J/A+A/684/A37 Walk on the Retrograde Side (WRS) project (Ceccarelli+, 2024)
A Walk on the Rettrograde Side (WRS) project.
I. Tidying up the retrograde halo with high-resolution spectroscopy.
Ceccarelli E., Massari D., Mucciarelli A., Bellazzini M., Nunnari A.,
Cusano F., Lardo C., Romano D., Ilyin I., Stokholm A.
<Astron. Astrophys. 684, A37 (2024)>
=2024A&A...684A..37C 2024A&A...684A..37C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Abundances ; Ultraviolet ; Optical ; Infrared
Keywords: stars: abundances - Galaxy: abundances - Galaxy: formation -
Galaxy: halo
Abstract:
Relics of ancient accretion events experienced by the Milky Way are
predominantly located within the stellar halo of our Galaxy. However,
debris from different objects display overlapping distributions in
dynamical spaces, making it extremely challenging to properly
disentangle their contribution to the build-up of the Galaxy. To shed
light on this chaotic context, we started a program aimed at the
homogeneous chemical tagging of the local halo of the Milky Way,
focusing on the component in retrograde motion, since this is expected
to host a large fraction of stars accreted from past mergers. The A
Walk on the Retrograde Side (WRS) project targets retrograde halo
stars in the Solar Neighborhood having accurate 6-D phase space
information available, measuring the precise chemical abundance of
several chemical elements from high-resolution spectroscopy. In this
first paper, we present the project and the analysis of
high-resolution spectra obtained with UVES at VLT and PEPSI at LBT for
186 stars. Accurate radial velocity and chemical abundance of several
elements have been obtained for all the target stars. In particular we
focus on the chemical composition of a specific subset of
substructures identified dynamically in the literature. Our study
reveals that two among the more recently discovered structures in the
retrograde halo, namely Antaeus / L-RL64 and ED-3, have identical
chemical patterns and similar integrals of motion, suggesting a common
origin. In turn, the abundance patterns of this unified system differ
from that of Gaia-Enceladus, confirming that it is an independent
structure. Finally, Sequoia exhibits a different chemistry with
respect to that of Gaia-Enceladus at [Fe/H]←1.5dex, showcasing an
excess of stars with lower Mg and Ca in the common metallicity range.
Description:
Gaia EDR3 ID, coordinates, magnitudes (G, BP, RP), color excess,
parallax, orbital energy, vertical and perpendicular angular momenta,
heliocentric line- of-sight velocity, atmospheric parameters,
abundances of Fe, Na, Al, Mg, Ca, TiI, TiII, ScII, Mn, Ni, Zn and YII.
Observations were done using the 564nm setup for UVES (480-660nm) and
both the CD3 (480-544nm) and CD6 (741-914nm) gratings for PEPSI.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 186 ID, positions, magnitudes, color excess,
parallax and instrument used
table3.dat 66 186 ID, orbital energy, vertical and perpendicular
angular momenta, line-of-sight velocity and
flag for binary star
table4.dat 48 186 ID, atmospheric parameters and [Fe/H]
table6.dat 83 93 ID, abundances of FeI, Mg, Ca, TiI, TiII and
associated substructure
table7.dat 110 93 ID, abundances of Na, Al, ScII, Mn, Ni, Zn
and YII
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaEDR3 Source_id from Gaia EDR3
21- 30 F10.6 deg RAdeg Right ascension (ICRS) at Ep=2016.0
32- 41 F10.6 deg DEdeg Declination (ICRS) at Ep=2016.0
43- 50 F8.5 mag Gmag Apparent G magnitude
52- 59 F8.5 mag BPmag Apparent BP magnitude
61- 68 F8.5 mag RPmag Apparent RP magnitude
70- 73 F4.2 mag E(B-V) Color excess
75- 82 F8.5 mas plx Parallax
84- 93 A10 --- Inst Instrument
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaEDR3 source_id from Gaia EDR3
21- 27 I7 km2/s2 En Energy
29- 32 I4 km2/s2 e_En Uncertainty on the energy
34- 38 I5 kpc.km/s Lz Vertical component of the angular momentum
40- 41 I2 kpc.km/s e_Lz Uncertainty on the vertical component of
the angular momentum
43- 46 I4 kpc.km/s Lperp Perpendicular component of
the angular momentum
48- 49 I2 kpc.km/s e_Lperp Uncertainty on the perpendicular component
of the angular momentum
51- 57 F7.2 km/s Vlos Line-of-sight velocity
59- 62 F4.2 km/s e_Vlos Uncertainty on the line-of- sight velocity
64- 66 F3.1 --- Bin [0/1] Possibly a binary star if set to 1
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaEDR3 source_id from Gaia EDR3
21- 24 I4 K Teff Effective temperature
26- 29 F4.2 [cm/s2] logg Surface gravity
31- 35 F5.1 km/s Vmicro ?=999 Microturbulent velocity
37- 43 F7.2 [Sun] [Fe/H] ?=999 Abundance [Fe/H]
45- 48 F4.2 [Sun] e_[Fe/H] ?=0 Uncertainty on the [Fe/H] abundance
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaEDR3 source_id from Gaia EDR3
21- 25 F5.2 [Sun] [Fe/H] Abundance [Fe/H]
27- 30 F4.2 [Sun] e_[Fe/H] Uncertainty on the [Fe/H] abundance
32- 36 F5.2 [Sun] [Mg/Fe] Abundance [Mg/Fe]
38- 41 F4.2 [Sun] e_[Mg/Fe] Uncertainty on the [Mg/Fe] abundance
43- 48 F6.2 [Sun] [Ca/Fe] ?=999 [Ca/Fe] abundance [Ca/Fe]
50- 53 F4.2 [Sun] e_[Ca/Fe] ?=0 Uncertainty on the [Ca/Fe] abundance
55- 58 F4.2 [Sun] [TiI/Fe] Abundance [TiI/Fe]
60- 63 F4.2 [Sun] e_[TiI/Fe] Uncertainty on the [TiI/Fe] abundance
65- 70 F6.2 [Sun] [TiII/Fe] ?=999 Abundance [TiII/Fe]
72- 75 F4.2 [Sun] e_[TiII/Fe] ?=0 Uncertainty on the [TiII/Fe] abundance
77- 83 A7 --- Substruct Associated progenitor
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaEDR3 source_id from Gaia EDR3
21- 27 F7.2 [Sun] [Na/Fe] ?=999 Abundance [Na/Fe]
29- 32 F4.2 [Sun] e_[Na/Fe] ?=0 Uncertainty on the [Na/Fe] abundance
34- 40 F7.2 [Sun] [Al/Fe] ?=999 Abundance [Al/Fe]
42- 45 F4.2 [Sun] e_[Al/Fe] ?=0 Uncertainty on the [Al/Fe] abundance
47- 53 F7.2 [Sun] [ScII/Fe] ?=999 Abundance [ScII/Fe]
55- 58 F4.2 [Sun] e_[ScII/Fe] ?=0 Uncertainty on the [ScII/Fe] abundance
60- 66 F7.2 [Sun] [Mn/Fe] ?=999 Abundance [Mn/Fe]
68- 71 F4.2 [Sun] e_[Mn/Fe] ?=0 Uncertainty on the [Mn/Fe] abundance
73- 79 F7.2 [Sun] [Ni/Fe] ?=999 Abundance [Ni/Fe]
81- 84 F4.2 [Sun] e_[Ni/Fe] ?=0 Uncertainty on the [Ni/Fe] abundance
86- 92 F7.2 [Sun] [Zn/Fe] ?=999 Abundance [Zn/Fe]
94- 97 F4.2 [Sun] e_[Zn/Fe] ?=0 Uncertainty on the [Zn/Fe] abundance
99-105 F7.2 [Sun] [YII/Fe] ?=999 Abundance [YII/Fe]
107-110 F4.2 [Sun] e_[YII/Fe] ?=0 Uncertainty on the [YII/Fe] abundance
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Acknowledgements:
Edoardo Ceccarelli, edoardo.ceccarelli3(at)unibo.it
(End) Patricia Vannier [CDS] 12-Mar-2024