J/AJ/162/109 Equivalent widths for putative members of G21-22 (Schuler+, 2021)
Combining astrometry and elemental abundances: the case of the candidate
pre-Gaia halo moving groups G03-37, G18-39, and G21-22.
Schuler S.C., Andrews J.J., Clanzy V.R., Mourabit M., Chaname J.,
Agueros M.A.
<Astron. J., 162, 109-109 (2021)>
=2021AJ....162..109S 2021AJ....162..109S (SIMBAD/NED BibCode)
ADC_Keywords: Stars, variable; Spectra, optical
Keywords: Chemical abundances; Stellar abundances; Stellar physics; Halo stars
Moving clusters; High resolution spectroscopy; Astrometry
Astronomy software
Abstract:
While most moving groups are young and nearby, a small number have
been identified in the Galactic halo. Understanding the origin and
evolution of these groups is an important piece of reconstructing the
formation history of the halo. Here we report on our analysis of three
putative halo moving groups: G03-37, G18-39, and G21-22. Based on Gaia
EDR3 data, the stars associated with each group show some scatter in
velocity (e.g., Toomre diagram) and integrals of motion (energy,
angular momentum) spaces, counter to expectations of moving-group
stars. We choose the best candidate of the three groups, G21-22, for
follow-up chemical analysis based on high-resolution spectroscopy of
six presumptive members. Using a new Python code that uses a Bayesian
method to self-consistently propagate uncertainties from stellar
atmosphere solutions in calculating individual abundances and spectral
synthesis, we derive the abundances of α-(Mg, Si, Ca, Ti),
Fe-peak (Cr, Sc, Mn, Fe, Ni), odd-Z (Na, Al, V), and neutron-capture
(Ba, Eu) elements for each star. We find that the G21-22 stars are not
chemically homogeneous. Based on the kinematic analysis for all three
groups and the chemical analysis for G21-22, we conclude the three are
not genuine moving groups. The case for G21-22 demonstrates the
benefit of combining kinematic and chemical information in identifying
conatal populations when either alone may be insufficient. Comparing
the integrals of motion and velocities of the six G21-22 stars with
those of known structures in the halo, we tentatively associate them
with the Gaia-Enceladus accretion event.
Description:
We obtained high-resolution spectroscopy of six stars members of
G21-22 in service mode with the Ultraviolet and Visual Echelle
Spectrograph (UVES) and the 8.2m Unit 2 (UT2, Kueyen) telescope of the
Very Large Telescope (VLT) at Cerro Paranal, Chile, between the months
of 2012 October and 2013 March. A standard dichroic setting (DIC 1)
was used to provide a wavelength (incomplete) coverage of
3280-6800Å. The slit width was set to 0.6", giving a nominal
resolving power of R∼65000, and the Poisson signal-to-noise ratio
(S/N) of the spectra is ∼100 near 6500Å.
Objects:
-------------------------------------------
RA (2000) DE Designation(s)
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18 39 09.72 +00 07 14.3 G21-22 = G21-22
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 58 275 Linelist and equivalent widths for putative
members of G21-22
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See also:
I/316 : Lowell GR* red stars (Giclas+ 1972-1978)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/ApJ/757/164 : Oxygen abundances of dwarf stars (Ramirez+, 2012)
J/ApJ/771/67 : Detailed abundances 97 metal-poor stars. II. (Ishigaki+, 2013)
J/AJ/147/136 : Stars very low metal abundance.VI. Abundances (Roederer+, 2014)
J/ApJ/808/103 : Kapteyn moving group star abundances (Navarrete+, 2015)
J/ApJ/815/5 : Detailed abundances KOI stars with planets. I. (Schuler+, 2015)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/AJ/156/18 : APOGEE DR14,Binary comps of evolved stars (Price-Whelan+, 2018)
J/ApJ/852/49 : Properties of metal-poor stars in APOGEE DR13 (Hayes+, 2018)
J/ApJ/855/83 : Abundances very metal-poor stars in Sagittarius (Hansen+, 2018)
J/ApJS/237/8 : Line lists for X1Σ+ AlF and AlCl (Yousefi+, 2018)
J/ApJ/874/148 : Metal-poor star RAVEJ093730.5-062655 abundances (Sakari+, 2019)
J/ApJ/891/39 : LAMOST DR3 very metal-poor stars of Galactic halo (Yuan+, 2020)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Species Species identifier
7- 13 F7.2 0.1nm Wave [4798/6751] Rest wavelength; Angstroms
15- 18 F4.2 eV ExPot [0/5.7] Excitation potential
20- 24 F5.2 [-] logg [-5.5/0.57] log oscillator strength
26- 30 F5.1 10-13m EW1 [3.5/102]? G02-38 equivalent width;
milli-Angstroms
32- 36 F5.1 10-13m EW2 [3.2/170]? G82-42 equivalent width;
milli-Angstroms
38- 41 F4.1 10-13m EW3 [5.3/98.9]? G108-48 equivalent width;
milli-Angstroms
43- 46 F4.1 10-13m EW4 [3.5/94.5]? G119-64 equivalent width;
milli-Angstroms
48- 52 F5.1 10-13m EW5 [2.3/122]? G161-73 equivalent width;
milli-Angstroms
54- 58 F5.1 10-13m EW6 [3.7/127]? HIP 36878 equivalent width;
milli-Angstroms
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 17-Jan-2022