First results from the CALYPSO IRAM-PdBI survey - III. Monopolar jets driven by a proto-binary system in NGC1333-IRAS2A

0.31 MB·

by  C. Codella

Astronomy&Astrophysicsmanuscriptno.codella˙astroph (cid:13)c ESO2014
January28,2014
LettertotheEditor
⋆
First results from the CALYPSO IRAM-PdBI survey
III. Monopolar jets driven by a proto-binary system in NGC1333-IRAS2A
C.Codella1,A.J.Maury2,3,F.Gueth4,S.Maret5,A.Belloche6,S.Cabrit7,5,andPh.Andre´8
1 INAF,OsservatorioAstrofisicodiArcetri,LargoE.Fermi5,50125Firenze,Italy
2 Harvard-SmithsonianCenterforAstrophysics,60Gardenstreet,Cambridge,MA02138,USA
3 ESO,KarlSchwarzchildStr.2,85748GarchingbeiMu¨nchen,Germany
4 4 IRAM,300ruedelaPiscine,38406SaintMartind’He`res,France
1 5 UJF-Grenoble1/CNRS-INSU,InstitutdePlane´tologieetd’AstrophysiquedeGrenoble(IPAG)UMR5274,Grenoble,38041,France
0 6 Max-Planck-Institutfu¨rRadioastronomie,AufdemHu¨gel69,53121Bonn,Germany
2 7 LERMA,ObservatoiredeParis,CNRS,ENS,UPMC,UCP,61Av.del’Observatoire,75014Paris,France
n 8 LaboratoireAIM-Paris-Saclay,CEA/DSM/Irfu-CNRS-Universite´ParisDiderot,CESaclay,91191Gif-sur-YvetteCedex,France
a
Receiveddate;accepteddate
J

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ABSTRACT
2

Context.Theearliestevolutionarystagesoflow-massprotostarsarecharacterisedbyhotandfastjetswhichremoveangularmomen-
]
tumfromthecircumstellardisk,thusallowingmassaccretionontothecentralobject.However,thelaunchmechanismisstillbeing
A
debated.
G Aims.Wewouldliketoexploithigh-angular (∼0′.′8)resolutionandhigh-sensitivityimagestoinvestigatetheoriginofprotostellar
. jetsusingtypicalmoleculartracersofshockedregions,suchasSiOandSO.
h Methods.Wemappedtheinner22′′oftheNGC1333–IRAS2AprotostarinSiO(5–4),SO(6 –5 ),andthecontinuumemissionat1.4
5 4
p mmusingtheIRAMPlateaudeBureinterferometerintheframeworkoftheCALYPSOIRAMlargeprogram.
- Results.Forthefirsttime,wedisentangletheNGC1333–IRAS2AClass0objectintoaproto-binarysystemrevealingtwoprotostars
o
(MM1, MM2) separated by ∼ 560 AU, each of them driving their own jet, while past work considered a single protostar with a
r
st quadrupolaroutflow.Wereveal(i)aclumpy,fast(upto|V–VLSR|≥50kms−1),andblueshiftedjetemergingfromthebrightestMM1
source,and(ii)aslowerredshiftedjet,drivenbyMM2.Siliconmonoxideemissionisapowerfultracerofhigh-excitation(T ≥100
a kin
K;n ≥105cm−3)jetsclosetothelaunchingregion.Atthehighestvelocities,SOappearstomimicSiOtracingthejets,whereasat
[ H2
velocitiesclosetothesystemicone,SOisdominatedbyextendedemission,tracingthecavityopenedbythejet.

1 Conclusions.Bothjetsareintrinsicallymonopolar,andintermittentintime.ThedynamicaltimeoftheSiOclumpsis≤30–90yr,
v indicatingthatone-sidedejectionsfromprotostarscantakeplaceonthesetimescales.
2
Keywords.Stars:formation–ISM:jetsandoutflows–ISM:molecules–ISM:individualobjects:NGC1333–IRAS2A
7
6
6
. 1. Introduction (e.g.vanDishoeck& Blake 1998).A typicalexampleisrepre-
1
sentedbySiO,whoseformationismainly(≥90%)attributedto
0
The so-called Class 0 objects represent the earliest low-mass
4 the sputtering of Si atoms from refractory core grains in high-
1 protostellarstagehaving(i)mostoftheirmassstillintheformof velocity (≥ 20 km s−1) shocks (e.g. Gusdorf et al. 2008ab), or
denseenvelopes,and(ii)alifetime≤afew105yr(e.g.Andre´et
: grainshatteringingrain-graincollisionsinsideJ-shocks(Guillet
v al.2000;Evansetal.2009;Mauryetal.2011).Class0protostars
etal.2010).Siliconmonoxidetracesshocksinsidejetswell,suf-
i thenrepresentanideallaboratoryfortracingthepristinecondi-
X feringminimalcontaminationfromlow-velocityswept-upmate-
tionsoflow-massstarformation.Becauseofthepaucityofthe
r rial(usuallytracedbylow-JCOemission),andisabletounam-
a sub-arcsec (sub)mm observations required to probe the inner- biguouslyprobethemasslossprocess.
most(≤100AU) regions,severalbasicquestionsremainopen,
So far, a quite limited number of Class 0 jets has been ob-
suchastheexistenceofmultiplesystems,orthelaunchingmech-
servedatsub-arcsecondangularresolution(neededtodisentan-
anismofprotostellarjets.Protostarsdrivefastjetssurroundedby
gle the jet and the outflow cavities): HH211 (Lee et al. 2007,
wide-anglewindsthatimpactthehigh-densityparentcloudgen-
2009, 2010), HH212 (Codella et al. 2007, Lee et al. 2008),
eratingshock fronts,whichtriggerendothermicchemicalreac-
IRAS04166+2706 (Tafalla et al. 2010), and L1448-C (Maury
tionsandicegrainmantlesublimationorsputtering.Asaconse-
etal.2010,Hiranoetal.2010).TheIRAMPlateaudeBurein-
quence,severalmolecules(suchasH O,CH OH,andS-bearing
2 3 terferometer(PdBI)largeprogramCALYPSO1(Continuumand
species) undergo significant enhancementsin their abundances
Lines from Young ProtoStellar Objects) is correcting this sit-
uation by providing the first sub-arcsecond statistical study of
Send offprint requests to: C. Codella, e-mail:
[email protected] inner jet properties in nearby low-luminosity Class 0 sources
in combination with studies of the envelopes, disks, and mul-
⋆ BasedonobservationscarriedoutwiththeIRAMPlateaudeBure
interferometer. IRAM is supported by INSU/CNRS (France), MPG
(Germany),andIGN(Spain) 1 http://irfu.cea.fr/Projects/Calypso
1
Codellaetal.:Monopolarjetsdrivenbyaproto-binarysysteminNGC1333-IRAS2A
Table1.Positionandintensityofthecontinuumpeaks. sources(herelabelledMM1,MM2,andMM3).Adetailedanal-
ysisofthecontinuumemissionisbeyondthescopeofthepresent
Source α(J2000)a δ(J2000)a Ipeak paper: it will be used to support the interpretation of the SiO
1.4mm
(03h28m s) (+31◦14′′′) (mJybeam−1) andSOimages.Table1summarisespositionsand1.4mmpeak
MM1 55.58 37.06 94(2) fluxes of the three continuum sources. The coordinates of the
MM2 55.71 35.33 15(1) brightestone(MM1)areconsistentwiththepositionofIRAS2A
MM3 55.50 34.75 21(1) previouslymeasuredusingtheVLA(3.6cm),SMA(0.8and1.3
mm), and BIMA (2.7 mm) telescopes (Rodr´ıguez et al. 1999;
aThefituncertaintiesare4,14,and17masforMM1,MM2,and
Jørgensenetal.2007;Looneyetal.2007).Inaddition,afainter
MM3,respectively.
andspatiallyunresolvedsource(MM2)isfound∼2′.′4(560AU)
fromMM1intheSEdirection.BothMM1andMM2havealso
been detected at 94 GHz in the framework of CALYPSO (see
tiplicity structure. One of the best documentedCALYPSO tar- AppendixA):thespectralindexα(wherefluxdensityS ∝να)
ν
gets is NGC1333-IRAS2A (hereafterIRAS2A), located at 235 is∼2-2.5,consistentwiththatofaprotostar.
pc2inthePerseusNGC1333cluster.ThesourceIRAS2Aispart Athirdsource(MM3)isdetected∼2′.′5 southofMM1.Its
of a wider system containing IRAS2B (not investigated here),
FWHPsizeis307masanditsnon-detectionat94GHz(witha
located at ∼ 31′′. The IRAS2A luminosity is ∼ 10 L⊙, and it peakflux≤ 0.1mJybeam−1 implyingα≥ 4)challengesapro-
was observed in continuum at cm (e.g. Reipurth et al. 2002),
tostellarnature.Alternatively,MM3mightbeanoutflowfeature
mm (Looney et al. 2000; Jørgensen et al. 2004a, 2007, 2009;
due to dust heated by shocks travelling along the SiO jet (see
Maury et al. 2010), and sub-mm wavelengths (e.g. Sandell &
Sect.3.2).
Knee 2001). The outflow activity was traced using single-dish
telescopes and interferometers and several tracers of swept-up
material(e.g.CO)andshocks(e.g.SiO,CH OH),revealingtwo 3.2.Differentjetsfromaproto-binarysystem
3
perpendicular outflows, directed NE-SW (PA ≃ 25◦; hereafter
calledN-Sforsakeofclarity)andSE-NW(PA≃105◦;hereafter Figure1 showsthatSiO(5–4)emission is mainly confinedto a
collimatedblueshiftedsouthernSiOjetwithaPAof25◦,emerg-
E-W),bothoriginatingtowithinafewarcsecondsfromIRAS2A
ingfromMM1,andextendingoutto∼4′′ (1000AU).TheSiO
(e.g.Bachilleretal.1998;Knee&Sandell2000;Jørgensenetal.
jet is narrow: after correction for the PdBI HPBW, the trans-
2004ab,2009;Wakelametal.2005;Perssonetal.2012;Plunkett
verseFWHMis≃0′.′7±0′.′1(165AU)at∼700AUfromMM1,
etal.2013).Theseoutflowsseemintrinsicallydifferent,theE-W
whileitappearsevennarrower(beingspatiallyunresolved)close
outflowbeingmorecollimatedandchemicallyricherthantheN-
tothedrivingsource.Position-velocity(PV)diagramsalongthe
Sone,supportingthepossibilitythatIRAS2Aisanunresolved
N-Sjetaxis(Fig.2)showthatSiOemissionextendstoveryhigh
proto-binary.
blueshiftedvelocities,∼–50kms−1withrespecttoV 5=+6.5
LSR
kms−1.
2. Observations The MM1 SiO jet is surprisingly asymmetric with a bright
(up to 90 K in T scale, see e.g. Fig. 3) blueshifted emis-
The source IRAS2A was observed with the IRAM PdB six- MB
sion and no clear red counterpart (down to 1 K), suggesting a
elementarrayinDecember2010andJanuary-February2011us-
monopolarnature.Thepresenceofmonopolaroutflowshasre-
ing both the A and C configurations. The shortest and longest
centlybeenobservedbyFerna´ndez-Lo´pezetal.(2013)towards
baselines are 19 m and 762 m, respectively, allowing us to re-
the complex high-mass star forming region IRAS18162-2048.
cover emission at scales from ∼ 8′′ down to 0′.′4 at 1.4 mm.
In that case, the authorspropose precession and deflection due
TheSiO(5–4)andSO(6 –5 )lines3at217104.98and219949.44
5 4 to high-density clumps to explain the asymmetric appearance.
MHz,respectively,wereobservedusingtheWideX backendto
In principle,asymmetries in ambientgas could affect emission
cover a 4 GHz spectral window and to probe continuumemis-
atlowvelocities(suchasswept-upgas,seee.g.Petyetal.2006),
sion at a 2 MHz (∼ 2.6 km s−1 at 1.4 mm) spectral resolution.
but not the jet emission. As far as we know, this is the first
Calibration was carried out following standard procedures, us-
timeaSiOmonopolarhigh-velocityjetejectedfromalow-mass
ing GILDAS-CLIC4. Phase (rms)was ≤ 50◦ and 80◦ forthe A
protostar has been observed. The lack of SiO redshifted emis-
and C tracks, respectively, pwv was 0.5-1 mm (A) and ∼ 1–2
sion could be due to the lack of dust if the northerncavity has
mm (C), and system temperatures were ∼ 100–160 K (A) and
beencompletelyevacuatedbypreviousejections.However,the
150–250K(C).Thefinaluncertaintyontheabsolutefluxscale
lackthehigh-velocityredshiftedemissioninSO(seeSect.3.3),
is≤15%.Thetypicalrmsnoiseinthe2MHzchannelswas3–9
whoseabundanceincreasesduetopuregasphaseneutral-neutral
mJybeam−1.Imageswereproducedusingrobustweighting,and
reactions,seems to rule outthis hypothesis.As a consequence,
restoredwithacleanbeamof0′.′81×0′.′69(PA=33◦).
the bright blueshifted jet from MM1 argues that, intrinsically,
one-sidedejectionsfromlow-massprotostarscanoccur,i.e.that
3. Resultsanddiscussion onesideoftheaccretingdiskisejectingmorematerialthanthe
other.AN-Soutflowonalargescale(∼2′)waspreviouslyde-
3.1.Continuumemission tectedwithbothsingle-dishantennasandinterferometersusing
CO(1–0) and (2–1)(e.g. Engargiola& Plambeck 1999),show-
Emissionmapofthe1.4mmcontinuumisshowninFig.1.The
ingextendedlobesatrelativelylowvelocity(|V–V |≤10km
sourceIRAS2Aisfoundtobeassociatedwiththreecontinuum LSR
s−1).Bipolarnon-collimatedN-Semissionhasbeenalsotraced
2 RecentestimatesofthedistancetoPerseusrangefrom220to350
pc.Hereweadopt235pcfollowingHirotaetal.(2008). 5 TheV ofIRAS2Aasgivenintheliteratureliesbetween+7.0km
LSR
3 Spectroscopic parameters have been extracted from the Jet s−1 and+7.7kms−1 (e.g.Perssonetal.2012,andreferencestherein);
PropulsionLaboratorymoleculardatabase(Pickettetal.1998). weadopt+6.5kms−1,accordingtoCALYPSOmeasurementsofhigh-
4 http://www.iram.fr/IRAMFR/GILDAS excitation(∼200K)hot-coretracers,Maretetal.(A&A,inpress).
2
Codellaetal.:Monopolarjetsdrivenbyaproto-binarysysteminNGC1333-IRAS2A
Fig.1. Left panel: Contour plots of the IRAS2A continuum emission at 1.4 mm. The ellipse shows the PdBI synthesised beam
(HPBW):0′.′81×0′.′69(PA=33◦).Firstcontoursandstepscorrespondto5σ(7.5mJybeam−1).Labelsindicatethemainsource
(MM1)andtwoweakersources(MM2andMM3).Middlepanel:Contourmapofblue-(–39,+3kms−1)andredshifted(+11,+21
kms−1)SiO(5–4)emissionssuperimposedontheSiOatlow-velocity(+3,+11kms−1;blackcontours).Firstcontourscorrespond
to 5σand10σ, followedbystepsof10σ.One σis 84(blue), 15(red),and12(black)mJy beam−1 kms−1. Crosses areforthe
positionofthefourSiO clumps(A,B, C, andD;see Figs. 2andB.3).Magentatrianglesstandforthepositionsof MM1,MM2,
andMM3.GreylinesarethedirectionsofthePVdiagramsshowninFigs.2andB.3.Rightpanel:SameasMiddlepanelforthe
SO(6 -5 ),averagedover(–29,+3),(+11,+19),and(+3,+11)kms−1 fortheblue-,red-,andblack-velocity,respectively.Oneσis
5 4
86(blue),18(red),and16(low-velocity)mJybeam−1kms−1.
on10′′–20′′angularscalesusingCS,HCO+,andHCNemission ingregion.Thejetismonopolarinthiscaseaswellandseemsto
at even lower velocities(|V–V | ≤ 5 km s−1; Jørgensenet al. decelerate(see the channelmapsand the PV diagramsin Figs.
LSR
2007,2009).Maret et al. (2009)observedbipolar H emission B.1andB.3).TheelongationofthejetisconsistentwiththePA
2
using the Spitzer telescope. Therefore, the present SiO image (∼105◦)oftheE-Woutflow,whichconsistsoftwohighlycolli-
revealsforthefirsttimethefastjetsweepinguptheslowerout- matedlobesobservedquitefar(60′′–80′′)fromIRAS2A,using
flow observedon largerscale. The jet kinematicalage, derived typical tracers (such as SiO, SO, SO , and CH OH) of shock
2 3
from the farthest SiO emission, is 88 years. Given that the jet chemistry (e.g.Bachiller et al. 1998;Wakelam et al. 2005).So
maps suggest an inclination θ with respect to the plane of the far, the driving sourcesof the two perpendicularE-W and N-S
sky≤45◦,thisestimatehastobeconsideredanupperlimit6.In outflows have not been revealed.The presentSiO (and contin-
conclusion,giventhebipolarityof CO onlargescales, the N-S uum)imagesallowustoresolveforthefirsttimetheoriginofthe
ejectionwassymmetricinthepast,whereasthepresentSiOim- IRAS2A quadrupolaroutflow,unveilinga Class 0 proto-binary
agesuggeststhatinthelast∼90yearsonlythesouthernsidehas system(MM1andMM2)drivingtwodifferentjets.
beenactive.
Fourdistinctclumps(labelledA,B,C,andD),tofirst-order
tracingasequenceofshocksalongthejet,areclearlyvisibleat 3.3.TheroleofSOemission:jetsandcavities
differentvelocities and differentpositions along the bright SW
bluelobe;theiroffsetswithrespecttoMM1are:(–0′.′01,+0′.′02), Atthehighestvelocities,theSOdistribution,astracedbyits(65–
(–0′.′59,–1′.′13),(–0′.′86,–2′.′31),and(–1′.′35,–2′.′90),respectively. 54)line(Fig.1),resemblestheSiO(5–4)one,showingabrightS
jetdrivenbyMM1,andsupportingtheassociationwiththeSiO
ClumpA,emittingatthehighestvelocities,iscloselyassociated
jet itself. Figure 3 plots as an examplethe SiO and SO spectra
withMM1,confirmingthatSiOisapowerfultracerofthejetat
observedtowardsclumpC,confirmingthattheyareverysimilar
thebasein Class0 sources(e.g.Codellaetal. 2007).ClumpC
(peakingat ∼ –25 km s−1) is instead associated with the MM3 atthehighestvelocities.Thesefindings(i)areinagreementwith
thedetectionofSOatextremelyhighvelocities(|V–V |≥50
continuum source; MM3 could be a young stellar object driv- LSR
ing the blueshifted SiO emission (between –10 and 0 km s−1, km s−1) using the IRAM 30 m antenna towardsthe L1448and
IRAS04166+2706outflows(Tafallaetal.2010),and(ii)confirm
as shown in Fig. 2; see also the channelmaps reported in Fig.
whatwasfoundbyLeeetal.(2010)forHH211,i.e.thatSOcan
B.1) which deviates from the N-S main axis, bending towards
beusedasmolecularjettracerinadditiontothewell-knownH ,
the east. Alternatively,the continuumsource MM3 could trace 2
CO,andSiO(andH Omasers),bringinganewconstraintonjet
dustemissionfromapre-existingclumpydenserregionwhich, 2
asasideeffect,bendspartoftheblueflow.Finally,thePVdia- chemicalmodels.Indeed,magnetohydrodynamic(MHD)mod-
elsshowthattheSOabundance,quicklyformedbythereaction
gramofFig.2suggestsajetdeceleration.Thedynamicaltimeof
theSiOclumpsis≤27–88yr,andisconsistentwiththatderived of S with OH, can reach the observed abundance of 2 10−7 in
jets(Tafallaetal.2010)throughambipolardiffusionheatingin
fortheHH212SiOjet(25yr;Cabritetal.2007).
C-shocks(PineauDesForeˆtsetal.1993)ormagneto-centrifugal
InadditiontotheN-Sjet,theSiOmaprevealsaredshiftedjet
(V–V upto∼+12kms−1;seeFig.B.1)withawidthsimilar diskwinds(Panoglouetal.2012).
LSR
totheN-Sjet(165AU)andspatiallyassociatedwiththeMM2 Close to the systemic velocity, the SiO intensity fades
continuumsource,confirmingSiOasaprobeofthejetlaunch- whereasSO increases.Thisis particularlyclear whenwe com-
paretheprofilesobservedtowardsclumpC(Fig.3)andthespa-
6 Theageshouldbecorrectedbyafactorofctg(θ). tial distributions in Fig. 1: low-velocity (|V–VLSR| ≤ 4 km s−1)
3
Codellaetal.:Monopolarjetsdrivenbyaproto-binarysysteminNGC1333-IRAS2A
Fig.3. Comparison between the SiO(5–4) and SO(6 –5 ) lines
5 4
asobservedtowardsclumpC(inmain-beamtemperature,T ,
MB
scale).
SiOwithshockedmaterial.IfwemodeltheT ∼30Kofthe
MB
high-velocitySO(6 –5 )emissionobservedtowardsclumpCus-
5 4
ingRADEXcoupledwiththecollisionratesprovidedbyGreen
Fig.2. Position-velocity cut of SiO(5–4) (grey scale and black
(1994),wefindN ∼1016–1017cm−2andn ≥105cm−3,sup-
contours)and SO(65–54) (magenta contours)along the N-S jet SO H2
(PA=25◦,seegreylineinFig.1).Firstcontoursandstepscor- porting,asforSiO,shocked(compressed)gas.
respond to 5σ (3.0 K for SiO and 4.5 K for SO) and 10σ, re-
spectively.DashedlinesmarkthepositionsofMM1,MM3,and
4. Conclusions
theambientV (+6.5kms−1).LabelsA,B, C, andD arefor
LSR
thefourclumpsalongtheSiObluejet.NoSiOorSOemission Thepresentcontinuum,SiO,andSOdataallowustodisentan-
isdetectedoutsidethegivenvelocityrange. gletheoriginoftheIRAS2Aquadrupolaroutflowintoaproto-
binarysystempoweringtwodifferentjets.Werevealedaclumpy
SjetemergingfromthebrightestMM1continuumsource,plus
SObrightemissiontracesextendedemissionin boththenorth- aredshiftedEjetassociatedwiththeweakerMM2source.The
ern and southern lobes (Fig. 2; see also the channel maps of jet gas has high-excitation conditions (≥ 100 K; ≥ 105 cm−3).
Fig. B.2). In particular, Fig. 1 suggests the association of low- Thefast, young(≤ 90yr)Sjetopeneda molecularcavity,effi-
velocity SO with a cavity with MM1 at the vertex. Emission cientlytracedbySOatvelocityclosetosystemic(|V–V |≤4
LSR
of SO redshifted by ∼ 5 km s−1 is also detected towards north kms−1).TheIRAS2Ajetsareintrinsicallymonopolaronscales
in addition to the SiO MM2 jet, but the morphology suggests <1000AUindicatingthatone-sideejectionsfromprotostarsare
that this emission is still associated with a cavity rather than possibleduringshortperiods(≤90yr).
the jet. In addition,an SO eastern clumpredshiftedby 2–3km
s−1 appearsalongthedirectionofthe E-Wjet, andis plausibly Acknowledgements. We are very grateful to all the IRAM staff, whose ded-
related to swept-up material. The low-velocitySiO emission is ication allowed us to carry out the CALYPSO project. The research leading
totheseresultshasreceived fundingfromtheEuropeanCommunitysSeventh
elongated,butitisdefinitelyweakerandoffsettotheNWwith
FrameworkProgramme(FP7/2007-2013/)undergrantagreements No229517
respecttothebluejetaxis,andsupportsitsassociationwiththe (ESOCOFUND)andNo291294(ORISTARS),andfromtheFrenchAgence
SO cavity.Theweaknessof SiO in the cavity shouldreflectits NationaledelaRecherche(ANR),underreferenceANR-12-JS05-0005.
low formation rate in low-velocity shocks (e.g. Gusdorf et al.
2008ab). Interestingly, the H18O emission imaged at PdBI by
2
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5
Codellaetal.:Monopolarjetsdrivenbyaproto-binarysysteminNGC1333-IRAS2A
Fig.A.1. Contour plots of the IRAS2A continuum emission at
3.2mm.TheellipseshowsthePdBIsynthesisedbeam(HPBW):
1′.′42×1′.′00(PA=38◦).Firstcontoursandstepscorrespondto
5σ (1.3 mJy beam −1). Labels indicate the main source MM1 Fig.B.3.Position-velocitycutofSiO(5–4)(greyscaleandblack
and the weaker source MM2. The black triangle stands for the contours)andSO(65–54)(magentacontours)alongthewholeE-
position of MM3, revealed at 1.4 mm and not detected at 3.2 Wjet(PA=105◦,seethegreylineinFig.1).Firstcontoursand
mm. steps correspond to 5σ (2.5 K for SiO and 4.0 K for SO) and
3σ, respectively.Dashed lines mark the positionsof MM2 and
the protostellar envelopeV (+6.5 km s−1). We note that the
LSR
AppendixA: The3.2mmcontinuumemission SiOandSOemissionatnegativeangularoffsetstracestheN-S
outflowdrivenbyMM1(seeFig.1).
Figure A.1 shows the emission map of the 3.2 mm continuum
dust emission, which was produced as the 1.4 mm map using
robustweighting,andrestoredwithacleanbeamof1′.′42×1′.′00
(PA=38◦).The3.2mmemissionallowsustodetecttheMM1
(α(J2000):03h28m55s.56,δ(J2000):+31◦14′36′.′93)andMM2
(α(J2000): 03h 28m 55s.69, δ(J2000): +31◦ 14′ 35′.′63) sources,
consistentwithwhatwasfoundinthe1.4mmimage(seeTable
1 and Fig. 1). The peak fluxes are 17 mJy beam−1 and 2 mJy
beam−1 for MM1 and MM2, respectively. On the other hand,
MM3 (revealed at 1.4 mm) is not detected at a 3σ sensitivity
levelof0.75mJybeam−1.
AppendixB: SiOandSOchannelmaps
We showin Figs. A.1 andA.2the channelmapsof theSiO(5–
4) and SO(6 –5 ) blue- and redshifted (continuum subtracted)
5 4
emissions towards IRAS2A. The images trace the clumpswell
atdifferentvelocitiesalongtheN-SjetdrivenbyMM1andalso
tracetheredshiftedElobeassociatedwithMM2.Thegreylines
showthedecelerationofthehighestvelocityclumps.
Figure A.3 shows the SiO and SO PV diagrams along the
E-W jet axis: as in the N-S case, the SiO emitting at the high-
estvelocitiesiscloselyassociatedwiththedrivingsourceMM2,
confirmingthatSiOisapowerfultracerofthejetlaunchingre-
gion.
6
Codellaetal.:Monopolarjetsdrivenbyaproto-binarysysteminNGC1333-IRAS2A
Fig.B.1.ChannelmapsoftheSiO(5–4)blue-andredshifted(continuumsubtracted)emissionstowardsIRAS2A.Eachpanelshows
theemissionintegratedoveravelocityintervalof2.5kms−1centredatthevaluegivenintheupper-rightcorner.Thethickboxand
themagentacontoursindicatetherangeassociatedwiththesystemicvelocity.Thickcontourscorrespondtothe5σemissionofthe
1.4mmcontinuummapshowninFig.1andindicatethepositionoftheMM1,MM2,andMM3continuumsources.Theellipsein
thetop-leftpanelshowsthePdBIsynthesisedbeam(HPBW):0′.′81×0′.′69(PA=33◦).Firstcontoursandstepscorrespondto5σ
(15mJybeam−1kms−1)and10σ,respectively.GreylinesindicatetheslowingdownofthehighestvelocitySiOclumps(seetext).
Fig.B.2. Channels map of the SO(6 –5 ) blue- and redshifted (continuum subtracted) emissions towards IRAS2A. Each panel
5 4
showstheemissionintegratedoveravelocityintervalof2.7kms−1 centredatthevaluegivenintheupper-rightcorner.Symbols
aredrawnasinFig.2.Theellipseinthetop-leftpanelshowsthePdBIsynthesisedbeam(HPBW):0′.′81×0′.′69(PA=33◦).First
contoursandstepscorrespondto5σ(15mJybeam−1 kms−1)and10σ,respectively.Greylinesindicatetheslowingdownofthe
highestvelocitySOclump(seetext).
7