Mu Cassiopeiae

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Template:Starbox visbin

μ Cassiopeiae
Template:Location mark
Location of μ Cassiopeiae (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Cassiopeia[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 5.159[3]
(5.14/11.45[4])
Characteristics
Spectral type G5Vb[5] + M4V[6]
U−B Template:Engvar +0.10[7]
B−V Template:Engvar Template:Val[6]
Variable type Suspected[8]
Astrometry
Radial velocity (Rv)Template:Val[2] km/s
Proper motion (μ) RA: +3,468.251 mas/yr[2]
Dec.: −1,564.844 mas/yr[2]
Parallax (π)130.2881±0.4348 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)5.78/11.6[9]
Details[6]
Aa
MassTemplate:Val Template:Solar mass
RadiusTemplate:Val Template:Solar radius
LuminosityTemplate:Val Template:Solar luminosity
Surface gravity (log g)Template:Val cgs
TemperatureTemplate:Val K
Metallicity [Fe/H]Template:Val dex
Rotational velocity (v sin i)2.4 km/s
AgeTemplate:Val Gyr
Ab
MassTemplate:Val[6] Template:Solar mass
Radius0.29[4] Template:Solar radius
Luminosity0.0062[4] Template:Solar luminosity
Temperature3,025[4] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBADdata

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Mu Cassiopeiae, Latinized from μ Cassiopeiae, is a binary star system in the constellation Cassiopeia. This system shares the name Marfak Template:IPAc-en with Theta Cassiopeiae, and the name was from Al Marfik or Al Mirfaq (المرفق), meaning "the elbow".[10] It is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.16.[3] The system is located at a distance of 25 light-years from the Sun based on parallax, and is moving closer with a high radial velocity of −97 km/s.[2] This star will move into the constellation Perseus around 5200 AD.[11]

Mu Cassiopeiae is given as a standard star for the spectral class G5Vb,[5] although it is frequently described as a subdwarf, meaning it has a luminosity below that expected for a G5 main sequence star.[12] The metallicity, or abundance of heavy elements, is about one-sixth that in the Sun.[6] It is slightly smaller than the Sun with less mass and a lower luminosity.[6] It is among the oldest known stars, with an age of Template:Val billion years making it possibly the oldest star visible to the unaided eye.[6]

This is one of the first high-velocity stars to be identified.[6] Compared to other nearby stars including the Sun, this pair are moving at a relatively high velocity of 167 km/s through the Milky Way galaxy.[6] They are low metal, Population II stars that are thought to have formed before the galactic disk first appeared.

Companions

There are five visible companions to Mu Cassiopeiae listed in the Washington Double Star Catalog. All are distant background objects fainter than 11th magnitude. The brightest of these is catalogued as component B, but the very high proper motion of Mu Cassiopeiae has caused it to almost double its distance from B. There are now two other stars brighter than magnitude 10 that are closer to Mu Cassiopeiae, although they are also background objects.[13] The companions C and D are separated from each-other by four arc seconds and form a binary system about Template:Val away.[14][15] Mu Cassiopeiae itself is known as an astrometric binary, a star that is observed to oscillate due to the gravitational influence of an unseen companion, and that companion has now been resolved.[4]

In 1961, the close binary nature of this system was discovered by Nicholas E. Wagman at the Allegheny Observatory.[16] Since then the orbital elements of the two stars have been fairly well established. The two stars are separated by a semimajor axis of 7.61 AUs with distance range of 3.3-11.9 AUs.[17] In 1966, the individual components were first resolved by the American astronomer Peter A. Wehinger using the 84-inch reflector at the Kitt Peak National Observatory, allowing an initial estimate of separate masses.[18] The companion is over six magnitudes (330 times) fainter than the primary star, and it is presumed to be a red dwarf, a class M main sequence or subdwarf star.[4]

See also

References

Template:Reflist

External links

Template:Stars of Cassiopeia

  1. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named xhip
  2. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named dr3
  3. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named aaa418_989
  4. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named drummond
  5. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named perkins
  6. ↑ a b c d e f g h i Cite error: Invalid <ref> tag; no text was provided for refs named Bond_et_al_2020
  7. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named apj1_233_211
  8. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gcvs
  9. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named jao
  10. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named allen1963
  11. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named moore
  12. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named apj683_1_424
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named wds
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dr2c
  15. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named dr2d
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj69_471
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named kaler
  18. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aj71_185
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