CDS active region results

1. CDS active region results Dr Peter Young, Rutherford Appleton Laboratory

2. Intense transition region brightenings • Oxygen and neon lines enhanced over q.s. by factors ≳ 20 • Photospheric abundances (Young & Mason 1997) • Velocity shifts? • Line broadenings? Dr Peter Young, Rutherford Appleton Laboratory

3. Intense transition region brightenings • Signatures: • Strong continuum (scattered Ly-alpha?) • O IV 625.8 strong ( high densities) • No response from corona Dr Peter Young, Rutherford Appleton Laboratory

4. Blinkers • Parnell et al. (2002) extended blinker study of Bewsher et al. (2003) to active regions • Properties are very similar, except • More frequent (up to 7 times more) • Intensity enhancement higher (up to factor 3) • Coronal response in some cases Dr Peter Young, Rutherford Appleton Laboratory

5. Oscillations • Typical feature of transition region above sunspots (Fludra, Brynildsen, etc.). ~3 min period • Other active region: Ireland et al. (1999), O’Shea et al. (2001) • 5 min oscillations most common  photospheric driver • Mg IX, Fe XVI: more significant oscillations in velocity than intensity Dr Peter Young, Rutherford Appleton Laboratory

6. Large TRACE loops • Ubiquitous feature of TRACE 171 images of active regions • Often show strong Mg/Ne enhancement in CDS data • Footpoint density (Mg VII) is around 1010 cm-3 • Leg density (Si X) is around 108.5 cm-3 • What is relation to sunspot plumes? Dr Peter Young, Rutherford Appleton Laboratory

7. Mg VI Mg VII Si VIII Mg X Mg IX Dr Peter Young, Rutherford Appleton Laboratory

8. Sunspot Plumes • “A sunspot plume is observed if the contours for peak line intensity are located with a considerable fraction of the emission inside the white light sunspot.” • Brynildsen et al. 1999, Sol.Phys. 186, 141 • Very weak coronal emission usually seen above sunspots, sunspot plumes not visible in corona • Are sunspot plumes the footpoints of TRACE loops? Dr Peter Young, Rutherford Appleton Laboratory

9. Dr Peter Young, Rutherford Appleton Laboratory

10. Active region structure • Small active regions have a core-halo structure (Gallagher et al. 2001, Mason et al. 1999) • High temperature (Fe XVI) core, with high density ~1010 cm-3 • Pressure falls off around this core Dr Peter Young, Rutherford Appleton Laboratory

11. Dynamic transition region loops • Loops seen in, e.g., O V above the limb are very dynamic • Doppler shifts 50-300 km/s • Independent of coronal loops • Can only be seen at limb! (Intensity is lower than average QS) Dr Peter Young, Rutherford Appleton Laboratory

12. Coronal loop structure • Controversial! • TRACE/EIT analyses give isothermal loops • Brkovic et al. (2001) find isothermal with CDS • Schmelz et al. (2002) do not find isothermal with CDS Dr Peter Young, Rutherford Appleton Laboratory

13. Flare Observations • Czaykowska et al. (1999) presented velocity measurements in O V, Fe XVI, Fe XIX in a flare • What else can be obtained from CDS observations? Dr Peter Young, Rutherford Appleton Laboratory