Theta Boötis

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Template:Short description

Theta Boötis
Template:Location mark
Location of θ Boötis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.05[2] + 13.23[3]
Characteristics
Spectral type F7 V[2] + M2.5V[3]
U−B Template:Engvar −0.02[4]
B−V Template:Engvar +0.50[2]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[5] km/s
Proper motion (μ) RA: −235.97 mas/yr[1]
Dec.: −399.696 mas/yr[1]
Parallax (π)69.0686±0.1579 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)3.25[6]
Details
A
MassScript error: No such module "val".[7] Template:Solar mass
RadiusScript error: No such module "val".[7] Template:Solar radius
LuminosityScript error: No such module "val".[7] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[7] cgs
TemperatureScript error: No such module "val".[7] K
Metallicity [Fe/H]0.03[8] dex
Rotational velocity (v sin i)29.2[9] km/s
AgeScript error: No such module "val".[10]
3.83[8] Gyr
B
Mass0.4–0.48[11] Template:Solar mass
RadiusScript error: No such module "val".[11] Template:Solar radius
Luminosity0.022[11] Template:Solar luminosity
Surface gravity (log g)4.91[11] cgs
Temperature3,521[11] K
Metallicity [Fe/H]−0.07[11] dex
Other designations
Template:Odlist[12]
Database references
SIMBADdata
ARICNSdata

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Theta Boötis is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism.[13] Its name is a Bayer designation that is Latinized from θ Boötis, and abbreviated Theta Boo or θ Boo. This star has the traditional name Asellus Primus, pronounced Template:IPAc-en, which is Latin for "first donkey colt".[13] Faintly visible to the naked eye, this star has a yellow-white hue with an apparent visual magnitude of 4.05.[2] It is located at a distance of Script error: No such module "convert". from the Sun based on parallax measurements,[1] but is drifting closer with a radial velocity of −10.6 km/s.[5] It has a relatively high proper motion, traversing the celestial sphere at the rate of 0.464 arc seconds per annum.[14]

Properties

File:Theta Boötis.jpg
θ Boötis in optical light

The stellar classification of Theta Boötis is F7 V,[2] matching an F-type main-sequence star. It is a solar-type star that may be near the end of its main sequence lifetime based on a high luminosity for a star of its type.[10] Theta Boötis is a suspected variable star[15] and a source of X-ray emission.[16] There is evidence for low amplitude radial velocity variation of about 5 km/s.[10] The star has a magnetic field with a mean longitudinal strength of Script error: No such module "val"..[17]

Theta Boötis has a 23% greater mass and a 73% larger radius than the Sun.[7] It is about 3–4 billion years old and is spinning with a projected rotational velocity of 29 km/s.[9] The star is radiating 4.2 times the luminosity of the Sun[18] from its photosphere at an effective temperature of 6,290 K.[7] Based on the proportion of iron found in the stellar spectrum, this star has a near-solar abundance of elements with mass greater than helium.[8]

There is a nearby 11th magnitude optical companion star about 70 arcseconds away. This is a class M2.5 red dwarf that is separated by a minimum of 1,000 AU. It is uncertain whether they are gravitationally bound, but they do have a common motion through space and so the two stars probably share a common origin.[19][3]

Nomenclature

θ Boötis, along with the other Aselli (ι Boo and κ Boo) and λ Boo, were Aulād al Dhiʼbah (أولاد الضّباع - awlād al-ḍibā‘), "the Whelps of the Hyenas".[13]

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Celestial Spear, refers to an asterism consisting of θ Boötis, κ2 Boötis and ι Boötis.[20] Consequently, the Chinese name for θ Boötis itself is Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx.)[21]

References

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  1. ↑ a b c d e Template:Cite DR3
  2. ↑ a b c d e Script error: No such module "citation/CS1".
  3. ↑ a b c Script error: No such module "citation/CS1".
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ a b Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b c d e f g Script error: No such module "citation/CS1".
  8. ↑ a b c Script error: No such module "citation/CS1".
  9. ↑ a b Script error: No such module "citation/CS1".Script error: No such module "Unsubst".
  10. ↑ a b c Script error: No such module "citation/CS1".
  11. ↑ a b c d e f Script error: No such module "citation/CS1".
  12. ↑ Template:Cite simbad
  13. ↑ a b c Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ 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".. See Table 10.
  19. ↑ Script error: No such module "citation/CS1".
  20. ↑ 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.
  21. ↑ Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.

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External links

Template:Sky Template:Stars of Boötes

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