Associating Sites of Methanol Masers at 6.7 GHz in Onsala East Asia VLBI Workshop, Seoul, Korea 2009, 3, Sugiyama, Koichiro 杉山 孝一郎 스기야마 코이치로 (Yamaguchi University)

Contents GHz methanol maser Associating sites : disk or outflow ? 2. Target : Onsala 1 3. Results 1.Superpose on other masers, lines, continuum 2.Internal proper motions 4. Summary

6.7 GHz methanol maser For study of massive star-forming regions (MSFRs) – –associated with only MSFRs – –tracing early evolutionary phase ： ～ 10 4 yr – –very strong and bright （ second to the water masers ） – –compact ： several AU For astrometry –many sources ： ～ 900 –long lifetime and stable ： > 4 yr –small effect by water vapor Potentially issue –Associating sites ： Disk or Outflow ?

Associating sites : disk or outflow ? Disk –Linear structure and velocity gradient => Edge-on rotating disk –Ring structure (Bartkiewicz et al. 2005) –Infall ? (Goddi et al. 2007) Outflow –Expanding shock (< 10 km s -1 ) (Walsh et al. 1998) –Expanding shock (< 10 km s -1 ) (Walsh et al. 1998) –Parallel to H 2 emission (De Buizer 2003) Planar shock (Dodson et al. 2004) G (Phillips et al. 1998) G (De Buizer 2003)

1. indirectly : superpose on other probes –water, OH masers –continuum : UC H II regions, dust emissions –molecular lines : outflow, rotating disk 2. directly : internal proper motions –measure at three epochs Purpose and approach Clarify associating sites of methanol maser

Target : Onsala 1

Target : Onsala 1 (ON 1) distance : 1.75 kpc (Rygl et al. in 9th EVN symp.) multiple location of MSFRs outflows in various directions water masers, CO, H 2 H 13 CO +, SiO Clear absolute position of methanol maser –measured with the MERLIN (Green et al. 2007) –mapping toward only red- shifted spectral feature Nagayama et al. (2008a) Kumar et al. (2004) CH 3 OH maser

Observational table with the JVN at 6.7 GHz velocity resolution : km s -1 synthesized beam : ~ 5×3 mas 2 phase referencing ON 1 date 2006, 09, , 05, , 10, 26 stationsY,U,M,IY,M,I,R,O Y, U, M, I, R, O integration time 3.4 hrs 1.5 hrs 0.5 hrs image sensitivity ＊ ＊ unit : mJy beam -1 Y:Yamaguchi 32-m, U:Usuda 64-m, M:Mizusawa 20-m, I:Ishigaki 20-m, R:Iriki 20-m, O:Ogasawara 20-m

Results

ON I : Spatial distribution Separated (spectrum) : ～ 15 km s -1 Boundary of systemic velocity –CS (J=2 ‐ 1) : 11.6±3.0 km s -1 –H76α : 5.1±2.5 km s -1 Isolated (spatial) : ～ 1800 AU –northeast-southwest direction V sys ~12 km s -1 H76 ~5.1 km s -1

ON II : Superposition Associated with the UC H II region –Coincided with OH maser –Separated from water maser different exciting sources Coincided with the H 13 CO +, SiO outflows –Northeast-southwest PA ~ 44 deg –Low speed : 4.5 km s -1 –~30 times smaller spatial size Similar trend for radial velocity –northeast : blue-shifted southwest : red-shifted Nagayama et al. (2008a) modified by our works

Identified 13 spots –within 4 mas (motion) –within 0.18 km s -1 (radial) Direction –roughly Northeast-southwest coincided with H 13 CO +, SiO Velocity of motions –0.4 ~ 7.0 km s -1 Mean value : 3.2 km s -1 Similar to H 13 CO + : 4.5 km s -1 ON III : Internal proper motion tracing Outflow ?

ON1 --- IV : Comparison with OH masers OH maser –Expanding motions （ Fish & Reid 2007 ） –Tracing expanding UC H II region Methanol maser –Similar to OH maser direction of motions spatial coincidence radial velocities Fish & Reid (2007) の図を改変 tracing the expanding UC H II region ?

Expanding shell model Expanding shell model (Nagayama et al. 2008b) –V : H76α~5.1 km s -1 –V sys : H76α~5.1 km s -1 –apply to the OH masers (Fish & Reid 2007) v exp ~5.4 km/s r ~1330 mas r shell ~1330 mas –Unsuitable for methanol masers particularly blue-shifted spots referred from Nagayama et al. (2008b) different from expanding motions of the OH masers

Summary 6.7 GHz methanol maser in ON 1 –Isolated in spatial distribution and spectrum –Superposition coincide with the UC HII region, H 13 CO +, SiO outflows coincide with the UC HII region, H 13 CO +, SiO outflows –Internal proper motion directed away between red- and blue-shifted spots roughly northeast-southwest direction –Comparison with the OH masers similar : spatial, radial velocity, proper motion Unsuitable the expanding shell model of OH masers possibly tracing Outflow

Prospects Measuring internal proper motions toward many methanol sources with EAVN –play a significant role in a development of EAVN Array construct –Shanghai (will be installed) make UV-coverage in east-west direction –Urumqi form maximum baseline ~3 times longer than that now –Australian stations advantage for observations of equatorial sources