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Creating a Legacy of High Quality COS Far Ultraviolet Spectra of Cataclysmic Variable Stars

Creating a Legacy of High Quality COS Far Ultraviolet Spectra of Cataclysmic Variable Stars. Edward M. Sion Department of Astronomy and Astrophysics Villanova University. Collaborators. xxxxxxxxxxx. 4444444444. xxxxxxxxxxx.

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Creating a Legacy of High Quality COS Far Ultraviolet Spectra of Cataclysmic Variable Stars

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  1. Creating a Legacy of High QualityCOS Far Ultraviolet Spectra of Cataclysmic Variable Stars Edward M. Sion Department of Astronomy and Astrophysics Villanova University

  2. Collaborators

  3. xxxxxxxxxxx 4444444444 xxxxxxxxxxx

  4. Orbital angular momentum loss drives mass transfer rate onto the WD via gravitational wave emission and magnetic stellar wind braking. WD temperature is linked to long term compressional heating and hence the time-averaged rate of accretion onto the WD (Sion 1995, Townsley and Bildsten 2003). CVs as potential Type Ia SN progenitors via the single degenerate model; Accretion onto the WD leads to Chandrasekhar Limit Mass. Do the masses of WDs in CVs increase or decrease with time? Thermal timescale mass transfer systems (e.g. supersoft X-ray Binaries) are the stable H-burning progenitors of the CVs with CNO-processed chemical Abundances but their WDs did not reach the Chandrasekhar Limit; hence they are “Failed” Type Ia SN. Overview

  5. Far Ultraviolet Spectra • IUE Archival • HST FOS, GHRS, STIS, COS • FUSE • EUVE

  6. Synthetic Spectra • High Gravity LTE and NLTE Model Atmospheres (TLUSTY200, SYNSPEC98) • Optically Thick, Steady State, Accretion Disk Models (TLUSDISK200) • Accretion Belt Models • Accretion Rings • Accretion Curtain Models

  7. Sion, E. M. et al. (2008), ApJ, 681, 543 Figure 6

  8. Godon, P. et al. (2008), ApJ, in press SS Aur SS Aur

  9. Sion, E.M. et al. (2008), ApJ, 681, 543 Figure 1

  10. Sion, E. and Szkody, P. 2012, White Dwarfs in CVs, in press

  11. RXJ0232-3718

  12. CONCLUSION GAIA will be launched next year, and will deliver HST/FGS-like parallaxes for practically all known CVs, turning fluxes and magnitudes into luminosities and accretion rate. SDSS and Other Ground-based surveys provide a deep, homogeneous population of CVs. HST/COS is the best facility that has ever been available. STIS Snapshot was limited by S/N and spectral resolution. Quadruple the number of WD masses; ~ 50 rotation rates, Vsini; double the number of reliable surface temperatures (~ 50), double the number of CV WDs with photospheric abundances. Increase the number of Post-TTMT Systems by a factor of 2 – 3. What is their Period distribution? The overall result of our Large GO will be a ‘Transformational Knowledge’ of compact binary evolution and accretion physics

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