J/A+A/690/A158 PseudoColor maps of RGB stars in 22 GCs (Carretta+, 2024)
Discrepancies between spectroscopy and HST photometry in tagging multiple
stellar populations in 22 globular clusters.
Carretta E, Bragaglia A.
<Astron. Astrophys. 690, A158 (2024)>
=2024A&A...690A.158C 2024A&A...690A.158C (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Photometry, ultraviolet ; Colors ; Abundances
Keywords: stars: abundances - stars: atmospheres - stars: Population II -
globular clusters: general
Abstract:
Multiple populations (MPs) in globular clusters (GCs) are stars
distinct by their abundances of light elements. The MPs can be
directly separated by measuring abundances of C, N, O, Na, Al, Mg with
spectroscopy or indirectly from photometric sequences created by the
impact of different chemistry on band passes of particular filters,
such as the HST pseudo-colours in the ultraviolet. An attempt to link
HST pseudo-colours maps (PCMs) and spectroscopy was done by Marino et
al. (2019MNRAS.487.3815M 2019MNRAS.487.3815M), using abundances mostly from our FLAMES
survey. However, we uncovered that an incomplete census of stars in
common was used in their population tagging. We correct the situation
by building our own PCMs and matching them with our abundances in 20
GCs, plus two GCs from other sources, doubling the sample with
spectroscopic abundances available. We found that the pseudo-colour
(magF275W-2*magF336W+magF438W) does not have a monotonic trend with Na
abundances, enhanced by proton-capture reactions in MPs. Moreover, on
average about 16% of stars with spectroscopic Na abundances show a
discrepant tagging of MPs with respect to the HST photometry. Stars
with chemistry of second generation (SG) are mistaken for first
generation (FG) objects according to HST photometry and vice versa. In
general, photometric indices tend to overestimate the fraction of FG
stars, in particular in low mass GCs. We offer a simple explanation
for these findings. Finally, we publish all our PCMs, with more than
31,800 stars in 22 GCs, with star ID and coordinates, for easy check
and reproduction, as it should be in science papers.
Description:
We list: in table3.dat we list all stars in common between
spectroscopy and HUGS (HST photometry), in tablea1.dat we list
coordinates, IDs and DeltaCOL, DeltaCOL3 for all RGB stars in our
paper.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 29 589 Stars in common between spectroscopy and
HST photometry
tablea1.dat 52 31812 Pseudo-colour maps (PCMs) for all 22 GCs
in the sample
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 --- NGC NGC number of galactic cluster
6- 13 A8 --- ID Star ID from HUGS (Nardiello et al.,
2018MNRAS.481.3382N 2018MNRAS.481.3382N
16- 21 F6.3 [-] [Na/Fe] ?=- Abundance [Na/Fe]
25 I1 --- pop [0/2] Population (1)
29 A1 --- Flag [F/M] star found (F) or missing (M) in
Marino et al., 2019MNRAS.487.3815M 2019MNRAS.487.3815M
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Note (1): Population as follows:
1 = first
2 = second
0 = unknown
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.4 --- DCol Pseudo-colour Deltacol (1)
9- 16 F8.4 --- DCol3 Pseudo-colour Deltacol3 (1)
18- 27 F10.6 deg RAdeg Right ascension (J2000)
29- 38 F10.6 deg DEdeg Declination (J2000)
40- 47 A8 --- ID ID HUGS (Nardiello et al. 2018MNRAS.481.3382N 2018MNRAS.481.3382N)
49- 52 I4 --- NGC ? Cluster NGC number
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Note (1): col = magF275W-magF814W,
Deltacol = Wcol((col-xr)/(xr-xb)) (see Section 2)
col3 = (magF275W-magF336W)-(magF336W-magF438W)
Deltacol3 = Wcol3((col3-yr)/(yr-yb)) (see Section 2)
Wcol and Wcol3 = widths of the RGB in col and col3
PCM = pseudo-colour map = col in abscissa and col3 in ordinate
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Acknowledgements:
Eugenio Carretta, eugenio.carretta(at)inaf.it
(End) Patricia Vannier [CDS] 23-Sep-2024