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EI Cancri

Coordinates: Sky map 08h 58m 15.194s, +19° 45′ 47.08″
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(Redirected from G 9-38)
This article is about G 9-38 and is not to be confused with G 29-38.
EI Cancri
EI Cancri is located in the constellation Cancer
EI Cancri is located in the constellation Cancer
EI Cancri
Location of EI Cancri in the constellation Cancer

Observation data
Epoch J2000      Equinox J2000
Constellation Cancer[1]
A
Right ascension 08h 58m 15.07493s[2]
Declination +19° 45′ 48.2581″[2]
Apparent magnitude (V) 13.93[3]
B
Right ascension 08h 58m 15.14813s[4]
Declination +19° 45′ 48.8367″[4]
Apparent magnitude (V) 13.75[3]
Characteristics
A
Spectral type M8Ve[5]
B
Spectral type M7V[6]
Astrometry
A
Radial velocity (Rv)13 ± 5[7] km/s
Proper motion (μ) RA: −767.060[2] mas/yr
Dec.: −100.176[2] mas/yr
Parallax (π)194.1443±0.1228 mas[2]
Distance16.80 ± 0.01 ly
(5.151 ± 0.003 pc)
B
Proper motion (μ) RA: −937.133[4] mas/yr
Dec.: −34.559[4] mas/yr
Parallax (π)196.2619 ± 0.1976 mas[4]
Distance16.62 ± 0.02 ly
(5.095 ± 0.005 pc)
Orbit[8]
Period (P)>42 years
Semi-major axis (a)7.0 AU
Details
A
Mass0.127±0.043[9] M☉
Radius0.136±0.020[9] R☉
Luminosity (bolometric)0.00135±0.00040[10] L☉
Temperature2,890±79[10] K
Metallicity [Fe/H]+0.08[9] dex
B
Mass0.111±0.045[9] M☉
Radius0.119±0.021[9] R☉
Luminosity (bolometric)0.000937±0.000028[10] L☉
Temperature2,802±78[10] K
Metallicity [Fe/H]+0.14[9] dex
Other designations
EI Cnc, GJ 1116, WDS J08582+1945AB, G 9-38, G 47-14, G 41-11, LP 426-40, LTT 12343, PLX 2144.03, GSC 01397-01138, 2MASS J08581519+1945470
A: Gaia DR2 660597997696173440, LHS 2076, NLTT 20638[11]
B: Gaia DR2 660597997697274752, LHS 2077, NLTT 20637[12]
Database references
SIMBADThe system
A
B

EI Cancri, also known as G 9-38 and GJ 1116, is a binary star system consisting of two M-type stars.[13] Located at a distance of 16.7 light-years, it is among the nearest star systems.[14]

This system consist of two very-low-mass stars that are orbiting each other at an estimated period of 42 years and orbital separation of 7.0 astronomical units.[8] Component A has an apparent magnitude 13.93,[3] 0.127 times the Sun's mass, 0.136 times the Sun's radius,[9] and 0.14% of the Sun's luminosity.[10] Component B has an apparent magnitude 13.75,[3] 0.111 times the Sun's mass, 0.119 times the Sun's radius,[9] and 0.09% of the Sun's luminosity.[10] At the very end of the main sequence, with spectral classifications of M8Ve[5] and M7V[6] respectively, their effective temperatures are below 3,000 K.[10] A 2015 search for a third star in the system has yielded inconclusive results.[15]

An ultraviolet band light curve showing several flares on EI Cancri, adapted from Pettersen (1985)[16]

In 1985, Bjørn Ragnvald Pettersen announced his discovery that the star shows very high stellar flare activity, with an average of five flares per hour.[16] It was given its variable star designation, EI Cancri, in 1987.[17]

References

[edit]
  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. ^ 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.
  3. ^ a b c d Lépine, Sébastien; Shara, Michael M. (2005-03-01). "A Catalog of Northern Stars with Annual Proper Motions Larger than 015 (LSPM-NORTH Catalog)". The Astronomical Journal. 129 (3): 1483. arXiv:astro-ph/0412070. Bibcode:2005AJ....129.1483L. doi:10.1086/427854. ISSN 1538-3881.
  4. ^ 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.
  5. ^ a b Cowley, A. P.; Hartwick, F. D. A. (1982). "Studies of late-type dwarfs. III. Radial velocities and spectral characteristics for 74 stars". The Astrophysical Journal. 253: 237–241. Bibcode:1982ApJ...253..237C. doi:10.1086/159628. ISSN 0004-637X.
  6. ^ a b Newton, Elisabeth R.; Charbonneau, David; Irwin, Jonathan; Berta-Thompson, Zachory K.; Rojas-Ayala, Barbara; Covey, Kevin; Lloyd, James P. (2013-12-12). "Near-infrared Metallicities, Radial Velocities and Spectral Types for 447 Nearby M Dwarfs". The Astronomical Journal. 147 (1): 20. arXiv:1310.1087. Bibcode:2014AJ....147...20N. doi:10.1088/0004-6256/147/1/20. ISSN 0004-6256.
  7. ^ "G9-38". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
  8. ^ a b Li, Hua-Li; Wang, Jing; et al. (September 2023). "White-light Superflare and Long-term Activity of the Nearby M7-type Binary EI Cnc Observed with GWAC System". The Astrophysical Journal. 954 (2): 142. arXiv:2307.14594. Bibcode:2023ApJ...954..142L. doi:10.3847/1538-4357/ace59b.
  9. ^ a b c d e f g h Cifuentes, C.; Caballero, J. A.; González-Payo, J.; Amado, P. J.; Béjar, V. J. S.; Burgasser, A. J.; Cortés-Contreras, M.; Lodieu, N.; Montes, D.; Quirrenbach, A.; Reiners, A.; Ribas, I.; Sanz-Forcada, J.; Seifert, W.; Zapatero Osorio, M. R. (January 2025). "CARMENES input catalogue of M dwarfs. IX. Multiplicity from close spectroscopic binaries to ultra-wide systems". Astronomy and Astrophysics. 693: A228. Bibcode:2025A&A...693A.228C. doi:10.1051/0004-6361/202452527. ISSN 0004-6361.
  10. ^ a b c d e f g Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal. 165 (6): 267. arXiv:2304.12490. Bibcode:2023AJ....165..267H. doi:10.3847/1538-3881/acd1ec.
  11. ^ "G9-38A". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
  12. ^ "G9-38B". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 29 September 2020.
  13. ^ Vizier query: Name=G* 1116, Centre de Données astronomiques de Strasbourg, accessed 30 December 2012.
  14. ^ Nearby Stars Catalog (NSC) Archived 2021-02-27 at the Wayback Machine, Planetary Habitability Laboratory, University of Puerto Rico at Arecibo accessed 31 December 2012.
  15. ^ Davison, Cassy L.; White, R. J.; Henry, T. J.; Riedel, A. R.; Jao, W-C.; Bailey Iii, J. I.; Quinn, S. N.; Cantrell, J. R.; Subasavage, J. P.; Winters, J. G. (2015). "A 3D Search for Companions to 12 Nearby M-Dwarfs". The Astronomical Journal. 149 (3): 106. arXiv:1501.05012. Bibcode:2015AJ....149..106D. doi:10.1088/0004-6256/149/3/106. S2CID 9719725.
  16. ^ a b Pettersen, B. R. (July 1985). "Discovery of flare activity on the low luminosity red dwarf system G9-38 AB". Astronomy & Astrophysics. 148: 151–154. Bibcode:1985A&A...148..151P. Retrieved 11 November 2021.
  17. ^ Kholopov, P. N.; Samus, N. N.; Kazarovets, E. V.; Kireeva, N. N. (August 1987). "The 68th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 3058: 1–30. Bibcode:1987IBVS.3058....1K. Retrieved 1 January 2025.

Further reading

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