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First evidence of multiple populations along the AGB from Strömgren photometry

Gruyters, Pieter LU ; Casagrande, Luca; Milone, Antonino P.; Hodgkin, Simon T.; Serenelli, Aldo and Feltzing, Sofia LU (2017) In Astronomy and Astrophysics 603.
Abstract

Spectroscopic studies have demonstrated that nearly all Galactic globular clusters (GCs) harbour multiple stellar populations with different chemical compositions. Moreover, colour-magnitude diagrams based exclusively on Strömgrem photometry have allowed us to identify and characterise multiple populations along the RGB of a large number of clusters. In this paper we show for the first time that Strömgren photometry is also very efficient at identifying multiple populations along the AGB, and demonstrate that the AGB of M 3, M 92, NGC 362, NGC 1851, and NGC 6752 are not consistent with a single stellar population. We also provide a catalogue of RGB and AGB stars photometrically identified in these clusters for further spectroscopic... (More)

Spectroscopic studies have demonstrated that nearly all Galactic globular clusters (GCs) harbour multiple stellar populations with different chemical compositions. Moreover, colour-magnitude diagrams based exclusively on Strömgrem photometry have allowed us to identify and characterise multiple populations along the RGB of a large number of clusters. In this paper we show for the first time that Strömgren photometry is also very efficient at identifying multiple populations along the AGB, and demonstrate that the AGB of M 3, M 92, NGC 362, NGC 1851, and NGC 6752 are not consistent with a single stellar population. We also provide a catalogue of RGB and AGB stars photometrically identified in these clusters for further spectroscopic follow-up studies. We combined photometry and elemental abundances from the literature for RGB and AGB stars in NGC 6752 where the presence of multiple populations along the AGB has been widely debated. We find that, while the MS, SGB, and RGB host three stellar populations with different helium and light element abundances, only two populations of AGB stars are present in the cluster. These results are consistent with standard evolutionary theory.

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organization
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type
Contribution to journal
publication status
published
subject
keywords
Globular clusters: General, Hertzsprung-Russell and C-M diagrams, Stars: Abundances, Techniques: Photometric
in
Astronomy and Astrophysics
volume
603
publisher
EDP Sciences
external identifiers
  • scopus:85022342394
  • wos:000406619100080
ISSN
0004-6361
DOI
10.1051/0004-6361/201630341
language
English
LU publication?
yes
id
d74a74f9-e492-47ba-b71d-737a00fbeccd
date added to LUP
2017-07-24 11:50:17
date last changed
2018-01-07 12:12:48
@article{d74a74f9-e492-47ba-b71d-737a00fbeccd,
  abstract     = {<p>Spectroscopic studies have demonstrated that nearly all Galactic globular clusters (GCs) harbour multiple stellar populations with different chemical compositions. Moreover, colour-magnitude diagrams based exclusively on Strömgrem photometry have allowed us to identify and characterise multiple populations along the RGB of a large number of clusters. In this paper we show for the first time that Strömgren photometry is also very efficient at identifying multiple populations along the AGB, and demonstrate that the AGB of M 3, M 92, NGC 362, NGC 1851, and NGC 6752 are not consistent with a single stellar population. We also provide a catalogue of RGB and AGB stars photometrically identified in these clusters for further spectroscopic follow-up studies. We combined photometry and elemental abundances from the literature for RGB and AGB stars in NGC 6752 where the presence of multiple populations along the AGB has been widely debated. We find that, while the MS, SGB, and RGB host three stellar populations with different helium and light element abundances, only two populations of AGB stars are present in the cluster. These results are consistent with standard evolutionary theory.</p>},
  articleno    = {A37},
  author       = {Gruyters, Pieter and Casagrande, Luca and Milone, Antonino P. and Hodgkin, Simon T. and Serenelli, Aldo and Feltzing, Sofia},
  issn         = {0004-6361},
  keyword      = {Globular clusters: General,Hertzsprung-Russell and C-M diagrams,Stars: Abundances,Techniques: Photometric},
  language     = {eng},
  month        = {07},
  publisher    = {EDP Sciences},
  series       = {Astronomy and Astrophysics},
  title        = {First evidence of multiple populations along the AGB from Strömgren photometry},
  url          = {http://dx.doi.org/10.1051/0004-6361/201630341},
  volume       = {603},
  year         = {2017},
}