J/A+A/700/A154 Local halo ED substructures stars abundances (Dodd+, 2025)
Chemical characterisation of small substructures in the local stellar halo.
Dodd E., Matsuno T., Helmi A., Balbinot E., Callingham T.M., Starkenburg E.,
Woudenberg H.C., Ruiz-Lara T.
<Astron. Astrophys. 700, A154 (2025)>
=2025A&A...700A.154D 2025A&A...700A.154D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, halo ; Abundances ; Equivalent widths ;
Ultraviolet
Keywords: Galaxy: abundances - Galaxy: halo - Galaxy: kinematics and dynamics
Abstract:
The local stellar halo of the Milky Way is known to contain the debris
from accreted dwarf galaxies and globular clusters, in the form of
stellar streams and over-densities in the space of orbital properties
(e.g. integrals of motion). While several over-densities have been
uncovered and characterised dynamically using Gaia data, their nature
is not always clear. Especially for a full understanding of the
smaller halo substructures, the kinematic information from Gaia needs
to be coupled with chemical information. In this work, we combine Gaia
data with targeted high-resolution UVES spectroscopy of five small
substructures that were recently discovered in the local halo, namely
the ED-2, 3, 4, 5 and 6; the ED streams. We present the chemical
abundances measured from our newly obtained UVES spectra (20 stars)
and from archival UVES spectra (9 stars). We compare these with
homogeneously derived abundances from archive spectra of 12 Gaia
Enceladus (GE) stars. The chemical abundances of all 5 substructures
suggest that they are of accreted origin, except for two stars that
present a high [alpha/Fe] at high [Fe/H] more in line with an in-situ
origin. All but ED-2 present a significant spread in [Fe/H],
suggestive of a dwarf galaxy origin. ED-3 and ED-4 tend to exhibit
lower [alpha/Fe] compared to GE stars. ED-5 and ED-6 are consistent
with the GE chemical track and could be high-energy tails of GE that
were lost earlier in the accretion process. We present new elemental
abundances for 5 ED-2 stars, including more elements for the Gaia BH3
companion star. Our findings are in line with the picture that ED-2 is
a disrupted ancient star cluster.
Description:
Linelist and chemical abundances of 27 species for 42 stars in the
local stellar halo. Stars kinematically associated with the ED streams
were targeted with UVES. These were supplemented with archival UVES
spectra including for 12 stars associated with Gaia Enceladus.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 90 42 Stellar parameters for all stars
table1.dat 64 9039 Equivalent widths
table2.dat 50 929 Abundances
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- --- [Gaia DR3]
10- 28 I19 --- GaiaDR3 Gaia DR3 source_id
30- 31 I2 h RAh Simbad right ascension (J2000)
33- 34 I2 min RAm Simbad right ascension (J2000)
36- 40 F5.2 s RAs Simbad right ascension (J2000)
42 A1 --- DE- Simbad declination sign (J2000)
43- 44 I2 deg DEd Simbad declination (J2000)
46- 47 I2 arcmin DEm Simbad declination (J2000)
49- 52 F4.1 arcsec DEs Simbad declination (J2000)
54- 62 A9 --- Name Name
64- 68 A5 --- Note Note
70- 73 I4 K Teff ?=- Effective temperature
75- 79 F5.3 [cm/s2] logg ?=- Surface gravity
81- 84 F4.2 km/s ksi ?=- Microturbulent velocity
86- 90 F5.2 [-] [Fe/H] ?=- Metallicity
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id
21- 24 A4 --- Species Name of of species
26- 32 F7.2 0.1nm lambda Wavelength
34- 38 F5.2 --- chi ? Excitation potential
40- 44 F5.2 [-] loggf ? Oscillator strength value
46- 51 F6.1 0.1pm EW ? Equivalent width
53- 58 F6.3 [-] ab1DLTE 1D LTE abundance
60- 64 F5.2 [-] ab1DNLTE ? 1D NLTE abundance
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id
21- 24 A4 --- Species Name of of species
26- 28 I3 --- Nlines Number of lines
30- 34 F5.2 --- [X/H] X abundance relative to H
36- 39 F4.2 --- e_[X/H] Uncertainty in X abundance relative to H
41- 45 F5.2 --- [X/Fe] X abundance relative to Fe
47- 50 F4.2 --- e_[X/Fe] Uncertainty in X abundance relative to Fe
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Acknowledgements:
Emma Dodd, emma.l.dodd(at)durham.ac.uk
(End) Patricia Vannier [CDS] 05-Jun-2025