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Winds in Symbiotic Red Giants: A Perspective from the Base of Outflow

Winds in Symbiotic Red Giants: A Perspective from the Base of Outflow. Cian Crowley School of Physics Trinity College Dublin. Collaborators: Dr. Brian Espey, Joseph Roche Trinity College Dublin Dr. Stephan McCandliss Johns Hopkins University

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Winds in Symbiotic Red Giants: A Perspective from the Base of Outflow

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  1. Winds in Symbiotic Red Giants:A Perspective from the Base of Outflow Cian Crowley School of Physics Trinity College Dublin Collaborators: Dr. Brian Espey, Joseph Roche Trinity College Dublin Dr. Stephan McCandliss Johns Hopkins University + Phoenix contributors & more… CS15 St. Andrews, July 2008

  2. Outline Outline Symbiotics Results Caveats? Project Direction Symbiotics? Symbiotics as probes of red giant winds Overview of Results Wind / Chromosphere conditions, parameters Caveats? Binarity affecting results? Project Direction Chromospheric modelling Photospheric conditions HST cycle 17 data CS15 St. Andrews, July 2008

  3. CS15 St. Andrews, July 2008 Outline Symbiotics Results Caveats? Project Direction Symbiotic Systems Binary Systems Containing: - Red Giant Primary (usually M) - White Dwarf Secondary White Dwarf as a UV search light to probe RG wind in absorption FUSE + HST/STIS data for 4 objects.... (see Espey poster, M3) ...also echelle optical data

  4. CS15 St. Andrews, July 2008 Outline Symbiotics Results Caveats? Project Direction Example of STIS data: non-eclipsed + eclipsed + Absorption Model (blue)‏ FeII Contribution to fit Contribution of HI + SiII, PII, TiII etc.

  5. Outline Symbiotics Results Caveats? Project Direction EG And absorption spectrum • Absorption lines from species such asCII, NI, OI, MgII, SiII, PII, ArI, MnII, FeII, NiII….etc. (no cool or hot bubbles detected) • Transitions observed from range of lower energy levels:absorption from 0 to 4.5ev above ground • Over 2.2 < RRG < 3.7 populated Fe+ levels imply 6,500 K < T < 8,500 K • Wind/chromosphere ‘clumpy’; sizes < 1% RRG • Wind velocity differs from Beta-law in EG And & SY Mus CS15 St. Andrews, July 2008

  6. Outline Symbiotics Results Caveats? Project Direction BF Cyg Absorption • M5 giant, Higher mass-loss rate (~4 - 5 times) • Wind probed further out (~4 - 6.5 RRG) • Similar excitation+ionisation (Texcite~6 - 8000K) • WD more luminous, but, Mass-loss higherionised region confined close to WD similar to EG And CS15 St. Andrews, July 2008

  7. CS15 St. Andrews, July 2008 Outline Symbiotics Results Caveats? Project Direction Caveats? Effect of Binarity on the wind? Effect of WD radiatively, gravitationally, mechanically? • Optical spectra show atmosphere unperturbed • Ionised zone confined close to WD (Cloudy models) • Absorption line profiles symmetric But… Eclipsing systems produce higher mass-loss rates & wind velocities  material deflected onto orbital plane? • Confident that chromos/inner wind diagnostics representitive of isolated stars!

  8. Outline Symbiotics Results Caveats? Project Direction Project Direction Phoenix chromospheric modeling Models need to show sharp temperature rise above photosphere  match plateau at ~8,000 K as observed Photospheric conditions Convective motions  asymmetries in line profiles (see poster of Joe Roche, M11) Also evolutionary status etc. from abundance study HST cycle 17 4 extra observations of EG And: Will tie down wind accel. shape, probe ‘clumpyness’ & test for wind variability, also 2 standards to be observed CS15 St. Andrews, July 2008

  9. Questions…? Crowley, Espey & McCandliss, 2008, ApJ, 675, 711-722 Separate papers on detailed EG And wind modeling & BF Cyg wind in prep. CS15 St. Andrews, July 2008

  10. CS15 St. Andrews, July 2008 Topics for Discussion… To increase rate of progress  more communication between members in field… TCD group propose hosting webpage summarising session, active topics for work & repository for models, spectra etc.  would be a central archive to be updated Identify points for discussion & areas for work…..

  11. CS15 St. Andrews, July 2008 Topics for Discussion… • Identify targets for models & for future observations • i.e., list binary giants (+ isolated proxy stars) that should be modelled in detail list on webpage (along with data + parameters, quick reference for future proposals, model params) • Need more optical data for binary objects? Basic photospheric params? vsin(i) values? • Thermodynamic models publicly available  i.e., can quickly compare to data, can produce radio models (Graham)

  12. CS15 St. Andrews, July 2008 Topics for Discussion (biased!)… • Conditions at photosphere: diagnose/model convective activity (low-mass models?) • Conditions in Chromosphere/inner wind: plateau ~8,000K? Chromos separate from wind? Structure? (neutral medium models?) • Wind accel profile: Delayed (static chromos)? Shallow? • Scaling to supergiants?  same v(r)?

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