Associating Sites of Methanol Masers at 6.7 GHz in Onsala 1

2009 East Asia VLBI Workshop, Seoul, Korea2009, 3, 18-20

Sugiyama, KoichiroSugiyama, Koichiro杉山 孝一郎杉山 孝一郎

스기야마 코이치로(Yamaguchi University)(Yamaguchi University)

ContentsContents

1.1. 6.7 GHz methanol maser6.7 GHz methanol maserAssociating sites : disk or outflow ?Associating sites : disk or outflow ?

2.2. Target : Onsala 1Target : Onsala 13.3. ResultsResults

1.1. Superpose on other masers, lines, continuumSuperpose on other masers, lines, continuum2.2. Internal proper motionsInternal proper motions

4.4. SummarySummary

6.7 GHz methanol maserFor study of massive star-forming regions (MSFRs)For study of massive star-forming regions (MSFRs)– associated with only MSFRs– tracing early evolutionary phase ： ～ 104 yr– very strong and bright （ second to the water masers ）– compact ： several AUFor astrometryFor astrometry– many sources many sources ： ～： ～ 900900– long lifetime and stable long lifetime and stable ： ： > 4 yr> 4 yr– small effect by water vaporsmall effect by water vapor

Potentially issuePotentially issue– Associating sites Associating sites ： ： Disk or Outflow ?Disk or Outflow ?

Associating sites : disk or outflow ?Associating sites : disk or outflow ?

DiskDisk– Linear structure and velocity gradientLinear structure and velocity gradient

=> Edge-on rotating disk=> Edge-on rotating disk– Ring structure Ring structure (Bartkiewicz et al. 2005)(Bartkiewicz et al. 2005)– Infall ? Infall ? (Goddi et al. 2007)(Goddi et al. 2007)

OutflowOutflow– Expanding shock (< 10 km sExpanding shock (< 10 km s-1-1) ) (Walsh et al. 1998)(Walsh et al. 1998) 　　　　– Parallel to HParallel to H22 emission emission (De Buizer 2003)(De Buizer 2003)

Planar shock Planar shock (Dodson et al. 2004)(Dodson et al. 2004)

G 327.120+0.511(Phillips et al. 1998)

G 320.23-0.28 (De Buizer 2003)

1.1. indirectly : superpose on other probesindirectly : superpose on other probes– water, OH maserswater, OH masers– continuum : UC Hcontinuum : UC HII regionsII regions, dust emissions, dust emissions– molecular lines : outflow, rotating diskmolecular lines : outflow, rotating disk

2.2. directly : internal proper motionsdirectly : internal proper motions– measure at three epochsmeasure at three epochs

Purpose and approachPurpose and approachClarify associating sites of methanol maserClarify associating sites of methanol maser

Target : Onsala 1Target : Onsala 1

Target : Onsala 1 (ON 1)Target : Onsala 1 (ON 1)distance : 1.75 kpc distance : 1.75 kpc (Rygl et al. in 9th EVN symp.)(Rygl et al. in 9th EVN symp.)

multiple location of MSFRsmultiple location of MSFRsoutflows in various directionsoutflows in various directions

water masers, CO, Hwater masers, CO, H22

HH1313COCO++, SiO, SiO

Clear absolute position of metClear absolute position of methanol maserhanol maser– measured with the MERLIN measured with the MERLIN

(Green et al. 2007) (Green et al. 2007)– mapping toward only red-shiftemapping toward only red-shifte

d spectral featured spectral feature

Nagayama

et al. (2008a)

Kumar et al. (2004)

CH3OH maser

Observational tableObservational tablewith the JVN at 6.7 GHzwith the JVN at 6.7 GHz

velocity resolution : 0.176 km svelocity resolution : 0.176 km s-1-1

synthesized beam : ~ 5×3 massynthesized beam : ~ 5×3 mas22

phase referencingphase referencing

ON 1ON 1datedate 2006, 09, 102006, 09, 10 2008, 05, 102008, 05, 10 2008, 10, 262008, 10, 26

stationsstations Y,U,M,IY,U,M,I Y,M,I,R,OY,M,I,R,O Y, U, M, I, R, OY, U, M, I, R, O

integration timeintegration time 3.4 hrs3.4 hrs 1.5 hrs1.5 hrs 0.5 hrs0.5 hrs

image sensitivityimage sensitivity ＊＊ 8080 200200 320320

＊ unit : mJy beam-1Y:Yamaguchi 32-m, U:Usuda 64-m, M:Mizusawa 20-m,I:Ishigaki 20-m, R:Iriki 20-m, O:Ogasawara 20-m

ResultsResults

ON 1 --- I : Spatial distributionON 1 --- I : Spatial distribution

Separated (spectrum) : Separated (spectrum) : ～～ 15 km s15 km s-1-1

Boundary of systemic velocityBoundary of systemic velocity– CS (CS (JJ=2‐1) : 11.6±3.0 km s=2‐1) : 11.6±3.0 km s-1-1 – H76α : 5.1±2.5 km sH76α : 5.1±2.5 km s-1-1

Isolated (spatial) : Isolated (spatial) : ～～ 1800 AU1800 AU– northeast-southwest directionnortheast-southwest direction

Vsys ~12 km s-1

H76 ~5.1 km s-1

ON 1 --- II : SuperpositionON 1 --- II : SuperpositionAssociated with the UAssociated with the UC HC HIIII region region– Coincided with OH maserCoincided with OH maser– Separated from water maserSeparated from water maser

different exciting sourcesdifferent exciting sources

Coincided with the HCoincided with the H1313COCO++, Si, SiO outflowsO outflows– Northeast-southwestNortheast-southwest

PA ~ 44 degPA ~ 44 deg– Low speed : 4.5 km sLow speed : 4.5 km s-1-1

– ~30 times smaller spatial size~30 times smaller spatial size

Similar trend for radial velocitySimilar trend for radial velocity– northeast : blue-shifted northeast : blue-shifted

southwest : red-shifted southwest : red-shifted

Nagayama et al. (2008a)modified by our works

Identified 13 spotsIdentified 13 spots– within 4 mas (motion)within 4 mas (motion)– within 0.18 km swithin 0.18 km s-1 -1 (radial)(radial)

DirectionDirection– roughly Northeast-southwestroughly Northeast-southwest

coincided with Hcoincided with H1313COCO++, SiO, SiO

Velocity of motionsVelocity of motions– 0.4 ~ 7.0 km s0.4 ~ 7.0 km s-1-1

Mean value : 3.2 km sMean value : 3.2 km s-1-1

Similar to HSimilar to H1313COCO+ + : 4.5 km s: 4.5 km s-1-1

ON 1 --- III : Internal proper motionON 1 --- III : Internal proper motion

tracing Outflow ?

ON1 --- IV : Comparison with OH masersON1 --- IV : Comparison with OH masers

OH maserOH maser– Expanding Expanding

motionsmotions （（ Fish & Reid Fish & Reid 20072007））

– Tracing expanding Tracing expanding UC HUC HII II regionregion

Methanol maserMethanol maser– Similar to OH maserSimilar to OH maser

direction of motionsdirection of motionsspatial coincidencespatial coincidenceradial velocitiesradial velocitiesFish & Reid (2007) の図を改変

tracing the expandingUC HII region ?

Expanding shell modelExpanding shell model

Expanding shell model Expanding shell model (Naga(Nagayama et al. 2008b)yama et al. 2008b)

– VVsys : H76α~5.1 km s: H76α~5.1 km s-1-1

– apply to the OH masers apply to the OH masers (Fis(Fish & Reid 2007)h & Reid 2007)

vvexpexp ~5.4 km/s ~5.4 km/s

rrshell ~1330 mas~1330 mas

– Unsuitable for methanol masUnsuitable for methanol masersers

particularly blue-shifted spotsparticularly blue-shifted spotsreferred from Nagayama et al. (2008b)

different from expanding motionsof the OH masers

SummarySummary6.7 GHz methanol maser in ON 16.7 GHz methanol maser in ON 1– Isolated in spatial distribution and spectrumIsolated in spatial distribution and spectrum– SuperpositionSuperposition

coincide with the UC HII region, Hcoincide with the UC HII region, H1313COCO++, SiO outflows, SiO outflows

– Internal proper motionInternal proper motiondirected away between red- and blue-shifted spotsdirected away between red- and blue-shifted spotsroughly northeast-southwest directionroughly northeast-southwest direction

– Comparison with the OH masersComparison with the OH maserssimilar : spatial, radial velocity, proper motionsimilar : spatial, radial velocity, proper motionUnsuitable the expanding shell model of OH masersUnsuitable the expanding shell model of OH masers

possibly tracing Outflow

ProspectsProspectsMeasuring internal proper motions toward many mMeasuring internal proper motions toward many methanol sources with EAVNethanol sources with EAVN– play a significant role in a development of EAVNplay a significant role in a development of EAVN

Array constructArray construct– Shanghai (will be installed)Shanghai (will be installed)

make UV-coverage in east-west directionmake UV-coverage in east-west direction– UrumqiUrumqi

form maximum baseline ~3 times longer than that nowform maximum baseline ~3 times longer than that now– Australian stationsAustralian stations

advantage for observations of equatorial sourcesadvantage for observations of equatorial sources