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Carina: Dwarf Spheroidal

THE STELLAR CONTENT OF GALAXIES: RESOLVED STELLAR POPULATIONS I . Theoretical foundations Laura Greggio - OAPd. Ciclo di Lezioni focalizzato sul problema della ricostruzione della Storia di Formazione Stellare dall’analisi dellla distribuzione delle stelle sul diagramma Colore-Magnitudine.

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Carina: Dwarf Spheroidal

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  1. THE STELLAR CONTENT OF GALAXIES: RESOLVED STELLAR POPULATIONSI. Theoretical foundationsLaura Greggio - OAPd Ciclo di Lezioni focalizzato sul problema della ricostruzione della Storia di Formazione Stellare dall’analisi dellla distribuzione delle stelle sul diagramma Colore-Magnitudine Lectures on Stellar Populations

  2. Carina: Dwarf Spheroidal Monelli et al. 2004 Lectures on Stellar Populations

  3. DISK FIELD BAR FIELD Recent enhancement (from 0.1 Gyr ago) Enhancement at 3.5 Gyr ago Old SF (from 10-3.0 Gyr ago) Large Magellanic Cloud Smecker-Hane et al. 2002 Lectures on Stellar Populations

  4. NGC 1705 – A Dwarf Blue Galaxy observations interpretation Annibali et al. 2003 Lectures on Stellar Populations

  5. Simulations: Color Coding Reflects AGE(Myr): <10Myr 10↔60 60↔1000 > 1000 SFR constant from 10 Myr to 2 Gyr ago SFR constant from now to 1 Gyr ago Lectures on Stellar Populations

  6. Outline of the Course: • Summary of Stellar Evolution Review of general properties of stellar tracks, which determine the appearance of the HRD and its systematics. • Bolometric Corrections and Colors How we transform from the theoretical (Log L, Log Teff) plane to the observational (Mag,Color) • Basic Relations between Stellar Counts in Selected Regions of the CMD and the SF History Illustrate potentials and limitations of the synthetic CMD method • The Simulator and Some Examples Various technicalities, including the treatment of photometric errors Lectures on Stellar Populations

  7. 100 MO ZAMS 2.5 MO 20 MO PAGB0.6 MO PN 5 MO 5 MO 2.5 MO 2.5 MO RGB ZAHB To WD 1 MO 1MO Evolutionary Tracks Padova 94 set Z=Zo Y=0.28 Lectures on Stellar Populations

  8. 100Ro 2 Mo 0.8 Mo RGB Bump 10 Ro RGB evolution Back to HRD Lectures on Stellar Populations

  9. 1.2 Mo 1 Mo RGB : bump and LF Back to HRD Lectures on Stellar Populations

  10. RGB tip 1 Ro 10 Ro 100 Ro RGB tip P-EAGB RGB base 0.12 0.07 0.03 M tr Flash and After Back to HRD Lectures on Stellar Populations

  11. 15 Age indicator Distance ind Lmax,He 9 Mo 7 6 TRGB Lmin,He 5 4 3 2.2 Mo 10 Ro ZAHB Clump and Loops Back to HRD Lectures on Stellar Populations

  12. BUMP RGB 5 Mo 4 Mo 3 Mo 2.2 Mo BUMP 1.5 Mo with cost=-0.5 RGB 1 Mo with cost=-1 AGB Bump Lectures on Stellar Populations

  13. Clump Clump Bump Bump Bump PMS LFRGBHBAGB Lectures on Stellar Populations

  14. TAGB Ist Pulse TRGB First Pulse and TAGB Lectures on Stellar Populations

  15. Massive Stars Evolution affected by MASS LOSS OVERSHOOTING Chiosi and Maeder 1986 Lectures on Stellar Populations

  16. BSG RSG WR C stars Miras Ceph Clump HB RRLyr WD Where the Stars are Back to HRD Dots are equally spaced in There are 1000 dots along each track Lectures on Stellar Populations

  17. 30 Mo 15 Mo 5 Mo AGB Manque’ 3 Mo Clumps Post E-AGB Clumps 0.9 Mo 0.55 Mo 0.6 Mo 0.5 Mo Dependence on Metallicity Lectures on Stellar Populations

  18. RGB phase transition overshooting tot He burning MS rgb Evolutionary Lifetimes Lectures on Stellar Populations

  19. TIP Base RGB Luminosities Lectures on Stellar Populations

  20. Ist Pulse He burn L-band RGB trans Helium Burning and beyond Lectures on Stellar Populations

  21. Isochrones Girardi et al. 2002 • As Z increases: • isochrones get • fainter and redder • loops get shorter • WR stars are more • easily produced Lectures on Stellar Populations

  22. Uncertainties and wish list Core Convection: affects star’s luminosity H and He lifetimes shape of tracks around Mhook first H shell burning and runway for intermediate mass stars MS width location of RGB bump values of Mtr and Mup ratios N(HB)/N(AGB) loops extension Mass Loss: on the RGBaffects Temperature extension of HB on the AGB affects value of Mup and TAGB for massive stars affects surface abundances, upper limit of Red SGs, productions of WR .. Opacity: affects MS width occurrence and extension of loops Blue to Red ratio Mixing Length, rotation, diffusion, meridional circulation, nuclear reactions… Separate dependence on Y and Z is important Lectures on Stellar Populations

  23. What have we learnt To place on the HRD whatever mass at whatever age we want to pay attention to: • Mtr Mup Mhook : lifetimes and tracks discontinuities • Place correctly RGB Tip (as distance indicator) • Describe accurately the evolution in core He burning close to RGB transition (Lum extension during evolution) • Allow spread of envelope masses for HB stars • Describe extension of the loops, location of BSG, Back-to-the-Blue evolution of high mass stars • …………. AND if we include a metallicity spread Correctly describe all these systematics as a function of Metallicity Lectures on Stellar Populations

  24. Bolometric Correctionsand Colors depends on .... stellar radius system throughput We do not observe Bolometric, we observe through filters: depends on Teff, gravity and Z Lectures on Stellar Populations

  25. Average of Observed Stellar Spectra:Dwarfs SpT T(K) F c.g.s. Lectures on Stellar Populations

  26. B V I U Dwarfs SED & Filters BC strongly depends on SpT Cool stars detected in Red Hot stars detected in Blue COLORS: are Temperature Indicators Cool stars are Red Hot stars are Blue Lectures on Stellar Populations

  27. B0 M5 B5 M2 K5 A0 Effect of gravity Gravity effects are very Important for very hot And very cool stars Lectures on Stellar Populations

  28. Johnson 1966 ARAA 4 193 COLORS: Empirical B-V colors are good Teff indicators for late A, F, G and early K stars For Hot stars SpT is preferred Lectures on Stellar Populations

  29. Bolometric Corrections: Empirical Hottest and Coolest stars are 3-4 mags fainter in V than in Bolometric Gravity dependence can amount to 0.5mags Lectures on Stellar Populations

  30. Models Empirical Model Atmospheres:Kurucz Grid revised by Castelli Lectures on Stellar Populations

  31. Model Atmospheres:dependence on gravity Models Empirical Lectures on Stellar Populations

  32. Molecules Blanketing Model Atmospheres:dependence on Metallicity Lectures on Stellar Populations

  33. Model Atmospheres:Calibration • The Models do a good job for the SED of Dwarfs, especially for intermediate Spectral Types • Not too bad for Giants and Supergiants also • Major problems are met al low Temperatures (Opacity, Molecules) • Anyway, the use of Model Atmospheres becomes a MUST because: they allow us to compute Colors and BCs for various Metallicities AND for whatever filters combinations To do that we: Take a grid of Models Perform calibration Produce Tables of BC, Col function of (Teff ,Log g, [M/H]) Lectures on Stellar Populations

  34. Balmer Jump Go Back Lectures on Stellar Populations

  35. Colors from Model Atmospheres Origlia and Leitherer 1998: Bessel, Castelli and Pletz models through Ground Based Filters Lectures on Stellar Populations

  36. Bolometric Correction from Model Atmospheres Nice and smooth BUT Probably off for Late K and M stars Have you noticed that lines of different colors Span different Temperature Range? THIS IS NOT A SUPERMONGO FALIURE: Lectures on Stellar Populations

  37. Tracks on the Log Teff – Log g Plane WE LACK LOW GRAVITY MODELS FOR MASSIVE STARS WE LACK LOW TEMPERATURE AND LOW GRAVITY MODELS FOR LOW MASS STARS (AT HIGH METALLICITIES) Lectures on Stellar Populations

  38. M&M: attach empirical calibrations Go back Montegriffo et al. (1998) traslated Lectures on Stellar Populations

  39. Bessel, Castelli & Pletz (1998, A&A 333, 231) Compare Kurucz’s revised models (ATLAS9)+ Gustafsson et al revised (NMARCS) models for red dwarfs and giants to empirical colors and BCs for stars in the Solar Neighbourhood (i.e. about solar metallicity). They show color-temperature, color-color, and BC-color relations. Conclude that : • There is a general good agreement for most of the parameter space • B-V predicted too blue for late type stars, likely due to missing atomic and molecular opacity • NMARCS to be preferred to ATLAS9 below 4000 K Lectures on Stellar Populations

  40. A-K Dwarfs Hot Dwarfs GKM Giants The models are shown as curves The data are shown as points The ptype encodes the literature source Lectures on Stellar Populations

  41. NM K Dwarfs Giants Lectures on Stellar Populations

  42. Dwarfs Giants Dwarfs Lectures on Stellar Populations

  43. BaSeL Grid(Lejeune, Cuisinier and Buser 1997 +) • Collect Model Atmospheres from Kurucz • +Bessel + Fluks (for RGs) + Allard (for M dwarfs) • Correct the model spectra so as to match empirical • calibration • Put the corrected models on the net Lectures on Stellar Populations

  44. Lejeune Models: Z dependenceCheck with Globulars’ Ridge Lines BaSeL 2.2 : Corrected Models at solar Z & Z theoretical dependence BaSeL 3.1: Corrected models at various Z based on GCs Ridge Lines 5 GGs with [Fe/H]=-2.2 to -0.7 in UBVRIJHKL For each get Te from V-K (using BaSel 2.2)  BCs vs (Te,g) BaSeL 3.1 Padova 2000: Correction at various Z made to match GCs Ridge Lines with Padova 2000 isochrones ”It is virtually impossible to establish a unique calibration In terms of Z which is consistent with both color –temperature Relations AND GCs ridge lines (with existing isochrones)” Westera et al. 2002 Lectures on Stellar Populations

  45. Libraries with high Spectral resolution Recently developed for Population Synthesis Studies, Stellar spectroscopy, Automatic Classification of Stellar and Galaxy Spectra … not so important for Broad Band Colors Observational Libraries take a sample of well observed stars with known parameters Log Te, Log g, [Fe/H] and derive their spectra INDO-US – Valdes et al. 2004 885 spectra between 3460 and 9464 A + 400 with smaller wavelength range sp. res. ~ 1 A STELIB – Le Borgne et al. 2003 249 spectra between 3200 and 9500 A, sp.res. ~ 3 A Lectures on Stellar Populations

  46. Libraries with high Spectral resolution THEORETICAL MODELS Usually constructed on top of a model atmosphere (Kurucz) + Code for synthetic spectrum which solves monochromatic radiative transport with a large list of lines not very important for broad band colors, but could suggest diagnostic tools Martins et al. 2005: 1654 spectra between 3000 and 7000 A with sp. res. ~0.3 A Special care to describe non-LTE and sphericity effects Lectures on Stellar Populations

  47. Check versus STELIB stars Check versus INDO-US stars Martins et al. 2005 30000 4.5 0.02 3500 1.0 0.01 3700 1.3 0.01 30262 4.18 0.02 14000 4.5 0.02 4000 1.0 0.02 3910 1.6 0.01 13622 3.80 0.05 7000 4.0 0.02 3500 0.0 0.02 3540 0 0.02 7031 4.04 0.01 4540 0.88 0.02 4500 0.0 0.01 Lectures on Stellar Populations

  48. Other Models: Munari et al. : 67800 spectra between 2500 and 10500 A with res of ~1 A cover Te from 3500 to 47500 K, Log g from 0 to 5 [M/H] from -2.5 to +0.5 and [A/Fe]=0,+0.4 Bertone et al. : 2500 spectra with resolution of ~ 0.3 A UV grid Optical grid between 850 and 4750 A 3500 and 7000 A Te from 3000 to 50000 K 4000 to 50000 K Log g from 1 to 5 0 to 5 [M/H] from -2.5 to +0.5 -3 to +0.3 Coelho et al. : spectra between 3000 and 1800 A with res of ~0.02 A cover Te from 3500 to 7000 K, Log g from 0 to 5 [M/H] from -2.5 to +0.5 and [A/Fe]=0,+0.4 Lectures on Stellar Populations

  49. Converted Tracks: B and V Lectures on Stellar Populations

  50. Converted Tracks: V and I Lectures on Stellar Populations

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