J/A+A/601/A41 Palomar 5 abundance analysis (Koch+, 2017)
Galactic Pal-eontology: abundance analysis of the disrupting globular cluster
Palomar 5.
Koch A., Code P.
<Astron. Astrophys. 601, A41 (2017)>
=2017A&A...601A..41K 2017A&A...601A..41K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Abundances
Keywords: techniques: spectroscopic - stars: abundances - Galaxy: abundances -
Galaxy: evolution - Galaxy: halo -
globular clusters: individual: Palomar 5
Abstract:
We present a chemical abundance analysis of the tidally disrupted
globular cluster (GC) Palomar 5. By co-adding high-resolution spectra
of 15 member stars from the cluster's main body, taken at low
signal-to-noise with the Keck/HIRES spectrograph, we were able to
measure integrated abundance ratios of 24 species of 20 elements
including all major nucleosynthetic channels (namely the light element
Na; α-elements Mg, Si, Ca, Ti; Fe-peak and heavy elements Sc, V,
Cr, Mn, Co, Ni, Cu, Zn; and the neutron-capture elements Y, Zr, Ba,
La, Nd, Sm, Eu). The mean metallicity of -1.56±0.02±0.06dex
(statistical and systematic errors) agrees well with the values from
individual, low-resolution measurements of individual stars, but it is
lower than previous high-resolution results of a small number of stars
in the literature. Comparison with Galactic halo stars and other
disrupted and unperturbed GCs renders Pal 5 a typical representative
of the Milky Way halo population, as has been noted before,
emphasizing that the early chemical evolution of such clusters is
decoupled from their later dynamical history. We also performed a test
as to the detectability of light element variations in this co-added
abundance analysis technique and found that this approach is not
sensitive even in the presence of a broad range in sodium of ∼0.6dex,
a value typically found in the old halo GCs. Thus, while methods of
determining the global abundance patterns of such objects are well
suited to study their overall enrichment histories, chemical
distinctions of their multiple stellar populations is still best
obtained from measurements of individual stars.
Description:
The Pal 5 data discussed here were taken as part of a broader program
to study the internal dynamics of outer halo GCs (see, e.g., Cote et
al., 2002ApJ...574..783C 2002ApJ...574..783C; Jordi et al., 2009AJ....137.4586J 2009AJ....137.4586J; Baumgardt
et al., 2009MNRAS.396.2051B 2009MNRAS.396.2051B; Frank et al., 2012, Cat.
J/MNRAS/423/2917).
Our Pal 5 target stars were chosen from the red giant branch (RGB) and
asymptotic giant branch (AGB) sequences identified in the early
photometric studies of Sandage & Hartwick (1977AJ.....82..459S 1977AJ.....82..459S, SH77)
and the unpublished photometry and astrometry from Cudworth,
Schweitzer, and Majewski (CSM; see Schweitzer et al., 1993, in The
Globular Cluster-Galaxy Connection, ASP Conf. Ser., 48, 113).
Objects:
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RA (2000) DE Designation(s)
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15 16 05.30 -00 06 41.0 Palomar 5 = UGC 9792
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 50 258 Line list
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See also:
J/MNRAS/423/2917 : Radial velocities in Pal 4 (Frank+, 2012)
J/ApJ/819/1 : Wide-field photometry of the GC Palomar 5 (Ibata+, 2016)
J/ApJ/823/157 : Pal 5 tidal stream LOS velocities + [Fe/H] (Ishigaki+, 2016)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Ion Ion designation
7- 13 F7.2 0.1nm Wave Wavelength
17- 20 F4.2 eV EP Excitation potential
24- 29 F6.3 [-] loggf Oscillator strength
34- 36 I3 10-13m EW255 ?=- Equivalent width for entire sample (1)
40- 43 I4 10-13m EW20 ?=- Equivalent width for RGB subsample (1)
47- 50 I4 10-13m EW9 ?=- Equivalent width for AGB subsample (1)
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Note (1): In milli-Angstroms.
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Acknowledgements:
Andreas Koch, a.koch1(at)lancaster.ac.uk
(End) Patricia Vannier [CDS] 08-Mar-2017