1. Ann E. Hornschemeier The Stellar Content of the CDF-N Survey: A Deep GALACTIC survey

2. Collaborators Eric Feigelson (PSU) Giusi Micela (Palermo) Franz Bauer (PSU) Mark Bautz (MIT) Pat Broos (PSU) Leisa Townsley (PSU) George Chartas (PSU) Wal Sargent (Caltech) Gillian Wilson (SSC) David Alexander (PSU) Niel Brandt (PSU) Gordon Garmire (PSU) Don Schneider (PSU)

3. The Evolution of Stellar X-ray Activity Decline in magnetic activity: rotational spin-down (Shrijver & Zwaan 2000) Micela et al. 2002 From studying stellar clusters  magnetic activity evolves strongly in stellar youth From studying stellar clusters  magnetic activity evolves strongly in stellar youth (e.g., Micela et al. 1985, Guedel et al. 1997, Feigelson & Montmerle 1999, Micela 2002) n Stellar magnetic activity on long timescales (1-10 Gyr) not well-constrained n High Galactic latitude & sensitivity of the CDF surveys  study of old-disk stars

4. Observational Tests n Star counts probe Galactic structure (e.g., review: Bahcall 1986) n XCOUNT (Micela et al. 1992) Convolution of stellar XLF and spatial distribution of stars Convolution of stellar XLF and spatial distribution of stars XCOUNT Prediction for 1 Ms CDF-N (assuming V=22.5 completeness) n Verification  EMSS (Favata et al. 1995)

5. XCOUNT Predictions for CDF-N Survey XCOUNT Predictions for CDF-N Survey n Overall, 20 stars predicted while 12 observed n Agreement in # of dM stars n Disagreement in # of “yellow” stars XCOUNT Prediction for 1 Ms CDF-N (assuming V=22.5 completeness)