jason kalirai (uc santa cruz)
DESCRIPTION
Stellar Remnants as Astrophysical Probes. March 11 th , 2008. Hubble Fellows Symp. 2008 -- STScI. Jason Kalirai (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 project: - PowerPoint PPT PresentationTRANSCRIPT
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