H Fluorescence in UV Active Binaries

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H? Fluorescence in UV Active Binaries

• Todd Vaccaro

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UV Active Binaries

• ?hot?cool
• Evolved (white dwarf or sub-dwarf companion)
• Small orbit ? illuminated secondary (tidal
  interaction, circular orbit, synchronous
  rotation)
• Orbit not too small ? detached binary (no
  accretion disks or rapid mass transfer)

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H? fluorescence in UV Active (eclipsing) Binaries

• Incident UV absorbed in secondarys chromosphere
  and reprocessed (H? emission)
• Fluorescent region rotates in and out of view
  (phase dependent emission)
• Max em. (inf. conj.) vs. Max abs. (eclipse)
• Model the profile and probe the chromosphere

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Wilson-Devinney (WD) Program

• Model lcs and rvs for photometry and
  spectroscopy
• Differential Corrections (DC) ? Stellar and
  orbital parameters
• Simultaneous solutions w/ lcs and rvs
• Model spectral line profiles

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Candidates FF Aqr V471 Tau

• Common characteristics
• -Phase dependent H? emission
• -Total eclipsing binaries
• -Circular orbits
• -Chromospheric activity
• -Both bright (V?9m)
• Differences
• -Stellar types (mass, size, temp.)
• -Orbital periods size

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Our Observations (Oct. 29-Nov. 9, 1998)

• Simultaneous photometry and spectroscopy
• KPNO
• -0.9m Coudé (KPNO)
• -0.9m BVRI CCD (SARA)
• Clear most nights (some wind/fog)
• Nov. 5 full moon too close to V471 Tau

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FF Aqr

• Eclipsing discovery (Dworetsky et al. 1977)
• - sdOB G8III
• - P9.2d
• - i81
• - q4.0 (?)
• - T140,000K, T24,700K
• - U light curve (original ephemeris)
• - Spots cover 40 (Dorren et al. 1983)
• - R1.1R? , R25.7R? , M1.5M? , M22M? (Etzel
  et al. 1988)
• - Phase dependent H? emission (Marilli et al.
  1995)

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Spot Analysis FF Aqr

• Initial T factor0.80
• 5 spots needed to fit our lcs
• DC adjustment of spot parameters

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Profile Analysis FF Aqr

• Model FeI line (6400.0Å)
• -
• - Star too small! (R27.1R?)
• H? Modeling
• - Fit absorption near eclipse
• - Fit emission near ?0.5 with 76? spot
• - Model too narrow
• - Over estimates intermediate phases
• - Multiple components (wide blue emission
  ?0.74)
• -

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Other emission sources FF Aqr

• Extended structures
• - AB Dor prominences (Cameron Robinson 1989)
• - FF Aqr extended atmosphere (Baliunas 1986)
• Mass loss
• - Eruptive events (coronal mass ejections)
• - Stellar wind
• - dP/dt scenario?

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Conclusion FF Aqr

• Period increased?
• Mass loss?
• Extended structures likely but more phase
  coverage needed
• Velocities of sdOB needed for q
• A future set of solutions for a range of q and i
  with the new stellar radius

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V471 Tau

• Eclipsing discovery (Nelson Young 1970)
• - White Dwarf K2V
• - P12.5 hr
• - i80
• - q1.0, SB2 (Shaefer 1995)
• - T132400K (Barstow et al. 1997), T25000K
• - Period changes binary ephemeris (Bois et al.
  1988)
• - 3rd body (brown dwarf?) (Guinan Ribas 2001)
• - Spots activity cycle?12 yrs (Ibanoglu 1989)
• - R1.01R? , R2.75R? , M1.8M? , M2.8M?
• - Phase dependent H? emission

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Profile Analysis V471 Tau

• Model H? line at eclipse (absorption)
• -
• - Star too small! (R20.94R?)

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Profile Analysis II V471 Tau

• H? emission Modeling
• - Fit emission near ?0.25 with 76? spot
• - Under estimates most phases
• Co-rotating component near ?0. 5
• - 180 km/s displaced near quadratures
• - Similar excess detected by Young et al. (1991)
• -

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Other emission sources V471 Tau

• AB Dor prominences (Donati et al. 1999)
• - 3-5 stellar radii
• - persist for several days
• - co-rotate
• Spot connection
• 1992 lack of emission (Rottler et al. 1998)
• - consistent with activity cycle
• - supports prominences

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Conclusion V471 Tau

• Extended structures likely
• - Possible mechanism for mass loss ?P
• Isolate chromo. Fluorescence during quiescence
  (2003?)
• General profile template