1. Jason Kalirai (Hubble Fellow - UC Santa Cruz) Collaborators: UMontreal - P. Bergeron UCLA - B. Hansen, D. Reitzel, R. M. Rich OCIW - D. Kelson UBC - H. Richer …also, for NGC 6397 Jay Anderson (STScI), Ivan King (UW) James Brewer and Saul Davis (UBC) Gregory Fahlman and Peter Stetson (HIA/NRC) Michael Shara (AMNH) Jarrod Hurley (Swinburne) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

2. Maryland Primary (Feb 12th)!

3. Jason Kalirai (Hubble Fellow - UC Santa Cruz) Collaborators: UMontreal - P. Bergeron UCLA - B. Hansen, D. Reitzel, R. M. Rich OCIW - D. Kelson UBC - H. Richer …also, for NGC 6397 Jay Anderson (STScI), Ivan King (UW) James Brewer and Saul Davis (UBC) Gregory Fahlman and Peter Stetson (HIA/NRC) Michael Shara (AMNH) Jarrod Hurley (Swinburne) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

4. Outline: 1.) What are white dwarfs and why should we study them ? 2.) A new imaging survey for white dwarfs: The CFHT Open Cluster Survey. 3.) The initial-final mass relation. chemical evolution and enrichment of the ISM the age of the Galactic disk the age of the Galactic halo: HST studies of globular clusters 4.) Stellar mass loss as a function of environment. UV upturn in elliptical galaxies planets around white dwarfs type Ia SNe 5.) Serendipity. 6.) Other projects: Galaxy Formation, Structure, and Evolution. Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

5. - Sirius: brightest star in the night sky (V = -1.5). - 1840’s - exhibits irregular motions on the sky (Bessel 1844). - Optical detection of companion by Alvan Clark in 1862. Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

6. - 50 year binary orbit 1 M sun companion, but M V = 11.3 (0.003 L sun )! - Sirius A and B have similar colors Radius of Sirius B = 1/100 Sirius A. - Adams (1914; 1925): spectrum is white, gravitational redshift measured. - White dwarf: very dense remnant of a hydrogen burning star (no fuel). Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

7. 1.) Over 97% of all stars will eventually form white dwarfs. Unique link to the distribution of first generation stars in old stellar populations. 2.) White dwarfs cool predictably with time use as chronometers. 3.) Upper mass limit to white dwarf production = lower limit to type II SNe. 4.) Constraining fundamental stellar evolution and stellar mass loss. 5.) Theoretical calibration of evolutionary models of AGB and PN phases. A Few Reasons to Study White Dwarfs Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

8. - Deep CFHT B,V imaging data set of two dozen, rich open clusters. Goals: 1.) Cluster ages, distances, reddening, richness, etc. 2.) Luminosity and mass functions. 3.) Test theoretical isochrones through numerical simulations. 4.) Catalogue large populations of white dwarfs in each system. Results - NGC 6819: Kalirai et al. (2001, AJ, 122, 267) - NGC 2099: Kalirai et al. (2001, AJ, 122, 3239) - NGC 2168 and NGC 2323: Kalirai et al. (2003, AJ, 126, 1402) - Numerical Simulations: Kalirai & Tosi (2004, MNRAS, 351, 649) - NGC 6791: Kalirai et al. (2007, ApJ, 671, 748) - NGC 7789: Kalirai et al. (2007, ApJ, in press, astro-ph/0706.3894) - data shared with many external groups… The CFHT Open Star Cluster Survey (Kalirai et al. 2001, AJ, 122, 257) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

9. NGC 2099 (M37) - Kalirai et al. (2001, AJ, 122, 3239) Stellar Remnants as Cosmological Probes West (1967)Mermilliod et al. (1996) Kalirai et al. (2001) Space Telescope Science Institute Feb 11 th, 2008

10. Some CFHT CMDs Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

11. Stellar Remnants as Cosmological Probes Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894) Space Telescope Science Institute Feb 11 th, 2008

12. Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

13. The Initial-Final Mass Relation - Total integrated stellar mass loss through post main-sequence evolution. - High mass end: Upper mass limit to WD production. - Low mass end: Ages of the Galactic disk and halo, stellar IMF. Curves from: Marigo (2001, A&A, 370, 194) Girardi et al. (2000, A&AS, 141, 371) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

14. Some CFHT CMDs Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

15. Weidemann + Reimers & Koester (1980’s) Claver et al. (2001) Dobbie et al. (2004, 2006) Williams et al. (2004, 2007) Kalirai et al. (2005) Liebert et al. (2005) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

16. Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894) Conclusion: M final = (0.109 +/- 0.007)M initial + (0.394 +/- 0.025) M sun Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

17. The Age of the MW Disk White dwarf mass function: Liebert, Bergeron & Holberg (2005) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

18. Kalirai et al. (2007, ApJL, 657, 93) The Age of the MW Halo NGC 6397 126 HST/ACS orbits Stellar Remnants as Cosmological Probes Richer et al. (2006, Science, 313, 936) Hansen et al. (2007, ApJ, 671,380) Space Telescope Science Institute Feb 11 th, 2008

19. Hansen et al. (2007, ApJ, 671, 380) The Age of the MW Halo NGC 6397 126 HST/ACS orbits Stellar Remnants as Cosmological Probes t NGC 6397 = 11.5 - 12.0 Gyrs t M4 = 10.1 - 12.5 Gyrs t 47 Tuc = ??? Space Telescope Science Institute Feb 11 th, 2008

20. Hansen et al. (2007, ApJ, 671, 380) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

21.    = +3.56 +/- 0.04 mas/yr    = -17.34 +/- 0.04 mas/yr Kalirai et al. (2007, ApJL, 657, 93) The Orbit of NGC 6397 Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

22. Kalirai et al. (2007, ApJ, 671, 748) A Strange Cluster (N6791): Age = 8 -10 Gyrs but… [Fe/H] = +0.4 Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

23. Bedin et al. (2005, ApJL, 624, 45) MS turnoff age = 8 Gyrs WD cooling age = 2.4 Gyrs ? Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

24. The Theory: - Mass Loss on the RGB (Faulkner 1972; Sweigart 1987, Castellani & Castellani 1993; Hansen 2005). Two Tests: 1.) RGB luminosity function. 2.) WD mass function. Kalirai et al. (2007, ApJ, 671, 748) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

25. Forming He-core White Dwarfs Kalirai et al. (2007, ApJ, 671, 748) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

26. Forming He-core White Dwarfs Bedin et al. (2008, ApJ, in press, astro-ph/0801.1346) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

27. Conclusions and Implications 1.) M final = (0.109 +/- 0.007)M initial + (0.394 +/- 0.025) M sun. 2.) Age of Galactic disk = 8 Gyr, Age of Galactic halo = 12 Gyr. 3.) Mass loss is more efficient in higher metallicity environments. 4.) NGC 6791 stars evolved along three channels…no age issue, 2nd peak. 5.) Source of UV upturn. -- variable excess among galaxies. -- correlation with metallicity ? 6.) Planets. -- currently no known planets around WDs. -- Fischer & Valenti (2005) - 25% MS stars with planets have [Fe/H] > +0.3 - 3% of MS stars with planets have -0.5 < [Fe/H] < 0.0 7.) Type Ia SNe rates. 8.) Kilic, Stanek, & Pinsonneault (2007, ApJ, 671, 761). - Fraction of [Fe/H] > +0.3 stars in Solar nbhd in the past 10 Gyrs = 3%. - Single, low mass WD formation rate = 4%. Space Telescope Science Institute Feb 11 th, 2008

32. Stellar Remnants as Cosmological Probes HST/ACS Gemini/GMOS Space Telescope Science Institute Feb 11 th, 2008

33. Kalirai et al. (2007, ApJ, submitted) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

34. The Andromeda Spiral Galaxy (M31) The Andromeda Team (UCSC): Raja Guhathakurta, Karrie Gilbert, Evan Kirby, Kirsten Howley, Priya Kollipara, Jedidah Isler, Carynn Luine, Johnathan Rice, Andrew Fittingoff, Basilio Yniguez, Jennifer Consiglio Non-UCSC folks: UVa - Steve Majewski, Jamie Ostheimer, Ricky Patterson, & Rachael Beaton STScI - Tom Brown UMass - Mark Fardal UCLA - Michael Rich & David Reitzel Arizona - Michael Cooper Yale - Marla Geha UC Irvine - James Bullock Wesleyan - Andreea Font Columbia - Kathryn Johnston Space Telescope Science Institute Feb 11 th, 2008

35. Spectroscopic and Photometric Landscape of Andromeda’s Stellar Halo SPLASH a

36. Background Image of Night Sky from Stellarium Planetarium Size of M31’s Stellar Halo Image Credit: GALEX team, Caltech, NASA Background Image of Night Sky from Stellarium Planetarium Image Credit: GALEX team, Caltech, NASA Size of M31’s Stellar Halo Background Image of Night Sky from Stellarium Planetarium

38. Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) - Hubble Space Telescope WFPC2 - STScI-PRC03-21

39. Image Credit: NASA and The Hubble Heritage Team (STScI/AURA) - Hubble Space Telescope WFPC2 - STScI-PRC03-21

40. Weidemann + Reimers & Koester (1980’s) Claver et al. (2001) Dobbie et al. (2004, 2006) Williams et al. (2004, 2007) Kalirai et al. (2005) Liebert et al. (2005) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

41. Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

42. Signature of a White Dwarf: Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

43. Hansen et al. (2007, ApJ submitted, astro-ph/0701738) The White Dwarf Cooling Age of NGC 6397: Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008

44. Peeling off the Luminosity Function Kalirai et al. (2007, ApJ, 671, 748) Stellar Remnants as Cosmological Probes Space Telescope Science Institute Feb 11 th, 2008