Mapping our Milky Way with Methanol Masers
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Transcript of Mapping our Milky Way with Methanol Masers
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Mapping our Milky Way with Methanol Masers
Collaborator:
M. J. Reid (CFA, US) , K. M. Menten (MPIR, Germany)
A. Brunthaler (MPIR, Germany), L. Moscadelli (Italy)
Y. Xu (PMO, China), B. Zhang (NJU, China)
M. Sato (VERA), M. Honma (VERA), T. Hirota (VERA)
K. Hachsuka (SHAO, China), Y. K. Choi (MPIR, Germany)
G. A. Moellenbrock (NRAO, US), A. Bartkiewicz (Poland)
A. Nakagawa(Japan), Y. Asaki (Japan)
Xingwu Zheng
Astronomy Department,Nanjing University,China
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outline
• progress of the project
• preliminary results
• Further work
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Radio instruments of mapping the Galactic structure:VLBA (Very large Baseline Arry)VERA (VLBI Exploration Radio Astrometry)
VLBAArray beam Astrometry accuracy
VERAArray beam Astrometry accuracy
Distance measurement 10 kpc (parallax 0.1 mas)
0.5θ / SNR 5μas
/ 1cm / 8000km 0.25masD
/ 1cm / 2300km 0.87masD
0.5θ / SNR μas
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Milky Way Parallaxes
W3OH:
= 0.512 mas
+/- 0.010 mas
Xu, Reid, Zheng & Menten (2006)
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Milky Way ParallaxesHonma et al. (2007)
S269:
= 0.189 mas
+/- 0.016 mas
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Milky Way ParallaxesHachisuka et al. (2009)
S269:
= 0.189 mas
+/- 0.016 mas
WB89-437:
= 0.167 mas
+/- 0.006 mas
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Orion Nebular Cluster Parallax
D = 414 +/- 7 pc
Menten, Reid, Forbrich & Brunthaler (2007)
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S Per -34 0.399+/-0.014 -0.38 -1.54 -34 9
S Car 2.33+/-0.13 -1.56 -5.16 34.7 10
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Methanol maser parallax measurementswith VLBA
First phase result:
project from 2004 to 2008
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CH3OH, SiO and H2O maser parallax with VLBA and VERA
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The model Thin disk disk rotation speed
R
0 0( ) ( )d
R R RdR
0
0R
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frame system: Cartesian Galactic coordinate
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1 1 1, ,HelioD D U V W v ,v ,v( ) ( )
LSR Heliov v( sin cos )cos sinStd Std Std
Helio LSR V l U l b W b v v
1
1
1
U
V G N N S
W
Helio
v
v
v
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1
0 1
0sin
cos
Hs U
HVs
U U U
VVV
+ +
dataModel values
Least-squarses Fitting
2 2
1( )
N
i iid m
0( , , , , )R R D l b
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2.3km/s
14.7km/ss
s
U
V
1 12.3kms kpcd
dR
0
0
8.4kpc
254km/s
R
00d
ordR
0d
dR
Average motion:
Best fitting:
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Discrepancy: kinematic distance? ? pecular motion?
0 0,R
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The Milky Way may have more mass
0 0
0 0
8.4, 254)1.3
8.5, 220)gal
gal
M R
M R
((
20
0galM
GR
Total dynamical mass of the Milky Way
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1 12.3kms kpcd
dR
Need more data
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2.3km/s
14.7km/ss
s
U
V
Dust lanes?Shocks?
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Second phase: 8 methanol sources data available until May 2009Third phase: 6 H2O sources data available until the end of 2009
More 10 SiO & H2Osources with VERA
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summary
• Measured ~20 CH3OH, H2O & SiO maser sources parallax and proper motion
• Have very interesting preliminary results of galactic rotation and important parameters
• Model need more data
• Need southern sky data
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美丽的南京大学天文系