mapping our milky way with methanol masers
DESCRIPTION
Mapping our Milky Way with Methanol Masers. Xingwu Zheng Astronomy Department,Nanjing University,China. Collaborator: M. J. Reid (CFA, US) , K. M. Menten (MPIR, Germany) Brunthaler (MPIR, Germany), L. Moscadelli (Italy) Y. Xu (PMO, China), B. Zhang (NJU, China) - PowerPoint PPT PresentationTRANSCRIPT
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
outline
• progress of the project
• preliminary results
• Further work
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
Milky Way Parallaxes
W3OH:
= 0.512 mas
+/- 0.010 mas
Xu, Reid, Zheng & Menten (2006)
Milky Way ParallaxesHonma et al. (2007)
S269:
= 0.189 mas
+/- 0.016 mas
Milky Way ParallaxesHachisuka et al. (2009)
S269:
= 0.189 mas
+/- 0.016 mas
WB89-437:
= 0.167 mas
+/- 0.006 mas
Orion Nebular Cluster Parallax
D = 414 +/- 7 pc
Menten, Reid, Forbrich & Brunthaler (2007)
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
Methanol maser parallax measurementswith VLBA
First phase result:
project from 2004 to 2008
CH3OH, SiO and H2O maser parallax with VLBA and VERA
The model Thin disk disk rotation speed
R
0 0( ) ( )d
R R RdR
0
0R
frame system: Cartesian Galactic coordinate
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
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
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:
Discrepancy: kinematic distance? ? pecular motion?
0 0,R
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
1 12.3kms kpcd
dR
Need more data
2.3km/s
14.7km/ss
s
U
V
Dust lanes?Shocks?
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
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
美丽的南京大学天文系