jason kalirai (uc santa cruz)

Jason Kalirai (UC Santa Cruz)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Collaborators:

UMontreal - P. Bergeron

UCLA - B. Hansen, D. Reitzel, R. M. Rich

OCIW - D. Kelson

UBC - H. Richer

…also for NGC 6397 project:

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)

Outline:

1.) A new imaging survey for white dwarfs: The CFHT Open Cluster Survey.

2.) The initial-final mass relation. chemical evolution and enrichment of the ISM

the age of the Galactic halo: HST studies of globular clusters the age of the Galactic disk

3.) Stellar mass loss as a function of environment. UV upturn in elliptical galaxies planets around white dwarfs

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

- 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 Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

NGC 6819 Synthetic CMD

Some ResultsAge = 2.2 +/- 0.2 GyrE(B-V) = 0.12(m-M)o = 12.20

Z = 0.02Overshooting required20-30% binariesMtot = 4 X 103 Msun

Inconsistent lower MS

Kalirai & Tosi (2004, MNRAS, 351, 649)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Some CFHT CMDs

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Kalirai et al. (2008, ApJ, 676, 594)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Kalirai et al. (2008, ApJ, 676, 594)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

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)Kalirai et al. (2008, ApJ, 676, 594)

Kalirai et al. (2008, ApJ, 676, 594)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Kalirai et al. (2007, ApJL, 657, 93)

The Age of the MW Halo

NGC 6397126 HST/ACS

orbits

Richer et al. (2006, Science, 313, 936)Hansen et al. (2007, ApJ, 671, 380)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Hansen et al. (2007, ApJ, 671, 380)

The Age of the MW Halo

NGC 6397126 HST/ACS

orbits

tNGC 6397 = 11.5 - 12.0 Gyrs

tM4 = 10.1 - 12.5 Gyrs

t47 Tuc = ???

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Kalirai et al. (2007, ApJ, 671, 748)

A Strange Cluster (N6791):

Age = 8 -10 Gyrs

but…

[Fe/H] = +0.4

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Bedin et al. (2005, ApJL, 624, 45)

MS turnoff age = 8 Gyrs

WD cooling age = 2.4 Gyrs?

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

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 Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Forming He-core White Dwarfs

Kalirai et al. (2007, ApJ, 671, 748)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Forming He-core White Dwarfs

Bedin et al. (2008, ApJ, in press, astro-ph/0801.1346)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

Summary:

age/distance/reddening/binary fraction/etc. measured for a large sample.

Mfinal = (0.109 +/- 0.007)Minitial + (0.394 +/- 0.025) Msun.

Age of globular cluster NGC 6397 = 11.5 - 12.0 Gyr Age of globular cluster NGC 6121 = 10.1 - 12.5 Gyr Age of Galactic disk = 8 Gyr Mass loss is more efficient in higher metallicity environments.

Implications: UV upturn in E’s planets around WDs

Conclusions

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008

The Age of the MW Disk

White dwarf mass function: Liebert, Bergeron & Holberg (2005)

Stellar Remnants as Astrophysical Probes

Hubble Fellows Symp. 2008 -- STScIMarch 11th, 2008