Mapping our milky way with methanol masers
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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)

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Mapping our Milky Way with Methanol Masers

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Mapping our milky way with methanol masers

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)

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)


Outline

outline

  • progress of the project

  • preliminary results

  • Further work


Mapping our milky way with methanol masers

Radio instruments of mapping the Galactic structure:

VLBA (Very large Baseline Arry)

VERA (VLBI Exploration Radio Astrometry)

VLBA

Array beam

Astrometry accuracy

VERA

Array beam

Astrometry accuracy

Distance measurement 10 kpc (parallax 0.1 mas)


Mapping our milky way with methanol masers

Milky Way Parallaxes

Xu, Reid, Zheng & Menten (2006)

  • W3OH:

  • = 0.512 mas

    +/- 0.010 mas


Mapping our milky way with methanol masers

Milky Way Parallaxes

Honma et al. (2007)

  • S269:

  • = 0.189 mas

    +/- 0.016 mas


Mapping our milky way with methanol masers

Milky Way Parallaxes

  • WB89-437:

  • = 0.167 mas

    +/- 0.006 mas

Hachisuka et al. (2009)

  • S269:

  • = 0.189 mas

    +/- 0.016 mas


Orion nebular cluster parallax

Orion Nebular Cluster Parallax

D = 414 +/- 7 pc

Menten, Reid, Forbrich & Brunthaler (2007)


Mapping our milky way with methanol masers

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


Mapping our milky way with methanol masers

Methanol maser parallax measurements

with VLBA

First phase result:

project

from 2004 to 2008


Mapping our milky way with methanol masers

CH3OH, SiO and H2O maser parallax

with VLBA and VERA


Mapping our milky way with methanol masers

The model

Thin disk

disk rotation speed


Mapping our milky way with methanol masers

frame system:

Cartesian Galactic coordinate


Mapping our milky way with methanol masers

data

Model values

Least-squarses Fitting


Mapping our milky way with methanol masers

Best fitting:

Average motion:


Mapping our milky way with methanol masers

Discrepancy:

kinematic distance?

?

pecular motion?


Total dynamical mass of the milky way

Total dynamical mass of the Milky Way

The Milky Way may have more mass


Mapping our milky way with methanol masers

Need more data


Mapping our milky way with methanol masers

Dust lanes?

Shocks?


Mapping our milky way with methanol masers

Second phase:

8 methanol sources

data available until

May 2009

Third phase:

6 H2O sources

data available until

the end of 2009

More 10 SiO & H2O

sources with VERA


Summary

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


Mapping our milky way with methanol masers

美丽的南京大学天文系


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