Delta Scorpii

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Delta Scorpii
Scorpius constellation map.svg
Red circle.svg
Location of δ Sco (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Scorpius
Right ascension 16h 00m 20.00528s[1]
Declination –22° 37′ 18.1431″[1]
Apparent magnitude (V) 2.307[2] (1.6[3] - 2.32[4])
Characteristics
Spectral type B0.3 IV[5] + B1-3V[6]
U−B color index –0.920[2]
B−V color index –0.124[2]
Variable type γ Cas[4]
Astrometry
Radial velocity (Rv)–7[7] km/s
Proper motion (μ) RA: -10.21[1] mas/yr
Dec.: -35.41[1] mas/yr
Parallax (π)6.64 ± 0.89[1] mas
Distance136.0[6] pc
Absolute magnitude (MV)–3.8[8]
Orbit[6][9]
Period (P)10.8092 ± 0.0005 yr
Semi-major axis (a)0.09874 ± 0.00007"
(13.5 ± 0.1 AU)
Eccentricity (e)0.936 ± 0.003
Inclination (i)36 ± 1°
Longitude of the node (Ω)174.0 ± 2.5°
Periastron epoch (T)2011 July 3rd
Argument of periastron (ω)
(secondary)
−2.3 ± 3.8°
Semi-amplitude (K1)
(primary)
23.9 ± 0.8 km/s
Details
δ Sco A
Mass13[6] M
Radius6.7[10] R
Diameter6.7[10] D
Luminosity38,000[11] L
Surface gravity (log g)3.92[8] cgs
Temperature27,400[11] K
Rotational velocity (v sin i)180[5] km/s
δ Sco B
Mass8.2[6] M
Temperature20-24,000[6] K
Age9-10[6][11] Myr
Other designations
Dschubba, Dzuba,[12] Al Jabba,[12] Iclarkrau,[12] 7 Scorpii, BD−22°4068, HD 143275, HIP 78401, HR 5953, FK5 594, SAO 184014, CCDM 16003-2237
Database references
SIMBADdata

Delta Scorpii (δ Scorpii, abbreviated Delta Sco, δ Sco) is a binary star (the presence of a third star in the system is still being debated[3]) in the constellation of Scorpius. The primary component is named Dschubba.[13]

Location[edit]

ρ Ophiuchi region. δ Scorpii is the bright white star on the left (north is down).

δ Scorpii was once used as a spectroscopic standard for the B0 IV classification, but is now considered too unusual and variable.[6]

δ Scorpii is a proper motion member of the Upper Scorpius subgroup of the Scorpius–Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.[8][11] The Upper Scorpius subgroup contains thousands of young stars with mean age 11 million years at average distance of 470 light years (145 parsecs).[11]

In 1981, Delta Scorpii was occulted by Saturn's rings as seen by Voyager 2, with starlight unexpectedly blocked even by the apparently empty gaps, indicating that "there is very little empty space anywhere in the main ring system."[14]

Nomenclature[edit]

δ Scorpii (Latinised to Delta Scorpii) is the system's Bayer designation. The two components are designated Delta Scorpii A and B.

Delta Scorpii bore the traditional name Dschubba. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)[15] to catalogue and standardize proper names for stars. The WGSN approved the name Dschubba for Delta Scorpii A on 21 August 2016 and it is now so entered in the IAU Catalog of Star Names.[13]

In Chinese, 房宿 (Fáng Xiù), meaning Room, refers to an asterism consisting of δ Scorpii, π Scorpii, ρ Scorpii, β1 Scorpii and β2 Scorpii.[16] Consequently, δ Scorpii itself is known as 房宿三 (Fáng Xiù sān), "the Third Star of Room".[17]

Properties[edit]

The primary, Delta Scorpii A, is a B class subgiant surrounded by a disc of material spun off by the rapidly rotating star. The secondary, Delta Scorpii B, orbits every 10.5 years in a highly elongated elliptical orbit; it appears to be normal B class main sequence star. There have been reports that Delta Scorpii A is itself a very close spectroscopic binary, but this does not appear to be the case.[3]

Variability[edit]

Delta Scorpii A is a Gamma Cassiopeiae variable star. This type of star shows irregular slow brightness variations of a few hundredths of a magnitude due to material surrounding the star.

In June 2000, Delta Scorpii was observed by Sebastian Otero to be 0.1 magnitudes brighter than normal. Its brightness has varied since then and has reached at least as high as magnitude 1.6, altering the familiar appearance of Scorpius. Spectra taken after the outburst began have shown that the star is throwing off luminous gases from its equatorial region. The companion passed close by in 2011, again resulting in the star peaking at 1.65 between 5 and 15 July 2011.[3][18]

References[edit]

  1. 1.0 1.1 1.2 1.3 1.4 van Leeuwen, F. (November 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.
  2. 2.0 2.1 2.2 Gutierrez-Moreno, Adelina; Moreno, Hugo (June 1968). "A photometric investigation of the Scorpio-Centaurus association". Astrophysical Journal Supplement 15: 459. Bibcode 1968ApJS...15..459G. doi:10.1086/190168.
  3. 3.0 3.1 3.2 3.3 Miroshnichenko, A. S.; Pasechnik, A. V.; Manset, N.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Gvaramadze, V. V.; Ribeiro, J. et al. (2013). "THE 2011 PERIASTRON PASSAGE OF THE Be BINARY δ Scorpii". The Astrophysical Journal 766 (2): 119. arXiv:1302.4021. Bibcode 2013ApJ...766..119M. doi:10.1088/0004-637X/766/2/119.
  4. 4.0 4.1 Samus, N. N.Expression error: Unrecognized word "etal". (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007–2013)". VizieR On-line Data Catalog: B/gcvs. Originally published in: 2009yCat....102025S 1: 02025. Bibcode 2009yCat....102025S.
  5. 5.0 5.1 Balona, L. A.; Dziembowski, W. A. (October 1999). "Excitation and visibility of high-degree modes in stars". Monthly Notices of the Royal Astronomical Society 309 (1): 221–232. Bibcode 1999MNRAS.309..221B. doi:10.1046/j.1365-8711.1999.02821.x.
  6. 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Miroshnichenko, A. S.; Pasechnik, A. V.; Manset, N.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Gvaramadze, V. V.; Ribeiro, J. et al. (2013). "THE 2011 PERIASTRON PASSAGE OF THE Be BINARY δ Scorpii". The Astrophysical Journal 766 (2): 119. arXiv:1302.4021. Bibcode 2013ApJ...766..119M. doi:10.1088/0004-637X/766/2/119.
  7. Lua error in Module:Citation/CS1 at line 3165: attempt to concatenate a table value.
  8. 8.0 8.1 8.2 de Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989). "Physical parameters of stars in the Scorpio-Centaurus OB association". Astronomy and Astrophysics 216 (1–2): 44–61. Bibcode 1989A&A...216...44D.
  9. Meilland, A. et al. (August 2011). "The binary Be star δ Scorpii at high spectral and spatial resolution. I. Disk geometry and kinematics before the 2011 periastron". Astronomy & Astrophysics 532: A80. arXiv:1106.1746. Bibcode 2011A&A...532A..80M. doi:10.1051/0004-6361/201116798.
  10. Underhill, A. B. et al. (November 1979). "Effective temperatures, angular diameters, distances and linear radii for 160 O and B stars". Monthly Notices of the Royal Astronomical Society 189 (3): 601–605. Bibcode 1979MNRAS.189..601U. doi:10.1093/mnras/189.3.601.
  11. 11.0 11.1 11.2 11.3 11.4 Mark J. Pecaut; Eric E. Mamajek; Eric J. Bubar (February 2012). "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius-Centaurus OB Association". Astrophysical Journal 746 (2): 154. arXiv:1112.1695. Bibcode 2012ApJ...746..154P. doi:10.1088/0004-637X/746/2/154.
  12. 12.0 12.1 12.2 Lua error in Module:Citation/CS1 at line 637: attempt to concatenate local 'chapter' (a table value).
  13. 13.0 13.1 Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  14. Lua error in Module:Citation/CS1 at line 379: attempt to call method 'match' (a nil value).
  15. IAU Working Group on Star Names (WGSN), International Astronomical Union, https://www.iau.org/science/scientific_bodies/working_groups/280/, retrieved 22 May 2016.
  16. (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.
  17. (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived 2008-10-25 at the Wayback Machine., Hong Kong Space Museum. Accessed on line November 23, 2010.
  18. Sigismondi, Costantino (2011), Differential photometry of delta Scorpii during 2011 periastron, 1112, pp. 2356, arXiv:1112.2356, Bibcode 2011arXiv1112.2356S


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