2MASS J18352154−3123385
Binary red dwarf system in the constellation Sagittarius
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2MASS J18352154−3123385, often shortened to be 2MASS J1835, is a binary red dwarf system about 56 light-years from the Earth. It was first reported due to its high proper motion in 2010 by J. D. Kirkpatrick et al.[7][8] It was then independently discovered from its X-ray radiation on June 10, 2015. Further investigation has shown the star to be a binary star with components of spectral type M6.5 and M8. They orbit each other in 1,400-1,800 years, and reached their closest point in mid-1968 assuming a constant proper motion. During their closest approach, they were separated by less than 0.1 arcsecond, compared to their current separation of 2 arcseconds.[citation needed]
| Observation data Epoch J2000.0 Equinox ICRS | |
|---|---|
| Constellation | Sagittarius[1] |
| 2MASS J18352154-3123385 | |
| Right ascension | 18h 35m 21.537s[2] |
| Declination | −31° 23′ 38.32″[2] |
| Apparent magnitude (V) | 12.5[citation needed] |
| 2MASS J18352205-3123421 | |
| Right ascension | 18h 35m 22.047s[3] |
| Declination | −31° 23′ 41.97″[3] |
| Apparent magnitude (V) | 13.0[citation needed] |
| Characteristics | |
| 2MASS J18352154−3123385 | |
| Spectral type | M4e[4] |
| Apparent magnitude (J) | 8.652[4] |
| Apparent magnitude (H) | 8.097[4] |
| Apparent magnitude (K) | 7.803[4] |
| 2MASS J18352205−3123421 | |
| Spectral type | M8V[citation needed] |
| Apparent magnitude (J) | 9.438[5] |
| Apparent magnitude (H) | 8.815[5] |
| Apparent magnitude (K) | 8.533[5] |
| Astrometry | |
| 2MASS J18352154−3123385 | |
| Radial velocity (Rv) | −6.39±0.75[2] km/s |
| Proper motion (μ) | RA: +23.625 mas/yr[2] Dec.: −383.091 mas/yr[2] |
| Parallax (π) | 58.0486±0.0342 mas[2] |
| Distance | 56.19 ± 0.03 ly (17.23 ± 0.01 pc) |
| 2MASS J18352205−3123421 | |
| Radial velocity (Rv) | −10.50±2.79[3] km/s |
| Proper motion (μ) | RA: +28.532 mas/yr[3] Dec.: −380.003 mas/yr[3] |
| Parallax (π) | 58.0782±0.0480 mas[3] |
| Distance | 56.16 ± 0.05 ly (17.22 ± 0.01 pc) |
| Orbit | |
| Primary | 2MASS J18352154−3123385 |
| Name | 2MASS J18352205−3123421 |
| Period (P) | ~1400–1800?[citation needed] yr |
| Semi-major axis (a) | 5070 AU[citation needed] |
| Inclination (i) | ~55[citation needed]° |
| Longitude of the node (Ω) | ~5[citation needed]° |
| Periastron epoch (T) | ~1968[a] |
| Details[6] | |
| 2MASS J18352154−3123385 | |
| Mass | 0.29 M☉ |
| Radius | 0.3 R☉ |
| Luminosity | 0.0012 L☉ |
| Temperature | 3376 K |
| Metallicity [Fe/H] | -0.07 dex |
| 2MASS J18352205−3123421 | |
| Other designations | |
| 1RXS J183520.9−312327, PM J18353−3123W, LP 923-18 | |
| 2MASS J18352154−3123385: LP923-18, PM J18353−3123W[4] | |
| 2MASS J18352205−3123421: LP923-19, PM J18353−3123E[5] | |
| Database references | |
| SIMBAD | 2MASS J18352154−3123385 |
| 2MASS J18352205−3123421 | |
Despite the fact that A and B are magnitude 12.5 and 13, respectively, their vicinity to the Earth was not noticed until 2015 due to the fact that it is in front of a relatively dense star field less than 15 degrees away from the Galactic Center.[citation needed]
2MASS J1835A may be a flare star, due to many similar low-mass stars known to flare. It has not been observed to flare directly by 2015, however.[citation needed]
A 19th-magnitude star at 18h 35m 22.76s −31° 23′ 27.7″ has been seen in the vicinity, with a similar proper motion to 2MASS J1835, but is probably not related as its proper motion is not as high as 2MASS J1835. Due to its dimness, insufficient data exists to determine its spectral type.[citation needed]
See also
Notes
- given date is not the date of periastron, but rather the date of the closest separation between 2MASS J1835A and B.