J/ApJ/844/164 HST astro-photometric analysis of NGC5139. III. (Bellini+, 2017)
The state-of-the-art HST astro-photometric analysis of the core of
ω Centauri.
III. The main sequence's multiple populations galore.
Bellini A., Milone A.P., Anderson J., Marino A.F., Piotto G.,
van der Marel R.P., Bedin L.R., King I.R.
<Astrophys. J., 844, 164 (2017)>
=2017ApJ...844..164B 2017ApJ...844..164B
ADC_Keywords: Clusters, globular ; Stars, dwarfs
Keywords: globular clusters: individual (NGC 5139);
Hertzsprung-Russell and C-M diagrams; stars: Population II;
techniques: photometric
Abstract:
We take advantage of the exquisite quality of the Hubble Space
Telescope 26-filter astro-photometric catalog of the core of
ωCen presented in the first paper of this series and the
empirical differential-reddening correction presented in the second
paper in order to distill the main sequence into its constituent
populations. To this end, we restrict ourselves to the five most
useful filters: the magic "trio" of F275W, F336W, and F438W, along
with F606W and F814W. We develop a strategy for identifying color
systems where different populations stand out most distinctly, then we
isolate those populations and examine them in other filters where
their subpopulations also come to light. In this way, we have
identified at least 15 subpopulations, each of which has a distinctive
fiducial curve through our five-dimensional photometric space. We
confirm the MSa to be split into two subcomponents, and find that both
the bMS and the rMS are split into three subcomponents. Moreover, we
have discovered two additional MS groups: the MSd (which has three
subcomponents) shares similar properties with the bMS, and the MSe
(which has four subcomponents) has properties more similar to those of
the rMS. We examine the fiducial curves together and use synthetic
spectra to infer relative heavy-element, light-element, and helium
abundances for the populations. Our findings show that the stellar
populations and star formation history of ω Cen are even more
complex than inferred previously. Finally, we provide as a supplement
to the original catalog a list that identifies for each star which
population it is most likely associated with.
Description:
The results presented here are the product of a massive effort, and
represent a continuation of what we published in Bellini+
(2010, J/AJ/140/631). Paper I of this series (Bellini+ 2017, J/ApJ/842/6)
describes the photometric techniques we adopted and applied to 650
individual exposures in 26 different bands. The photometry has been
corrected for differential reddening and zero-point spatial variations
in Bellini+ (2017ApJ...842....7B 2017ApJ...842....7B, Paper II). In this paper, we analyze
the CMDs and the so-called "chromosome" maps (Milone+ 2017MNRAS.464.3636M 2017MNRAS.464.3636M)
of the MS of the cluster, and finally identify at least 15 distinct
stellar populations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 9 478477 Multi-population identifier
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See also:
VII/195 : Globular Clusters in the Milky Way (Harris, 1996)
J/ApJ/654/915 : Deep FORS1 BR photometry of omega Cen (Sollima+, 2007)
J/AJ/140/631 : HST WFC3/UVIS photometry of omega Cen core (Bellini+, 2010)
J/ApJ/722/1373 : ω Centauri giants abundances (Johnson+, 2010)
J/ApJ/731/64 : Spectroscopy of 300 RGBs in ω Cen (Marino+, 2011)
J/ApJ/791/107 : Parameters of NGC 5139 SGBs stars (Villanova+, 2014)
J/ApJ/842/6 : Astro-photometric cat. of the core of NGC5139 (Bellini+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- ID [1/478477] Star ID, Bellini+ (2017, J/ApJ/842/6)
8- 9 I2 --- Pop [0/15]? Sub-population identity (1)
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Note (1): Sub-population identity as follows:
0 = any star in the astro-photometric catalog not in a sub-population,
including those that did not qualify for this analysis;
1 = MSa1 (Fe:+++, He:+++, N:?);
2 = MSa2 (Fe:+++, He:+++, N:?);
3 = bMS1 (Fe:+, He:+++, N:++);
4 = bMS2 (Fe:+, He:+++, N:++);
5 = bMS3 (Fe:+, He:+++, N:++);
6 = rMS1 (Fe:-, He:-, N:-);
7 = rMS2 (Fe:-, He:-, N:+);
8 = rMS3 (Fe:-, He:-, N:+);
9 = MSd1 (Fe:++, He:++, N:+);
10 = MSd2 (Fe:++, He:++, N:+);
11 = MSd3 (Fe:++, He:++, N:+);
12 = MSe1 (Fe:-, He:-, N:+);
13 = MSe2 (Fe:+, He:-, N:-);
14 = MSe3 (Fe:+, He:-, N:+);
15 = MSe4 (Fe:+, He:-, N:-).
(One or more "+" signs indicate an increasingly high abundance,
a "-" sign refers a relative abundance similar to that of the
reference subpopulation, and a "?" means that that abundance cannot
be qualitatively quantified with the tools at our disposal.)
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History:
From electronic version of the journal
References:
Bellini et al. Paper I. 2017ApJ...842....6B 2017ApJ...842....6B Cat. J/ApJ/842/6
Bellini et al. Paper II. 2017ApJ...842....7B 2017ApJ...842....7B
Bellini et al. Paper III. 2017ApJ...844..164B 2017ApJ...844..164B This Catalog
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Mar-2018