Detection of FIP Effect on Late-type Giants D. Garcia-Alvarez, J.J. Drake, L.Lin, V. Kashyap and B.Ball Smithsonian Astrophysical Observatory Coronal Abundances and Thermal Structure Coronal Abundances and Thermal Structure The late-type giants  Ceti, 31 Com and  Vel The late-type giants  Ceti, 31 Com and  Vel  Objects and Observations features  The DEMs and Coronal Abundances  Conclusions

Coronal Abundances and Thermal Structure Abundance anomalies (FIP and inverse-FIP effect, flares). Abundance anomalies (FIP and inverse-FIP effect, flares). Larger range of stars is needed. Larger range of stars is needed. It will help to interpret X-ray observations of stars. It will help to interpret X-ray observations of stars. Why derive Stellar Coronal Abundances? Why/how to derive the Coronal Thermal Structure? Key to understanding the coronal heating. Key to understanding the coronal heating. Must be known before elemental abundances can be determined. Must be known before elemental abundances can be determined. Abundance-independent structure obtained by using ratios of ions from same element. Abundance-independent structure obtained by using ratios of ions from same element.

INPUTS: INPUTS:  Strong lines with the best atomic data (H-like and He-like and Fe ions).  Line ratios from different ions of the same element.  Continuum points are use to normalize model continua computed using a test DEM. THE CODE: THE CODE:  Markov-Chain Monte-Carlo simulations using a Metropolis algorithm (Kashyap & Drake 1998). THE OUTPUT: THE OUTPUT:  Abundance-independent DEM.  Estimation of uncertainties and no artificial smoothing constrains on the derived DEM. The MCMC[M] Method

Objects and Observations Features Stellar photospheric abundances

The Observed Spectra

The Differential Emission Measurements Same slope/shape for the low temperature range. Same slope/shape for the low temperature range. A plateau around log T[K]~6.8±0.2 is observed in  Ceti and  Vel. A plateau around log T[K]~6.8±0.2 is observed in  Ceti and  Vel. Smooth increase and peak at log T[K]~7.1 is observed in 31 Com. Smooth increase and peak at log T[K]~7.1 is observed in 31 Com. Little evidence for substantial amount of plasma at log T[K]>7.3. Little evidence for substantial amount of plasma at log T[K]>7.3.

The Synthetic Spectrum

Finally … the Coronal Abundances We observe solar-like FIP effect for  vel and  Ceti. No clear effect is seen in 31 Com. We observe solar-like FIP effect for  vel and  Ceti. No clear effect is seen in 31 Com. Coronae Na-rich agree with predictions for F-K giants (Drake & Lambert 1994). Coronae Na-rich agree with predictions for F-K giants (Drake & Lambert 1994). O-Na anti-correlation possibly due to very deep mixing (Langer & Hoffman 1998). O-Na anti-correlation possibly due to very deep mixing (Langer & Hoffman 1998). No clear dependency on rotational velocity (  Ceti vsini~3 km/s, 31 Com vsini~67 km/s). No clear dependency on rotational velocity (  Ceti vsini~3 km/s, 31 Com vsini~67 km/s). Structural changes might produce the observed coronal pattern. Structural changes might produce the observed coronal pattern.

 Ceti + 31 Com = Capella ?

Conclusions The late-type giants  Ceti, 31 Com and  Vel share similarities in coronal composition. The late-type giants  Ceti, 31 Com and  Vel share similarities in coronal composition. We detected a solar-like FIP effect for  Ceti and  Vel but not for 31 Com. We detected a solar-like FIP effect for  Ceti and  Vel but not for 31 Com. No clear dependency between rotational velocity and FIP trend. No clear dependency between rotational velocity and FIP trend. Structural changes during their evolution might produce the observed coronal pattern in late-type giants. Structural changes during their evolution might produce the observed coronal pattern in late-type giants.