J/A+A/670/L7 Gaia DR3 orbital parameters and actions (Palicio+, 2023)
Spiral-like features in the disc revealed by Gaia DR3 radial actions.
Palicio P.A., Recio-Blanco A., Poggio E., Antoja T., McMillan P.J.,
Spitoni E.
<Astron. Astrophys. 670, L7 (2023)>
=2023A&A...670L...7P 2023A&A...670L...7P (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Positional data ; Space velocities ; Models ; Optical
Keywords: Galaxy: kinematics and dynamics - Galaxy: structure - Galaxy: disk
Abstract:
We aim to explore the actions of the new Gaia DR3 astrometry to find
structures in the Galactic disc. We compute the actions and the
orbital parameters of the Gaia DR3 stars with full astrometry and
velocities assuming an axisymmetric model for the Milky Way. Using
Gaia DR3 photometric data, we select a subset of giants stars with
better astrometry as control sample. The maps of the percentiles of
the radial action J_R reveal spiral-like shape structures. We find a
high JR region centered at R∼10.5kpc of 1kpc width, as well as
three arc-shape regions dominated by circular orbits at inner radii.
We also identify the spiral arms in the overdensities of the giant
population. We find a good agreement with the literature in the
innermost region for the Scutum-Sagittarius spiral arms. At larger
radii, the low J_R structure tracks the Local arm at negative X, while
for the Perseus arm the agreement is restricted to the X<2kpc region,
with a displacement with respect to the literature at more negative
longitudes. We detect a high JR area at a Galactocentric radii of
∼10.5kpc, consistent with some estimations of the Outer Lindblad
Resonance location. We conclude that the pattern in the dynamics of
the old stars is consistent in several places with spatial
distribution of the spiral arms traced by young populations, with
small potential contributions from the moving groups.
Description:
Galactocentric Cartesian coordinates, velocities, orbital parameters
and actions computed for the Gaia DR3 stars with full kinematic
information. The orbital parameters and actions have been estimated
assuming the Staeckel approximation (2012MNRAS.426.1324B 2012MNRAS.426.1324B,
2018PASP..130k4501M 2018PASP..130k4501M) for a rescaled version of the potential of
McMillan 2017 (2017MNRAS.465...76M 2017MNRAS.465...76M). The median and the confidence
values (16th and 84th percentiles) have been computed by performing 25
random realisations of the input data using the associated errors.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
raw.dat 188 33653049 Values computed directly from the input data
stat.dat 452 33653049 Percentiles computed after
25 random realisations of the input data
ori/* . 2 Original fits files
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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: raw.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Unique gaia DR3 identifier
21- 30 F10.6 kpc X Galactocentric Cartesian coordinate X
32- 41 F10.6 kpc Y Galactocentric Cartesian coordinate Y
43- 52 F10.6 kpc Z Galactocentric Cartesian coordinate Z
54- 65 E12.6 km/s VZ Vertical Galactocentric Velocity (1)
67- 78 E12.6 km/s Vphi Azimuthal velocity (2)
80- 91 E12.6 km/s VR Radial Galactocentric velocity (3)
93-104 E12.6 kpc rapo ?=- Maximum distance to the Galactic Center
(apocenter)
106-114 F9.6 kpc rperi ?=- Minimum distance to the Galactic Center
(pericenter)
116-123 F8.6 --- ecc ?=- Orbital eccentricity (4)
125-136 E12.6 kpc zmax ?=- Maximum distance to the Galactic Plane
138-149 E12.6 kpc.km/s Jr ?=- Radial action per unit mass
151-162 E12.6 kpc.km/s Jz ?=- Vertical action per unit mass
164-175 E12.6 kpc.km/s Lz Vertical component of the angular momentum
per unit mass
177-188 E12.6 km2/s2 Energy Total energy per unit mass
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Note (1): Equivalent to the W component in the (U,V,W) velocity system
Note (2): Positive counter-clockwise
Note (3): Positive outwards
Note (4): Computed as (rapo-rperi)/(rapo+rperi)
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Byte-by-byte Description of file: stat.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- GaiaDR3 Unique gaia DR3 identifier (source_id)
21- 29 F9.6 kpc Rlower Lower confidence value of the
plane-projected Galactocentric distance
(R_lower)
31- 39 F9.6 kpc Rmedian Median plane-projected Galactocentric
distance (R_median)
41- 49 F9.6 kpc Rupper Upper confidence value of the
plane-projected Galactocentric distance
(R_upper)
51- 61 F11.6 kpc Z-lower Lower confidence value of the Cartesian
coordinate Z (Z_lower)
63- 72 F10.6 kpc Z-median Median value of the Cartesian
coordinate Z (Z_median)
74- 83 F10.6 kpc Z-upper Upper confidence value of the Cartesian
coordinate Z (Z_upper)
85- 96 E12.6 km/s VR-lower Lower confidence value of the
Galactocentric radial velocity
(VR_lower)
98-109 E12.6 km/s VR-median Median Galactocentric radial velocity
(VR_median)
111-122 E12.6 km/s VR-upper Upper confidence value of the
Galactocentric radial velocity
(VR_upper)
124-135 E12.6 km/s VZ-lower Lower confidence value of the
Galactocentric vertical velocity
(VZ_lower)
137-148 E12.6 km/s VZ-median Median Galactocentric vertical velocity
(VZ_median)
150-161 E12.6 km/s VZ-upper Upper confidence value of the
Galactocentric vertical velocity
(VZ_upper)
163-170 F8.6 --- ecc-lower ?=- Lower confidence value of the
eccentricity (ecc_lower)
172-179 F8.6 --- ecc-median ?=- Median value of the eccentricity
(ecc_median)
181-188 F8.6 --- ecc-upper ?=- Upper confidence value of the
eccentricity (ecc_upper)
190-201 E12.6 km2/s2 Energy-lower Lower confidence limit of the total
orbital energy per unit mass
(Energy_lower)
203-214 E12.6 km2/s2 Energy-median Median orbital energy per unit mass
(Energy_median)
216-227 E12.6 km2/s2 Energy-upper Upper confidence limit of the total
orbital energy per unit mass
(Energy_upper)
229-240 E12.6 kpc.km/s Jr-lower ?=- Lower confidence value of the radial
action per unit mass (Jr_lower)
242-253 E12.6 kpc.km/s Jr-median ?=- Median radial action per unit mass
(Jr_median)
255-266 E12.6 kpc.km/s Jr-upper ?=- Upper confidence value of the radial
action per unit mass (Jr_upper)
268-279 E12.6 kpc.km/s Jz-lower ?=- Lower confidence limit of the
vertical action per unit mass (Jz_lower)
281-292 E12.6 kpc.km/s Jz-median ?=- Median vertical action per unit mass
(Jz_median)
294-305 E12.6 kpc.km/s Jz-upper ?=- Upper confidence value of the
vertical action per unit mass (Jz_upper)
307-318 E12.6 kpc.km/s Lz-lower Lower confidence limit of the vertical
angular momentum per unit mass
(Lz_lower)
320-331 E12.6 kpc.km/s Lz-median Median value of the vertical angular
angular momentum per unit mass
(Lz_median)
333-344 E12.6 kpc.km/s Lz-upper Upper confidence limit of the vertical
angular momentum per unit mass
(Lz_upper)
346-357 E12.6 kpc rapo-lower ?=- Lower confidence limit of the maximum
Galactocentric distance (apocenter)
(rapo_lower)
359-370 E12.6 kpc rapo-median ?=- Median value of the apocenter
(rapo_median)
372-383 E12.6 kpc rapo-upper ?=- Upper confidence limit of the maximum
Galactocentric distance (apocenter)
(rapo_upper)
385-393 F9.6 kpc rperi-lower ?=- Lower confidence limit of the minimum
Galactocentric distance (pericenter)
(rperi_lower)
395-403 F9.6 kpc rperi-median ?=- Median value of the pericenter
(rperi_median)
405-413 F9.6 kpc rperi-upper ?=- Upper confidence limit of the minimum
Galactocentric distance (pericenter)
(rperi_upper)
415-426 E12.6 kpc zmax-lower ?=- Lower confidence limit of the maximum
distance to the Galactic Plane
(zmax_lower)
428-439 E12.6 kpc zmax-median ?=- Median value of the maximum distance
to the Galactic Plane (zmax_median)
441-452 E12.6 kpc zmax-upper ?=- Upper confidence limit of the maximum
distance to the Galactic Plane
(zmax_upper)
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Acknowledgements:
Pedro Alonso Palicio, pedro.alonso-palicio(at)oca.eu
(End) Patricia Vannier [CDS] 24-Jan-2023