The RGB and AGB of Simple Stellar Populations (SSP) Unusual views, perspectives, new applications by Michele Bellazzini (INAF – OA Bologna) The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Francesco has already discussed the use of GCs as calibrators for RGB/AGB properties; RGB in NIR etc. Carme will review RGB/AGB in resolved galaxies Let me have a look to less frequented corners Some of the results shown here are have been obtained with: F. Ferraro, R. Ibata, L. Monaco, E. Pancino, A. Sollima, G. Beccari, E. Carretta, A. Bragaglia and many other friends and collaborators

Both the best observational facilities of the future will be optimized for the near infrared JWST will “see” also the I,i, and z) band A dSph in the Virgo cluster. Durrel et al. (2007) HST/ACS AGBs and RGBs is what we will see of newly resolved distant galaxies (old pop) The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Understanding and calibrating the AGB/RGB [SSPs!] will be crucial for future stellar astronomy

RGB as metallicity indicators: do they work well? Photometric MDs from interpolation on grids of GC RGB templates compares very well with their spectroscopic counterparts The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Leo I CaT metallicities for 52 stars Koch et al. 2007ApJ, 657, 241 Bosler et al. 2007, MNRAS, 378, 318 Bellazzini et al. 2004, 2005 CaT metallicities from Bellazzini et al Sgr dSph M54 Spec Phot

The RGB Tip: latest calibrations The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 The RGB Tip is a mature and widely used technique. It can be used to build-up a comprehensive cosmological distance ladder independent of Cepheids [Tamman et al. 2008; Mould et al. 2009] Classical empirical calibrators are GCs See: Madore et al. (2009); Bellazzini et al. (2008); Rizzi et al. (2007) for recent developments and reviews

RGB in the SDSS ugriz system. 1 perspectives The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 SDSS already cover part of the Northern Hem. LSST and Pan-STARRS will provide deep And accurate photometry of the whole sky: 1.Catalogues to work with 1.Photometric “standards” in each field Optimization of the productivity of large telescopes: get the best observations under the best conditions and don’t care of absolute calibration, it comes for free VV124 with LBC D=1.3 Mpc

RGB in the SDSS ugriz system. The RGB Tip: r, i, z The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 i and z are the most interesting SDSS bands for the TRGB, but r seems also very good for [M/H]<-1 Basti and Girardi et al isochrones differ widely for very red models in i and z (T eff - color transformations to be blamed, as usual for low T eff ?). To be checked with observations. Also with SDSS passbands, calibrations as a function of color strongly mitigate the age dependency [this is true for any set of models and any color I’ve looked at]. Models of similar Z has similar Y For comparisons with other sets of models see Bellazzini (2008)

RGB in the SDSS ugriz system. Playing with real data The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Clem et al. (2008) u’g’r’i’z’ of 5 clusters from CFHT deep images; only ridge lines are pubicily available An et al. (2008) DAOPHOT photometry for all the clusters included in the SDSS, from SDSS original images: ugriz An et al. (2008): all the catalogues are publicily available. We can start to play.

RGB in the SDSS ugriz system. The non-simple SPSSs - premise The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Marino et al., 2008, A&A, 490, 625: M4 See Yong et al. 2008, 2009; Lee et al 2009 NHCN -CN-weak, Na-poor “primordial” stars -CN-strong, Na-rich “second-generation” stars See Carretta et al. 2008

RGB in the SDSS ugriz system. The non-simple SPSSs - results The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Abundances from GIRAFFE spectra Carretta et al. (2009) Bimodality in (u-g) emerges from stars selected to lie very close to the RGB rigde line in (g-r)

RGB in the SDSS ugriz system. The non-simple SPSSs - perspectives The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 We can search for Multiple Populations in distant clusters, where it is difficult to obtain large samples of abundances from HR spectra We are looking into other clusters for which both abundances and SDSS photometry is available: more can be observed

RGB in the SDSS ugriz system. The observed RGB bump The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 The luminosity of the bump depends on: 1.metallicity, 2. age, and 3. He content Is a good observable (easy to spot and to measure accurately) as it is a PEAK in the Luminosity Function.

AMR from the bump - premise The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 Richardson et al. (2008) The bump can be used to disentangle different Populations: substructures in M31 Sollima et al. (2008) Coupled with independent info on the metallicity it can be used to Constrain the (average) Age, the and the Age-Metallicity Relation. We have done this in Sgr, Leo II, ω Cen, etc.

AMR from the bump - a view of a special case Sollima et al. (2009) Individual metallicities of individual stars from Giraffe HR spectroscopy (elemental abundance analisys ongoing). The run of the bump mag with [Fe/H]: Constraints on the SFH/AMR at the earliest stages of chemical evolution of ω Cen Vel and met for 2557 stars in the outskirts of the cluster: 318 of which are bona fide members

The RGB and AGB of SSP Concluding remarks… An era is approaching in which our ability to extract information about stellar systems from their AGB/RGB will become more and more important It’s time to look at old problems with new eyes: new photometric systems, new techniques etc… Thank you very much! The Giant Branches Workshop – Leiden, The Netherlands, May 11-15, 2009 A special thank to the organizers for having invited me to this very interesting meeting!