Astronomy:Delta Boötis

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Short description: Double star in the northern constellation Boötes
δ Boötis
Boötes IAU.svg
Red circle.svg
Location of δ Boötis (circled)
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Boötes
BD+33 2561
Right ascension  15h 15m 30.16295s[1]
Declination +33° 18′ 53.3926″[1]
Apparent magnitude (V) 3.482[2]
BD+33 2562
Right ascension  15h 15m 38.34898s[3]
Declination +33° 19′ 15.3187″[3]
Apparent magnitude (V) 7.81[4]
Characteristics
BD+33 2561
Spectral type G8 III[5]
U−B color index +0.656[2]/
B−V color index +0.951[2]/
BD+33 2562
Spectral type G0 V[4]
U−B color index +0.02[4]
B−V color index +0.59[4]
Astrometry
BD+33 2561
Radial velocity (Rv)−12.29±0.16[6] km/s
Proper motion (μ) RA: +84.74[1] mas/yr
Dec.: –111.58[1] mas/yr
Parallax (π)26.78 ± 0.16[1] mas
Distance121.8 ± 0.7 ly
(37.3 ± 0.2 pc)
Absolute magnitude (MV)+0.700[7]
BD+33 2562
Radial velocity (Rv)−11.83±0.18[3] km/s
Proper motion (μ) RA: +82.776[3] mas/yr
Dec.: –110.040[3] mas/yr
Parallax (π)27.0648 ± 0.0307[3] mas
Distance120.5 ± 0.1 ly
(36.95 ± 0.04 pc)
Details
BD+33 2561
Radius10.5±0.2[8] R☉
Luminosity53.7[7] L☉
Surface gravity (log g)2.56[9] cgs
Temperature4,847[9] K
Metallicity [Fe/H]–0.44[9] dex
Rotational velocity (v sin i)3.6[10] km/s
BD+33 2562
Mass0.98[11] M☉
Radius0.91±0.02[3] R☉
Luminosity0.87[11] L☉
Temperature5,812±67[11] K
Age3.09[11] Gyr
Other designations
STF 4027, ADS 9559, WDS 15155+3319[12]
A: δ Boo, 49 Boötis, BD+33 2561, FK5 563, HD 135722, HIP 74666, HR 5681, SAO 64589[12]
B: BD+33 2562, HIP 74674, SAO 64591[13]
Database references
SIMBADdata
SIMBADdata

Delta Boötis, Latinized from δ Boötis, is a double star in the northern constellation of Boötes, forming the easternmost member of the constellation's kite-shaped asterism of brighter stars.[14] Based upon parallax measurements, it is located at a distance of approximately 121.8 light-years (37.3 parsecs) from the Earth.[1] This star is sometimes called Princeps /ˈprɪnsɛps/,[15] meaning prince or prime in Latin. The origin of this name is unclear, although it usually appears in an astrological context.[16][17] The apparent visual magnitude of this star is 3.5,[2] making it visible to the naked eye even during a Full Moon. The magnitude 7.81[4] companion can be viewed in binoculars or a small telescope.[14]

In Chinese, 七公 (Qī Gōng), meaning Seven Excellencies, refers to an asterism consisting of δ Boötis, 42 Herculis, τ Herculis, φ Herculis, χ Herculis, ν1 Boötis and μ1 Boötis.[18] Consequently, the Chinese name for δ Boötis itself is 七公七 (Qī Gōng qī, English: the Seventh Star of Seven Excellencies.)[19]

Properties

δ Boötis in optical light

This system consists of a pair of stars located in physical proximity to each other and sharing a similar motion through space, suggesting that they may form a binary star system. Based upon their angular separation and their distance, they have a projected separation of 3,800 Astronomical Units (AU). However, their separation along the line of sight from the Earth remains uncertain, so all that can really be said is that they are separated by at least 3,800 AU. If they are gravitationally bound to each other, it requires a minimum of 120,000 years to complete an orbit.[20]

The brighter member of the pair has a stellar classification of G8 III,[5] indicating that it has exhausted the supply of hydrogen at its core and evolved into a giant star. It now has a radius more than ten times the radius of the Sun.[8] Compared to the Sun, this star appears deficient in elements other than hydrogen and helium—what astronomers term the star's metallicity. The outer envelope of this star has an effective temperature of 4,847 K,[9] which is what gives it the characteristic yellow hue of a G-type star.[21]

The secondary component has a stellar classification of G0 V,[4] which suggests it is a main sequence star that may be similar in physical properties to the Sun. The apparent visual magnitude of this star is 7.81,[4] making it much less luminous than the primary component.[22]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics 474 (2): 653–664, doi:10.1051/0004-6361:20078357, Bibcode: 2007A&A...474..653V 
  2. ↑ 2.0 2.1 2.2 2.3 Jennens, P. A.; Helfer, H. L. (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.", Monthly Notices of the Royal Astronomical Society 172 (3): 667–679, doi:10.1093/mnras/172.3.667, Bibcode: 1975MNRAS.172..667J 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 Tolbert, Charles Ray (May 1964), "A UBV Study of 94 Wide Visual Binaries", Astrophysical Journal 139: 1105, doi:10.1086/147852, Bibcode: 1964ApJ...139.1105T 
  5. ↑ 5.0 5.1 Tsvetkov, A. S.; Popov, A. V.; Smirnov, A. A. (January 2008), "Inaccuracies in the spectral classification of stars from the Tycho-2 Spectral Type Catalogue", Astronomy Letters 34 (1): 17–27, doi:10.1134/S1063773708010039, Bibcode: 2008AstL...34...17T 
  6. ↑ Soubiran, C. et al. (2008), "Vertical distribution of Galactic disk stars. IV. AMR and AVR from clump giants", Astronomy and Astrophysics 480 (1): 91–101, doi:10.1051/0004-6361:20078788, Bibcode: 2008A&A...480...91S. 
  7. ↑ 7.0 7.1 Böhm-Vitense, Erika et al. (December 2000), "Ultraviolet Emission Lines in BA and Non-BA Giants", The Astrophysical Journal 545 (2): 992–999, doi:10.1086/317850, Bibcode: 2000ApJ...545..992B. 
  8. ↑ 8.0 8.1 Nordgren, Tyler E. et al. (December 1999), "Stellar Angular Diameters of Late-Type Giants and Supergiants Measured with the Navy Prototype Optical Interferometer", The Astronomical Journal 118 (6): 3032–3038, doi:10.1086/301114, Bibcode: 1999AJ....118.3032N, http://digitalcommons.wcupa.edu/cgi/viewcontent.cgi?article=1008&context=phys_facpub 
  9. ↑ 9.0 9.1 9.2 9.3 Frasca, A. et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, doi:10.1051/0004-6361/200913327, Bibcode: 2009A&A...508.1313F 
  10. ↑ Massarotti, Alessandro et al. (January 2008), "Rotational and Radial Velocities for a Sample of 761 HIPPARCOS Giants and the Role of Binarity", The Astronomical Journal 135 (1): 209–231, doi:10.1088/0004-6256/135/1/209, Bibcode: 2008AJ....135..209M 
  11. ↑ 11.0 11.1 11.2 11.3 Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal 150 (3): 88, doi:10.1088/0004-6256/150/3/88, Bibcode: 2015AJ....150...88L. 
  12. ↑ 12.0 12.1 "del Boo". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=del+Boo. 
  13. ↑ "BD+33 2562". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=BD%2B33+2562. 
  14. ↑ 14.0 14.1 English, Neil (May 14, 2014), Grab 'n' Go Astronomy, Springer New York, p. 214, ISBN 9781493908264, Bibcode: 2014gnga.book.....E, https://books.google.com/books?id=0mkgBAAAQBAJ&pg=PA214. 
  15. ↑ princeps (3rd ed.), Oxford University Press, September 2005, http://oed.com/search?searchType=dictionary&q=princeps  (Subscription or UK public library membership required.)
  16. ↑ Robson, Vivian E. (2005), The Fixed Stars and Constellations in Astrology, Astrology Center of America, p. 112, ISBN 1-933303-13-1, https://books.google.com/books?id=me7_4RdVwxsC&pg=PA112 
  17. ↑ "Princeps – Constellations of Words" (in en-US). https://www.constellationsofwords.com/princeps/. 
  18. ↑ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN:978-986-7332-25-7.
  19. ↑ (in Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 6 月 26 日
  20. ↑ Kaler, James B., "DELTA BOO (Delta Bootis)", Stars (University of Illinois), http://stars.astro.illinois.edu/sow/deltaboo.html, retrieved 2012-01-05 
  21. ↑ "The Colour of Stars", Australia Telescope, Outreach and Education (Commonwealth Scientific and Industrial Research Organisation), December 21, 2004, http://outreach.atnf.csiro.au/education/senior/astrophysics/photometry_colour.html, retrieved 2012-01-16 
  22. ↑ The actual brightness ratio is given by 2.512Δm, where Δm is the difference in magnitude. For this pair, Δm = –4.33, so the ratio is 2.512−4.33 = 0.019. Hence the secondary component is 1.9% as bright as the primary.

External links



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