Creating a Legacy of High QualityCreating a Legacy of High QualityCOS Far Ultraviolet Spectra of COS Far Ultraviolet Spectra of
Cataclysmic Variable Stars Cataclysmic Variable Stars
Edward M. SionEdward M. SionDepartment of Astronomy and Astrophysics Department of Astronomy and Astrophysics
Villanova UniversityVillanova University
Collaborators
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• 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
Far Ultraviolet SpectraFar Ultraviolet Spectra
IUE ArchivalIUE Archival
HST FOS, GHRS, STIS, COSHST FOS, GHRS, STIS, COS
FUSEFUSE
EUVEEUVE
Synthetic Spectra Synthetic Spectra
High Gravity LTE and NLTE Model High Gravity LTE and NLTE Model Atmospheres (TLUSTY200, SYNSPEC98)Atmospheres (TLUSTY200, SYNSPEC98)
Optically Thick, Steady State, Accretion Optically Thick, Steady State, Accretion Disk Models (TLUSDISK200)Disk Models (TLUSDISK200)
Accretion Belt ModelsAccretion Belt Models
Accretion RingsAccretion Rings
Accretion Curtain ModelsAccretion Curtain Models
Figure 6
Sion, E. M. et al. (2008), ApJ, 681, 543
SS AurSS Aur Godon, P. et al. (2008), ApJ, in press
Figure 1
Sion, E.M. et al. (2008), ApJ, 681, 543
Object Mass(Msun ) Type Method
U Gem 1.12 Dwarf Nova S
IP Peg 1.09 Dwarf Nova S
SDSS1035+05 0.94 Dwarf Nova E
SDSS1702+32 0.94 Dwarf Nova E
V1500 Cyg >0.9 Dwarf Nova S
OU Vir 0.89 Dwarf Nova E
AM Her 0.88 Polar S
WZ Sge 0.85 Dwarf Nova S
SDSS0926+36 0.84 AM CVn E
GY Cnc 0.82 Dwarf Nova S
QS Vir 0.78 Dwarf Nova S
ST LMi 0.76 Polar S
EX Dra 0.75 Dwarf Nova E
MR Ser 0.71 Polar S
QQ Vul 0.70 Polar S
OY Car 0.69 Dwarf Nova E
HT Cas 0.61 Novalike E
DQ Her 0.60 Nova S
Z Cha 0.54 Dwarf Nova E
Sion, E. and Szkody, P. 2012, White Dwarfs in CVs, in press
Object Type Porb Teff
GW Lib DN 76.8 14,700
BW Scl DN 78.2 14,800
LL And DN 79.2 14,300
HS2331 DN 81 10,500
SDSS1610 DN 81 14,500
WZ Sge DN 81.6 14,900
AL Com DN 81.6 16,300
SW UMa DN 81.8 13,900
SDSS1339 DN 82.5 12,500
HV Vir DN 83.5 13,300
WX Cet DN 83.9 14,500
T Leo DN 84.7 16,000
EG Cnc DN 86.4 13,300
BC UMa DN 90.2 15,200
VY Aqr DN 90.8 14,000
EK Tra DN 91.6 18,800
SDSS0131 DN 98 14,500
VW Hyi DN 106.9 22,000
CU Vel DN 113.0 18,500
Object Type Porb Teff
EF Peg DN 123 16,600
MV Lyr NL 191.0 47,000
DW UMa NL 198.0 46,000
TT Ari NL 198.0 39,000
UU Aql DN 235.5 27,000
WW Ceti DN 253 26,000
U Gem DN 254.7 31,000
SS Aur DN 263.2 31,000
RX And DN 302.2 34,000
Z Cam DN 417.4 57,000
RU Peg DN 539.4 70,000
CH UMa DN 0.343d 40,000
BV Cen DN 878.6 40,000
SDSS2205 DN 15,000
V794 Aql NL >47,000
V895 Cen Polar 285.9 13,800
V1043 Cen Polar 251.4 15,000
EF Eri Polar 81.0 9,500
HU Aqr Polar 125.0 14,000
RXJ0232-3718
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