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
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The RGB and AGB of Simple Stellar Populations (SSP)
The RGB and AGB of Simple Stellar Populations (SSP). 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. Unusual views, perspectives, new applications - PowerPoint PPT Presentation
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The RGB and AGB of Simple Stellar
Populations (SSP)Unusual views, perspectives, new applicationsby 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 bestobservational facilities ofthe future will
beoptimized for
thenear 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 RGBsis what we will
seeof newly resolveddistant 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 starsKoch et al. 2007ApJ, 657, 241 Bosler et al. 2007, MNRAS, 378, 318
Bellazzini et al. 2004, 2005CaT metallicities from Bellazzini et al. 2008
Sgr dSph
M54
SpecPhot
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 deepAnd accurate photometry of the whole sky:
1. Catalogues to work with
1. Photometric “standards” in each field
Optimization of the productivity of largetelescopes: get the best observations underthe best conditions and don’t care ofabsolute 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. 2004 isochrones differ widely for very red models in i and z
(Teff - color transformations to be blamed, as usual for low Teff?). 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 YFor 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: M4See Yong et al. 2008, 2009; Lee et al 2009
NH CN CNCN
- 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, 2009Richardson et al. (2008)
The bump can be used todisentangle 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 SSPConcluding 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!