2. Studying Binary Stars a Few Photons at a Time Elliott Horch, CIS

3. Astronomy Stars are very VERY …cool.

4. What do we want to know about stars? n How do they form? How much matter is needed? Are planets involved? n How do stars work? n Do they change? How long do they live? n Why do they appear in groups sometimes? n What can they tell us about how the Galaxy formed?

5. What’s going to help us out in answering those questions? n Mass n Luminosity (total light output) n Size (radius) n Surface Temperature n Age n Heavy Metal Content (“metallicity”) n etc.

6. What do we think we know about stars? n Energy production mechanisms n Basic life cycle features n Pulsation n Spectral features

7. What still confuses us? n Details, details… (Sigh.) ä e.g. how to calibrate luminosities, etc?? n Neutrinos n Formation Processes n “Jumps” in HR diagram n etc.

8. Masses and the “MLR” n Theory: Mass and luminosity are related. log(M/M sun ) log(L/L sun ) 0 0 Our favorite star!

9. Reality: Large Uncertainties!

10. Why are masses so hard to measure? n Binary stars. Gravitation --> orbit. N   N   N   N  N  N  N  N  N  N  N  Okay, well how? Scales? Ha! BUT: need SIZE of orbit, which means we need the distance.

11. Why are distances so hard to measure? n Parallax Earth

12. Our Home Galaxy

13. Our Home Galaxy - The Comic Book Version Bulge Disk Halo Globular Clusters

14. Two “Populations” n Population I: ä Disk dwellers ä metal rich n Population II: ä Halo dwellers ä metal poor log(M/M sun ) log(L/L sun ) 0 0 MLR Pop I Pop II

15. Imaging Binary Stars n That *3$%^*&$$% Atmosphere!! ä Blurs out star images, can’t see both stars distinctly if they’re too close together. ä Related to twinkling. n Telescopes and camera systems: the rest of the optical system. ä Big telescopes can resolve closer pairs. ä Need high-speed cameras to “freeze” the twinkling.

16. Why the atmosphere is such a bummer... Ground Atmosphere light

17. At Big Telescopes, Stars “Speckle” speckle images integrated image

18. At Big Telescopes, Stars “Speckle” speckle images integrated image

19. Speckling Binary Star t=0.00s t=0.05s t=0.10s t=0.15s

20. Speckling Binary Star t=0.00s t=0.05s t=0.10s t=0.15s

21. Speckling Binary Star t=0.00s t=0.05s t=0.10s t=0.15s

22. Reminds me of...

23. A “Close Binary” t=0.00s t=0.05s t=0.10s t=0.15s

24. A “Close Binary” t=0.00s t=0.05s t=0.10s t=0.15s

25. A “Close Binary” t=0.00s t=0.05s t=0.10s t=0.15s

26. We can Beat the Atmosphere!! long exposure speckle analysis 1 arcsec

27. KPNO The WIYN Telescope Kitt Peak, Arizona

28. Inside the WIYN Dome

29. Hipparcos (True) Binaries H91 W97W98 W99 H91 C95 W99.02 W99.89

30. Space Telescope FGSs single star double star x signal

31. Koesters Prism

32. A Real FGS Transfer Function n FGS will help us study Pop II binaries. n Orbits n Masses n Luminosities n Pop II MLR !!!!!!! n Better Ages and Distances to Glob. Clusters!!!! Henry et al. (1999) arcsec -0.8 0.8

33. Conclusions n Stars are interesting. n Star images taken at big telescopes “speckle.” n Interferometric imaging of binary stars helps us determine their masses and luminosities, which in turn helps us understand how they work. ä Speckle imaging from the ground. ä Fine Guidance Sensor data from the Hubble Space Telescope.