J/ApJ/783/130 Parallaxes of high mass star forming regions (Reid+, 2014)
Trigonometric parallaxes of high mass star forming regions: the structure and
kinematics of the Milky Way.
Reid M.J., Menten K.M., Brunthaler A., Zheng X.W., Dame T.M., Xu Y., Wu Y.,
Zhang B., Sanna A., Sato M., Hachisuka K., Choi Y.K., Immer K.,
Moscadelli L., Rygl K.L.J., Bartkiewicz A.
<Astrophys. J., 783, 130 (2014)>
=2014ApJ...783..130R 2014ApJ...783..130R (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Masers ; Parallaxes, trigonometric ; Proper motions ;
Associations, stellar
Keywords: Galaxy: fundamental parameters - Galaxy: kinematics and dynamics -
Galaxy: structure - gravitational waves - parallaxes -
stars: formation
Abstract:
Over 100 trigonometric parallaxes and proper motions for masers
associated with young, high-mass stars have been measured with the Bar
and Spiral Structure Legacy Survey, a Very Long Baseline Array key
science project, the European VLBI Network, and the Japanese VLBI
Exploration of Radio Astrometry project. These measurements provide
strong evidence for the existence of spiral arms in the Milky Way,
accurately locating many arm segments and yielding spiral pitch angles
ranging from about 7° to 20°. The widths of spiral arms
increase with distance from the Galactic center. Fitting axially
symmetric models of the Milky Way with the three-dimensional position
and velocity information and conservative priors for the solar and
average source peculiar motions, we estimate the distance to the
Galactic center, R0, to be 8.34±0.16kpc, a circular rotation speed
at the Sun, Θ0, to be 240±8km/s, and a rotation curve that
is nearly flat (i.e., a slope of -0.2±0.4km/s/kpc) between
Galactocentric radii of ~5 and 16kpc. Assuming a "universal"
spiral galaxy form for the rotation curve, we estimate the thin disk
scale length to be 2.44±0.16kpc. With this large data set, the
parameters R0 and Θ0are no longer highly correlated and are
relatively insensitive to different forms of the rotation curve. If
one adopts a theoretically motivated prior that high-mass star forming
regions are in nearly circular Galactic orbits, we estimate a global
solar motion component in the direction of Galactic rotation,
V☉=14.6±5.0km/s. While Θ0and V☉are significantly
correlated, the sum of these parameters is well constrained,
Θ0+V☉=255.2±5.1km/s, as is the angular speed of the
Sun in its orbit about the Galactic center,
(Θ0+V☉)/R0=30.57±0.43km/s/kpc. These parameters
improve the accuracy of estimates of the accelerations of the Sun and
the Hulse-Taylor binary pulsar in their Galactic orbits, significantly
reducing the uncertainty in tests of gravitational radiation predicted
by general relativity.
Description:
Table1 lists the parallaxes and proper motions of 103 regions of
high-mass star formation measured with Very Long Baseline
Interferometry (VLBI) techniques, using the National Radio Astronomy
Observatory's Very Long Baseline Array (VLBA), the Japanese VLBI
Exploration of Radio Astrometry (VERA;
http://veraserver.mtk.nao.ac.jp) project, and the European VLBI
Network (EVN). We have include three red supergiants (NML Cyg, S Per,
VY CMa) as indicative of high-mass star forming regions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 108 103 Parallaxes and proper motions of high-mass star
forming regions
refs.dat 151 47 References
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See also:
V/112 : Catalog of Star-Forming Regions in the Galaxy (Avedisova, 2002)
J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)
http://bessel.vlbi-astrometry.org/ : BeSSeL survey
http://veraserver.mtk.nao.ac.jp/ : Japanese VERA
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Galactic source name/coordinates
16- 30 A15 --- Alias Alias name
32- 33 I2 h RAh Hour of Right Ascension (J2000)
35- 36 I2 min RAm Minute of Right Ascension (J2000)
38- 42 F5.2 s RAs Second of Right Ascension (J2000)
44 A1 --- DE- Sign of the Declination (J2000)
45- 46 I2 deg DEd Degree of Declination (J2000)
48- 49 I2 arcmin DEm Arcminute of Declination (J2000)
51- 54 F4.1 arcsec DEs Arcsecond of Declination (J2000)
56- 60 F5.3 mas plx Trigonometric Parallax
62- 66 F5.3 mas e_plx Uncertainty in plx (1)
68- 72 F5.2 mas/yr pmX Eastward Proper Motion (Motion in RA
multiplied by cos(Dec);
µx=µαcosδ) (2)
74- 77 F4.2 mas/yr e_pmX Uncertainty in pmX
79- 83 F5.2 mas/yr pmY Northward Proper Motion
(µy=µδ (2)
85- 88 F4.2 mas/yr e_pmY Uncertainty in pmY
90- 92 I3 km/s VLSR Local Standard of Rest velocity vLSR (2)
94- 95 I2 km/s e_VLSR Uncertainty in VLSR
97- 99 A3 --- Arm Spiral arm designator; based mostly on
association with structure seen in l-V
plots of CO and HI emission (not using the
measured parallaxes) (3)
101-108 A8 --- Ref Reference (in refs.dat file)
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Note (1): Parallax uncertainties for sources with multiple (N) maser spots have
been adjusted upwards by {sqrt}(N), if not done so in the original
publications.
Note (2): Some parameter values listed here are preliminary ones and may be
slightly different from final values appearing in published papers. Motion
components and their uncertainties are meant to reflect that of the central
star that excites the masers, and may be larger than formal measurement
uncertainties quoted in some papers.
Note (3): Spiral arm designator defined as follows:
Con = Connecting arm;
3-k = 3kpc arm;
4-k = 4kpc/Norma arm;
Sct = Scutum-Crux-Centaurus arm;
Sgr = Sagittarius arm;
Loc = Local arm;
Per = Perseus arm;
Out = Outer arm;
... = Source that could not be confidently assigned to an arm.
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Ref Reference identifier
4- 32 A29 --- Aut Author's name
34- 52 A19 --- BibCode Bibliographic code
54-151 A98 --- Com Comment
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 21-Apr-2016