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θ Sagittae
Location of θ Sagittae (circled)
Observation data
Epoch J2000.0       Equinox J2000.0 ( ICRS)
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  mas [1]
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  mas [3]
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: HIP 99352, HR 7705, SAO 88276
B: HIP 99351, SAO 88275
Database references
SIMBAD A
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  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. ^ a b c d e f g h Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (2000), "The Tycho-2 catalogue of the 2.5 million brightest stars", Astronomy and Astrophysics, 355: L27, Bibcode: 2000A&A...355L..27H.
  3. ^ a b c d e f g h Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  4. ^ a b Abt, H. A. (September 1985), "Visual multiples. VIII. 1000 MK types", Astrophysical Journal Supplement Series, 59: 95–112, Bibcode: 1985ApJS...59...95A, doi: 10.1086/191064.
  5. ^ a b 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, Bibcode: 1935ApJ....81..187A, doi: 10.1086/143628.
  7. ^ a b Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv: 1108.4971, Bibcode: 2012AstL...38..331A, doi: 10.1134/S1063773712050015, S2CID  119257644.
  8. ^ a b 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, arXiv: 1103.4651, Bibcode: 2011A&A...530A.138C, doi: 10.1051/0004-6361/201016276, S2CID  56118016.
  9. ^ a b c d e f 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, arXiv: 1501.03154, Bibcode: 2015ApJ...804..146D, doi: 10.1088/0004-637X/804/2/146, S2CID  33401607.
  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, arXiv: astro-ph/0307196, Bibcode: 2003A&A...405..723D, doi: 10.1051/0004-6361:20030633, S2CID  1106754.
  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, arXiv: astro-ph/9911002, 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, arXiv: 1706.02208, Bibcode: 2017MNRAS.471..770M, doi: 10.1093/mnras/stx1433.
  13. ^ "tet Sge". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2017-07-10.{{ cite web}}: CS1 maint: postscript ( link)
  14. ^ a b Mason, Brian D.; et al. (May 2012), "Speckle Interferometry at the U.S. Naval Observatory. XVIII", The Astronomical Journal, 143 (5): 6, Bibcode: 2012AJ....143..124M, doi: 10.1088/0004-6256/143/5/124, 124, archived from the original on June 13, 2017.
  15. ^ van Leeuwen, F. (2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653–664, arXiv: 0708.1752, Bibcode: 2007A&A...474..653V, doi: 10.1051/0004-6361:20078357, S2CID  18759600.
  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, Bibcode: 2012MNRAS.422...14H, doi: 10.1111/j.1365-2966.2012.20308.x.
  17. ^ a b c d Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode: 2001AJ....122.3466M, doi: 10.1086/323920
  18. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  19. ^ Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv: 1804.09365. Bibcode: 2018A&A...616A...1G. doi: 10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
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