J/A+A/678/A111 Milky Way through A stars (Ardevol+, 2023)
Exploring the structure and kinematics of the Milky Way through A stars.
Ardevol J., Monguio M., Figueras F., Romero-Gomez M., Carrasco J.M.
<Astron. Astrophys. 678, A111 (2023)>
=2023A&A...678A.111A 2023A&A...678A.111A (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic plane ; Stars, A-type ; Photometry;
Proper motions ; Radial velocities
Keywords: Galaxy: disc - Galaxy: structure - Galaxy: kinematics and dynamics -
catalogs
Abstract:
Despite their relatively high intrinsic brightness and the fact that
they are more numerous than younger OB stars and kinematically colder
than older red giants, A-type stars have rarely been used as Galactic
tracers. They may, in fact, be used to fill the age gap between these
two tracers, thereby allowing us to study the transition between them.
We analyse Galactic disc structure and kinematic perturbations up to
6kpc from the Sun based on observations of A-type stars.
This work presents a catalogue of A-type stars selected using the
IGAPS photometric survey. It covers the Galactic disc within
30°<l<215° and |b|<5° up to a magnitude of r<19mag with
about 3.5 million sources. We used Gaia Data Release 3 parallaxes and
proper motions, as well as the line-of-sight velocities, to analyse
the large-scale features of the Galactic disc. We carried out a study
of the completeness of the detected density distributions, along with
a comparison between the b<0° and b>0° regions. Possible
biases caused by interstellar extinction or by the usage of some
kinematic approximations were examined as well.
We find stellar overdensities associated with the Local and the
Perseus spiral arms, as well as with the Cygnus region. A-type stars
also provide kinematic indications of the Galactic warp towards the
anticentre, which displays a median vertical motion of ∼6-7km/s at a
Galactocentric radius of R=14kpc. It starts at R=12kpc, which supports
the scenario where the warp begins at larger radii for younger tracers
when compared with other samples in the literature. We also detect a
region with downward mean motion extending beyond 2kpc from the Sun
towards 60°<l<75° that may be associated with a compression
breathing mode. Furthermore, A-type stars reveal very clumpy
inhomogeneities and asymmetries in the VZ-Vphi velocity space
plane.
Description:
The sample of A-type stars was selected using IGAPS photometric
bands i, Hα, and r from IPHAS (Drew et al.,
2005MNRAS.362..753D 2005MNRAS.362..753D), which are centred at 774.3, 656.8, and 624.0nm,
respectively.
We constructed an extended sample of A-type stars to unveil
Milky Way disc density structures and kinematic perturbations. It was
selected using a colour-colour diagram from IGAPS photometric bands
and includes Gaia DR3 astrometry and line-of sight velocities.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
astars.dat 358 3532751 Northern Galactic disc A-type stars
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
V/165 : IGAPS. merged IPHAS & UVEX of northern Galactic plane (Monguio+, 2020)
Byte-by-byte Description of file: astars.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Name IGAPS source designation
(JHHMMSS.ss+DDMMSS.s)
21- 26 F6.3 mag rmag IGAPS r-band magnitude
28- 35 F8.6 mag e_rmag IGAPS r-band magnitude uncertainty
37- 42 F6.3 mag Hamag IGAPS Ha-band magnitude
44- 51 F8.6 mag e_Hamag IGAPS Ha-band magnitude uncertainty
53- 58 F6.3 mag imag IGAPS i-band magnitude
60- 67 F8.6 mag e_imag IGAPS i-band magnitude uncertainty
69- 87 I19 --- GaiaDR3 ?=- Gaia DR3 source identifier
89- 97 F9.6 mag Gmag ?=- Gaia DR3 G-band apparent magnitude
99-107 F9.6 mag BP-RP ?=- Gaia DR3 GBP-GRP colour
109-123 F15.11 deg RAdeg ?=- Right ascension (ICRS) at Ep=2016.0
from Gaia DR3
125-131 F7.4 mas e_RAdeg ?=- Right ascension error from Gaia DR3
133-147 F15.11 deg DEdeg ?=- Declination (ICRS) at Ep=2016.0
from Gaia DR3
149-155 F7.4 mas e_DEdeg ?=- Declination error from Gaia DR3
157-165 F9.4 mas plx ?=- Gaia DR3 parallax
167-172 F6.4 mas e_plx ?=- Error of Gaia DR3 parallax
174-181 F8.3 mas/yr pmRA ?=- Proper motion in right ascension
direction from Gaia DR3
183-187 F5.3 mas/yr e_pmRA ?=- Error of proper motion in right ascension
direction from Gaia DR3
189-196 F8.3 mas/yr pmDE ?=- Proper motion in declination direction
from Gaia DR3
198-202 F5.3 mas/yr e_pmDE ?=- Error of proper motion in declination
direction from Gaia DR3
204-209 F6.3 --- RUWE ?=- Gaia DR3 renormalised unit weight error
211-218 F8.3 km/s RV ?=- Gaia DR3 radial velocity
220-228 F9.6 km/s e_RV ?=- Gaia DR3 radial velocity error
230-236 F7.4 kpc Dist ?=- Distance to the Sun computed according to
an exponentially decreasing space density
prior with a length scale of 3kpc
238-245 F8.4 kpc Xgal ?=- Galactocentric X coordinate
247-254 F8.4 kpc Ygal ?=- Galactocentric Y coordinate
256-262 F7.4 kpc Zgal ?=- Galactocentric Z coordinate
264-270 F7.4 kpc R ?=- Cylindrical Galactocentric
radial coordinate
272-279 F8.4 deg phi ?=- Cylindrical Galactocentric
azimuthal coordinate
281-288 F8.3 mas/yr pmGLON ?=- Proper motion in Galactic longitude
direction
290-297 F8.3 mas/yr pmGLAT ?=- Proper motion in Galactic latitude
direction
299-306 F8.2 km/s vbcorr ?=- Velocity in Galactic latitude direction
corrected for solar motion
308-315 F8.2 km/s vlcorr ?=- Velocity in Galactic longitude direction
corrected for solar motion
317-324 F8.3 km/s VR ?=- Cylindrical Galactocentric radial
velocity
326-333 F8.3 km/s Vphi ?=- Cylindrical Galactocentric azimuthal
velocity
335-342 F8.3 km/s VZ ?=- Cylindrical Galactocentric vertical
velocity
344-350 F7.4 mag AG ?=- G-band extinction derived from
Green et al. (2019ApJ...887...93G 2019ApJ...887...93G) dustmap
352-358 F7.4 mag E(BP-RP) ?=- GBP-GRP reddening derived from
Green et al. (2019ApJ...887...93G 2019ApJ...887...93G) dustmap
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Acknowledgements:
Judith Ardevol, jardevol(at)icc.ub.edu
(End) J. Ardevol [Univ. Barcelona, ICCUB], P. Vannier [CDS] 15-Sep-2023