J/MNRAS/485/2312 Outer Galactic disk A and F stars space motions (Harris+, 2019)
A study of full space motions of outer Galactic disk A and F stars in two deep
pencil-beams.
Harris A., Drew J.E., Monguio M.
<Mon. Not. R. Astron. Soc. 485, 2312-2323 (2019)>
=2019MNRAS.485.2312H 2019MNRAS.485.2312H (SIMBAD/NED BibCode)
ADC_Keywords: Galactic plane ; Milky Way ; Radial velocities ;
Proper motions ; Spectrophotometry ; Stars, early-type
Keywords: methods: observational - stars: early-type - Galaxy: disc -
Galaxy: kinematics and dynamics
Abstract:
A and F stars can be used as probes of outer Galactic disk kinematics:
here we extend the work of Harris et al. (2018, Cat. J/MNRAS/475/1680)
by crossmatching their A/F sample with Gaia DR2 to bring in proper
motions. These are combined with the already measured radial
velocities and spectro-photometric distances to obtain full space
motions. We use this sample of 1173 stars, located in two pencil-beam
sightlines (l=178° and l=118°), to sample the Galactocentric
velocity field out to almost RG=15kpc. We find there are significant
differences in all three (radial, azimuthal and vertical) kinematic
components between the two directions. The rotation curve is roughly
flat in the anticentre direction, confirming and extending the result
of Kawata et al. (2018MNRAS.479L.108K 2018MNRAS.479L.108K) thanks to the greater reach of
our spectro-photometric distance scale. However at l=118° the
circular velocity rises outwards from RG=10.5kpc and there is a more
pronounced gradient in radial motion than is seen at l=178°.
Furthermore, the A star radial motion differs from the F stars by
∼10km/s. We discuss our findings in the context of perturbers
potentially responsible for the trends, such as the central bar,
spiral arms, the warp and external satellites. Our results at
l=178° are broadly consistent with previous work on K giants in
the anticentre, but the kinematics at l=118° in the Perseus region
do not yet reconcile easily with bar or spiral arm perturbation.
Description:
Full space motions of 1105 A and F type stars are presented. The
spectro-photometric distances and radial velocities are from the
sample of Harris et. al. (2018, Cat. J/MNRAS/475/1680), and these are
combined with Gaia proper motions in order to compute all 3 components
of Galactocentric velocity. The stars are located in two pencil-beam
sightlines in the Galactic plane, at (l=118°, b=+2°) and
(l=178°, b=+1°).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 219 1105 Table of data
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/MNRAS/475/1680 : Parameters of 1183 A and F stars (Harris+, 2018)
Byte-by-byte Description of file: table.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Target ID
12- 32 F21.17 deg RAdeg Right ascension (J2000.0)
34- 51 F18.15 deg DEdeg Declination (J2000.0)
53- 70 F18.14 deg GLON Galactic longitude
72- 89 F18.16 deg GLAT Galactic latitude
91- 97 F7.2 km/s HRV Heliocentric radial velocity
99-103 F5.2 km/s e_HRV Radial velocity negative error
105-109 F5.2 km/s E_HRV Radial velocity positive error
111-115 F5.3 kpc Dist Heliocentric distance
117-121 F5.3 kpc e_Dist Heliocentric distance error
123-128 F6.3 kpc RG Galactocentric distance
130-134 F5.3 kpc e_RG Galactocentric distance error
136-154 I19 --- SourceID Gaia DR2 Source ID
156-161 F6.3 mas/yr pmGLON* Proper motion in Galactic longitude,
pmGLON*cosGLAT (1)
163-167 F5.3 mas/yr e_pmGLON* Error of proper motion in Galactic longitude
169-174 F6.3 mas/yr pmGLAT Proper motion in Galactic latitude direction
176-180 F5.3 mas/yr e_pmGLAT Error in proper motion in Gal. latitude
182-187 F6.2 km/s u Galactocentric radial velocity
189-193 F5.2 km/s e_u Galactocentric radial velocity error
195-200 F6.2 km/s v Galactocentric azimuthal velocity
202-206 F5.2 km/s e_v Galactocentric azimuthal velocity error
208-213 F6.2 km/s w Galactocentric vertical velocity
215-219 F5.2 km/s e_w Galactocentric vertical velocity error
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Note (1): Proper motion in Galactic longitude direction multiplied by cos(b)
factor.
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Acknowledgements:
Amy Harris, a.harris7(at)herts.ac.uk
(End) Amy Harris [Univ. of Hertfordshire, UK] Patricia Vannier [CDS] 14-Feb-2019