J/other/Nat/583.768 2050 red giants CaII EWs (Wan+, 2020)
The tidal remnant of an unusually metal-poor globular cluster.
Wan Z., Lewis G.F., Li T.S., Simpson J.D., Martell S.L., Zucker D.B.,
Mould J.R., Erkal D., Pace A.B., Mackey D., Ji A.P., Koposov S.E.,
Kuehn K., Shipp N., Balbinot E., Bland-Hawthorn J., Casey A.R.,
Da Costa G.S., Kafle P., Sharma S., De Silva G.M.
<Nature, 583, 768-770 (2020)>
=2020Natur.583..768W 2020Natur.583..768W (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Stars, giant ; Equivalent widths ; Optical
Abstract:
Globular clusters are some of the oldest bound stellar structures
observed in the Universe. They are ubiquitous in large galaxies and
are believed to trace intense star-formation events and the
hierarchical build-up of structure. Observations of globular clusters
in the Milky Way, and a wide variety of other galaxies, have found
evidence for a 'metallicity floor', whereby no globular clusters are
found with chemical (metal) abundances below approximately 0.3 to 0.4
per cent of that of the Sun. The existence of this metallicity floor
may reflect a minimum mass and a maximum redshift for surviving
globular clusters to form-both critical components for understanding
the build-up of mass in the Universe. Here we report measurements from
the Southern Stellar Streams Spectroscopic Survey of the spatially
thin, dynamically cold Phoenix stellar stream in the halo of the Milky
Way. The properties of the Phoenix stream are consistent with it being
the tidally disrupted remains of a globular cluster. However, its
metal abundance ([Fe/H]=-2.7) is substantially below the empirical
metallicity floor. The Phoenix stream thus represents the debris of
the most metal-poor globular clusters discovered so far, and its
progenitor is distinct from the present-day globular cluster
population in the local Universe. Its existence implies that globular
clusters below the metallicity floor have probably existed, but were
destroyed during Galactic evolution.
Description:
We present summed equivalent widths of the CaII spectral lines for
2050 red giants in 18 Galactic globular clusters spanning a broad
metallicity range.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
fig2.dat 106 2050 Equivalent widths of the CaII spectral lines for
2050 red giants in 18 Galactic globular clusters
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq Sequential number
6- 24 I19 --- GaiaDR2 GaiaDR2 designation
26- 47 F22.19 mag GMAG GaiaDR2 absolute G magnitude
49- 53 F5.2 [-] [Fe/H] Metallicity
55- 58 F4.2 [-] e_[Fe/H] Metallicity error
60- 77 F18.16 0.1nm EW Equivalent width of the CaII triplet
79- 98 F20.18 0.1nm e_EW Equivalent width of the CaII triplet error
100-106 A7 --- Cluster Cluster name
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 17-Feb-2022