Ross 128

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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
FI Virginis, FI Vir, G 010-050, GCTP 2730, GJ 447, HIP 57548, LHS 315, Vyssotsky 286, LTT 13240, LFT 852.[1]
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]

Distances of the nearest stars from 20,000 years ago until 80,000 years in the future. The approach of Ross 128 is represented by the light salmon-hued line.

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]

See also

References

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Notes

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External links

Coordinates: Sky map 11h 47m 44.4s, +00° 48′ 16″

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  3. ↑ 3.0 3.1 3.2 3.3 Lua error in package.lua at line 80: module 'strict' not found.
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  9. ↑ 9.0 9.1 9.2 Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ 10.0 10.1 Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ 11.0 11.1 Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ 12.0 12.1 Lua error in package.lua at line 80: module 'strict' not found.
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