kinemuchi, Karen (2015). "A prediction of a luminous red nova eruption" (PDF). American Astronomical Society. 225 (225): 415.05. Bibcode:2015AAS...22541505M. Archived from the original (PDF) on 7 January 2017.
  6. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 8 December 2021.
  7. ^ Molnar, Lawrence A.; Van Noord, Daniel; Kinemuchi, Karen; Smolinski, Jason P.; Alexander, Cara E.; Kobulnicky, Henry A.; Cook, Evan M.; Jang, Byoungchan; Steenwyk, Steven D. (2017). "KIC 9832227: A red nova precursor". American Astronomical Society. 229: 417.04. Bibcode:2017AAS...22941704M.
  8. ^ a b Molnar, Lawrence A. (7 September 2018). "Supplementary material to Calvin College press release "Team of researchers challenge bold astronomical prediction", September 7, 2018". Archived from the original on 16 December 2018. Retrieved 8 September 2018.
  9. ^ a b Kucinski, Matt (7 September 2018). "Team of researchers challenge bold astronomical prediction". Retrieved 8 September 2018.
  10. ^ Parks, Jake (7 September 2018). "Two stars will NOT merge and explode into red fury in 2022".
  11. ^ Carlisle, Camille (6 January 2017). "Paired Stars in Cygnus En Route to Merger". Sky and Telescope. Retrieved 12 January 2017.
  12. ^ Socia, Quentin J.; Welsh, William F.; Short, Donald R.; Orosz, Jerome A.; Angione, Ronald J.; Windmiller, Gur; Caldwell, Douglas A.; Batalha, Natalie M. (11 September 2018). "KIC 9832227: Using Vulcan Data to Negate the 2022 Red Nova Merger Prediction". Astrophysical Journal Letters. 864 (2): L32. arXiv:1809.02771. Bibcode:2018ApJ...864L..32S. doi:10.3847/2041-8213/aadc0d. S2CID 56134618.

External links[edit]