Ross 128
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Virgo |
| Right ascension | 11h 47m 44.3964s[1] |
| Declination | +00° 48′ 16″[1] |
| Apparent magnitude (V) | 11.13[2] |
| Characteristics | |
| Spectral type | M4 V[3] |
| U−B color index | 2.685[4] |
| B−V color index | 1.59[5] |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | -31.0[6][7] km/s |
| Proper motion (μ) | RA: 605.66[1] mas/yr Dec.: -1219.32[1] mas/yr |
| Parallax (π) | 298.2 ± 1.7[8] mas |
| Distance | 10.94 ± 0.06 ly (3.35 ± 0.02 pc) |
| Absolute magnitude (MV) | 13.51[2] |
| Details | |
| Mass | 0.15[9] M☉ |
| Radius | 0.21[10] R☉ |
| Luminosity | 0.00036[11] L☉ |
| Luminosity (bolometric) | 0.0035[12] L☉ |
| Surface gravity (log g) | 3.40[9] cgs |
| Temperature | 3,180[3] K |
| Other designations | |
| Database references | |
| SIMBAD | data |
Ross 128 is a small star in the equatorial zodiac constellation of Virgo, the virgin. The apparent magnitude of Ross 128 is 11.13,[2] which is much too faint to be seen with the naked eye. Based upon parallax measurements, the distance of this star from Earth is 10.89 light-years (3.34 parsecs), making it the twelfth closest star to the Solar System. It was first cataloged in 1926 by American astronomer Frank Elmore Ross.[13]
This low mass star has a stellar classification of M4 V,[3] which places it among a category of stars known as red dwarfs. It has 15%[9] of the mass of the Sun and 21%[10] of the Sun's radius, but generates energy so slowly that it has only 0.036% of the Sun's visible luminosity.[11] However, most of the energy being radiated by the star is in the infrared band, with the bolometric luminosity being equal to 0.35% of solar.[12] This energy is being radiated from the star's outer atmosphere at an effective temperature of 3,180 K.[3] This gives it the cool orange-red glow of an M-type star.
Ross 128 is an old disk star, which means it has a low abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, and it orbits near the plane of the Milky Way galaxy.[14] It is classified as an active flare star since it can undergo unpredictable and dramatic increases in luminosity for a period of several minutes.[15] Because of the low rate of flare activity, it is thought to be a magnetically evolved star. That is, there is some evidence that the magnetic braking of the star's stellar wind has lowered the frequency of flares, but not the net yield.[16]
On multiple occasions this star has been examined for the existence of a low stellar mass or brown dwarf companion orbiting at a distance of at least 1 astronomical unit from the primary. However, no companions have yet been discovered.[17][18] The star also lacks a strong excess of infrared radiation. An infrared excess is usually an indicator of a dust ring in orbit around the star.[19][20]
Ross 128 is orbiting through the Milky Way with an orbital eccentricity of 0.122, causing its distance from the Galactic Center to range between 26.8–34.2 kly (8.2–10.5 kpc).[21] This orbit will bring the star closer to the Solar System in the future. The nearest approach will occur in about 71,000 years, when it will come within 6.233 ± 0.085 ly (1.911 ± 0.026 pc).[7]
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See also
References
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