YSO jets in the Galactic Plane from UWISH2: I - MHO catalogue for Serpens and Aquila

0.58 MB·English

by  G. Ioannidis

Mon.Not.R.Astron.Soc.000,1–13(2011) Printed17January2012 (MNLATEXstylefilev2.2)
YSO jets in the Galactic Plane from UWISH2:
I - MHO catalogue for Serpens and Aquila
G. Ioannidis1(cid:63), D. Froebrich1†
2 1CentreforAstrophysicsandPlanetaryScience,UniversityofKent,Canterbury,CT27NH,UK
1
0
2
Receivedsooner;acceptedlater

n
a
J ABSTRACT

6
1 JetsandoutflowsfromYoungStellarObjects(YSOs)areimportantsignpostsofcurrently
ongoingstarformation.Inordertostudytheseobjectsweareconductinganunbiasedsurvey

] along the Galactic Plane in the 1-0S(1) emission line of molecular hydrogen at 2.122µm
A
using the UKInfrared Telescope.In this paperwe arefocusing ona 33square degreesized
G regioninSerpensandAquila(18◦<l<30◦;-1.5◦<b<+1.5◦).
. We trace 131 jets and outflows from YSOs, which results in a 15 fold increase in the
h
totalnumberofknownMolecularHydrogenOutflows.Comparedtothis,thetotalintegrated
p
1-0S(1)fluxofallobjectsjustaboutdoubles,sincetheknownobjectsoccupythebrightend
-
o ofthefluxdistribution.Ourcompletenesslimitis3·10−18Wm−2 with70%oftheobjects
r havingfluxesoflessthan10−17Wm−2.
t
s Generally, the flows are associated with Giant Molecular Cloud complexes and have a
a
scale height of 25–30pc with respect to the Galactic Plane. We are able to assign potential
[
source candidates to about half the objects. Typically, the flows are clustered in groups of

1 3–5 objects, within a radius of 5pc. These groups are separated on average by about half
v a degree, and 2/3rd of the entire survey area is devoid of outflows. We find a large range of
7 apparentoutflowlengthsfrom4(cid:48)(cid:48) to130(cid:48)(cid:48).Ifweassumeadistanceof3kpc,only10%ofall
3 outflowsareofparsecscale.Thereisa2.6σ overabundanceofflowpositionanglesroughly
2
perpendiculartotheGalacticPlane.
3
1. Keywords: ISM:jetsandoutflows;stars:formation;stars:winds,outflows;ISM:individual:
0 GalacticPlane
2
1
:
v
i 1 INTRODUCTION rence in other star forming regions (low and high mass)? Is star
X
formationtriggeredininfrequentburstsorisitanongoing,multi-
The interstellar medium (ISM) in galaxies is radically influenced
r pleepochprocessineachGMC?ThepresenceofjetsfromYSOsis
a bystarformation.GiantMolecularClouds(GMCs)areheatedand
anindicationofayoungpopulationandactiveaccretionwhilethe
excitedbyoutflowsfromprotostarsandradiationfromhigh-mass
sparsityoftheminregionswithasizeablepopulationofreddened
young stellar objects (YSO). Changes in chemistry and probably
sources shows a more evolved region with a larger population of
theturbulentmotioninGMCsarearesultofstarformation,espe-
pre-main-sequencestars.Thedynamicalageofaprotostellarout-
ciallymassivestarformation.Therefore,itisofgreatimportance
flowis10to100-timeslessthantheturbulentlifetimeofaGMC.
tounderstandtheformationofstars.
Therefore,thepresenceofalargenumberofoutflowswillbeanin-
JetsandoutflowsfromYSOsaresign-postsofcurrentlyongo-
dicationofcurrentlyongoingormultipleepochsofstarformation.
ingstarformation(e.g.Ballyetal.(1995);Eislo¨ffel(2000);Froe-
brich&Scholz(2003);Davisetal.(2009)).Previousstudiesofstar
forming regions like the OrionA molecular ridge by Davis et al. Outflows from YSOs are also a direct tracer of mass accre-
(2009)andStankeetal.(2002),DR21/W75byDavisetal.(2007), tion and ejection and can be used to estimate star formation effi-
aswellastheTaurus-Auriga-PerseuscloudsbyDavisetal.(2008), ciencyfromregiontoregion.Thisisparticularlythecaseinhigh
haveshownalargenumberofoutflowsfromYSOs.However,there massstarformingregionswheretheefficiencyisgrosslyaffected
areanumberofopenquestionswhicharestilltobeaddressed.For byexistingmassiveyoungstars,whichinfluencetheenvironment
example:Isalargenumberofjetsandoutflowsacommonoccur- via their hugely energetic winds and intense UV fluxes. Further-
more,inmassivestarformingregions,whereyoungstarsformin
clusters and massive stars influence their lower-mass neighbours,
(cid:63) E-mail:[email protected] photo-evaporation and ablation of protostellar disks can suppress
† E-mail:[email protected] accretion.Asaresultthemechanismthatdrivesthejetsandout-
(cid:13)c 2011RAS
2 Ioannidis&Froebrich
flowsisswitchedoff.Towhatdegreedotheseinteractionsaffect positions and distribution of outflows, the lengths and flux distri-
accretioninYSOs? butions as well as their orientation. We conclude our findings in
Thepositionofindividualprotostarscanbedetectedfromjets Sect.4.
andoutflowswhiletheirevolutionarystage(e.g.Class0,ClassI)is
closelyrelatedtothebrightnessinH emission(CarattioGaratti
2
et al. 2006). The mass infall/ejection history can be determined
2 DATAANDANALYSIS
from jets since there is a correlation between the jet parameters,
mass infall rates and accretion luminosities (Beck 2007; Antoni- 2.1 NearinfraredUKIRTWFCAMdata
uccietal.2008).
We obtained our near infrared narrow band imaging data in the
Studies by Eislo¨ffel et al. (1994) and Banerjee & Pudritz
1-0S(1) line of H using the Wide Field Camera (WFCAM
(2006) suggest that outflows are aligned parallel with the local 2
- Casali et al. (2007)) at the United Kingdom Infrared Tele-
magneticfieldandperpendiculartothechainsofcores.However,
scope(UKIRT). Thecamera consistsof fourRockwell Hawaii-II
existingobservationsgivemixedresultswithoutadefiniteanswer
(HgCdTe 2048×2048) arrays with a pixel scale of 0.4(cid:48)(cid:48). The 1-
(Anathpindika & Whitworth 2008; Davis et al. 2009). Is there a
0S(1)filteriscentredat2.122µmwith∆λ=0.021µm.Ourdata
correlationbetweenthemassofthedrivingsourceandtheorienta-
is part of the UWISH2 survey (see F11 for details) and the H
tionoftheflowwithrespecttothecloudfilament(i.e.aremassive 2
images are taken with a per pixel integration time of 720s under
outflowsmorelikelytobeorthogonaltothefilamentsthanflows
verygoodseeingconditions.Thetypicalfullwidthhalfmaximum
fromlowmassstars)?Furthermore:Whatfractionofoutflowsand
(fwhm) of the stellar point spread function is 0.7(cid:48)(cid:48), the 5σ point
jetsarecollimated,andwhatfractionareparsec-scaleinlength?Is
sourcedetectionlimitisabout18mag(inbroad-bandK)andthe
thereacorrelationbetweenthemedianageoftheembeddedpop-
surfacebrightnesslimitisabout10−19Wm−2arcsec−2 whenav-
ulationandthemeanflowlength?Areoutflowssufficientinnum-
eraged over the typical seeing (F11). Our narrow band data were
bersandenergeticenoughtoaccountfortheturbulentmotionsin
takenbetween31stofJuly2009and9thofSeptember2010.
GMCs?
Furthermore, we utilised the UK Infrared Deep Sky Survey
In order to answer the above outlined questions we need to
(UKIDSS) data in the near infrared JHK bands taken with the
have a representative sample of jets and outflows from young
sametelescope,sameinstrumentalset-upandtilingaspartofthe
stars which is free from selection effects. This will allow us to
GalacticPlaneSurvey(GPS,Lucasetal.(2008))inordertoper-
perform a statistically meaningful investigation of the dynamical
formthecontinuumsubtraction(H -K)ofournarrowbandimages
processes associated with (massive) star formation. Therefore we 2
andtogeneratethreebandcolourimages(JHK,JHH ,JKH ;
are conducting an unbiased search for jets and outflows in the 2 2
see Sect.2.3). When compared to our narrow band data the NIR
Galactic Plane using the UKIRT Wide Field Infrared Survey for
broadbanddatahasverysimilarquality(fwhmanddepth).Both
H (UWISH2 – Froebrich et al. (2011), hereafter F11). The data
2 datasetsaretakentypicallyabout2.5to4.0yearsapart.
is taken in the H 1-0S(1) emission line at 2.122µm, and thus
2 DatareductionandphotometryforbothNIRdatasetsaredone
highlights regions of shock excited molecular gas (T ≈ 2000K,
by the Cambridge Astronomical Survey Unit (CASU). Reduced
n >103cm−3),aswellasfluorecentlyexcitedmaterial.Hence,
H2 imagesandphotometrytablesareavailableviatheWideFieldAs-
itcanbeusedtotraceoutflowsandjetsfromembeddedyoungstars.
tronomy Unit (WFAU). The basic data reduction procedures ap-
In this project we focus our attention on the Serpens/Aquila
pliedaredescribedinDyeetal.(2006).Calibration(photometric
regionintheGalacticPlane,coveredbyUWISH2.Inparticularwe
as well astrometric) is performed using 2MASS (Skrutskie et al.
investigatethearea18◦<l<30◦;-1.5◦<b<+1.5◦,whichapprox-
(2006))andthedetailsaredescribedinHodgkinetal.(2009).
imatelycovers33squaredegrees(seeFig.1foranoverviewofthe
region). It is the first continuous area of this size completed and
coversabout20%ofthetotalUWISH2area.Hence,itwillallow
2.2 DifferenceImages
ustoobtainfirstbutstatisticallysignificantresultsaboutthepopu-
lationofjetsandoutflowsfromyoungstarsintheGalacticPlane. In order to reveal mutually exclusive emission line regions asso-
Inthispaperwepresentouranalysisoftheabovementioned ciated with H2 jets and outflows (or other H2 emitters), the H2
region.Wefocusonthedetectionofthejetsandoutflows,aswellas narrowbandimageshavebeencontinuum-subtractedusingtheK-
theirpotentialsources.Wefurtheranalysethespatialdistributionof bandimagesfromtheGPS.Notethatweareworkingwithimages
thediscoveredobjects,theirapparentlengths,positionanglesand about13.3(cid:48)×13.3(cid:48) insizethroughouttheproject,sincetheseare
fluxes.Toconvertapparentmeasurements(suchassize)intophys- the images delivered by CASU. Every set of images (H2, K) is
icallymeaningfulmeasurementsweneedthedistance.Weassume alignedbasedontheirWorldCoordinateSystem(WCS).Photom-
that all outflows are at a distance of 3kpc throughout the paper, etryisperformedtodeterminethemeanfwhmofeachimage.
since this turns out to be the most commonly measured distance Tocompensateforthedifferentseeingconditionsinbothim-
for outflows in our sample. In our forthcoming paper (Ioannidis agesandtoenhancethesignaltonoiseratiointhedifferenceim-
& Froebrich, in prep., PaperII) we will discuss in detail our dis- agesweGaussiansmoothedbothimagesbeforethecontinuumsub-
tancemeasurementmethodoftheindividualjetsandoutflows.We traction.Theimagewiththeworseseeing(imageb)issmoothed
willthendetermineindetailstatisticallycorrectedluminosityfunc- using a Gaussian with a fwhm of rsb=0.4(cid:48)(cid:48). The image with the
tionsandlengthdistributionsofthejetsandoutflowsandinvesti- better seeing (image a) is smoothed with a Gaussian of a larger
gatetheirdistributionintheGalacticPlane.Finally,inIoannidis& fwhm(rsa),whichwecalculateas:
Froebrich(inprep.,PaperIII)wewillinvestigatethedrivingsource
properties as well as the environment (cloud structure, clustered ra =(cid:112)(fwhmb)2−(fwhma)2+(rb)2
andisolatedstarformingregions)thejetsandoutflowsarein. s s
InSect.2wediscussourdataandanalysismethods.Wethen wherefwhma isthemeanfwhmofimageaandfwhmb is
present our results and discussion in Sect.3, which includes the themeanfwhmofimageb.Typicallytheseeinginbothimagesis
(cid:13)c 2011RAS,MNRAS000,1–13
YSOjetsintheGalacticPlanefromUWISH2:I-MHOcatalogueforSerpensandAquila 3
Figure1.Positionsofoutflows(blacksquares)overplottedonarelativeextinctionmap(greyscaleimage)basedonnearinfraredcolourexcessinGPSdata.
Pleaseseetextfordetailsonthebackgroundmap.
very similar and the smoothing radii ra and rb are thus not very takenattwodifferentepochs,very’red’orvery’green’objectscan
s s
different. be identified as K-band variable stars in the JKH composites.
2
Inordertocompletelyremovecontinuumsourcessuchasstars Incontrast,theJHKandJHH imagescanbeusedtodetectob-
2
in the difference images, the K-band images need to be scaled. jectswithK-bandexcessemission,inotherwordscandidateyoung
Sincethescalingfactorscdependsontheforegroundextinctionto stellarobjects.
thestars,weexpectthistovarysignificantlyacrossimagestakenin
theGalacticPlane.Wethususeapositiondependentscalingfactor
sc(x,y)(’scalingimage’)forthecontinuumsubtraction. 2.4 Outflowdetection
For this purpose we determine the mean scale factor for all
Ouraimtoinvestigateanunbiasedsampleofjetsandoutflowsfrom
starsinsmallsub-regions(10(cid:48)(cid:48)×10(cid:48)(cid:48)).Beforeapplyingthescaling
youngstarsintheGalacticPlanecannotjustbeachievedbyper-
image to the K-band it is smoothed with a radius of 30(cid:48)(cid:48). Thus,
forming an unbiased survey. We also need to take great care not
wetraceasmuchstructureoftheforegroundextinctionaspossible
tointroduceanydetectionbiaswhenidentifyingtheobjectsinour
whileensuringasufficientsignaltonoiseofthescalefactor.
data.Thus,wefollowthestrategydescribedbelowtofindallpo-
Thefinaldifferenceimagesarethencreatedas:
tentialjetandoutflowcandidates.
AllH -K differenceimageshavebeenvisuallyinspectedfor
2
DifferenceH2−K =H2−K∗sc extendedH2 emissionfeaturesinfullresolution.Theorderofin-
spectionwascompletelyrandomtoavoidtheintroductionofbiases
DuetotheGaussiansmoothingtoadaptthestellarfwhm,the duetooursearchpattern.Theoriginalsearchhasbeenperformed
resultingdifferenceimageshaveahighersignaltonoisethanthe byjustoneofus.However,thesubsequentcleaningofthisinput
originalH2 andK images.Whilemostofthenonsaturatedstars catalogue(seebelow)hasbeendonebytwopeople.
arenotpresenttheH2emissionfeaturesarepreserved.Wenotethat Everydetectedemissionfeaturethathasbeenidentifiedinthe
thedifferenceimagesareonlyusedforthepurposeofdetectionof H -K difference images at first has been confirmed in the corre-
2
jetsandoutflowsfromprotostars(seeSubsection2.4)andnotfor spondingH imagetoavoidtheinclusionofimageartefacts.We
2
photometry. thencheckeditagainstthefullresolutionJKH colourcomposite
2
of the region (such as the one shown in Fig.2). Thus, any object
thatcouldpotentiallybeanimageartefacthasbeenremovedfrom
2.3 NIRColourimages
thesourcelist.
ThesearchforH emissionfeatures(asdescribedinSection2.4) Finally,weneedtocleantheremainingobjectsfromrealemis-
2
ismainlybasedontheH -Kdifferenceimages.However,thever- sioncontaminants.Theseincludee.g.PlanetaryNebulae(PN),Su-
2
ification that the observed feature is indeed a jet or outflow from pernovaRemnants(SNR)andfluorescentlyexcitedregionssuchas
a young stellar object is greatly facilitated by the additional use edgesofmolecularclouds,HIIregionsandareasaroundyoungem-
ofnearinfraredcolourcompositeimagesobtainablefromourdata beddedclusterswithmassivestars.PlanetaryNebulaecanusually
sets. These images are also extremely useful to identify potential beidentifiedbytheirvisualappearance.InthecaseofSNshocks
drivingsourcesforthediscoveredjetsandoutflows. andfluorescentlyexcitedcloudedgesthisismorecomplicated,as
We thus created full resolution near infrared JHK, JHH they can mimic shocks from jets and outflows. We searched the
2
andJKH colourcompositesforeveryimage.Eachofthecolour SIMBADdatabaseforknownSNRsneartoouridentifiedobjects.
2
combinationsenhancesdifferentaspectsofthespectrumandthere- AnypotentialfeaturedetectednearsuchknownSNRshasbeenex-
foremakesiteasiertovisuallydetectand/orverifyobjectsofin- cludedfromourlist.Weinspectedregionswith(obviously)fluores-
terest.Morespecifically,theJKH imagescanbeusedtodetect centlyexcitedcloudedgesverycarefullyandexcludedanyobject
2
pureH emissionregions.SincetheH andK imageshavebeen thatpotentiallywasnotajet/outflowfeature.
2 2
(cid:13)c 2011RAS,MNRAS000,1–13
4 Ioannidis&Froebrich
TheresultinglistofH emissionlineobjectsisthuscomplete theH feature,correctedforthelocalbackgroundlevelandrepeat
2 2
uptothesurveydetectionlimit,contains(almost)nofalsepositives thatmeasurement,usingidenticalaperturepositions,inthescaled
andisunbiased. (usingsc(x,y),seeSect.2.2above)K-bandimagetocorrectfor
thecontinuumcontainedinthenarrowbanddata.
The background- and continuum-corrected H counts for
2.5 Drivingsourcesofoutflows 2
each emission feature are then converted into physical flux units
Onevitaltaskinordertounderstandthepropertiesofthedetected (W/m2)usingthefluxzeropointsprovidedbyCASU.Thefinal
jetsandoutflows(e.g.thelengthdistribution)istheidentification flux values for the H2 emission in the 1-0S(1) line (summed up
oftheirpotentialdrivingsources.Weutiliseanumberofpublished over all knots in each MHO) are shown in TableA1 in the Ap-
catalogues of YSOs as well as mid and far infrared source lists pendix.
forthispurpose.TheseincludethecatalogueofYSOscompiledby Uncertaintiesinthephotometryarebasedonthevariationof
Robitailleetal.(2008)fromtheSpitzerGLIMPSEsurvey(Church- thelocalbackgroundlevelintheH2 andK-bandimagesandthe
well et al. 2009), detections in the AKARI/IRC mid-infrared all- choiceoftheexactpositionoftheaperturesenclosingtheH2emis-
skysurveybrightsourcecatalogue(Ishiharaetal.2010;Yamamura sionregions.Typicaluncertaintiesofthemeasuredfluxesaredis-
etal.2009),detectionsintheIRASPointandFaintSourceCata- cussedinSect.3.5.
logue(Moshir1989,1991)anddetectionsintheBolocamGalactic
PlaneSurvey(Aguirreetal.2011),whichallcoverourentiresur-
veyfield.AdditionallyweusedK-bandexcesssourcesidentified 3 RESULTSANDDISCUSSION
fromJHK detectedobjectsintheUKIDSSGPS,aswellasK-
bandvariablesourcesidentifiedintheH -K differenceimagesas Wehavedetectedatotalof131molecularhydrogenoutflowsfrom
2
potentialdrivingsourcecandidates. YSOsinoursurveyfieldof33squaredegrees.Outofthese,121
TodecideonthemostlikelysourceforeachH feature,we (92%)objectsarenewdiscoveries.Ofthetenalreadyknownout-
2
over-plotallpotentialsourcecandidatesovertheH -K difference flows, two have been recently identified by Lee et al. (2011 in
2
images. Basedon the vicinityof source candidatesand H emis- preparation)usingUWISH2dataaswell.Thus,94%ofourout-
2
sion,thealignmentofanumberofemissionknotswithapotential flowsarenewlydiscoveredinourdataset.Hence,inthefieldin-
source, or the shape of bow-shock like features we grouped the vestigatedhere,theUWISH2dataincreasedthenumberofknown
H emissionobjectsintooutflowsandassignedoneMHOnumber molecularhydrogenoutflowsbyafactorof15.
2
to each of them, following the procedure outlined in Davis et al. InTableA1intheAppendixwelisttheassignedMHOnum-
(2010).Figure2showsMHO2204asanexampleofadetectedjet bers, positions, fluxes, apparent lengths, position angles, source
withapotentialsourcecandidate. candidatesandtheirpositions.InTableB1weshowH2-K images
Therearecaseswithseveralpotentialsourcecandidates.Ifit ofeachMHOandgiveabriefdescriptionofitsmorphologyand
is impossible to decide on one specific one we consider all pos- potential sources. We note that there is a difference between the
sibilities. In cases where non of the above mentioned catalogues number of outflows (131) and the number of MHOs (134). The
allowed us to find a potential source for an H feature, we ad- reason for this is that some of the already assigned MHO num-
2
ditionally searched the SIMBAD database for other indicators of bers are part of the same outflow. More specifically MHO2206,
YSO outflow sources, such as masers and (sub)-mm sources. Fi- MHO2207andMHO2208arepartofthesameoutflow.Similarly,
nally, if there are several source candidates which apparently are thebowshockMHO2212ispartofthesameflowasMHO2201.
thesameobject(suchasanIRAS,BolocamandGlimpsedetection IncaseslikethesewetreatallMHOsasoneoutflow.Allobjectsin
atroughlythesamecoordinates),weuseasthesourcepositionand TableA1thatarepartofanoutflowcontainingseveralMHOsare
identifier the object in the survey with the highest spatial resolu- markedwithanasterisk.
tion.Thereareanumberofcaseswhereweclearlydetectasmall,
bipolar and symmetric jet but no object has been detected in any
3.1 Spatialdistributionandclusteringofoutflows
surveyatthesuspectedsourceposition.Inthesecasesweassume
thesourcetobesituatedbetweentheH2featuresontheflowaxis, WeshowthepositionsofalldetectedoutflowsinourfieldinFig.1.
anditisgiventheidentifier’Noname’.Note,thatMHO2444would Thegrey-scalebackgroundmapinthisfigureisarelativeextinction
beoneoftheseobjects,ifithadnothaddeepJCMTdatafromDi mapbasedonmediannearinfraredcolourexcess(e.g.Rowles&
Francescoetal.(2008). Froebrich(2009))determinedfromUKIDSSGPSdata(Lucasetal.
(2008)).NotethatsomeregionsinthemaphavesmallA off-sets.
V
Thisiscausedbyknown,minorphotometriccalibrationissuesof
2.6 Photometry
theGPSdatawhichwillbecorrectedinfuturedatareleases.Since
AfterthedetectionoftheH emissionfeatureswehavetomeasure wearenotusingtheactualA valuesinthepaper,thisisapure
2 V
theirfluxes.Thisisstraightforward,sinceourH imageshavebeen ’cosmetic’issue.
2
fluxcalibratedbyCASU. As expected, the outflows are mainly located in areas with
We define apertures around each emission feature in the H highextinction.Theiroveralldistributionhencefollowsnicelythe
2
images.Greatcareistakenthatcontinuumsources(suchasforeor giant molecular cloud complexes visible in the A map. Only a
V
backgroundstarsatthesamelineofsight)arenotincludedinthe smallnumberofobjectsisnotsituatedwithindenseclouds.How-
apertures. We also ensure that the apertures contain as little area ever,therearenumerousareasofhighextinctionwherenooutflows
as possible that seems to be free of emission in order not to add havebeendetected.InPaperIIIwewillinvestigateindetailifthere
noise. Simultaneously, we use for each H feature a nearby sky- isanA thresholdforthedetectionofmolecularhydrogenflows,
2 V
aperturethatiscompletelyemissionfreeanddefinesthelocalsky and which fraction of high column density clouds does not show
level (see Fig.2 for an example of the apertures used in the pho- signsofon-goingstarformationintheformofjetsandoutflows.
tometryofMHO2204).Wethenmeasurethenumberofcountsin Histograms of the outflow positions along and across the
(cid:13)c 2011RAS,MNRAS000,1–13
YSOjetsintheGalacticPlanefromUWISH2:I-MHOcatalogueforSerpensandAquila 5
Figure2.Left:GreyscalerepresentationoftheH2-KdifferenceimageofMHO2204.ThegreenellipsesindicatetheaperturesusedtoenclosetheH2flux,
whiletheblueaperturesrepresentthenearbysky.Thesolidlineindicatesthedirectionoftheflow.Right:JKH2colorcompositeofthesameregion.Both
imagesare95(cid:48)(cid:48)×66(cid:48)(cid:48)insize,NorthistothetopandEasttotheleft.
GalacticPlaneareshowninFig.3.AsonecanalsoseeinFig.1, groups,theaveragegroupseparation,thetotalnumberofobjects
thereisanonhomogeneousdistributionalongthePlane,withpeaks andthefieldsize,wecanestimatethatabouttwothirdsofthesur-
atl=20◦andl=25◦andaminimumaroundl=23◦.Thisindicates veyareaaremoreorlessdevoidofmolecularhydrogenemission
theconcentrationofoutflowstospecificareasi.e.thegiantmolec- lineobjects,afactsupportedbythedistributionshowninFig.1.
ularcloudcomplexes.ThelatitudedistributionshowsaGaussian
like distribution with a width of about one degree. Its centre is
shifted to about b=-0.25◦ hinting that the main cloud complexes 3.2 Drivingsourcecandidates
in this part of the Galactic Plane are at negative latitudes. If we Wehavebeenabletoassigndrivingsourcecandidates,asdescribed
assumeadistanceof3kpcfortheoutflows,thewidthofthedis- in Sect.2.5, to 68 of our 131 molecular hydrogen outflows. This
tribution corresponds to a scale height of about 25-30pc. This is corresponds to just over half the objects. Overall, 75 source can-
verysimilartovaluesforyoungstellarclusters(55pc,(Friel1995)) didateshavebeenidentified,sincesomeoutflowshavemorethan
andOBstars(30–50pc,(Reed2000;Eliasetal.2006)),butsig- oneprobabledrivingsource.Acompletelistoftheoutflowdriving
nificantly smaller than the about 125pc found for the dust at the sourcecandidatesispresentedinTableA1intheAppendix.
solargalactocentricdistance(e.g.Drimmeletal.(2003);Marshall WefindthattypicallybrighterMHOs(accordingtotheirin-
etal.(2006)).Theprominentincreaseofthenumberofobjectsat tegrated1-0S(1)flux,seeSect.3.5below)aremorelikelytohave
b=1.5◦(rightpanelofFig.3)iscausedbyanumberofhigherlati- asourcecandidateassignedtothem.Inparticulartheaverageflux
tudecloudsinparticularatl=26.5◦(seealsoFig.1). of MHOs with an assigned source candidate is almost five times
Wehaveinvestigatedtheclusteringofthedetectedoutflowsby higher than for MHOs without source candidate. For the median
meansofnearestneighbourdistance(NND)distributions.Hence, fluxesthisratio,however,islowerbyafactorofthree.Inafuture
wecalculatedthedistancetotheNthnearestneighbourforallout- paperwewillinvestigateifthisisapureselectioneffect.Itcould
flows in our sample and determined a histogram to analyse these simplybethatbrightMHOsareclose-byandhencetheirsources
distancedistributions.The1st,2ndand3rdNNDsallshowasharp areeasiertodetect.Ontheotherhand,brightMHOscouldbein-
peak at small separations, indicating that the flows are typically trinsicallyluminousandthusbedrivenbybrighter,easiertodetect
foundincloseproximitytoeachother.Thispeakalmostdisappears sources.
inthe4th NNDdistributionandiscertainlygoneinthe5th NND
distribution,whereitisreplacedbyawiderpeakatabout20-30(cid:48)
separation. 3.3 Apparentoutflowlengths
Thus,wefindthattheoutflowstypicallyoccuringroupswith For all outflows with assigned source candidate(s) we have mea-
afew(3-5)members.Thesizeofthesegroupsisabout6(cid:48)(atypical suredtheapparentlength(s).Ahistogramoftheresultinglengths
valueforthe3rdNND),whichcorrespondstoabout5pcifweas- distribution is shown in Fig.4. The light grey bars represent all
sumeallobjectsareatadistanceof3kpc.Thissizeisclearlylarger theoutflows(68),whilethedarkgreyareasrepresentthealready
thanthetypicalembeddedcluster(about1pcorslightlysmaller; knownobjects(9).Notethatthelengthsarenotcorrectedforthe
e.g.Lada&Lada(2003))andsmallerthantypicalnearbyGMCs unknowninclinationanglesorthepotentialdetectionofjustparts
suchasTaurusandOrion.Thus,currentlyongoingstarformation oftheoutflow.Forsinglesidedflowsthelengthscorrespondtothe
occursinthose5pcsizedregionswithinGMCsandisnotneces- separationofthesourceandthemostdistantH feature,whilefor
2
sarilyconfinedtoembeddedclusters. bipolarflowsthelengthscorrespondtothetotallengthoftheflow,
Thegroupsofoutflowsareseparatedbyabouthalfadegree aprocedurealsoadoptedinothersurveys(Stankeetal.2002).The
ontheskyfromeachother.Giventhenumberofmembersinthese knownflowsdonotoccupyaspecialpartofthediagram,butrather
(cid:13)c 2011RAS,MNRAS000,1–13
6 Ioannidis&Froebrich
Figure3.Histogramofthepositionsofthedetectedoutflowsalong(leftpanel)andacross(rightpanel)theGalacticPlane.
3.4 Outflowpositionangles
Previousstudies(e.g.Mouschovias(1976))suggestedthatclouds
collapsealongmagneticfieldlinestoformelongated,clumpyfila-
mentsfromwhichchainsofprotostarsareborn.Furthermore,the
associated outflows are aligned parallel with the local magnetic
fieldandperpendiculartothechainsofcores(Banerjee&Pudritz
2006).Oursampleisidealtostudytherelationbetweencores,fil-
amentsandoutflowsbecauseofthelargesampleofflowsthatare
distributed over a considerable number of molecular clouds. We
hencedeterminedtheoutflowpositionanglesandlisttheminTa-
bleA1intheAppendix.
AhistogramofthepositionanglesisshowninFig.5,usinga
bin-sizeof30degrees.Theplotshowsthatalargefractionofout-
flowshasahomogeneousdistributionofpositionangles,withfive
of the six bins occupied by 11.2 objects on average. However, at
anglesbetween120◦and150◦onecanidentifyanoverabundance
ofoutflows.Thereare20outflowsinthisbin,whichcorrespondsto
Figure4.Histogramoftheapparentoutflowlengths.Thelightgreyareas
a2.6σdeviationfromtheaverageoftheotherbins.Weperformeda
showalloutflows,whilethedarkgreyareasrepresenttheknownobjects.
Incasethereareseveralsourcecandidatesforoneflow,thelengthcorre- Kolmogorov-Smirnovtesttodeterminetheprobabilitythattheob-
spondingtothemostlikelysourceisplotted.Notethatanapparentlength servedpositionangledistributionisidenticaltoahomogeneously
of60(cid:48)(cid:48)correspondstoabout0.9pcfortheassumeddistanceof3kpc. distributed sample. For outflows with two potential sources, and
hence two possible position angles, each angle was weighted by
half;iftherearethreesourcestheweightforeachanglewasone
third.Wefindaprobabilityofjust10%thatourobjectsaredrawn
representarandomsub-sample.Notethatincasesofseveralsource fromahomogeneouslydistributedsample.
candidatesforanoutflow,weplotthedistancecorrespondingtothe Wefurtherinvestigatedifthereisatrendofobjectswithapar-
mostlikelysource.Thedistributionwillnotchangesignificantlyif ticularrangeofpositionangleswithskyposition.Nothingcouldbe
weplotanyotherlengths. found.Theobjectsfallingintoaparticularbininthepositionangle
Thereisalargerangeofapparentoutflowlengths(from4(cid:48)(cid:48)to histogramaredistributedcompletelyhomogeneouslyamongstthe
130(cid:48)(cid:48))andastrongdecreaseofthenumberofoutflowswithincreas- entiresample.
inglength.Ofthe68outflows, morethan60%haveanapparent TheGalacticplanehasaninclinationofabout64degreeswith
lengthoflessthan30(cid:48)(cid:48)(orlessthan0.4pcifweassumeadistance respecttotheeclipticinoursurveyarea.Thus,thepeakintheposi-
of3kpc).Thisisinagreementwiththedistributionoflengthsfound tionanglehistogrambetween120◦and150◦indicatesthatthereis
byDavisetal.(2009)andStankeetal.(2002)alongtheOrionA a2.6σoverabundanceofoutflowsorientatedalmost(PA=20◦with
molecularridgeandDavisetal.(2008)inTaurus-Auriga-Perseus respecttoGalacticNorth)perpendiculartotheGalacticPlane.Itis
(NGC1333, L1455, L1448 and B1). Only 10% of all outflows therefore possible that our measured flow position angles are in-
have a length of more than 1pc (if they are at 3kpc). In PaperII fluencedbythelargescalecloudstructure.Previousstudiesofthe
we will discuss the physical outflow length distribution in parsec OrionA molecular cloud by Davis et al. (2009) and Stanke et al.
afterconsideringtheindividualdistancestotheobjects.Notethat (2002) and in Taurus-Auriga-Perseus by Davis et al. (2008) have
theobserveddistributiondoesnotagreewitharandomlyorientated shownahomogeneousdistributionwithnosignificanttrendsinthe
sampleofflowswhichallhavethesamelength. orientationofoutflows.However,studiesofDR21/W75byDavis
(cid:13)c 2011RAS,MNRAS000,1–13
YSOjetsintheGalacticPlanefromUWISH2:I-MHOcatalogueforSerpensandAquila 7
Figure5.Histogramofthedistributionofpositionanglesfromthedetected Figure6.Histogramofintegrated1-0S(1)fluxes(inlogarithmicunits)for
outflowsin30degreesbins.Thedistributionshowsa2.6sigmaoverabun- thedetectedoutflows.Thelightgreyareasincludealloutflowswhilethe
danceofflowswithpositionanglesbetweenl=120◦ andl=150◦,oran darkgreyareasrepresentthealreadyknownMHOs.Ourcompletenesslimit
orientationroughlyperpendiculartotheGalacticPlane. isabout3·10−18Wm−2.
statisticallycorrectedluminositydistributionwillbediscussedina
etal.(2007)haveshownthatflows(inparticularmassiveones)are
forthcomingpaper(PaperII).
orthogonaltosomedegreetothemolecularridge.InPaperIIIwe
will analyse this distribution in more detail. We will measure, if
possible,theorientationoftheoutflowswithrespecttoitsparental
cloudfilament,toverifyordisprovetheabovefindings. 4 CONCLUSIONS
Inordertoinvestigatethedynamicalcomponentofthestarforma-
tionprocessweperformanunbiasedsearchforjetsandoutflows
3.5 Outflowfluxdistribution
fromYSOsalongtheGalacticPlane.Ourdatahasbeentakenas
Themeasuredintegrated1-0S(1)fluxesoftheoutflowsarelistedin partoftheUWISH2survey(F11).Itusesasatracerthe1-0S(1)
TableA1intheAppendix.Figure6showsahistogramofthisflux emissionlineofH ,andherewefocusourattentiononacontinu-
2
distribution.Thelightgreyareasincludealltheoutflowswhilethe ous33squaredegreesizedregion(18◦<l<30◦;-1.5◦<b<+1.5◦)
darkgreyareasarethealreadyknownobjects.Clearly,theknown inSerpensandAquila.
outflowsdominatethebrightendofthedistributionandallbutone Weidentify131outflowsfromYSOsfromwhich94%(123
are brighter than 10−17Wm−2. In particular, about 60% of the objects)arenewdiscoveriesinourdataset.Therefore,oursurvey
integrated flux in the 1-0S(1) line of molecular hydrogen can be hasincreasedthenumberofknownmolecularhydrogenoutflows
attributed to already known MHOs. Thus, our survey just about byafactorof15intheareainvestigated.
doublestheknownintegrated1-0S(1)fluxfromjetsandoutflows We find a flux completeness limit for our outflow detection
inthesurveyarea,incontrasttothe15foldincreaseintotaloutflow of 3·10−18Wm−2, with 70% of the objects showing fluxes of
numbers. 10−17Wm−2 or less. Typically, the already known outflows oc-
IngeneralwefindasharpriseofthenumberofMHOswith cupy the bright end of the flux distribution. Our survey thus in-
decreasingintegratedflux.Morethan70%oftheMHOshavean creases the known integrated 1-0S(1) H flux from jets and out-
2
integratedfluxoflessthan10−17Wm−2.Themaximumnumber flowsonlybyafactoroftwo,comparedtothelargeincreaseinthe
of MHOs occurs at about 3·10−18Wm−2 which corresponds to totalnumberofflows.
about10−3 solarluminositiesinthe1-0S(1)lineofH atouras- Theoverallspatialdistributionofthedetectedoutflowsshows
2
sumed distance of 3kpc. We hence conclude that this flux is the thattheyfollowtheGMCcomplexesintheGalacticPlane.Onlya
completenesslimitforoutflowsdetectedinoursurvey.Thereare, smallnumberofobjectsisnotsituatedwithindenseclouds.How-
however,anumberofobjectswithasignificantlysmallerintegrated ever,therearelargeareaswithhighextinctionwherenooutflows
flux,indicatingthattheactualdetectionlimitfor1-0S(1)fluxesis havebeendetected.Overall,about2/3rdofthesurveyareaismore
lower than even 10−18Wm−2 in some regions (most likely dark orlesscompletelydevoidofjetsandoutflows.Wefurtherfindthat
cloudsdevoidoffore/backgroundstars).Thisisalsosupportedby the flows typically occur in groups of 3–5 members with a size
factthatmanyoftheoutflowswithasmalloverallintegratedflux ofabout5pc(atourassumeddistanceof3kpc).Thesegroupsare
consistofonlyoneemissionlinefeature, typicallyseparatedbyabouthalfadegreeonthesky.
Foreachoftheintegratedfluxeswelistthephotometricuncer- ThedistributionofflowsperpendiculartotheGalacticPlane
tainties in TableA1. Typical uncertainties of the measured fluxes showsaGaussianlikedistributionwithawidthofabout25–30pc
are of the order of 10%. For bright objects they are significantly (atourassumeddistanceof3kpc),similartovaluesforyoungstel-
smaller.Wherevertheintegratedfluxisverylowandthevariation larclustersandOBstars.
ofthelocalbackgroundlevelishighweonlydetermineanupper Weareabletoassignpossibledrivingsourcestoabout50%
fluxlimit. oftheoutflows.BrighterMHOsaremorelikelytohaveasource
Howthemeasuredintegratedfluxdistributionconvertsintoa candidateassignedtothem.
(cid:13)c 2011RAS,MNRAS000,1–13
8 Ioannidis&Froebrich
Wemeasuretheapparentoutflowlengthforoutflowswithas- Froebrich D., Davis C. J., Ioannidis G., Gledhill T. M., Takami
signeddrivingsources.Thereisawiderangeoflengthsfrom4(cid:48)(cid:48) M.,ChrysostomouA.,DrewJ.,Eislo¨ffelJ.,etal.2011,MNRAS,
to130(cid:48)(cid:48)andastrongdecreaseofthenumberofflowswithincreas- 413,480
inglength.Morethan60%oftheoutflowshaveanapparentlength FroebrichD.,ScholzA.,2003,A&A,407,207
of less than 30(cid:48)(cid:48) (or less than 0.4pc if we assume a distance of HillT.,BurtonM.G.,MinierV.,ThompsonM.A.,WalshA.J.,
3kpc)whileparsec-scaleoutflowsarenotcommon.Only10%of Hunt-CunninghamM.,GarayG.,2005,MNRAS,363,405
alloutflowswouldhavealengthofgreaterthan1pcatourassumed HodgkinS.T.,IrwinM.J.,HewettP.C.,WarrenS.J.,2009,MN-
distance. RAS,394,675
Thepositionangledistributionofflowswithassignedsource IshiharaD.,OnakaT.,KatazaH.,SalamaA.,AlfagemeC.,etal
showsan2.6σover-abundanceatanglesbetween120◦and150◦. 2010,A&A,514,A1+
LadaC.J.,LadaE.A.,2003,ARA&A,41,57
LucasP.W.,HoareM.G.,LongmoreA.,Schro¨derA.C.,Davis
C.J.,AdamsonA.,BandyopadhyayR.M.,etal.2008,MNRAS,
ACKNOWLEDGEMENTS
391,136
GI acknowledges a University of Kent scholarship. The United MarshallD.J.,RobinA.C.,Reyle´ C.,SchultheisM.,PicaudS.,
Kingdom Infrared Telescope is operated by the Joint Astronomy 2006,A&A,453,635
Centre on behalf of the Science and Technology Facilities Coun- MoshirM.,1989,IRASFaintSourceSurvey,Explanatorysupple-
cil of the U.K. The data reported here were obtained as part of mentversion1andtape.CaliforniaInstituteofTechnology
the UKIRT Service Program. This research has made use of the MoshirM.,1991,JournaloftheBritishInterplanetarySociety,44,
WEBDAdatabase,operatedattheInstituteforAstronomyofthe 495
UniversityofVienna. MouschoviasT.C.,1976,ApJ,207,141
ReedB.C.,2000,AJ,120,314
RobitailleT.P.,MeadeM.R.,BablerB.L.,WhitneyB.A.,John-
stonK.G.,IndebetouwR.,CohenM.,PovichM.S.,etal.2008,
REFERENCES
AJ,136,2413
AguirreJ.E.,GinsburgA.G.,DunhamM.K.,DrosbackM.M., RowlesJ.,FroebrichD.,2009,MNRAS,395,1640
BallyJ.,BattersbyC.,BradleyE.T.,CyganowskiC.,etal.2011, SkrutskieM.F.,CutriR.M.,StieningR.,WeinbergM.D.,Schnei-
ApJS,192,4 derS.,CarpenterJ.M.,etal.2006,AJ,131,1163
AnathpindikaS.,WhitworthA.P.,2008,A&A,487,605 StankeT.,McCaughreanM.J.,ZinneckerH.,2002,A&A,392,
AntoniucciS.,NisiniB.,GianniniT.,LorenzettiD.,2008,A&A, 239
479,503 ToddS.P.,RamsayHowatS.K.,2006,MNRAS,367,238
BallyJ.,DevineD.,FesenR.A.,LaneA.P.,1995,ApJ,454,345 VarricattW.P.,DavisC.J.,RamsayS.,ToddS.P.,2010,MNRAS,
BanerjeeR.,PudritzR.E.,2006,ApJ,641,949 404,661
BeckT.L.,2007,AJ,133,1673 Yamamura I., Makiuti S., Ikeda N., Fukuda Y., Yamauchi C.,
CarattioGarattiA.,GianniniT.,NisiniB.,LorenzettiD.,2006, Hasegawa S., Nakagawa T., Narumi H., Baba H., et al. 2009,
A&A,449,1077 inT.Usuda,M.Tamura,&M.Ishiied.,AmericanInstituteof
CasaliM.,AdamsonA.,AlvesdeOliveiraC.,AlmainiO.,Burch Physics Conference Series Vol. 1158 of American Institute of
K.,etal2007,A&A,467,777 PhysicsConferenceSeries,TheFirstreleaseoftheAKARI-FIS
ChurchwellE.,BablerB.L.,MeadeM.R.,WhitneyB.A.,Ben- BrightSourceCatalogue.pp169–170
jaminR.,IndebetouwR.,CyganowskiC.,RobitailleT.P.,etal.
2009,PASP,121,213
Davis C. J., Froebrich D., Stanke T., Megeath S. T., Kumar
M.S.N.,AdamsonA.,Eislo¨ffelJ.,GredelR.,etal.2009,A&A,
496,153
Davis C. J., Gell R., Khanzadyan T., Smith M. D., Jenness T.,
2010,A&A,511,A24+
Davis C. J., Kumar M. S. N., Sandell G., Froebrich D., Smith
M.D.,CurrieM.J.,2007,MNRAS,374,29
DavisC.J.,ScholzP.,LucasP.,SmithM.D.,AdamsonA.,2008,
MNRAS,387,954
DavisC.J.,VarricattW.P.,ToddS.P.,RamsayHowatS.K.,2004,
A&A,425,981
DiFrancescoJ.,JohnstoneD.,KirkH.,MacKenzieT.,Ledwosin-
skaE.,2008,ApJS,175,277
Drimmel R., Cabrera-Lavers A., Lo´pez-Corredoira M., 2003,
A&A,409,205
DyeS.,WarrenS.J.,HamblyN.C.,CrossN.J.G.,HodgkinS.T.,
IrwinM.J.,etal.2006,MNRAS,372,1227
Eislo¨ffelJ.,2000,A&A,354,236
Eislo¨ffelJ.,MundtR.,BohmK.-H.,1994,AJ,108,1042
EliasF.,AlfaroE.J.,Cabrera-Can˜oJ.,2006,AJ,132,1052
FrielE.D.,1995,ARA&A,33,381
(cid:13)c 2011RAS,MNRAS000,1–13
YSOjetsintheGalacticPlanefromUWISH2:I-MHOcatalogueforSerpensandAquila 9
C e
DE0)0044 2 62 4458128260 0148pag
source(J200-12:07:2-12:07:2-11:50:2-11:50:2--05:59:4**-05:59:4-05:59:4--12:22:3-11:50:2-11:50:2-11:31:5-11:47:5-11:55:4-11:56:2-11:39:5-11:40:3-12:55:0--10:33:2-10:18:1-10:18:2-10:18:4onnext
d
e
ourceRA(J2000)8:17:57.98:17:57.98:29:14.78:29:14.7 8:34:20.9 8:34:20.08:34:20.9 8:25:44.78:29:14.78:29:13.38:26:57.68:29:13.28:30:11.18:30:06.98:28:19.98:28:18.98:25:22.7 8:27:15.28:29:10.28:29:09.38:29:08.6Continu
s 1111-1**11-1111111111-1111
TableA1:SummarytableoftheMHOproperties.ThetableliststheMHOnum-ber,RightAscensionandDeclination(J2000),theintegrated1-0S(1)fluxanditsuncertainty,theapparentlength,thepositionangle,thesourcecandidate(s)anditsposition(s).IncaseswhereseveralMHOsbelongtothesameoutflow,theMHOnumberislabelledwithanasterisk.Ifthefluxisanupperlimit,nofluxerrorsaregiven.Onlyforobjectswithasourcecandidate,wedeterminedtheapparentlengthandthepositionangle.Flowlengthsareend-to-endforbipolaroutflowsorsource-to-endforsinglesidedflows.Sourcenamescorrespondtothecatalogueentriesthesourcewastakenfrom.Theseareeithercoordinatebased,SIMBADnames,UKIDSSGPSIDs(12digitnumbers),orAKARIIDs(7digitnumbers).Sourceslabelled’Noname’areobjectswhereitisassumedthatthereisadrivingsourceatthelistedposition,however,nonofthecataloguesusedshowsadetectionoftheobject.Pleaseseethemaintextfordetailsonthevaluesinthetable. F[1-0S(1)]Fluxerrorlengthpositionanglepossible2210E-18W/m][10E-18W/m](arcsec)(degrees)source379.11937.88573132IRAS18151-120877.4815.6322132IRAS18151-1208278.89319.5864267G019.884-00.535509.65942.89250116G019.884-00.53558.4293.918-29-286.00018.60793131IRAS18316-06029.6641.027***8.7200.609***25.3401.9822613743864913020320.1501.26040168IRAS18316-060226.3631.926---3.0050.21735160332925212.5870.733187G019.884-00.5357.5881.3851055G019.8810-00.530019.7729.5327045G019.896+00.1033.8002.06526884385219406683.6690.2139595G019.9122-00.77996414533186248.2880.53929133G019.9357-00.25583.0330.42741304385218182142.4060.2298.519334980810.4970.640---9.4630.543544430547561.0580.2791066G021.2369+00.19403.4350.277968Noname4.8620.751189G021.2248+00.1953
[
90764987522681734 89297744
EC000)07:107:350:150:149:559:559:359:059:200:106:422:450:050:331:447:555:3 39:240:354:501:533:518:018:218:5
DJ22:2:1:1:1:5:5:5:5:6:2:2:1:1:1:1:1: 1:1:2:2:0:0:0:0:
(11111000001111111 11111111
----------------- --------
72609754834887936 91876935
0)7.7.6.3.6.2.0.8.8.1.5.4.4.2.8.2.4. 8.9.2.4.2.0.9.8.
ABLE RA(J2008:17:58:17:58:29:18:29:18:29:18:34:28:34:28:34:18:34:18:34:28:17:58:25:48:29:18:29:18:26:58:29:18:30:0 8:28:18:28:18:25:28:25:58:27:18:29:18:29:08:29:0
T 11111111111111111 11111111
O
H * *** *
M O 201202203204205206207208209210212244245246247248249 250251252253254255256257
A: MH O2O2O2O2O2O2O2O2O2O2O2O2O2O2O2O2O2 O2O2O2O2O2O2O2O2
X HHHHHHHHHHHHHHHHH HHHHHHHH
I MMMMMMMMMMMMMMMMM MMMMMMMM
D
N
E
P
P
A
(cid:13)c 2011RAS,MNRAS000,1–13
10 Ioannidis&Froebrich
C e
DE0) 92230820 66 0 2 32 11101110 524pag
source(J200---09:34:4-09:34:5-07:55:3-08:18:1-08:18:2-10:06:1-10:06:1-09:34:4---08:42:4-08:51:3--08:41:1--07:39:0----06:49:5-06:51:0----07:31:4-07:31:5-07:31:4-07:31:4-07:31:5-07:31:4-07:31:5-07:31:4-----07:11:3-07:20:2-06:12:4onnext
d
e
ourceRA(J2000) 8:30:33.58:30:34.08:33:19.48:34:21.18:34:22.78:33:12.78:33:11.48:30:41.6 8:34:31.48:35:28.3 8:35:51.4 8:36:40.9 8:36:09.98:38:52.1 8:37:22.78:37:20.78:37:22.78:37:23.38:37:20.78:37:22.78:37:20.78:37:23.3 8:37:19.48:39:11.88:38:59.6Continu
s --11111111--11-1-1---11---11111111----111
0
5
2
4
8
0
possiblesource 96153729615655006008-00.014770725505172549830535+00.1980 SEJ183431.5-me 4319-00.5212 1042387 995913239 80164386280-00.31758016438635-00.3256280-00.317580164386280-00.3175635-00.325 926-00.1576899733me
--438374383730585G023.305744385143851G022.--JCMTNona-G023.-43851---3338943874---43836G024.43836G024.G024.43836G024.G024.----G024.43836Nona
e
uspageonanglgrees)--7829142166401001360--77158-45-0--13436117---39103170121031413925126---140147147
evioositi(de
rp
p
m
ohc)
nuedfrlengt(arcse--257218231818528--608-4-66---205---2034182034333338----271126
onti 2]
TableA1–cFluxerror10E-18W/m0.4280.8671.7687.425UpperLimit1.0591.0730.469 0.5090.246UpperLimit5.2790.0990.4650.2390.3382.0882.2640.1651.8470.9360.2151.0730.6200.2330.242 0.674 0.183 1.0880.1920.6220.1821.1973.4320.622
[
]
2
F[1-0S(1)]0E-18W/m4.0447.42422.33962.58815.4956.43915.1853.983 5.9763.2360.11132.4771.1486.5783.8222.53517.82917.1812.77724.14413.8233.0236.7706.3503.5612.511 3.745 2.482 13.0933.23910.0873.03612.73538.8327.950
1
[
93574175 814837370073717546 8 4 8686494
EC000)34:144:134:435:055:417:518:006:1 34:557:533:242:451:452:141:105:439:242:419:106:150:051:052:353:148:231:5 31:5 32:1 37:011:211:311:411:420:012:4
DJ20:9:9:9:7:8:8:0: 9:8:8:8:8:8:8:8:7:7:7:7:6:6:6:6:6:7: 7: 7: 7:7:7:7:7:7:6:
(10000001 000000000000000000 0 0 0000000
-------- ------------------ - - -------
17041746 733057301090294369 9 1 4367836
0)7.3.5.3.0.0.3.1. 1.1.1.1.8.1.1.7.1.3.2.1.9.1.5.7.6.1. 2. 2. 2.2.1.1.9.1.9.
RA20032:129:030:330:333:234:234:233:1 30:434:534:234:335:235:335:535:036:436:135:233:536:038:538:538:536:537:2 37:2 37:2 37:237:137:237:237:139:138:5
(J8:8:8:8:8:8:8:8: 8:8:8:8:8:8:8:8:8:8:8:8:8:8:8:8:8:8: 8: 8: 8:8:8:8:8:8:8:
11111111 111111111111111111 1 1 1111111
89012345 678901234567890123 4 5 6789012
O 2525262626262626 262626262727272727272727272728282828 28 28 28282828292929
H 22222222 222222222222222222 2 2 2222222
M OOOOOOOO OOOOOOOOOOOOOOOOOO O O OOOOOOO
HHHHHHHH HHHHHHHHHHHHHHHHHH H H HHHHHHH
MMMMMMMM MMMMMMMMMMMMMMMMMM M M MMMMMMM
(cid:13)c 2011RAS,MNRAS000,1–13