jason kalirai (hubble fellow - uc santa cruz)

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 InstituteFeb 11th, 2008

Maryland Primary (Feb 12th)!

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 InstituteFeb 11th, 2008

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 InstituteFeb 11th, 2008

- 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 InstituteFeb 11th, 2008

- 50 year binary orbit 1 Msun companion, but MV = 11.3 (0.003 Lsun)!

- 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 InstituteFeb 11th, 2008

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 InstituteFeb 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 Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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 InstituteFeb 11th, 2008

Some CFHT CMDs

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Stellar Remnants as Cosmological Probes

Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894)

Space Telescope Science InstituteFeb 11th, 2008

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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 InstituteFeb 11th, 2008

Some CFHT CMDs

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 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)

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894)

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

The Age of the MW Disk

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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

The Age of the MW Halo

NGC 6397126 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 InstituteFeb 11th, 2008

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

The Age of the MW Halo

NGC 6397126 HST/ACS

orbits

Stellar Remnants as Cosmological Probes

tNGC 6397 = 11.5 - 12.0 Gyrs

tM4 = 10.1 - 12.5 Gyrs

t47 Tuc = ???

Space Telescope Science InstituteFeb 11th, 2008

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

= +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 InstituteFeb 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 Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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 InstituteFeb 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 Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Forming He-core White Dwarfs

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Forming He-core White Dwarfs

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Conclusions and Implications

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

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] < 0.07.) 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 InstituteFeb 11th, 2008

Stellar Remnants as Cosmological Probes

HST/ACS Gemini/GMOS

Space Telescope Science InstituteFeb 11th, 2008

Kalirai et al. (2007, ApJ, submitted)

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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 BeatonSTScI - Tom BrownUMass - Mark FardalUCLA - Michael Rich & David ReitzelArizona - Michael CooperYale - Marla GehaUC Irvine - James BullockWesleyan - Andreea FontColumbia - Kathryn Johnston

Space Telescope Science InstituteFeb 11th, 2008

Spectroscopic and Photometric Landscape of Spectroscopic and Photometric Landscape of Andromeda’s Stellar HaloAndromeda’s Stellar Halo

SPLASH

a

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

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

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

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 InstituteFeb 11th, 2008

Kalirai et al. (2007, ApJ in press, astro-ph/0706.3894)

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

Signature of a White Dwarf:

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008

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 InstituteFeb 11th, 2008

Peeling off the Luminosity Function

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

Stellar Remnants as Cosmological Probes

Space Telescope Science InstituteFeb 11th, 2008