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Title: Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST /WFC3 Systems

Abstract

The analysis of multiple populations (MPs) in globular clusters (GCs), both spectroscopically and photometrically, is key in understanding their formation and evolution. The relatively narrow Johnson U, F336W, and Stromgren and Sloan u filters have been crucial in exhibiting these MPs photometrically, but in Paper I we showed that the broader Washington C filter can more efficiently detect MPs in the test case GC NGC 1851. Additionally, In Paper I we detected a double main sequence (MS) that has not been detected in previous observations of NGC 1851. We now match this photometry to NGC 1851's published RGB abundances and find that the two RGB branches observed in C generally exhibit different abundance characteristics in a variety of elements (e.g., Ba, Na, and O) and in CN band strengths, but no single element can define the two RGB branches. However, simultaneously considering [Ba/Fe] or CN strength with either [Na/Fe], [O/Fe], or CN strength can separate the two photometric RGB branches into two distinct abundance groups. Matches of NGC 1851's published SGB and HB abundances to the Washington photometry shows consistent characterizations of the MPs, which can be defined as an O-rich/N-normal population and an O-poor/N-rich population. Photometric synthesis for bothmore » the Washington C filter and the F336W filter finds that these abundance characteristics, with appropriate variations in He, can reproduce for both filters the photometric observations in both the RGB and the MS. This photometric synthesis also confirms the throughput advantages that the C filter has in detecting MPs.« less

Authors:
 [1]; ;  [2]
  1. Center for Astrophysical Sciences, Johns Hopkins University, Baltimore, MD 21218 (United States)
  2. Departamento de Astronomía, Casilla 160, Universidad de Concepción (Chile)
Publication Date:
OSTI Identifier:
22663717
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 4; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; BARIUM; ELEMENT ABUNDANCE; GIANT STARS; IRON; MAIN SEQUENCE STARS; OXYGEN; PHOTOMETRY; SODIUM; STAR CLUSTERS; SYNTHESIS; VARIATIONS

Citation Formats

Cummings, Jeffrey D., Geisler, D., and Villanova, S. Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST /WFC3 Systems. United States: N. p., 2017. Web. doi:10.3847/1538-3881/AA63E5.
Cummings, Jeffrey D., Geisler, D., & Villanova, S. Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST /WFC3 Systems. United States. doi:10.3847/1538-3881/AA63E5.
Cummings, Jeffrey D., Geisler, D., and Villanova, S. Sat . "Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST /WFC3 Systems". United States. doi:10.3847/1538-3881/AA63E5.
@article{osti_22663717,
title = {Multiple Populations in NGC 1851: Abundance Variations and UV Photometric Synthesis in the Washington and HST /WFC3 Systems},
author = {Cummings, Jeffrey D. and Geisler, D. and Villanova, S.},
abstractNote = {The analysis of multiple populations (MPs) in globular clusters (GCs), both spectroscopically and photometrically, is key in understanding their formation and evolution. The relatively narrow Johnson U, F336W, and Stromgren and Sloan u filters have been crucial in exhibiting these MPs photometrically, but in Paper I we showed that the broader Washington C filter can more efficiently detect MPs in the test case GC NGC 1851. Additionally, In Paper I we detected a double main sequence (MS) that has not been detected in previous observations of NGC 1851. We now match this photometry to NGC 1851's published RGB abundances and find that the two RGB branches observed in C generally exhibit different abundance characteristics in a variety of elements (e.g., Ba, Na, and O) and in CN band strengths, but no single element can define the two RGB branches. However, simultaneously considering [Ba/Fe] or CN strength with either [Na/Fe], [O/Fe], or CN strength can separate the two photometric RGB branches into two distinct abundance groups. Matches of NGC 1851's published SGB and HB abundances to the Washington photometry shows consistent characterizations of the MPs, which can be defined as an O-rich/N-normal population and an O-poor/N-rich population. Photometric synthesis for both the Washington C filter and the F336W filter finds that these abundance characteristics, with appropriate variations in He, can reproduce for both filters the photometric observations in both the RGB and the MS. This photometric synthesis also confirms the throughput advantages that the C filter has in detecting MPs.},
doi = {10.3847/1538-3881/AA63E5},
journal = {Astronomical Journal (Online)},
number = 4,
volume = 153,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}