Panchromatic Studies of Galactic Stellar Populations

1. Panchromatic Studies of Galactic Stellar Populations Jason Kalirai (STScI) Outline - The role that Galactic stellar populations play in astrophysics. - The current “State of the Art” – The ACS Survey of Galactic Globular Clusters. - Why go panchromatic? Hints from an HST survey of 47 Tuc. - The potential of synergistic UV, optical, and IR imaging and spectroscopy. +

2. Panchromatic Studies of Galactic Stellar Populations

3. Panchromatic Studies of Galactic Stellar Populations J. Dalcanton (2010, priv comm) Very Wide Field Surveys - STScI June 16th, 2011

4. J. Dalcanton (2010, priv comm.) Panchromatic Studies of Galactic Stellar Populations Summary 1.) Imaging observations of nearby (resolved) stellar populations have provided some of our most important constraints on global astrophysical relations. Calibration of models, IMF, stellar evolution rates, age-metallicity relation, SF law, feedback relations,… 2.) These studies directly inform both galactic and extragalactic astronomy. Very Wide Field Surveys - STScI June 16th, 2011

5. Panchromatic Studies of Galactic Stellar Populations Example: When did baryonic structure formation begin? Star clusters are excellent tracers of parent population star formation histories

6. Panchromatic Studies of Galactic Stellar Populations The Color-Magnitude Diagram Messier 3 (Photographic plates from 200”) Buonanno et al. (1994) Sandage (1953)

7. Panchromatic Studies of Galactic Stellar Populations The Milky Way’s Globular Clusters NGC 2808 M80 M55 NGC 6397 M92 Omega Cen

8. Panchromatic Studies of Galactic Stellar Populations • The Current State of the Art • The HST/ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007) • Homogenous photometry and reduction. • Modeled consistently with updated physics. • Large sample of 60+ clusters. The Milky Way’s Globular Clusters

9. Panchromatic Studies of Galactic Stellar Populations • The Current State of the Art • The HST/ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007) • Homogenous photometry and reduction. • Modeled consistently with updated physics. • Large sample of 60+ clusters. NGC 6362 - Dotter et al. (2010) Dotter et al. (2010)

10. Panchromatic Studies of Galactic Stellar Populations • The Current State of the Art • The HST/ACS Survey of Galactic Globular Clusters (Sarajedini et al. 2007) • Homogenous photometry and reduction. • Modeled consistently with updated physics. • Large sample of 60+ clusters. • Only V and I optical filters. • Small fields of view. The Milky Way’s Globular Clusters

11. Panchromatic Studies of Galactic Stellar Populations • The Current State of the Art • What about the Infrared? • We have never had a high-resolution wide-field IR imager in space!

12. Resolved Stellar Populations in the Near IR Wide Field Deep IR Photometry Measure the stellar inventory of the Milky Way. Calibration of stellar evolution models at red wavelengths. Measure the initial mass function and its dependency on environment. Characterize the hydrogen burning limit. Push into sub-stellar evolutionary studies (L and T dwarfs).

13. Panchromatic Studies of Galactic Stellar Populations Why Go Panchromatic with a Large Field of View? Calibrate UV – IR color-magnitude relations. Increase the sensitivity of main-sequence turnoff fitting methods. Probe complete stellar populations, from the cores to periphery. Carina Nebula - NASA, ESA, N. Smith (UC Berkeley), and the Hubble Heritage Team (STScI/AURA) Hubble Space Telescope ACS/WFC - STScI-PRC07-16A Very Wide Field Surveys - STScI June 16th, 2011

14. Panchromatic Studies of Galactic Stellar Populations Example: Towards more accurate ages Main-Sequence Turnoff Fitting - Well separated filters in l. - Superb sensitivity. - Large field of view.

15. Panchromatic Studies of Galactic Stellar Populations Based on HST/ACS and HST/WFC3 Data Collected as a Part of GO-11677 (PI H. Richer) UBC:Harvey Richer AMNH: Mike Shara, David Zurek HIA/NRC: Greg Fahlman, Peter Stetson Swinburne: Jarrod Hurley STScI: Jay Anderson, Aaron Dotter UBC: Jeremy Heyl, Ryan Goldsbury, Kristen Woodley UCLA: Brad Hansen, Mike Rich, David Reitzel UW: Ivan King

16. Panchromatic Studies of Galactic Stellar Populations

17. Panchromatic Studies of Galactic Stellar Populations

18. Panchromatic Studies of Galactic Stellar Populations ACS/WFC visible color-magnitude diagram

19. Panchromatic Studies of Galactic Stellar Populations WFC3/IR color-magnitude diagram

20. Panchromatic Studies of Galactic Stellar Populations WFC3/UVIS and IR color-magnitude diagrams (1 HST orbit per filter)

21. Panchromatic Studies of Galactic Stellar Populations A panchromatic data set: The color-magnitude relation

22. Panchromatic Studies of Galactic Stellar Populations NIRSpec MSA in Dense Stellar Fields Jason Tumlinson & Jay Anderson + Targets in operable shutter xTargets outside shutters - NIRSpec can be extremely effective at obtaining large (~10,000 stars) statistical samples of stellar spectra in dense fields. Depending on density, 10-40% of all stars can be recovered. - This technique is very efficient because it can be done by reconfiguring the MSA only, without dithering. Sky background exposures are obtained “for free”. - This technique could be employed in globular clusters, star forming regions, the Galactic disk, and the bulge - provided the user requires a statistical sampling of stars.

23. Panchromatic Studies of Galactic Stellar Populations Imaging billions of southern hemisphere stars with wide-field, deep, multi-color, time-series photometry will revolutionize our understanding of stellar populations Looking Forward to Stellar Population Studies 1.) The Ages of Field Stars and SFHs Stellar ages possible through gyrochronology, age-activity relations, eclipsing binaries. 2.) Improving the Variable Star Distance Ladder Probe intrinsic variations in cepheid P-L relation in all southern spirals to 8 Mpc. Calibrate absolute lum. of type IaSNethrough LPV characterization in distant galaxies. 3.) Measuring the Properties of the First Populations Cool subdwarfs are the low mass (metal-poor) end of population II stars Direct photometric selection of most metal-poor halo stars. 4.) Towards a Complete Stellar Inventory: The Mass Function of Stars and the Galactic Mass Budget L0 dwarfs out to 2.1 kpc, T0 dwarfs to 100 pc. 50 million white dwarfs! 5.) Calibration of Stellar Evolution Models 6.) Most of the above in star clusters and nearby galaxies (e.g., LMC/SMC).