J/A+A/694/A248 Metallicity spread and dispersion among P1 stars (Latour+, 2025)
A stellar census in globular clusters with MUSE.
Metallicity spread and dispersion among first-population stars.
Latour M., Kamann S., Martocchia S., Husser T.-O., Saracino S., Dreizler S.
<Astron. Astrophys. 694, A248 (2025)>
=2025A&A...694A.248L 2025A&A...694A.248L (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Spectroscopy ; Abundances, [Fe/H]
Keywords: stars: abundances - stars: fundamental parameters -
globular clusters: general
Abstract:
Multiple populations are ubiquitous in the old massive globular
clusters (GCs) of the Milky Way. It is still unclear how they arose
during the formation of a GC. The topic of iron and metallicity
variations has recently attracted attention with the measurement of
iron variations among the primordial population (P1) stars of Galactic
GCs. We use the spectra of more than 8000 RGB stars in 21 Galactic GCs
observed with MUSE to derive individual stellar metallicities [M/H].
For each cluster, we use the HST photometric catalogs to separate
the stars into two main populations (P1 and P2). We measure the
metallicity spread within the primordial population of each cluster by
combining our metallicity measurements with the stars
ΔF275W,F814W pseudo-color. We also derive metallicity
dispersions (σ[M/H]) for the P1 and P2 stars of each GC. In
all but three GCs, we measure a significant correlation between the
metallicity and the ΔF275W,F814W pseudo-color of the P1 stars
such that stars with larger {DeltaF275W,F814W have higher
metallicities. We measure metallicity spreads that range from 0.03 to
0.24dex and correlate with the GC masses. As for the intrinsic
metallicity dispersions, when combining the P1 and P2 stars, we
measure values ranging from 0.02 dex to 0.08dex that correlate very
well with the GC masses. We compared the metallicity dispersion
among the P1 and P2 stars and found that the P2 stars have metallicity
dispersions that are smaller or equal to that of the P1 stars. We find
that both the metallicity spreads of the P1 stars (from the
{DeltaF275W,F814W spread in the chromosome maps) and the metallicity
dispersions ({sigma[M/H]) correlate with the GC masses, as predicted
by some theoretical self-enrichment models presented in the
literature.
Description:
We provide various measurements for the stars that are included in our
samples of both P1 and P2 stars in the 21 Globular clusters. The star
identification numbers are unique per cluster. The surface gravity
(logg) is obtained from the position of the star in the CMD when
compared to an isochrone. The effective temperature and metallicity
are derived from a full fit of the MUSE spectra. The values are then
averaged over the number of spectra available for a given star. The
metallicity that we measured is an overal one, and is not a direct
iron abundance measurement. We also include the coordinates of the
star in our chromosome maps.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 132 8382 Properties of the RGB stars in our spectral sample
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See also:
J/A+A/635/A114 : EW and [Fe/H] for 30000 globular cluster RGB stars
(Husser+ 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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2- 7 I6 --- Source Star identification number
10- 20 F11.7 deg RAdeg Right ascension (J2000)
23- 33 F11.7 deg DEdeg Declination (J2000)
36- 42 A7 --- Cluster Cluster name
46- 51 F6.3 [Sun] [M/H] Metallicity
54- 58 F5.3 [Sun] e_[M/H] Error on the metallicity
65- 68 I4 K Teff Effective temperature
75- 76 I2 K e_Teff Error on the effective temperature
79- 81 I3 --- SNR Average signal-to-noise of the Nspec spectra
86- 87 I2 --- Nspec Number of spectra used to average
Teff and [M/H]
93- 97 F5.3 [cm/s2] logg Surface gravity
102-106 F5.3 [cm/s2] e_logg Error on the surface gravity (1)
109-115 F7.4 --- CMx Delta(F275W,F814W), X-axis position on the
Chromosome map
118-124 F7.4 --- CMy DeltaC(F275W,F336W,F438W), Y-axis position
on the Chromosome map
128 I1 --- P1 [0/1] =1 if the star belongs to P1
132 I1 --- P2 [0/1] =1 if the star belongs to P2
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Note (1): For three clusters there is not uncertainty (=0) on the surface
gravity measurements because it was obtained with only one set of photometry.
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Acknowledgements:
Marilyn Latour, marilyn.latour(at)uni-goettingen.de
(End) Patricia Vannier [CDS] 21-Jan-2025