Sigma Boötis

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σ Boötis
Template:Location mark
Location of σ Boötes (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.46[2]
Characteristics
Spectral type F4VkF2mF1[3]
U−B Template:Engvar −0.084[2]
B−V Template:Engvar +0.366[2]
Variable type Suspected[4]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[5] km/s
Proper motion (μ) RA: +188.574 mas/yr[1]
Dec.: +131.580 mas/yr[1]
Parallax (π)63.4679±0.1173 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)3.52[6]
Details
MassScript error: No such module "val".[7]
1.18[8] Template:Solar mass
RadiusScript error: No such module "val".[9] Template:Solar radius
LuminosityScript error: No such module "val".[9] Template:Solar luminosity
Surface gravity (log g)4.30[6] cgs
TemperatureScript error: No such module "val".[9] K
Metallicity [Fe/H]−0.24[10] dex
Rotational velocity (v sin i)7.32[11] km/s
Age1.7 Gyr[12]
2.42 Gyr[8]
3.1[13] Gyr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[14]
Database references
SIMBADdata

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Sigma Boötis is a single,[15][16] yellow-hued star in the northern constellation of Boötes. Its name is a Bayer designation that is Latinized from σ Boötis, and abbreviated Sigma Boo or σ Boo. This star is visible to the naked eye with an apparent visual magnitude of 4.46.[2] Located to the southeast of Rho Boötis, the dwarf Sigma may at first appear as a naked-eye double, but the angular proximity with Rho is merely line-of-sight. Sigma Boötis is located at a distance of Script error: No such module "convert". from the Sun based on parallax.[17] The star has a relatively high proper motion and is traversing the sky at the rate of Script error: No such module "val". yr−1.[18]

Properties

The stellar classification of Sigma Boötis is F4VkF2mF1.[3] This notation is used for so-called "metal-weak" stars; Am stars with absorption lines of some metals weaker than expected in comparison with other spectral features. The 'F4V', indicating an F-type main-sequence star, is derived from the hydrogen spectral lines and the shape of the metallic lines, the 'kF2' means it has the Calcium K line strength of a hotter F2 star and 'mF1' showing it has the metallic line strength of an F1 star.[19] It is around twice as luminous as a comparable zero age main sequence star, which may indicate it is near the end of its main sequence lifetime.[13]

Sigma Boötis is a solar-type star but is larger and more massive than the Sun. It has an estimated age of around two[12] to three[13] billion years and is spinning with a projected rotational velocity of 7 km/s.[11] There is some evidence of variation in radial velocity as well as rotational modulation of active latitudes.[13] Even though the outer convective zone of the star only occupies a few percent of the stellar radius, a surface magnetic field has been detected with a strength of Script error: No such module "val"..[20] This surface field forms a relatively simple dipole topology.[21] The star is radiating 3.5[9] times the luminosity of the Sun from its photosphere at an effective temperature of 6,594 K.[9] It appears to be a source for X-ray emission.[22]

Infrared surveys with the Spitzer and Herschel space telescopes failed to detect an infrared excess around this star at wavelengths up to Script error: No such module "val".. However, the HOSTS Survey with the Large Binocular Telescope reported a detection of an excess in the far infrared, indicating the presence of exozodiacal dust near the habitable zone of the star.[23]

Nomenclature

Sigma Boötis is known by several different names, including σ Boo, 28 Boötis, BD+30°2536, GC 19659, GJ 557, HD 128167, HIP 71284, HR 5447, SAO 83416, and CCDM 14347+2945.[14]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Celestial Lance, refers to an asterism consisting of σ Boötis, ε Boötis and ρ Boötis.[24] Consequently, the Chinese name for σ Boötis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[25]

References

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  1. ↑ a b c d Template:Cite Gaia DR3
  2. ↑ a b c d Script error: No such module "citation/CS1".
  3. ↑ a b Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ 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. ↑ a b Script error: No such module "citation/CS1".
  9. ↑ a b c d e Script error: No such module "citation/CS1".. See Table 10.
  10. ↑ Script error: No such module "citation/CS1".
  11. ↑ a b Script error: No such module "citation/CS1".
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ a b c d Script error: No such module "citation/CS1".
  14. ↑ a b Template:Cite simbad
  15. ↑ Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Template:Cite Gaia DR2
  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".
  23. ↑ Script error: No such module "citation/CS1".
  24. ↑ Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.
  25. ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 29 日 Template:Webarchive

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External links

Template:Stars of Boötes

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