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The 2011 Periastron Passage of the Bebinary  Sco

The 2011 Periastron Passage of the Bebinary  Sco. Anatoly Miroshnichenko University of North Carolina at Greensboro USA. Parameters of the  Sco Binary The Primary’s Disk During the Last Orbital Cycle Current Status and Predictions for the Periastron. Parameters of  Sco.

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The 2011 Periastron Passage of the Bebinary  Sco

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  1. The 2011 Periastron Passage of the Bebinary Sco Anatoly Miroshnichenko University of North Carolina at Greensboro USA • Parameters of the  Sco Binary • The Primary’s Disk During the Last Orbital Cycle • Current Status and Predictions for the Periastron

  2. Parameters of  Sco Optical brightness without disk, V=2.32 mag Spectral type B0.3 IV Distance, D = 12315 pc Luminosity, log L/Lʘ = 4.40.1 Surface temperature, Teff = 27500500 K Surface gravity, log g = 4.0 (typical of a dwarf) This is a binary system with an angular separation at apoastron of 0.2 arcseconds Orbital period, P = 10.8 years Eccentricity, e = 0.940.01 Secondary, V ~1.7 mag, Sp.T. ~B3 (uncertain)

  3. Scoin the HRD

  4. Orbit of Sco Angular Separation: Apoastron – 200 mas Periastron – 6 mas Interferometric data from 1970’s to 1990’s  Sco A

  5.  Sco without Disk

  6. When did the Emission Appear? Koubsky 2005, Astrophys. & Space Science, 296, 165

  7. Orbit of  Sco Average radial velocities of the H emission line near periastron in 2000 4 months Add 10.8 years

  8. Brightness  Spectrum

  9. Disk in 2001

  10. Disk in 2001 From Carciofi et al. (2006, ApJ, 652, 1617)

  11. Recent Brightness Variations

  12. Current State Data from Sebastian Otero as of 5/5/2011

  13. H Line Width Drop

  14. Possible Explanations The brightness decrease in 2004/5 can be due to a decreasing mass loss from the primary The disk became a ring Observed consequences: The H line width decreased (no contribution from rapidly rotating part of the disk) The line equivalent width (EW) decreased

  15. What to Expect at Periastron The primary’s disk size was ~ 20 R1 or ~ 150 Rʘ Distance between the stars at periastron is d = 24 R1 Primary’s Roche lobe size ~ 0.6 d or ~ 15 R1 Consequences: Some disk material may flow into the secondary’s Roche lobe Disk may become denser and line emission will rise Single- or triple-peak profiles may be observed

  16. Roche Lobes

  17. H line in 2000 and 2010/11

  18. What to Observe • He II 4686 Ǻ to trace the photospheric radial velocity • H to trace the entire disk changes • He I 5876 and 6678 Ǻ to trace changes in the inner parts of the disk • Very high signal-to-noise spectra of the HeI 4471 + Mg II 4481 Ǻ to try to detect the secondary • Spectra need accompanying photometry • Interferometry will further constrain the orbit

  19. Secondary’s Signature at Periastron Radial velocity difference is ~120 km/s

  20. He II 4686 Ǻ Region OII OII NIII OII

  21. Disk Before Periastron

  22. Disk At Periastron

  23. Disk After Periastron

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