Astronomy:Theta Sagittae

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Short description: Double star in the constellation Sagitta
θ Sagittae
Sagitta constellation map.svg
Red circle.svg
Location of θ Sagittae (circled)
Observation data
{{#ifeq:J2000.0|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000.0]]      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0}}
Constellation Sagitta
A
Right ascension  20h 09m 56.6470s[1]
Declination +20° 54′ 54.094″[1]
Apparent magnitude (V) +6.516[2]
B
Right ascension  20h 09m 56.2405s[3]
Declination +20° 55′ 04.228″[3]
Apparent magnitude (V) +8.769[2]
Characteristics
A
Spectral type F3V[4]
U−B color index −0.04[5]
B−V color index +0.38[5]
B
Spectral type G5V[6]
B−V color index +0.732[2]
Astrometry
A
Radial velocity (Rv)−40.92[1] km/s
Proper motion (μ) RA: +58.387[1] mas/yr
Dec.: +98.274[1] mas/yr
Parallax (π)22.3262 ± 0.0326[1] mas
Distance146.1 ± 0.2 ly
(44.79 ± 0.07 pc)
Absolute magnitude (MV)+3.24[7]
B
Radial velocity (Rv)−43.0[8] km/s
Proper motion (μ) RA: +64.726[3] mas/yr
Dec.: +101.800[3] mas/yr
Parallax (π)22.3841 ± 0.0305[3] mas
Distance145.7 ± 0.2 ly
(44.67 ± 0.06 pc)
Absolute magnitude (MV)+5.58[7]
Details
A
Mass1.52[9] M☉
Radius1.45[1] R☉
Luminosity4.0[1] L☉
Surface gravity (log g)4.32[9] cgs
Temperature6,750±229[9] K
Metallicity [Fe/H]−0.17[8] dex
Rotational velocity (v sin i)33.6[10] km/s
Age2.089[9] Gyr
B
Mass0.95[11] M☉
Radius0.82[3] R☉
Luminosity0.516[3] L☉
Surface gravity (log g)4.526[12] cgs
Temperature5,394[3] K
Other designations
θ Sge, 17 Sge, BD+20°4453, HD 191570, WDS J20099+2055[13]
A: {{{names2}}}
B: {{{names3}}}
Database references
SIMBADA
B

Theta Sagittae (θ Sagittae) is a double star in the northern constellation of Sagitta.[14] With a combined apparent visual magnitude of +6, it is near the limit of stars that can be seen with the naked eye. According to the Bortle scale the star is visible in dark suburban/rural skies. Based upon an annual parallax shift of 22.15 mas as seen from Earth,[15] it is located roughly 147 light years from the Sun.

The binary pair consists of two stars separated by 502 astronomical unit|AU.[16] The primary, component A,[17] is an F-type main sequence star with a stellar classification of F3V.[4] This star is about two billion years old[9] with 52% more mass than the Sun.[9] It forms a double star with a magnitude 8.85 companion,[17] which is located at an angular separation of 11.58 arc seconds along a position angle of 331.1°, as of 2011.[14] The star is sometimes described as a triple star, with a 7th magnitude companion 91″ away.[17] This is an unrelated giant star much further away than the close pair.[18] A fainter star separated by nearly 3′ was also listed as a companion by Struve,[17] again just an accidental optical association.[19]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 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.
  2. ↑ 2.0 2.1 2.2 Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P. et al. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics 355: L27, Bibcode: 2000A&A...355L..27H. 
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 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 Abt, H. A. (September 1985), "Visual multiples. VIII. 1000 MK types", Astrophysical Journal Supplement Series 59: 95–112, doi:10.1086/191064, Bibcode: 1985ApJS...59...95A. 
  5. ↑ 5.0 5.1 Hoffleit, Dorrit; Jaschek, Carlos (1991), "The Bright star catalogue", New Haven, Bibcode: 1991bsc..book.....H. 
  6. ↑ Adams, Walter S. et al. (April 1935), "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars", Astrophysical Journal 81: 187, doi:10.1086/143628, Bibcode: 1935ApJ....81..187A. 
  7. ↑ 7.0 7.1 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  8. ↑ 8.0 8.1 Casagrande, L. et al. (2011), "New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey", Astronomy & Astrophysics 530 (A138): 21, doi:10.1051/0004-6361/201016276, Bibcode: 2011A&A...530A.138C. 
  9. ↑ 9.0 9.1 9.2 9.3 9.4 9.5 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal 804 (2): 146, doi:10.1088/0004-637X/804/2/146, Bibcode: 2015ApJ...804..146D. 
  10. ↑ do Nascimento, J. D. Jr. et al. (July 2003), "On the link between rotation, chromospheric activity and Li abundance in subgiant stars", Astronomy and Astrophysics 405 (2): 723–731, doi:10.1051/0004-6361:20030633, Bibcode: 2003A&A...405..723D. 
  11. ↑ Allende Prieto, C.; Lambert, D. L. (1999), "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures", Astronomy and Astrophysics 352: 555–562, Bibcode: 1999A&A...352..555A. 
  12. ↑ McDonald, I.; Zijlstra, A. A.; Watson, R. A. (2017), "Fundamental parameters and infrared excesses of Tycho–Gaia stars", Monthly Notices of the Royal Astronomical Society 471 (1): 770–791, doi:10.1093/mnras/stx1433, Bibcode: 2017MNRAS.471..770M. 
  13. ↑ "tet Sge". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=tet+Sge. 
  14. ↑ 14.0 14.1 Mason, Brian D. et al. (May 2012), "Speckle Interferometry at the U.S. Naval Observatory. XVIII", The Astronomical Journal 143 (5): 6, doi:10.1088/0004-6256/143/5/124, 124, Bibcode: 2012AJ....143..124M, http://www.dtic.mil/get-tr-doc/pdf?AD=ADA561759. 
  15. ↑ van Leeuwen, F. (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. 
  16. ↑ Halbwachs, J.-L. et al. (May 2012), "Double stars with wide separations in the AGK3 - I. Components that are themselves spectroscopic binaries", Monthly Notices of the Royal Astronomical Society 422 (1): 14–24, doi:10.1111/j.1365-2966.2012.20308.x, Bibcode: 2012MNRAS.422...14H. 
  17. ↑ 17.0 17.1 17.2 17.3 Mason, B. D. et al. (2014), The Washington Visual Double Star Catalog, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M 
  18. ↑ 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.
  19. ↑ 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.



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