Red Giants

Transcript

1. RED GIANTS: A CASE STUDY FOR DISENTANGLING OBSERVATION AND THEORY KOLBY WEISENBURGER 9 MARCH 2016 ASTR 521
2. OBSERVATION PHOTOMETRY SPECTROSCOPY
3. CLASSICAL MODELS DYANAMIC MODELS THEORY OBSERVATION PHOTOMETRY SPECTROSCOPY
4. CLASSICAL MODELS DYNAMIC MODELS SPECTROSCOPY PHOTOMETRY Teff , log g, metallicity, color indices, age
5. OBSERVATION MV RUSSELL 1914 -  Red giants are humungous, luminous, cool stars -  Red giants are an intermediate stage in stellar evolution -  Eventually, something “radioactive” must have happened to counter gravity “This is a revolutionary conclusion; but, so far as I can see, we are simply shut up to it with no reasonable escape.”
6. OBSERVATION + THEORY SANDAGE 1957 Measure: - Color - Magnitude - Luminosity function Assume: - Salpeter function - Evolutionary model !  Effective temperature ! Bolometric magnitude and luminosity
7. OBSERVATION ! THEORY PEARSON EDUCATION
8. THEORY 1D MODELS MARCS Empirical data needed: Ionization and dissociation energies, partition functions, continuous absorption and scattering coefficients, line lists -  Spherically symmetric or plane-parallel geometry -  LTE + mixing length convection -  A to M spectral types, -1 < log g < 5 -  -5 < [Me/H] < 1, various α, C, N -  10-5 to 10 times solar luminosity ~104 models Temperature (K) Log Ross Ross GUSTAFSSON ET AL. 2008
9. THEORY 1D MODELS MARCS + NEXTGEN + KURUCZ + PHOENIX + ATLAS9 + BGEN + PLEZ ET AL. Temperature (K) GUSTAFSSON ET AL. 2008 log Ross Ross
10. THEORY “Here, we are not so much presenting results as rather pointing out problems which are still lingering.” Ludwig & Steffen 2011 3D MODELS?
11. THEORY + OBSERVATION Relative Flux DATA FROM SEROTE ROOS ET AL. 1996; PLOT FROM BERTRAND PLETZ Relative Flux Wavelength (Å)
12. THEORY + OBSERVATION DATA FROM SEROTE ROOS ET AL. 1996; PLOT FROM BERTRAND PLETZ Wavelength (Å) Relative Flux
13. THEORY + OBSERVATION ARINGER ET AL. 2016 1 2 3 4 5 6 7 8 9 10 0.5 1 1.5 (J-K) 1 2 3 4 5 6 7 8 9 10 (V-K) 1 2 3 4 5 (V-I) observed synthetic sun SYNTHETIC PHOTOMETRY -  K and M giants -  Used COMARCS atmospheres to generate spectra then derived observable parameters (e.g. color indices) -  This provides us with a tool to evaluate the effect of Teff , log g, and elemental abundances on photometric parameters
14. THEORY + OBSERVATION OHNAKA 2013 For broad spectral types and characterization, 1D models suffice. For precise abundances and a more detailed understanding of RG physics, one dimension is not sufficient.   GARCÍA-HERNÁNDEZ ET AL. 2007
15. THEORY ! OBSERVATION : HOW CAN WE USE EXISTING DATA TO BETTER CONSTRAIN THEORETICAL MODELS?
16. MEASURE ABUNDANCES WITH APOGEE - 100,000 giant stars to magnitude H = 12.2 - Wavelengths 1.51-1.70 μm - Stellar parameters including log g, Teff , [Fe/H], [α/Fe] - Abundance of 15 chemical species to 0.1 dex precision - Velocity errors < 100 m/s HOW CAN WE USE EXISTING DATA TO BETTER CONSTRAIN THEORETICAL MODELS?
17. OBSERVATION MEASURE ABUNDANCES WITH APOGEE Wavelength (nm) Relative Flux AHN ET AL. 2014
18. OBSERVATION MEASURE ABUNDANCES WITH APOGEE ASTR511 ET AL. 2015 … (ALSO QUAL-DELAYED)
19. OBSERVATION MEASURE ABUNDANCES WITH APOGEE 15325 15330 15335 15340 15345 15350 wavelength ( ˚ A) 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 Normalized Flux 15710 15715 15720 15725 15730 wavelength ( ˚ A) 15210 15215 15220 15225 15230 15235 wavelength ( ˚ A) 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 Normalized Flux 16355 16360 16365 16370 16375 16380 wavelength ( ˚ A) 15230 15235 15240 15245 15250 15255 wavelength ( ˚ A) 0.70 0.75 0.80 0.85 0.90 0.95 1.00 1.05 Normalized Flux 16180 16185 16190 16195 16200 16205 wavelength ( ˚ A) NESS ET AL. 2015
20. PROBE 3D STRUCTURE WITH KEPLER HOW CAN WE USE EXISTING DATA TO BETTER CONSTRAIN THEORETICAL MODELS? -  Thousands of targets between Kepler and K2 campaigns (KASC) -  Reflects the turbulence and near- surface convection within the star -  Oscillations have important ramifications for 3D structure of red giant atmospheres -  Radiative cooling in atmosphere from upwelling gas – models should account for this!
21. OBSERVATION PROBE 3D STRUCTURE WITH KEPLER KEPLER WEBCAST, 10 OCT. 2010
22. ESTIMATE AGES (!!) USING APOGEE AND KEPLER NESS ET AL. 2015
23. OBSERVATION ESTIMATE AGES (!!) USING APOGEE AND KEPLER NESS ET AL. 2015
24. CLASSICAL MODELS DYNAMIC MODELS SPECTROSCOPY PHOTOMETRY T eff , log g, metallicity, color indices, age