Delta Scorpii

Delta Scorpii


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
Mass13 + 8.2[6] M☉
Radius6.7[10](A) R☉
Luminosity38,000[11](A) L☉
Surface gravity (log g)3.92[8](A) cgs
Temperature27,400[11] + 20-24,000[6] K
Rotational velocity (v sin i)180[5](A) km/s
Age9-10[11][6] 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 Sco, δ Scorpii) is a star in the constellation Scorpius. It has the traditional name Dschubba.

Because it is near the ecliptic δ Scorpii is occasionally occulted by the Moon, or (extremely rarely) by planets. It was once used as a spectroscopic standard for the B0 IV classification, but is now considered too unusual and variable.[6]

Delta 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]

System

Dschubba is a binary star. The primary is a B class subgiant surrounded by a disc of material spun off by the rapidly rotating star. The secondary orbits every 10.5 years in a highly elongated elliptical orbit. The secondary 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. The presence of a third star in the system is still being debated.[3]

Variability

Delta Scorpii 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.[13][3]

References

  1. 1 2 3 4 5 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. 1 2 3 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. 1 2 3 Miroshnichenko, A. S.; Pasechnik, A. V.; Manset, N.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Gvaramadze, V. V.; Ribeiro, J.; Fernando, A.; Garrel, T.; Knapen, J. H.; Buil, C.; Heathcote, B.; Pollmann, E.; Mauclaire, B.; Thizy, O.; Martin, J.; Zharikov, S. V.; Okazaki, A. T.; Gandet, T. L.; Eversberg, T.; Reinecke, N. (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. 1 2 Samus, N. N.; Durlevich, O. V.; et al. (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. 1 2 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. 1 2 3 4 5 6 7 Miroshnichenko, A. S.; Pasechnik, A. V.; Manset, N.; Carciofi, A. C.; Rivinius, Th.; Štefl, S.; Gvaramadze, V. V.; Ribeiro, J.; Fernando, A.; Garrel, T.; Knapen, J. H.; Buil, C.; Heathcote, B.; Pollmann, E.; Mauclaire, B.; Thizy, O.; Martin, J.; Zharikov, S. V.; Okazaki, A. T.; Gandet, T. L.; Eversberg, T.; Reinecke, N. (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. ↑ Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick, eds. The Revision of the General Catalogue of Radial Velocities. Determination of Radial Velocities and their Applications 30 (University of Toronto: International Astronomical Union). p. 57. Bibcode:1967IAUS...30...57E.
  8. 1 2 3 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. 1 2 3 4 5 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. 1 2 3 Moore, Patrick (2010). "Scorpion in the Sky". The Sky at Night. p. 95. doi:10.1007/978-1-4419-6409-0_24. ISBN 978-1-4419-6408-3.
  13. ↑ Sigismondi, Costantino (2011), Differential photometry of delta Scorpii during 2011 periastron 1112, p. 2356, arXiv:1112.2356, Bibcode:2011arXiv1112.2356S

External links

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