J/A+A/666/L4 Chemical signature of Galactic spiral arms (Poggio+, 2022)
The chemical signature of the Galactic spiral arms revealed by Gaia DR3.
Poggio E., Recio-Blanco A., Palicio P.A., Re Fiorentin P., de Laverny P.,
Drimmel R., Kordopatis G., Lattanzi M.G., Schultheis M., Spagna A.,
Spitoni E.
<Astron. Astrophys. 666, L4 (2022)>
=2022A&A...666L...4P 2022A&A...666L...4P (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, luminous ; Effective temperatures ;
Abundances ; Stars, distances ; Optical
Keywords: Galaxy: disk - Galaxy: evolution - Galaxy: structure -
Galaxy: abundances - Galaxy: stellar content
Abstract:
Taking advantage of the recent Gaia Data Release 3 (DR3), we mapped
chemical inhomogeneities in the Milky Way's disc out to a distance
of ∼4kpc from the Sun, using different samples of bright giant stars.
The samples were selected using effective temperatures and surface
gravities from the GSP-Spec module, and they are expected to trace
stellar populations of a different typical age. The cool (old) giants
exhibit a relatively smooth radial metallicity gradient with an
azimuthal dependence. Binning in Galactic azimuth φ, the slope
gradually varies from d[M/H]/dR~-0.054dex/kpc at φ~-20°
to ~-0.036dex/kpc at φ∼20°. On the other hand, the
relatively hotter (and younger) stars present remarkable
inhomogeneities, which are apparent as three (possibly four)
metal-rich elongated features in correspondence with the spiral
arms' locations in the Galactic disc. When projected onto the
Galactic radius, those features manifest themselves as statistically
significant bumps on top of the observed radial metallicity gradients
with amplitudes up to ∼0.05-0.1dex, making the assumption of a
linear radial decrease not applicable for this sample. The strong
correlation between the spiral structure of the Galaxy and the
observed chemical pattern in the young sample indicates that the
spiral arms might be at the origin of the detected chemical
inhomogeneities. In this scenario, the spiral arms would leave a
strong signature in the younger stars which progressively disappears
when cooler (and older) giants are considered.
Description:
The files samplea.dat, sampleb.dat, and samplec.dat contain the three
samples adopted in this work (labelled as Sample A, Sample B, and
Sample C, respectively) defined in Appendix A.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
samplea.dat 215 17411 *Sample A
(interc_left=-8.3dex, interc_right=-7.3dex)
sampleb.dat 215 155694 *Sample B
(interc_left=-8.8dex, interc_right=-7.8dex)
samplec.dat 215 370925 *Sample C
(interc_left=-9.3dex, interc_right=-8.3dex)
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Note on samplea.dat, sampleb.dat, samplec.dat: where interc_left and
interc_right delimiting the selected regions on the left and right side
(see paper, Appendix A).
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See also:
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: samplea.dat sampleb.dat samplec.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source_id (source_id)
21- 43 E23.19 deg RAdeg Right ascension (ICRS) at Ep=2016.0 (ra)
45- 66 E22.18 deg DEdeg Declination (ICRS) at Ep=2016.0 (dec)
67- 87 F21.18 mas Plx Parallax (parallax)
89-100 F12.10 mas e_Plx Standard error of parallax (parallax_error)
102-124 E23.19 deg GLON Galactic longitude (l)
126-147 E22.19 deg GLAT Galactic latitude (b)
149-154 F6.1 K Teff Effective temperature from GSP-Spec
(teff_gspspec)
156-161 F6.1 K B_Teff 16th percentile of effective temperature
from GSP-Spec (teffgspspecupper)
163-168 F6.1 K b_Teff 84th percentile of effective temperature
from GSP-Spec (teffgspspeclower)
170-173 F4.2 [cm/s2] logg Logarithm of the stellar surface gravity
from GSP-Spec (logg_gspspec)
175-178 F4.2 [cm/s2] B_logg 16th percentile of the logarithm of the
stellar surface gravity from GSP-Spec
(logggspspecupper)
180-184 F5.2 [cm/s2] b_logg 84th percentile of the logarithm of the
stellar surface gravity from GSP-Spec
(logggspspeclower)
186-190 F5.2 [-] [M/H] Global metallicity [M/H] from GSP-Spec
(mh_gspspec)
192-196 F5.2 [-] B_[M/H] 16th percentile of the global metallicity
[M/H] from GSP-Spec (mhgspspecupper)
198-202 F5.2 [-] b_[M/H] 84th percentile of the global metallicity
[M/H] from GSP-Spec (mhgspspeclower)
204-215 F12.6 pc rgeo Median of the geometric distance posterior
from Bailer-Jones et al., 2021, Cat. I/352
(rmedgeo)
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Acknowledgements:
Eloisa Poggio, poggio.eloisa(at)gmail.com
References:
2022arXiv220800211G 2022arXiv220800211G : Vallenari et al., Gaia Data Release 3:
Summary of the content and survey properties (Gaia Collaboration)
2022arXiv220605541R 2022arXiv220605541R : Recio-Blanco et al., Gaia Data Release 3:
Analysis of RVS spectra using the General Stellar Parametriser from
spectroscopy
(End) Patricia Vannier [CDS] 12-Sep-2022