Messenger No. 134supp (December 2008)

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Conference Supplement

2-2 (PDF)
F. Primas, A. Weiss
Special Report on the MPA/ESO/MPE/USM 2008 Joint Astronomy Conference Chemical Evolution of Dwarf Galaxies and Stellar Clusters

ADS BibCode:
2008Msngr.134S...2P
Section:
Conference Supplement
Author(s)/Affiliation(s):
Primas, F.; Weiss, A.
AA(ESO) AB(Max-Planck-Institut für Astrophysik, Garching, Germany)
3-8 (PDF)
M. Mateo
The Complex Evolution of Simple Systems

ADS BibCode:
2008Msngr.134S...3M
Section:
Conference Supplement
Author(s)/Affiliation(s):
Mateo, M.
AA(University of Michigan, Ann Arbor, USA)
Abstract:
The simplicity and extreme ages of globular clusters and dwarf galaxies imply that these systems may be useful windows to the earliest era of galaxy formation. Recent discoveries of local dwarfs have, in some ways, begun to blur the distinctions between the two types of systems. However, it remains clear that the two types of systems arose from fundamentally different conditions in the early Universe. Globular clusters result from ‘intense’ (what is often referred to as ‘efficient’) star formation processes, possibly related to major merging, while dwarf galaxies represent regions of much more ‘se-date’ (low efficiency) star formation, possibly independent of significant contributions from merging. I review spatial, kinematic and chemical results that support this interpretation.
References:
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9-12 (PDF)
R. Gratton
Abundances in Globular Cluster Stars: What is the Relation with Dwarf Galaxies?

ADS BibCode:
2008Msngr.134S...9G
Section:
Conference Supplement
Author(s)/Affiliation(s):
Gratton, R.
AA(INAF - Osservatorio Astronomico di Padova, Italy)
Abstract:
In the last few years increasing evidence has accumulated for some chemical evolution within globular clusters. The evidence is much clearer for the most massive clusters. Many authors have proposed that (at least the most massive) globular clusters may be closely related to the nuclei of dwarf galaxies. I review recent results on the chemical inhomogeneities in globular clusters and discuss the perspectives opened up by these results.
References:
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13-17 (PDF)
S. Cassisi et al.
Evidence for Sub-Populations in Globular Clusters: Their Properties and Relationship with Cluster Properties

ADS BibCode:
2008Msngr.134S..13C
Section:
Conference Supplement
Author(s)/Affiliation(s):
Cassisi, S.; Bragaglia, A.; Gratton, R.; Milone, A.; Piotto, G.; Renzini, A.
AA(INAF – Astronomical Observatory of Teramo, Italy) AB(INAF – Astronomical Observatory of Bologna, Italy) AC(INAF – Astronomical Observatory of Padova, Italy) AD(Department of Astronomy, University of Padova, Italy) AE(Department of Astronomy, University of Padova, Italy) AF(INAF – Astronomical Observatory of Padova, Italy)
Abstract:
An increasing number of both photometric and spectroscopic observations over the last decade have shown the existence of distinct sub-populations in some Galactic globular clusters. This evidence severely challenges the paradigm of globular clusters as the prototypes of single, simple stellar populations. In this review, we briefly summarise the main empirical findings collected so far and discuss the properties of these sub-populations and their possible relationship with global cluster properties.
References:
Anderson, J. 1997, PhD thesis, University of California, Berkeley Baumgardt, H., Makino, J. & Hut, P. 2005, ApJ, 620, 238 Bedin, L. R. et al. 2000, A&A, 363, 159 Bedin, L. R. et al. 2004, ApJ, 605, L125 Busso, G. et al. 2007, A&A, 474, 105 Calamida, A. et al. 2007, ApJ, 670, 400 Calamida, A. et al. 2008, in preparation Caloi, V. & D’Antona, F. 2007, A&A, 463, 949 Carretta, E. et al. 2006, A&A, 450, 523 Cassisi, S. et al. 2008, ApJ, 672, L115 Choi, E. & Yi, S. K. 2007, MNRAS, 375, L1 Cohen, J. G., Briley, M. M. & Stetson, P. B. 2002, AJ, 123, 2525 D’Antona, F. & Caloi, V. 2004, ApJ, 611, 871 Decressin, T. et al. 2007, A&A, 464, 1029 Ferraro, F. R. et al. 1998, ApJ, 500, 311 Ferraro, F. R., Bellazzini, M. & Pancino, E. 2002, ApJ, 573, L95 Gratton, R. G. et al. 2001, A&A, 369, 87 Gratton, R., Sneden, C. & Carretta, E. 2004, ARAA, 42, 385 Hesser, J. E. et al. 1982, AJ, 87, 1470 Hughes, J. et al. 2004, AJ, 127, 980 King, I. R. et al. 1998, ApJ, 492, L37 Lee, Y.-W. et al. 2005, ApJ, 621, L57 Marino, A. F. et al. 2008, A&A, in press (astro-ph/0808.1414) Milone, A. P. et al. 2008, ApJ, 673, 241 Miocchi, P. 2007, MNRAS, 381, 103 Norris, J. E. 2004, ApJ, 612, L25 Noyola, E., Gebhardt, K. & Bergmann, M. 2008, ApJ, 676, 1008 Pancino, E. et al. 2000, ApJ, 534, L83 Pancino, E. et al. 2003, MNRAS, 345, 683 Pancino, E. et al. 2007, ApJ, 661, L155 Piotto, G. et al. 1999, AJ, 118, 1727 Piotto, G. et al. 2005, ApJ, 621, 777 Piotto, G. et al. 2007, ApJ, 661, L53 Piotto, G. 2008, Mem. Soc. Astr. It., 79, 334 Recio-Blanco, A. et al. 2006, A&A, 452, 875 Renzini, A. 2008, MNRAS, in press (astro-ph/0808.4095) Rich, R. M. et al. 1997, ApJ, 484, L25 Salaris, M., Cassisi, S. & Pietrinferni, A. 2008, ApJ, 678, L25 Salaris, M., Cassisi, S. & Weiss, A. 2002, PASP, 114, 375 Siegel, M. H. et al. 2007, ApJ, 667, L57 Sollima, A. et al. 2005, ApJ, 634, 332 Stanford, L. M. et al. 2006, ApJ, 647, 1075 Trenti, M. et al. 2007, MNRAS, 374, 857 Ventura, P. & D’Antona, F. 2008, MNRAS, 385, 2034 Ventura, P. et al. 2001, ApJ, 550, L65 Villanova, S. et al. 2007, ApJ, 663, 296 Yong, D. & Grundahl, F. 2008, ApJ, 672, L29
18-22 (PDF)
F. D’Antona, P. Ventura
Linking Chemical Signatures of Globular Clusters to Chemical Evolution

ADS BibCode:
2008Msngr.134S..18D
Section:
Conference Supplement
Author(s)/Affiliation(s):
D’Antona, F.; Ventura, P.
AA(INAF - Astronomical Observatory of Rome, Italy) AB(INAF - Astronomical Observatory of Rome, Italy)
Abstract:
The majority of Globular Clusters (GC) show chemical inhomogeneities in the composition of their stars, apparently attributable to a second stellar generation in which the forming gas is enriched by hot CNO-cycled material processed in stars belonging to a first stellar generation. We review the reasons why the site of the nucleo-synthesis can be identified with hot-bottom burning in the envelopes of massive asymptotic giant branch (AGB) stars and super-AGB stars. The analysis of spectroscopic data and photometric signatures, such as the horizontal branch morphology, shows that the percentage of ‘anomalous’ stars is 50 % or more in most GCs examined so far. If anomalies are the rule and not the exception, then they clearly are closely related to the dynamical way in which GCs form and survive. We show a possible solution obtained by a hydrodynamical model followed by the N-body evolution of the two stellar populations, and propose that most GCs survive thanks to the formation of the second stellar generation.
References:
Angulo, C. et al. 1999, Nucl. Phys. A, 656, 3 Bedin, L. R. et al. 2004, ApJ, 605, L125 Bekki, K. & Norris, J. E. 2006, ApJ, 637, L109 Bonifacio, P. et al. 2002, A&A, 390, 91 Busso, G. et al. 2007, A&A, 474, 105 Caloi, V. & D’Antona, F. 2005, A&A, 121, 95 Caloi, V. & D’Antona, F. 2007, A&A, 463, 949 Canuto, V. M., Goldman, I. & Mazzitelli, I. 1996, ApJ, 473, 550 Carretta, E. et al. 2005, A&A, 433, 597 Cohen, J. G., Briley, M. M. & Stetson, P. B. 2002, AJ, 123, 2525 Cohen, J. G. & Meléndez, J. 2005, AJ, 129, 303 Cottrell, P. L. & Da Costa, G. S. 1981, ApJ, 245, L79 D’Antona, F. et al. 2002, A&A, 395, 69 D’Antona, F. & Caloi, V. 2004, ApJ, 611, 871 D’Antona, F. & Caloi, V. 2008, MNRAS, 390, 693 D’Antona, F. et al. 2005, ApJ, 631, 868 Decressin, T. et al. 2007a, A&A, 464, 1029 D’Ercole, A. et al. 2008, MNRAS, in press Gratton, R. G., Sneden, C. & Carretta, E. 2004, ARA&A, 42, 385 Hale, S. E. et al. 2002, Phys. Rev. C, 65, 5801 Iben, I. & Renzini, A. 1983, ARA&A, 21, 271 Ivanova, N. et al. 2008, MNRAS, 386, 553 Karakas, A. & Lattanzio, J. C. 2007, PASA, 24, 103 King, I. R. et al. 1998, ApJ, 492, L37 Moehler, S. et al. 2004, A&A, 415, 313 Moehler, S. et al. 2007, A&A, 475, L5 Norris, J. E. 2004, ApJL, 612, L25 Pasquini, L. et al. 2005, A&A, 441, 549 Pasquini, L. et al. 2008, A&A, 489, 315 Piotto, G. et al. 2005, ApJ, 621, 777 Piotto, G. et al. 2007, ApJ, 661, L53 Pumo, M. L., D’Antona, F. & Ventura, P. 2008, ApJ, 672, L25 Richer, H. B. et al. 2006, Science, 313, 936 Ritossa, C., Garca-Berro, E. & Iben, I. J. 1999, ApJ, 515, 381 Salaris, M. et al. 2006, ApJ, 645, 1131 Siess, L. 2007a, A&A, 476, 893 Siess, L. 2007b, Why Galaxies Care About AGB Stars: Their Importance as Actors and Probes, in ASP Conf. Series, 378, 9 Ventura, P. & D’Antona, F. 2005, A&A, 431, 279 Yong, D. & Grundahl, F. 2008, ApJ, 672, L29
23-27 (PDF)
K.A. Venn, V.M. Hill
Chemical Signatures in Dwarf Galaxies

ADS BibCode:
2008Msngr.134S..23V
Section:
Conference Supplement
Author(s)/Affiliation(s):
Venn, K.A.; Hill, V.M.
AA(University of Victoria, British Columbia, Canada) AB(Observatoire de la Côte d’Azur, Nice, France)
Abstract:
Chemical signatures in dwarf galaxies describe the examination of specific elemental abundance ratios to investigate the formation and evolution of dwarf galaxies, particularly when compared with the variety of stellar populations in the Galaxy. Abundance ratios can come from HII region emission lines, planetary nebulae, or supernova remnants, but mostly they come from stars. Since stars can live a very long time, for example, a 0.8 MSun star born at the time of the Big Bang would only now be ascending the red giant branch, and, if, for the most part, its quiescent main sequence lifetime had been uneventful, then it is possible that the surface chemistry of stars actually still resembles their natal chemistry. Detailed abundances of stars in dwarf galaxies can be used to reconstruct their chemical evolution, which we now find to be distinct from any other component of the Galaxy, questioning the assertion that dwarf galaxies like these built up the Galaxy. Potential solutions to reconciling dwarf galaxy abundances and Galaxy formation models include the timescale for significant merging and the possibility for uncovering different stellar populations in the new ultra-faint dwarfs.
References:
Abadi, M. G. et al. 2003, ApJ, 597, 21 Battaglia, G. et al. 2006, A&A, 459, 423 Belokurov, V. et al. 2007, ApJ, 654, 897 Bellazzini, M. et al. 2006, A&A, 446, 1 Brook, C. et al. 2007, ApJ, 661, 10 de Blok, W. J. G. & Walter, F. 2000, ApJ, 537, 95 Demers, S., Battinelli, P. & Kunkel, W. E. 2006, ApJ, 636, 85 Eggen, O., Lynden-Bell, D. & Sandage, A. R. 1962, ApJ, 136, 748 Fenner, Y. et al. 2006, ApJ, 646, 184 Geisler, D. et al. 2005, AJ, 129, 1428 Helmi, A. et al. 2006, ApJ, 651, L121 Hill, V. M. et al. 2008, in prep. Kirby, E. N. et al. 2008, ApJ, 685, 43 Koch, A. et al. 2008, AJ, 135, 1580 Lanfranchi, G. A., Matteucci, F. & Cescutti, G. 2006, A&A, 453, 67 Lanfranchi, G. A., Matteucci, F. & Cescutti, G. 2008, A&A, 481, 635 Leaman, R., et al. 2008, ApJ, submitted Letarte, B., Hill, V. M. & Tolstoy, E. 2007, EAS Publications Series, 24, 33 Letarte, B. et al. 2006, A&A, 453, 547 Marcolini, A. et al. 2008, MNRAS, 386, 2173 Olszewski, E. W., Suntzeff, N. & Mateo, M. 1996, ARAA, 34, 511 Pompéia, L. et al. 2008, A&A, 480, 379 Sbordone, L. et al. 2007, A&A, 465, 815 Schoerck, T. et al. 2008, arXiv:0809.1172 Shetrone, M. D., Bolte, M. & Stetson, P. B. 1998, AJ, 115, 1888 Shetrone, M. D. et al. 2003, AJ, 125, 684 Simon, J. & Geha, M. 2007, ApJ, 670, 313 Smecker-Hane, T. et al. 2002, ApJ, 566, 239 Suntzeff, N. 1985 in ESO Workshop on Production and Distribution of C, N, O Elements, European Southern Observatory, 83 Tinsley, B. M. 1979, ApJ, 229, 1046 Tolstoy, E. et al. 2003, AJ, 125, 707 Tolstoy, E. et al. 2001, MNRAS, 327, 918 Travaglio, C. et al. 2004, ApJ, 601, 864 Venn, K. A. et al. 2004, AJ, 128, 1177
28-30 (PDF)
K.C. Freeman
Chemical Evolution of Dwarf Galaxies and Stellar Clusters: Conference Summary

ADS BibCode:
2008Msngr.134S..28C
Section:
Conference Supplement
Author(s)/Affiliation(s):
Freeman, K.C.
AA(Research School of Astronomy and Astrophysics, The Australian National University, Canberra, Australia)
Abstract:
The summary begins by considering the contributions on the differences between globular clusters (GCs) and dwarf spheroidal (dSph) galaxies. Then I discuss globular clusters: the topics include multiple sequences in the colour-magnitude plane, light element abundance anomalies, globular cluster systems and other issues. The next section is devoted to dwarf galaxies, summarising new results on their kinematics, masses and baryon content, their star formation histories, and their chemical abundance ranges and chemical signatures. The last section discusses some of the other interesting related points that came up during the meeting.