Ross 248

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Ross 248
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Observation data
Epoch J2000      Equinox J2000
Constellation Andromeda
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 12.23 - 12.34[2]
Characteristics
Spectral type M6 V[3]
U−B Template:Engvar +1.48Script error: No such module "Unsubst".
B−V Template:Engvar +1.92Script error: No such module "Unsubst".
Variable type BY Dra[2]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[1] km/s
Proper motion (μ) RA: Script error: No such module "val". mas/yr[1]
Dec.: Script error: No such module "val". mas/yr[1]
Parallax (π)316.4812±0.0444 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)14.79[4]
Details
Mass0.145[5] Template:Solar mass
Radius0.190[5] Template:Solar radius
Luminosity0.0022[6] Template:Solar luminosity
Surface gravity (log g)5.13[6] cgs
Temperature2,930[5] K
Metallicity [Fe/H]+0.23[5] dex
RotationScript error: No such module "val".[7] days
Rotational velocity (v sin i)0.1[8] km/s
Age2.6[5] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
HH Andromedae, HH And, 2MASS J23415498+4410407, G 171-010, GCTP 5736.00, GJ 905, LHS 549.[9]
Database references
SIMBADdata

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Ross 248, also called HH Andromedae or Gliese 905, is a small star approximately Script error: No such module "convert".[10] from Earth in the northern constellation of Andromeda. Despite its proximity it is too dim to be seen with the naked eye.[11] It was first catalogued by Frank Elmore Ross in 1926 with his second list of proper-motion stars;[12] on which count it ranks 261st in the SIMBAD database. It was too dim to be included in the Hipparcos survey. In about 40,000 years, Voyager 2 will pass 1.7 light-years (9.7 trillion miles) from the star.

Within the next 80,000 years, Ross 248 is predicted to be the nearest star to the Sun for around 9,000 years, overtaking the current nearest star, the triple system Alpha Centauri.

Characteristics

File:HHAndLightCurve.png
A visual band light curve for HH Andromedae, adapted from Weis (1994)[13]

This star has about 14% of the Sun's mass and 19% of the Sun's radius, but only 0.2% of the Sun's luminosity. It has a stellar classification of M6 V,[3] which indicates it is a type of main-sequence star known as a red dwarf. This is a chromospherically-active star.[14] With high probability, there appears to be a long-term cycle of variability with a period of 4.2 years. This variability causes the star to range in visual magnitude from 12.23 to 12.34.[13] In 1950, this became the first star to have a small variation in magnitude attributed to spots on its photosphere as it rotates,[15] a class known as BY Draconis variables.[2]

Examining the proper motion of Ross 248 has found no evidence of a brown dwarf or stellar companion orbiting between 100–1,400 AU,[16] and other unsuccessful searches have been attempted using both the Hubble Space Telescope Wide Field Planetary Camera[4] and by near-infrared speckle interferometry.[17] Long-term observations by the Sproul Observatory show no astrometric perturbations by any unseen companion.[15]

Distance from the Sun

File:Near-stars-past-future-en.svg
Distances of the nearest stars from 20,000 years ago until 80,000 years in the future

The space velocity components of this star in the galactic coordinate system are [U, V, W] = [Script error: No such module "val"., Script error: No such module "val"., Script error: No such module "val".] km/s.[10] The trajectory of Ross 248 will bring it closer to the Solar System. In 1993, Matthews projected that in about 33,000 years it would enter a period of about 9,000 years as the closest star to the Sun, as close as Script error: No such module "convert". in 36,000 years.[18] A more precise estimate in 2022 has it approaching to within Template:Cvt in 36,500 years.[19]

Any future spacecraft that escaped the Solar System with a velocity of 25.4 km/s would reach this star 37,000 years from now, when the star just passes its nearest approach. By comparison, the Voyager 1 has an escape velocity of 16.6 km/s.[20]

Voyager 2 is not headed toward any particular star, although in roughly 42,000 years, it will pass the star Ross 248 at a distance of 1.7 light-years.[21]

The closest stellar neighbors to Ross 248 are the binary systems Groombridge 34, at 1.8 light-years away, and Kruger 60, at 4.5 light-years.[22]

See also

References

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  5. ↑ a b c d e Script error: No such module "Citation/CS1".
  6. ↑ a b Script error: No such module "Citation/CS1".
  7. ↑ Script error: No such module "Citation/CS1".
  8. ↑ Script error: No such module "Citation/CS1".
  9. ↑ Template:Cite simbad
  10. ↑ a b Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ a b Script error: No such module "Citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ a b Script error: No such module "Citation/CS1".
  16. ↑ Script error: No such module "Citation/CS1".
  17. ↑ Script error: No such module "Citation/CS1".
  18. ↑ Script error: No such module "Citation/CS1".
  19. ↑ Script error: No such module "Citation/CS1".
  20. ↑ Script error: No such module "Citation/CS1".
  21. ↑ Script error: No such module "Citation/CS1".
  22. ↑ Script error: No such module "citation/CS1".

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Sources

External links

Template:Nearest systems Template:Stars of Andromeda Template:Portal bar

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