J/ApJ/847/123 Local velocity substructures in the Milky Way disk (Pearl+, 2017)
A map of the local velocity substructure in the Milky Way disk.
Pearl A.N., Newberg H.Jo, Carlin J.L., Smith R.F.
<Astrophys. J., 847, 123 (2017)>
=2017ApJ...847..123P 2017ApJ...847..123P
ADC_Keywords: Positional data; Milky Way; Surveys
Keywords: astrometry ; Galaxy: disk ; Galaxy: kinematics and dynamics ;
Galaxy: structure ; stars: kinematics and dynamics
Abstract:
We confirm, quantify, and provide a table of the coherent velocity
substructure of the Milky Way disk within 2kpc of the Sun toward the
Galactic anticenter, with a 0.2kpc resolution. We use the radial
velocities of ∼340000 F-type stars obtained with the Guoshoujing
Telescope (also known as the Large Sky Area Multi-Object Fiber
Spectroscopic Telescope, LAMOST), and proper motions derived from the
PPMXL catalog. The PPMXL proper motions have been corrected to remove
systematic errors by subtracting the average proper motions of
galaxies and QSOs that have been confirmed in the LAMOST spectroscopic
survey, and that are within 2.5° of the star's position. We
provide the resulting table of systematic offsets derived from the
PPMXL proper motion measurements of extragalactic objects identified
in the LAMOST spectroscopic survey. Using the corrected phase-space
stellar sample, we find statistically significant deviations in the
bulk disk velocity of 20km/s or more in the three-dimensional
velocities of Galactic disk stars. The bulk velocity varies
significantly over length scales of half a kiloparsec or less. The
rotation velocity of the disk increases by 20km/s from the Sun's
position to 1.5kpc outside the solar circle. Disk stars in the second
quadrant, within 1kpc of the Sun, are moving radially toward the
Galactic center and vertically toward a point a few tenths of a
kiloparsec above the Galactic plane; looking down on the disk, the
stars appear to move in a circular streaming motion with a radius of
the order of 1kpc.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 51 518400 *Data from our proper motion correction table
fig11.dat 76 673 Data behind figure 11
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Note on table1.dat: Each of the (1440x360) 518400 rows corresponds to a bin
representing a small region in the sky at which the following correction
values apply. Each bin is 0.25°x0.25°,
spanning 0°≪α<360° and -15°≤δ<75°.
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See also:
I/317 : The PPMXL Catalog (Roeser+ 2010)
V/146 : LAMOST DR1 catalogs (Luo+, 2015)
V/149 : LAMOST DR2 catalogs (Luo+, 2016)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
J/A+AS/103/427 : Second Quito Astrolabe Catalogue (Kolesnik+ 1994)
J/ApJ/588/824 : Velocities of blue stars near (l,b)=(198,-27) (Yanny+, 2003)
J/ApJ/688/237 : Disk corrugations in IC 2233 (Matthews+, 2008)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/A+A/569/A125 : Spiral structure of the Milky Way (Hou+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 F7.3 deg RAdeg Rigth ascension; center value α of the bin
(J2000) (ra) (1)
9- 15 F7.3 deg DEdeg [-15/75] Declination; center value δ of
the bin (J2000) (dec) (1)
17- 24 F8.4 mas/yr pmraCor [-12/15]?=0 Proper motion correction in RA
(pmra_shift)
26- 33 F8.4 mas/yr pmdeCor [-10.3/18.3]?=0 Proper motion correction in DEC
(pmde_shift)
35- 42 F8.4 mas/yr e_pmraCor [0.08/12]?=100 Uncertainty on pmraCor (pmra_se)
44- 51 F8.4 mas/yr e_pmdeCor [0.1/10]?=100 Uncertainty on pmdeCor (pmde_se)
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Note (1): Note that the table only contains useful data between a decl. of
-10.50°<δ<61.75°, resulting in no correction values
given to many rows at the beginning and end of the table.
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Byte-by-byte Description of file: fig11.dat
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Bytes Format Units Label Explanations
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1- 3 F3.1 kpc R [8.1/9.9] R Galactic coordinate (1)
5- 8 F4.1 kpc Z [-1.3/1.5] Z Galactic coordinate (1)
10- 15 F6.2 deg theta [-10.5/7.8] θ Galactic coordinate (1)
17- 21 I5 --- count [10/13365] Count
23- 28 F6.2 km/s vr [-36.2/30] Galactic Standard of Rest velocity
in R
30- 35 F6.2 km/s vz [-26.1/37.5] Galactic Standard of Rest velocity
in Z
37- 43 F7.2 km/s vtheta [-247.2/-159.6] Galactic Standard of Rest
velocity in θ
45- 49 F5.2 km/s s_vr [0.2/21] vr uncertainty (vr_err)
51- 55 F5.2 km/s s_vz [0.1/23] vz uncertainty (vz_err)
57- 61 F5.2 km/s s_vtheta [0.1/18] vtheta uncertainty (vtheta_err)
63- 66 F4.2 km/s e_vr [0.7/8] One standard deviation in vr (vr_se)
68- 71 F4.2 km/s e_vz [0.6/9.1] One standard deviation in vz (vz_se)
73- 76 F4.2 km/s e_vtheta [0.7/9] One standard deviation in vtheta
(vtheta_se)
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Note (1): In this paper, we adopt the same right-handed Galactic cylindrical
(R,θ,Z) coordinate systems used in Carlin+ (2013ApJ...777L...5C 2013ApJ...777L...5C)
to represent positions. Note that both coordinate systems are
Galactocentric, and θ increases in the same direction as
Galactic longitude, with the Sun centered at θ=0. We use
(VR,Vθ,VZ) to represent the Galactic Standard of Rest
velocities in these coordinate systems. See section 3.
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History:
From electronic version of the journal
(End) Prepared by Emmanuelle Perret [CDS] 31-May-2018