G 9-38, also known as EI Cancri and GJ 1116, is a binary star system consisting of two M-type stars.[11] At 16.7 light-years from the Sun, the system is relatively nearby.[12] The system has a very high stellar flare activity, with average five flares per hour.[1]
 An ultraviolet band light curve showing several flares on EI Cancri, adapted from Pettersen (1985)[1] | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cancer |
| Right ascension | 08h 58m 15.194s[2] |
| Declination | +19° 45′ 47.08″[2] |
| Apparent magnitude (V) | 13.720[3] |
| Characteristics | |
| Spectral type | M8Ve+M7V[4][5] |
| Astrometry | |
| G 9-38 A | |
| Radial velocity (Rv) | 13 ± 5[6] km/s |
| Proper motion (μ) | RA: −767.060±0.122[7] mas/yr Dec.: −100.176±0.083[7] mas/yr |
| Parallax (π) | 194.1443 ± 0.1228 mas[7] |
| Distance | 16.80 ± 0.01 ly (5.151 ± 0.003 pc) |
| G 9-38 B | |
| Proper motion (μ) | RA: −937.133±0.190[8] mas/yr Dec.: −34.559±0.138[8] mas/yr |
| Parallax (π) | 196.2619 ± 0.1976 mas[8] |
| Distance | 16.62 ± 0.02 ly (5.095 ± 0.005 pc) |
| Orbit | |
| Primary | G 9-38A |
| Companion | G 9-38B |
| Period (P) | 360 yr |
| Semi-major axis (a) | 33 AU |
| Details[9][10] | |
| G 9-38A | |
| Mass | 0.12 M☉ |
| Luminosity (bolometric) | 0.000965 L☉ |
| Temperature | 2896±18 K |
| Metallicity [Fe/H] | -0.12(unreliable) dex |
| G 9-38B | |
| Mass | 0.10 M☉ |
| Luminosity (bolometric) | 0.000992 L☉ |
| Other designations | |
| A: Gaia DR2 660597997696173440, LHS 2076[4], NLTT 20638[4] | |
| B: Gaia DR2 660597997697274752, LHS 2077[5], NLTT 20637[5] | |
| Database references | |
| SIMBAD | The system |
| A | |
| B | |
  G 9-38 Location of G 9-38 in the constellation Cancer | |
In 2015, the search for third star in the system has yielded inconclusive results.[13]
References
- Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Berta-Thompson, Zachory K. (2014). "Trigonometric Parallaxes for 1507 Nearby Mid-to-late M Dwarfs". The Astrophysical Journal. 784 (2): 156. arXiv:1312.3241. Bibcode:2014ApJ...784..156D. doi:10.1088/0004-637X/784/2/156. S2CID 18789867. Table with parallaxes.