APEX-CHAMP+ high-J CO observations of low-mass young stellar objects

29 Pages·2015·11.16 MB·English

A&A576,A109(2015) Astronomy
DOI:10.1051/0004-6361/201424538 &
(cid:13)c ESO2015 Astrophysics
+
APEX-CHAMP high-J CO observations
of low-mass young stellar objects
IV. Mechanical and radiative feedback(cid:63),(cid:63)(cid:63)
U.A.Yıldız1,2,L.E.Kristensen3,E.F.vanDishoeck1,4,M.R.Hogerheijde1,A.Karska4,A.Belloche5,A.Endo6,
W.Frieswijk7,8,R.Güsten5,T.A.vanKempen1,S.Leurini5,Z.Nagy9,J.P.Pérez-Beaupuits5,C.Risacher5,7,
N.vanderMarel1,R.J.vanWeeren3,andF.Wyrowski5
1 LeidenObservatory,LeidenUniversity,POBox9513,2300RALeiden,TheNetherlands
2 JetPropulsionLaboratory,CaliforniaInstituteofTechnology,4800OakGroveDrive,Pasadena,CA91109,USA
e-mail:[email protected]
3 Harvard-SmithsonianCenterforAstrophysics,60GardenStreet,Cambridge,MA02138,USA
4 Max-Planck-InstitutfürExtraterrestrischePhysik(MPE),Giessenbachstrasse1,85748Garching,Germany
5 Max-Planck-InstitutfürRadioastronomie,AufdemHügel69,53121Bonn,Germany
6 KavliInstituteofNanoscience,DelftUniversityofTechnology,Lorentzweg1,2628CJDelft,TheNetherlands
7 KapteynInstitute,UniversityofGroningen,Landleven12,9747ADGroningen,TheNetherlands
8 ASTRON,OudeHoogeveensedijk4,7991PDDwingeloo,TheNetherlands
9 I.PhysikalischesInstitutderUniversitätzuKöln,ZülpicherStrasse77,50937Köln,Germany
Received4July2014/Accepted7January2015
ABSTRACT
Context.Duringtheembeddedstageofstarformation,bipolarmolecularoutflowsandUVradiationfromtheprotostarareimportant
feedbackprocesses.Bothprocessesreflecttheaccretionontotheformingstarandaffectsubsequentcollapseorfragmentationofthe
cloud.
Aims.Ouraimistoquantifythefeedback,mechanicalandradiative,foralargesampleoflow-masssourcesinaconsistentmanner.
TheoutflowactivityiscomparedtoradiativefeedbackintheformofUVheatingbytheaccretingprotostartosearchforcorrelations
andevolutionarytrends.
Methods.Large-scalemapsof26youngstellarobjects,whicharepartoftheHerschelWISHkeyprogramareobtainedusingthe
CHAMP+ instrument on the Atacama Pathfinder EXperiment (12CO and 13CO 6−5; E ∼ 100 K), and the HARP-B instrument
up
ontheJamesClerkMaxwellTelescope(12COand13CO3−2;E ∼ 30K).Themapshavehighspatialresolution,particularlythe
up
CO6−5mapstakenwitha9(cid:48)(cid:48)beam,resolvingthemorphologyoftheoutflows.Themapsareusedtodetermineoutflowparameters
andtheresultsarecomparedwithhigher-J COlinesobtainedwithHerschel.Envelopemodelsareusedtoquantifytheamountof
UV-heatedgasanditstemperaturefrom13CO6−5observations.
Results.Allsourcesinoursampleshowoutflowactivity,withthespatialextentdecreasingfromtheClass0totheClassIstage.
Consistentwithpreviousstudies,theoutflowforce,F ,islargerforClass0sourcesthanforClassIsources,eveniftheirluminosities
CO
arecomparable.Theoutflowinggastypicallyextendstomuchgreaterdistancesthanthepower-lawenvelopeandthereforeinfluences
thesurroundingcloudmaterialdirectly.ComparisonoftheCO6−5resultswithHIFIH OandPACShigh-JCOlines,bothtracing
2
currentlyshockedgas,showsthatthetwocomponentsarelinked,eventhoughthetransitionsdonotprobethesamegas.Thelink
doesnotextenddowntoCO3−2.TheconclusionisthatCO6−5dependsontheshockcharacteristics(densityandvelocity),whereas
CO3−2ismoresensitivetoconditionsinthesurroundingenvironment(density).Theradiativefeedbackisresponsibleforincreasing
thegastemperaturebyafactoroftwo,upto30–50K,onscalesofafewthousandAU,particularlyalongthedirectionoftheoutflow.
ThemassoftheUVheatedgasexceedsthemasscontainedintheentrainedoutflowintheinner∼3000AUandisthereforeatleastas
importantonsmallscales.
Keywords.astrochemistry–stars:formation–stars:protostars–ISM:molecules–techniques:spectroscopic
1. Introduction star-disk system, which sweep up surrounding envelope mate-
rial in large bipolar outflows. The material is accelerated and
Duringtheearlyphasesofstar-formation,materialsurrounding
pushed to distances of several tens of thousands of AU, and
the newly forming star accretes onto the protostar. At the same
these outflows play a pivotal role in the physics and chemistry
time, winds or jets are launched at supersonic speeds from the
of the star-forming cores (Snell et al. 1980; Goldsmith et al.
1984;Lada1987;Greeneetal.1994;Bachiller&Tafalla1999;
(cid:63) AppendixAisavailableinelectronicformat
http://www.aanda.org Arce & Sargent 2006; Tafalla et al. 2013). The youngest pro-
(cid:63)(cid:63) TheCHAMP+maps(datacubes)areonlyavailableattheCDSvia tostars have highly collimated outflows driven by jets, whereas
anonymousftptocdsarc.u-strasbg.fr(130.79.128.5)orvia atlaterstageswide-anglewindsdrivelesscollimatedoutflows.
http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/576/A109 However, there is still not a general consensus to explain the
ArticlepublishedbyEDPSciences A109,page1of29
A&A576,A109(2015)
launchingmechanismsandnatureoftheseoutflows(Arceetal. sincebeendemonstratedandquantifiedforafewmoresources
2007;Franketal.2014). byvanKempenetal.(2009b),Yıldızetal.(2012),Visseretal.
The goal of this paper is to investigate how the outflow ac- (2012).WenotethatthisUV-heatedgasiswarmgaswithtem-
tivity varies with evolution and how this compares with other peratures higher than that of the dust, and is thus in excess of
measures of the accretion processes for low-mass sources. The warmmaterialintheenvelopethathasbeenheatedbytheproto-
outflowsreflecttheintegratedactivityovertheentirelifetimeof stellarluminosity,wherethegastemperatureisequaltothedust
theprotostar,whichcouldbetheresultofmultipleaccretionand temperature. Although UV heating toward photo-dissociation
ejectionevents.Itisimportanttodistinguishthisprobefromthe regions (PDRs) is readily traced by emission from polycyclic
current accretion rate, as reflected for example in the luminos- aromatichydrocarbons(PAHs),thePAHabundancetowardem-
ity of the source, in order to understand the accretion history. bedded protostars is too low for them to be used as a tool in
Thewell-knownluminosityprobleminlow-massstar-formation thiscontext(Geersetal.2009).Hereweinvestigatetheimpor-
indicatesthatprotostarsareunderluminouscomparedtotheoret- tanceofradiativefeedbackforamuchlargersampleoflow-mass
icalmodels(Kenyonetal.1990;Evansetal.2009;Enochetal. sources and compare the gas temperatures and involved mass
2009; Dunham et al. 2010, 2013). One of the possible resolu- withthatoftheoutflows.
tions to this problem is that of episodic accretion, in which the Tracingwarmgas(T (cid:38) 30K)intheenvelopeorinthesur-
star builds up through short bursts of rapid accretion over long roundings requires observations of higher-J transitions of CO,
periodsoftimeratherthancontinuoussteady-stateaccretion.An e.g., J ≥ 5, for which ground-based telescopes demand excel-
u
accurateandconsistentquantificationofoutflowproperties,such lent weather conditions on dry observing sites. The CHAMP+
as the outflow force and mass, is essential for addressing this instrument, mounted on the Atacama Pathfinder EXperiment
problem. (APEX)telescopeisideallysuitedtoobservehigher-JCOtran-
Outflows have been observed in CO emission in the last sitions and efficiently map extended sources. The broad line
fewdecadestowardsmanysources,butthoseobservationswere wingsofCO6−5(E /k=115K)sufferlessfromopacityeffects
u
mainly done via lower-J CO rotational transitions (J ≤ 3), than CO3−2 (E /k = 33K) (van Kempen et al. 2009a; Yıldız
u u
whichprobecolderswept-uporentrainedgas(T ∼ 50−100K) etal.2012).Moreover,theambientcloudcontributionissmaller
(e.g., Bachiller et al. 1990; Blake et al. 1995; Bontemps et al. for these higher-J transitions, except close to the source posi-
1996; Tafalla et al. 2000; Curtis et al. 2010, and many others). tion,wherethedenseprotostellarenvelopemaystillcontribute.
Oneofthemostimportantparametersthatisusedfortheevolu- Even higher-J CO lines up to J ∼ 50 were routinely observed
u
tionarystudiesofstarformationisthe“outflowforce”,whichis withtheHerschel(Pilbrattetal.2010)andprovideinformation
known as the strength of an outflow and defined similar to any on the shocked gas in the Herschel beam (Herczeg et al. 2012;
r−2-typeforce.Thesestudiesconcludethattheoutflowforcecor- Goicoechea et al. 2012; Benedettini et al. 2012; Manoj et al.
relateswellwithbolometricluminosity,L ,acorrelationwhich 2013;Greenetal.2013;Nisinietal.2013;Karskaetal.2013).
bol
holdsoverseveralordersofmagnitude.Furthermore,theoutflow This currently shocked gas is different from that observed in
force from Class 0 sources is stronger than for Class I sources, low-J CO transitions, as is evident from their different spatial
indicatinganevolutionarytrend.Thecorrelations,however,of- distributions(Tafallaetal.2013;Santangeloetal.2013).
ten show some degree of scatter, typically more than an order In this paper, we present an APEX-CHAMP+ survey of
of magnitude in F for any value of L . Some of the uncer- 26low-massyoungstellarobjects(YSOs),whichweremapped
CO bol
tainties in these studies include the opacity in the line wings, in COJ =6−5 and isotopologues in order to trace their out-
the adopted inclination angle and cloud contamination at low flowactivity,followingvanKempenetal.(2009a,b)andYıldız
outflowvelocities(e.g.,vanderMareletal.2013).Comparison et al. (2012), Papers I, II and III in this series, on individual or
withotheroutflowtracerssuchaswaterrecentlyobservedwith more limited samples of sources. These data complement our
theHerschelSpaceObservatoryisfurthercomplicatedbecause earlier surveys at lower frequency of CO and other molecules
thevariousstudiesusedifferentanalysismethodstoderiveout- with the James Clerk Maxwell Telescope (JCMT) and APEX
flowparametersfromlow-J COmaps.Oneofthegoalsofthis (e.g.,Jørgensenetal.2002,2004;vanKempenetal.2009c).The
paperistoprovideaconsistentsetofoutflowparametersdeter- samesourcesarecoveredintheHerschelkeyproject,“Waterin
minedbythesamemethodusingdatafromthesametelescopes star-formingregionswithHerschel”(WISH;vanDishoecketal.
forcomparisonwiththeHerschellines. 2011), which has observed H O and selected high-J CO lines
2
Recently, the importance of radiative feedback from low- withHIFIandPACSinstruments.Manyofthesourcesarealso
mass protostars on all scales of star formation has been ac- includedinthe“Dust,IceandGasinTime”program(DIGIT;PI:
knowledged. On cloud scales (>104 AU) the feedback sets the N.Evans;Greenetal.2013),whichhasobtainedfullPACSspec-
efficiency at which cores fragment from the cloud and form tralscans.Theresultsobtainedfromthe12COmapsarecomple-
stars (Offner et al. 2009, 2010; Hansen et al. 2012) because mentedby13CO6−5dataofthesamesources,withthenarrower
the Jeans length scales as T0.5. Simulations including radiative 13CO6−5linesprobingtheUVphoton-heatedgas.
feedback and radiative transfer reproduce the observed initial The YSOs in our sample cover both the deeply embedded
massfunction(IMF)betterthanmodelswithouttheseeffectsin- Class0stageaswellasthelessembeddedClassIstage(André
cluded (Offner et al. 2009). On the scales of individual cores et al. 2000; Robitaille et al. 2006). Physical models of the dust
(<3000 AU), the radiative feedback suppresses the fragmenta- temperature and density structure of the envelopes have been
tion into multiple systems and serves to stabilize the protostel- developed for all sources by Kristensen et al. (2012) through
lar disk (Offner et al. 2010). Thus, quantifying observationally spherically symmetric radiative transfer models of the contin-
thetemperaturechangesasafunctionofpositionfromthepro- uumemission.Thefulldatasetcoveringmanysources,together
tostar are important steps toward more accurate models of star withtheenvelopemodels,allowsustoaddressimportantcharac-
formation.Thefirstobservationalevidenceofheatingofthegas teristicsofYSOsthroughtheevolutionfromClass0toClassI
aroundlow-massprotostarsonscalesof∼1000AUbyUVradi- in a more consistent manner. These characteristics can be in-
ationescapingthroughtheoutflowcavitiesdatesbacktoSpaans ferred from their different morphologies, outflow forces, enve-
et al. (1995) based on strong narrow 13CO 6−5 lines, and has lopemasses,etc.andeventuallybecomparedwithevolutionary
A109,page2of29
U.A.Yıldızetal.:Mechanicalandradiativefeedback
luminosities makes the sample well suited for studying trends
Class 0 withvarioussourceparameters.Therangeofluminositiesstud-
Class I ied is similar to that of Bontemps et al. (1996), ∼0.5 to 15 L ,
(cid:12)
101 butoursampleismoreweightedtowardhigherluminositiesand
earlierstages.
]
⊙
M
2.2. Observations
[
nv Molecular line observations of CO in the J = 6−5 transitions
e 100
M were done with the 12-m submillimeter Atacama Pathfinder
EXperiment(APEX1;Güstenetal.2008)atLlanodeChajnantor
inChile,whereastheJ =3−2transitionwasprimarilyobserved
atthe15-mJamesClerkMaxwellTelescope(JCMT)2 atMauna
Kea,Hawaii.
10-1 APEX: 12CO and 13CO 6−5 maps of the survey were
100 101 obtained with the CHAMP+ instrument on APEX between
L [L ] June2007andSeptember2012.TheCHAMP+ instrumentcon-
bol
⊙ sistsoftwoheterodynereceiverarrays,eachwithsevenpixelde-
tectorelementsforsimultaneousoperationsinthe620–720GHz
Fig.1.Envelopemass,M ,vs.bolometricluminosity,L ,forthesur-
env bol
and 780–950 GHz frequency ranges (Kasemann et al. 2006;
veyed sources. Red diamonds and blue squares indicate Class 0 and
ClassIsources,respectively. Güstenetal.2008).Theobservationalproceduresareexplained
in detail in van Kempen et al. (2009a,b,c) and Yıldız et al.
(2012).Simultaneousobservationsweredonewiththefollowing
models.Thestudypresentedhereisalsocomplementarytothat settingsofthelowerandhigherfrequencybands:12CO6−5with
ofYıldızetal.(2013),whereonlythesourcepositionwasstud- 12CO7–6;13CO6−5with[C]2–1.12COmapscovertheentire
ied with spectrally resolved CO line profiles from J = 2−1 to outflowextentwithafewexceptions(L1527,Ced110IRS4,and
10−9(E ∼300K),andtrendswithevolutionwereexamined. L1551-IRS5),whereas 13COmapscover onlya∼100(cid:48)(cid:48) × 100(cid:48)(cid:48)
up
Theoutlineofthepaperisasfollows.InSect.2,theobser- region around the central source position. L1157 is part of
vationsandthetelescopeswherethedatahavebeenobtainedare the WISH survey, but because it is not accessible from APEX
described.InSect.3,physicalparametersobtainedfrommolecu- (Dec=+68◦),noCO6−5dataarepresented.
laroutflowsaregivenandtheUVheatedgascomponentisiden- The APEX beam size is ∼9(cid:48)(cid:48) (∼1800 AU for a source
tified. In Sect. 4, these results are discussed, and conclusions at 200 pc) at 691 GHz. The observations were done using
fromthisworkarepresentedinSect.5. position-switching toward an emission-free reference position.
TheCHAMP+ instrumentusesthefastFouriertransformspec-
trometer(FFTS)backend(Kleinetal.2006)forallsevenpixels
2. Sampleandobservations witharesolutionof0.183MHz(0.079kms−1at691GHz).The
rmsatthesourcepositionislistedinYıldızetal.(2013)forthe
2.1. Sample
CO6−5and13CO6−5observationsandistypically0.3–0.5K
Thesampleselectioncriteriawiththecoordinatesandotherba- for the former and 0.1–0.3 K for the latter, both in 0.2 km s−1
sicinformationofthesourcelistarepresentedinvanDishoeck channels.Thermsincreasesnearthemapedgeswheretheeffec-
etal.(2011)withupdatesinKristensenetal.(2012),andisthe tiveintegrationtimeperbeamwassignificantlysmallerthanin
sameasthesamplepresentedinYıldızetal.(2013).Itconsistsof the central parts; near the edges the rms may be twice as high.
15Class0and11ClassIembeddedprotostellarsourceslocated Apart from the high-J CO observations, some of the 3−2 line
in the Perseus, Ophiuchus, Taurus, Chamaeleon, and Serpens observationswerealsoconductedwithAPEXforafewsouthern
molecular clouds. The average distance is 200pc, with a max- sources, e.g., DK Cha, Ced110IRS4, and HH46 (van Kempen
imumdistanceof450pc. etal.2009c).
Figure 1 presents the envelope mass (M ) as a function JCMT: Fully sampled jiggle maps of 12CO and 13CO3−2
env
of bolometric luminosity (L ) for all sources. The parameters were obtained using the HARP-B instrument mounted on the
bol
are taken from the continuum radiative transfer modeling by JCMT (Buckle et al. 2009). HARP-B consists of 16 SIS detec-
Kristensenetal.(2012)basedonfitsofthespectralenergydis- torswith4×4pixelelementsof15(cid:48)(cid:48)eachat30(cid:48)(cid:48)separation.Most
tributions(SEDs)includingnewHerschel-PACSfluxes,aswell ofthemapswereobtainedthroughourowndedicatedproposals,
as the spatial extent of the envelopes observed at submillime- withasubsetobtainedfromtheJCMTpublicarchive3.
ter wavelengths. The envelope mass is measured either at the
T = 10 K radius or at the n = 104 cm−3 radius, depending 1 This publication is based on data acquired with the Atacama
dust
on which is smaller. Class 0 and Class I sources are well sep- Pathfinder Experiment (APEX). APEX is a collaboration between
the Max-Planck-Institut für Radioastronomie, the European Southern
arated in the diagram, with the Class 0 sources having higher
Observatory,andtheOnsalaSpaceObservatory.
envelopemasses.Thistypeofcorrelationdiagramhasbeenput
2 The James Clerk Maxwell Telescope has historically been oper-
forward by Saraceno et al. (1996) and subsequently used as an
ated by the Joint Astronomy Centre on behalf of the Science and
evolutionarydiagramforembeddedYSOswithlowerenvelope
Technology Facilities Council of the United Kingdom, the National
masses representing later stages (e.g., Bontemps et al. 1996;
Research Council of Canada and the Netherlands Organisation for
Hogerheijde et al. 1998; Hatchell et al. 2007). In our sample, ScientificResearch.
envelopemassesrangefrom0.04 M(cid:12) (Elias29)to16 M(cid:12) (Ser- 3 This research used the facilities of the Canadian Astronomy Data
SMM1)andtheluminositiesrangefrom0.8 L(cid:12) (Ced110IRS4) CentreoperatedbytheNationalResearchCouncilofCanadawiththe
to35.7L(cid:12)(NGC1333-IRAS2A).Thelargerangeofmassesand supportoftheCanadianSpaceAgency.
A109,page3of29
A&A576,A109(2015)
Table1.Inclinationcorrectionfactors. separately, and V is measured as described above. The
out
differences between the velocity, where the emission reaches
i(◦) 10 30 50 70 1σlevel(Vout)withVLSR aretakenastheglobalVmax valuesfor
the correspondingblue and red-shiftedlobes (Cabrit & Bertout
c 1.2 2.8 4.4 7.1
i 1992).
Notes. Line-of-sight inclinations, where i = 0◦ indicates pole-on
(Downes&Cabrit2007). TwoissuesarisewhendeterminingV (e.g.,vanderMarel
max
etal.2013;Dunhametal.2014):first,V isafunctionofthe
max
rmsnoiselevelandgenerallydecreaseswithincreasingrms.For
The data were acquired on the T∗ antenna temperature noisy data, Vmax may be underestimated compared to its true
A value. For this reason, the 3−2 lines are chosen to determine
scale and were converted to main-beam brightness tempera-
tures T = T∗/η using the beam efficiencies (η ). The Vmax because of their higher S/N than the 6−5 lines. Second,
CHAMMP+BbeamAefficMiBenciesweretakenfromtheCHAMMPB+web- if the outflow lobes are inclined, Vmax suffers from projection
site4 and forward efficiencies are 0.95 in all observations. The effects. Both effects will increase the value of Vmax if properly
variousbeamefficienciesareallgiveninYıldızetal.(2013,their takenintoaccount.
Appendix C) and are typically ∼0.5. The JCMT beam efficien-
ciesweretakenfromtheJCMTefficienciesdatabase5,and0.63 Concerningthesecondissue,theinclinationisdifficulttoes-
isusedforallHARP-Bobservations.Calibrationerrorsareesti- timate from these data alone; proper-motion studies along with
matedtobe∼20%forbothtelescopes.Typicalrmsnoiselevels radial velocities are required to obtain an accurate estimate of
of the J = 3−2 data are from 0.05 K to 0.1 K in 0.2 km s−1 theinclination.Alternatively,thevelocitystructuremaybemod-
channels. eledassumingsomedistributionofmaterial,e.g.,awind-driven
Forthedatareductionandanalysis,theContinuumandLine shellwithaHubble-likeflow(Leeetal.2000),wheretheincli-
Analysis Single Dish Software (CLASS program), which is part nationthenentersasafreeparameter.Itisdefinedastheangle
of the GILDAS software6, is used. In particular, linear base- between the outflow direction and the line of sight (Cabrit &
linesweresubtractedfromallspectra.12COand13CO6−5and Bertout1990,i = 0◦ ispoleon).Smallradialvelocitiesareex-
3−2lineprofilesofthecentralsourcepositionsofallthesources pectedforoutflowswhichlieintheplaneofthesky.Thereforea
inthesamplearepresentedinYıldızetal.(2013). correctionfactorforinclinationci isappliedinthecalculations.
InTable1,thecorrectionfactorsfromDownes&Cabrit(2007)
are tabulated; these correction factors come from detailed out-
2.3. 12COmaps flow modeling and synthetic observations of the model results.
Moreover, we note that these correction factors include correc-
Allspectraarebinnedtoa0.5kms−1velocityresolutionforan-
tionformissingmasswithin±2kms−1 fromthesourceveloc-
alyzingtheoutflows.Theintensitiesoftheblueandredoutflow
ity.Thecorrectionfactorshavebeenappliedtotheoutflowrate,
lobesarecalculatedbyintegratingtheblueandredemissionin
forceandluminosityaslistedinTables2and3.Thevelocity,asa
each of the spectra separately, where the integration limits are
measuredparameter,isnotcorrectedforinclination.Theinclina-
carefullyselectedforeachsourcebyusingthe0.2kms−1 reso-
tionanglesareestimatedfromtheoutflowmapsasfollows:ifthe
lutionCO3−2or6−5spectraiftheformerisnotavailable(see
outflowlobesareoverlapping,theoutflowislikelyveryinclined.
Fig.A.1).First,theinnervelocitylimit,V ,closesttothesource
in Iftheoutflowshowslow-velocitylinewingsbutalargeextenton
velocity is determined by selecting a spatial region not associ-
thesky,theinclinationisverylikelylow.Inthiswayeachout-
ated with the outflow. The 12CO spectra in this region are av-
flow is classified individually, and divided into inclination bins
eraged to determine the narrow line emission coming from the
at 10◦, 30◦, 50◦, and 70◦. Our estimates are listed in Tables 2
envelope and surrounding cloud, and V is estimated from the
in and 3, and are consistent with the literature where available
widthofthequiescentemission(seeFig.A.1intheAppendix).
(Cabrit & Bertout 1992; Gueth et al. 1996; Bourke et al. 1997;
Second, the outer velocity limits V are determined from the
highest S/N spectrum inside each oouftthe blue and red outflow Hogerheijdeetal.1997;Miconoetal.1998;Brown&Chandler
1999;Lommenetal.2008;Tobinetal.2008;vanKempenetal.
lobes.Theoutervelocitylimitsareselectedasthevelocitywhere
2009b), except for IRAS 15398 for which we find a larger in-
the emission in the spectrum goes down to the 1σ limit for the
clination than van Kempen et al. (2009c). Our inclination of
firsttime.Itthereforeexcludesextremelyhighvelocityor“bul-
IRAS 15398 is consistent with newer values from (Oya et al.
let” emission which is seen for a few sources. The blue- and
2014). Although the method for determining the outflow incli-
red-shifted integrated intensity is measured by integrating over
nationsissubjective,theinclinationsagreewithliteraturevalues
these velocity limits across the entire map, but excluding any
whereavailable,whichlendssomecredibilitytothemethod,and
extremelyhighvelocity(EHV)or“bullet”emission.
weestimatethattheuncertaintyis30◦.Thatis,thecorrectionin-
troducesapotentialsystematicerrorofuptoafactorof2inthe
2.3.1. Outflowvelocity outflowparameters.
The maximum outflow velocity, V is defined as |V –V |,
max out LSR The resulting maps of all sources are presented in Figs. 2
the total velocity extent measured relative to the source veloc-
and 3 for 12CO 6−5 and 3−2, respectively, where blue and red
ity. In order to estimate V , representative spectra from the
max contours show the blue- and red-shifted outflow lobes, respec-
blue and red outflow lobes observed in CO 3−2 are selected
tively. The velocity limits are summarized in Table A.1 in the
4 http://www3.mpifr-bonn.mpg.de/div/submmtech/ Appendix.Afewmapscoveronlythecentral∼2(cid:48) ×2(cid:48),specifi-
heterodyne/champplus/champ_efficiencies.29-11-13.html callythethreeClass0sourcesNGC1333-IRAS2A,L723mm,
5 http://www.jach.hawaii.edu/JCMT/spectral_line/ L1527, and the two Class I sources Elias 29 and L1551-IRS5.
Standards/eff_web.html Source-by-sourceoutflowandintensitymapsobtainedfromthe
6 http://www.iram.fr/IRAMFR/GILDAS CO6−5and3−2dataarepresentedinFigs.A.2.
A109,page4of29
U.A.Yıldızetal.:Mechanicalandradiativefeedback
Table2.OutflowpropertiesoftheredandblueoutflowlobesofClass0sources.
Source Trans. Inclination Lobe R a t a,b M a,c M˙d,e F d,f L d,g
CO dyn outflow CO kin
[◦] [AU] [103yr] [M ] [M yr−1] [M yr−1kms−1] [L ]
(cid:12) (cid:12) (cid:12) (cid:12)
L1448MM CO3−2 50 Blue 5.9×104 5.5 9.0×10−2 7.2×10−5 2.0×10−3 2.8×100
Red 5.9×104 9.7 6.2×10−2 2.8×10−5 1.7×10−3 2.3×100
NGC1333-IRAS2A CO6−5 70 Blue 1.4×104 2.9 7.9×10−3 2.0×10−5 3.4×10−4 1.7×10−1
Red 1.4×104 3.9 2.2×10−2 4.0×10−5 2.0×10−3 1.7×100
CO3−2 70 Blue 2.4×104 4.8 8.5×10−2 1.3×10−4 2.6×10−3 1.2×100
Red 2.4×104 6.4 6.9×10−2 7.7×10−5 4.8×10−3 5.4×100
NGC1333-IRAS4A CO6−5 50 Blue 2.5×104 5.3 8.1×10−3 6.7×10−6 1.5×10−4 5.6×10−2
Red 3.5×104 8.4 1.9×10−2 9.9×10−6 5.4×10−4 5.4×10−1
CO3−2 50 Blue 2.8×104 6.1 2.1×10−2 1.5×10−5 3.5×10−4 1.6×10−1
Red 3.9×104 9.3 2.5×10−2 1.2×10−5 1.7×10−3 1.8×100
NGC1333-IRAS4B CO6−5 10 Blue 2.4×103 0.6 8.2×10−4 1.6×10−6 3.2×10−5 7.4×10−3
Red 1.2×103 0.4 7.3×10−4 2.2×10−6 1.6×10−4 1.8×10−1
CO3−2 10 Blue 3.5×103 0.8 8.3×10−4 1.3×10−6 2.9×10−5 1.1×10−2
Red 2.4×103 0.9 2.7×10−3 3.6×10−6 1.9×10−4 1.8×10−1
L1527 CO6−5 70 Blue 1.5×104 9.1 2.3×10−3 1.8×10−6 3.1×10−5 9.9×10−3
Red 1.1×104 6.5 2.5×10−3 2.7×10−6 1.1×10−4 7.5×10−2
CO3−2 70 Blue 3.2×104 20.6 1.0×10−2 3.5×10−6 6.1×10−5 2.0×10−2
Red 1.1×104 6.5 9.0×10−3 9.8×10−6 3.8×10−4 2.6×10−1
Ced110-IRS4 CO6−5 30 Blue 3.8×103 4.2 2.7×10−4 1.8×10−7 2.1×10−6 4.6×10−4
Red 3.8×103 4.7 2.5×10−4 1.5×10−7 4.1×10−6 2.0×10−3
BHR71 CO6−5 70 Blue 4.4×104 13.4 3.4×10−2 1.8×10−5 7.7×10−4 6.2×10−1
Red 4.0×104 8.5 6.9×10−2 5.8×10−5 7.7×10−4 3.3×10−1
IRAS15398 CO6−5 30 Blue 2.6×103 1.4 3.4×10−4 1.7×10−6 6.4×10−6 1.4×10−3
Red 2.6×103 1.2 2.7×10−4 1.5×10−6 2.6×10−5 2.0×10−2
CO3−2 30 Blue 3.2×103 1.8 4.4×10−4 1.8×10−6 9.2×10−6 2.5×10−3
Red 2.0×103 0.9 2.5×10−4 1.9×10−6 2.8×10−5 2.0×10−2
L483MM CO6−5 70 Blue 1.2×104 5.2 4.2×10−3 5.7×10−6 6.7×10−5 1.6×10−2
Red 1.0×104 4.4 3.4×10−3 5.4×10−6 2.1×10−4 1.5×10−1
CO3−2 70 Blue 1.4×104 6.2 7.0×10−3 8.0×10−6 7.7×10−5 1.6×10−2
Red 1.0×104 4.4 8.5×10−3 1.4×10−5 5.1×10−4 3.4×10−1
Ser-SMM1 CO6−5 50 Blue 3.4×104 8.4 1.6×10−2 8.2×10−6 1.5×10−4 5.7×10−2
Red 1.8×104 3.9 1.2×10−2 1.4×10−5 8.7×10−4 9.8×10−1
CO3−2 50 Blue 3.4×104 8.6 6.4×10−2 3.3×10−5 6.7×10−4 2.8×10−1
Red 1.8×104 3.9 3.3×10−2 3.7×10−5 2.3×10−3 2.7×100
Ser-SMM4 CO6−5 30 Blue 1.8×104 4.6 2.4×10−2 1.5×10−5 2.5×10−4 9.3×10−2
Red 1.8×104 7.3 2.8×10−2 1.1×10−5 5.9×10−4 5.8×10−1
CO3−2 30 Blue 1.8×104 4.6 1.6×10−1 9.9×10−5 2.0×10−3 8.3×10−1
Red 1.8×104 7.6 1.3×10−1 4.7×10−5 2.8×10−3 2.9×100
Ser-SMM3 CO6−5 50 Blue 4.6×103 1.0 6.9×10−3 3.1×10−5 6.0×10−4 2.6×10−1
Red 4.6×103 1.6 3.0×10−3 8.1×10−6 4.9×10−4 5.4×10−1
CO3−2 50 Blue 4.6×103 1.0 2.7×10−2 1.2×10−4 2.4×10−3 1.0×100
Red 4.6×103 1.6 1.1×10−2 3.0×10−5 1.8×10−3 1.9×100
B335 CO6−5 70 Blue 6.2×103 3.4 4.7×10−4 9.9×10−7 2.3×10−5 9.4×10−3
Red 8.8×103 4.8 1.3×10−3 1.9×10−6 9.0×10−5 7.6×10−2
CO3−2 70 Blue 1.0×104 5.3 3.7×10−3 4.9×10−6 1.3×10−4 6.2×10−2
Red 7.5×103 4.1 5.4×10−3 9.3×10−6 4.7×10−4 4.3×10−1
L723MM CO6−5 50 Blue 1.2×104 4.1 6.0×10−3 6.6×10−6 1.8×10−4 1.0×10−1
Red 1.2×104 3.8 7.5×10−3 8.5×10−6 5.5×10−4 6.3×10−1
CO3−2 50 Blue 1.8×104 6.0 3.0×10−2 2.2×10−5 6.5×10−4 3.7×10−1
Red 1.8×104 5.8 4.2×10−2 3.2×10−5 2.2×10−3 2.8×100
L1157 CO3−2 70 Blue 4.4×104 16.8 1.2×10−1 4.9×10−5 5.0×10−4 1.9×10−1
Red 5.2×104 14.1 1.5×10−1 7.3×10−5 3.2×10−3 3.1×100
Notes. (a) Outflow extents and outflow masses are not corrected for inclination. (b) Dynamical timescale. (c) Constant temperature of 75 K is
assumedforbothCO6−5andCO3−2calculations. (d)CorrectedforinclinationasexplainedinSect.3.2.(e)Massoutflowrate.(f)Outflowforce.
(g)Kineticluminosity.
A109,page5of29
A&A576,A109(2015)
Table3.OutflowpropertiesoftheredandblueoutflowlobesofClassIsources.
Source Trans. Inclination Lobe RCOa tdyna,b Moutflowa,c M˙d,e FCOd,f Lkind,g
[◦] [AU] [103yr] [M(cid:12)] [M(cid:12)yr−1] [M(cid:12)yr−1kms−1] [L(cid:12)]
L1489 CO6−5 50 Blue 3.5×103 1.2 4.0×10−5 1.5×10−7 1.8×10−6 3.2×10−4
Red 2.1×103 1.3 1.3×10−4 4.6×10−7 2.3×10−5 2.0×10−2
CO3−2 50 Blue 3.5×103 1.2 6.9×10−4 2.5×10−6 3.9×10−5 1.3×10−2
Red 2.1×103 1.3 7.1×10−4 2.5×10−6 1.2×10−4 1.1×10−1
L1551-IRS5 CO3−2 70 Blue 1.7×104 8.2 7.4×10−3 6.4×10−6 9.3×10−5 2.7×10−2
Red 1.7×104 6.7 9.6×10−3 1.0×10−5 4.2×10−4 3.1×10−1
TMR1 CO6−5 50 Blue 4.9×103 2.9 1.2×10−4 1.8×10−7 2.0×10−6 4.9×10−4
Red 3.5×103 4.5 2.4×10−4 2.3×10−7 8.0×10−6 4.8×10−3
CO3−2 50 Blue 4.9×103 3.0 2.6×10−4 3.8×10−7 5.1×10−6 1.4×10−3
Red 3.5×103 4.5 5.8×10−4 5.7×10−7 2.0×10−5 1.3×10−2
TMC1A CO6−5 50 Blue 5.6×103 1.4 2.3×10−4 7.2×10−7 1.3×10−5 7.6×10−3
Red 2.1×103 1.8 4.0×10−6 9.5×10−9 3.7×10−7 2.4×10−4
CO3−2 50 Blue 5.6×103 1.6 2.8×10−3 7.8×10−6 1.1×10−4 3.7×10−2
Red 1.7×103 1.5 1.4×10−4 4.1×10−7 1.8×10−5 1.4×10−2
TMC1 CO6−5 50 Blue 3.5×103 1.2 1.3×10−4 4.7×10−7 3.2×10−6 4.0×10−4
Red 4.9×103 1.6 3.8×10−4 1.1×10−6 5.0×10−5 4.4×10−2
CO3−2 50 Blue 3.5×103 1.2 5.6×10−4 2.0×10−6 2.7×10−5 7.9×10−3
Red 2.1×103 0.7 1.4×10−3 8.9×10−6 4.2×10−4 3.7×10−1
HH46-IRS CO6−5 50 Blue 1.1×104 9.9 2.6×10−3 1.2×10−6 1.2×10−5 2.9×10−3
Red 2.5×104 7.9 3.2×10−2 1.8×10−5 7.7×10−4 6.5×10−1
CO3−2 50 Blue 1.6×104 13.6 2.2×10−2 7.2×10−6 2.5×10−4 1.7×10−1
Red 2.5×104 7.9 2.2×10−2 1.2×10−5 8.1×10−4 9.3×10−1
DKCha CO6−5 10 Blue 1.8×103 1.6 1.8×10−4 1.3×10−7 6.6×10−7 7.3×10−5
Red 1.8×103 0.9 1.1×10−4 1.4×10−7 2.5×10−6 4.4×10−4
GSS30-IRS1 CO6−5 30 Blue 1.5×104 5.5 1.5×10−2 7.9×10−6 5.1×10−5 1.1×10−2
Red 1.5×104 4.9 8.9×10−3 5.1×10−6 2.0×10−4 1.6×10−1
CO3−2 30 Blue 1.5×104 5.5 2.1×10−2 1.1×10−5 6.0×10−5 8.8×10−3
Red 1.5×104 4.9 2.4×10−2 1.4×10−5 4.6×10−4 3.0×10−1
Elias29 CO6−5 30 Blue 7.5×103 3.1 6.4×10−4 5.7×10−7 4.4×10−6 1.2×10−3
Red 5.0×103 1.7 6.3×10−4 1.0×10−6 3.9×10−5 2.7×10−2
CO3−2 30 Blue 7.5×103 3.6 1.4×10−3 1.1×10−6 6.6×10−6 1.0×10−3
Red 7.5×103 3.3 1.8×10−3 1.5×10−6 5.7×10−5 3.9×10−2
Oph-IRS63 CO6−5 50 Blue 3.8×103 1.6 1.0×10−4 2.8×10−7 4.3×10−6 2.1×10−3
Red 3.8×103 4.2 8.6×10−5 9.0×10−8 2.1×10−6 8.3×10−4
CO3−2 50 Blue 8.8×103 3.7 7.0×10−4 8.4×10−7 5.6×10−6 1.5×10−3
Red 5.0×103 7.4 5.0×10−4 3.0×10−7 5.2×10−6 2.2×10−3
RNO91 CO6−5 50 Blue 3.1×103 1.0 2.5×10−4 1.1×10−6 2.9×10−5 2.1×10−2
Red 1.9×103 2.5 7.3×10−5 1.3×10−7 1.1×10−6 1.8×10−4
CO3−2 50 Blue 6.2×103 2.0 3.5×10−3 7.7×10−6 1.0×10−4 4.1×10−2
Red 1.9×103 2.5 2.3×10−4 4.0×10−7 2.3×10−6 2.6×10−4
Notes. (a) Outflow extents and outflow masses are not corrected for inclination. (b) Dynamical timescale. (c) Constant temperature of 75 K is
assumedforbothCO6−5andCO3−2calculations.(d)CorrectedforinclinationasexplainedinSect.3.2.(e)Massoutflowrate.(f)Outflowforce.
(g)Kineticluminosity.
2.4. 13COmaps and spectra (Figs. 2, 3, and Figs. A.1–A.2). The advantage of
the CO 6−5 maps is that they have higher spatial resolution by
The 13CO 6−5 and 3−2 transitions were mapped around
a factor of 2 than the CO 3−2 maps. On the other hand, the
the central ∼1(cid:48) × 1(cid:48) region, corresponding to typically CO3−2mapshavetheadvantageofhigherS/NthantheCO6−5
∼104 AU × 104 AU. The total integrated intensity is mea-
mapsbytypicallyafactorof4inmainbeamtemperature.
sured for all the sources and presented in Table C.1-26 of
Most sources show a clear blue-red bipolar structure. In
Yıldızetal.(2013) for the source positions. All maps are pre-
a few cases only one lobe is observed. Specific examples
sented as contour maps in Figs. A.3 and as spectral maps in
are TMC1A, which shows no red-shifted outflow lobe, and
Figs.A.5,A.6intheAppendix.
HH46, which has only a very small blue-shifted outflow
lobe. One explanation is that these sources are at the edge
3. Results of the cloud and that there is no cloud material to run into
(vanKempenetal.2009b).ForL723mm,NGC1333-IRAS2A
3.1. Outflowmorphology
and BHR71, two outflows are driven by two independent pro-
All sources show strong outflow activity in both CO transi- tostars (Lee et al. 2002; Parise et al. 2006; Codella et al.
tions, J = 6−5 and 3−2, as is evident from both the maps 2014) and both outflows are detected in our CO 3−2 maps.
A109,page6of29
U.A.Yıldızetal.:Mechanicalandradiativefeedback
100 40
30 L1527 30 Ced110IRS4 40 IRAS15398 L483mm
50 20 50 20 20 50
10 10
0 IRAS4A (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
−10
−50 IRAS4B −−3200 −50 −−2100 −20 −50
IRAS2A
−40 −30 −40
−100 −50
100 50 0 −50 −100 40 20 0 −20 −40 50 0 −50 30 20 10 0 −10−20−30 40 20 0 −20 −40 50 0 −50
80 40 40
4600 SMM1 50 SMM3 2300 B335 2400 L723mm 2400 L1489 2300 TMR1
20 0 (cid:120) 10 10
0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
−20 −50 −10 −20 −20 −10
−40 −20
−20
−60 −100 SMM4 −30 −40 −40 −30
−80 −40
80 40 0 −40 −80 50 0 −50 −100 40 30 20 10 0−10−20−30−40 40 20 0 −20 −40 40 20 0 −20 −40 30 20 10 0 −10−20−30
40 40 TMC1 2300 HH46 4600 GSS30IRS1 4600 2300
20 20 10 20 20 10
0 (cid:120)
0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
−10
−−4200 TMC1A −−4200 −−3200 −−4200 −−4200 Elias29 −−2100 OphIRS63
−40 −60 −60 −30
40 20 0 −20 −40 40 20 0 −20 −40 30 20 10 0 −10−20−30−40 60 40 20 0 −20−40−60 60 40 20 0 −20−40−60 30 20 10 0 −10−20−30
60 200
40 RNO91 150 20 DKCha
Arcsec] 200 (cid:120) 105000 BHR71 (cid:120) 100 (cid:120)
∆δ[ −20 −−10500 −10
−40 −150
−20
−60 −200
60 40 20 0 −20−40−60 200 100 0 −100 −200 20 10 0 −10 −20
∆α[Arcsec]
Fig.2.Overviewoftheoutflowstracedbythe12CO6−5observationswiththeAPEX-CHAMP+instrument.ContourlevelsaregiveninTableA.1
andthesourceislocatedat(0,0)ineachmap,withtheexceptionofthemapsofNGC1333-IRAS4AandIRAS4B,andSer-SMM3andSer-
SMM4,whicharelocatedinthesamemapsandcenteredonNGC1333-IRAS4AandSer-SMM3,respectively.Thecircleineachplotcorresponds
toaregionof5000AUradiusatthedistanceofeachsource.VelocityrangesoverwhichtheintegrationwasdoneareprovidedinTableA.1.
In CO 6−5, only one outflow shows up toward L723 mm and 3.2. Outflowparameters
NGC 1333-IRAS 2A, whereas both outflows are seen toward
In the following, different outflow parameters, including mass,
BHR71.
forceandluminosity,aremeasured.Theseparametershavepre-
Visual inspection shows that the Class 0 outflows are more
viously been determined from lower-J lines for several young
collimatedthantheirClassIcounterpartsasexpected(e.g.,Arce
stellar objects (e.g., Cabrit & Bertout 1992; Bontemps et al.
et al. 2007). The length of the outflows can be quantified for
1996;Hogerheijdeetal.1998;Hatchelletal.2007;Curtisetal.
most of the sources. R is defined as the total outflow extent
CO
2010;vanderMareletal.2013;Dunhametal.2014)andmore
assuming that the outflows are fully covered in the map. R
CO recentlyfromCO6−5byvanKempenetal.(2009b)andYıldız
is measured separately for the blue and red outflow lobes as
the projected size, with sometimes significantly different val- etal.(2012)forasmallsubsetofthesourcespresentedhere.All
resultsarelistedinTables2and3.Uncertaintiesinthemethods
ues.R asmeasuredfromCO6−5isappliedtoCO3−2inthe
CO
arediscussedextensivelyinvanderMareletal.(2013).
cases where the CO 6−5 maps are larger than their 3−2 coun-
terparts. Toward some sources, e.g., DK Cha and NGC 1333-
IRAS4B,theblueandredoutflowlobesoverlap,likelybecause
3.2.1. Outflowmass
the outflows are observed nearly pole on. In other cases the
outflow lobes cannot be properly isolated from nearby neigh- One of the most basic outflow parameters is the mass. The
boring outflow lobes. Such a confusion is most pronounced inferred mass depends on three assumptions: the line opacity,
in Ophiuchus (e.g., GSS30-IRS1). In those cases, R could the distribution of level populations, and the CO abundance
CO
not be properly estimated and the estimated value is a lower with respect to H . In the following, we assume that the line
2
limit. Figure 4 shows a histogram of total R for Class 0 and wingsareopticallythin,ashasbeendemonstratedobservation-
CO
Isources.Class0sourcesshowanearlyflatdistributionacross ally for CO 6−5 for a few sources with massive outflows (e.g.,
themeasuredrangeofextents,whereasfewClassIsourcesshow NGC 1333-IRAS 4A, Yıldız et al. 2012). CO 3−2 emission is
largeoutflows(L1551isanotableexception).InFig.5,R is also assumed optically thin in the following, although that as-
CO
plottedagainstR ,theradiusofthemodeledenvelopewithin sumption may not be fully valid (see discussion below). The
10K
a 10 K radius. The outflowing gas typically extends to much level populations are assumed to follow a Boltzmann distribu-
greater distances than the surrounding envelope and thus influ- tionwithasingletemperature,T .Finally,theabundanceratio
ex
encesthesurroundingcloudmaterialdirectly. istakenas[H /12CO]=1.2×104,asinYıldızetal.(2012).
2
A109,page7of29
A&A576,A109(2015)
100 60 150
IRAS2A L1527 30 Ced110IRS4 40 IRAS15398 L483mm
40 100
50 20 50 1200 20 50
IRAS4A
0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
−20 −50 −10
−50 IRAS4B −40 −20 −20 −50
−100
−60 −30 −40
−100 −150
100 50 0 −50 −100 60 40 20 0 −20−40−60150100 50 0 −50−100−150 30 20 10 0 −10−20−30 40 20 0 −20 −40 50 0 −50
80 100 40 40
60 SMM1 30 B335 40 L723mm 40 L1489 30 TMR1
40 50 SMM3 20 20 20 20
20 10
10
0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
0 (cid:120)
−20 −10
−40 −50 −20 −20 −20 −10
−60 SMM4 −30 −40 −40 −20
−80 −100 −40 −30
80 40 0 −40 −80 50 0 −50 −100 40 20 0 −20 −40 40 20 0 −20 −40 40 20 0 −20 −40 40 30 20 10 0 −10−20−30
30 60 60
40 TMC1A 40 TMC1 20 HH46 40 GSS30IRS1 40 40 OphIRS63
20 20 10 20 20 20
0 (cid:120)
0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120) 0 (cid:120)
−10
−20 −20 −20 −20 −20 −20
−30 −40 −40 Elias29
−40 −40 −40
−40 −60 −60
40 20 0 −20 −40 40 20 0 −20 −40 30 20 10 0 −10−20−30−40 60 40 20 0 −20−40−60 60 40 20 0 −20−40−60 40 20 0 −20 −40
60 150 200
150
40 RNO91 100 150 L1448mm 100 L1551IRS5
Arcsec] 200 (cid:120) 500 L1157 (cid:120) 150000 (cid:120) 500 (cid:120)
∆δ[ −20 −50 −50 −50
−40 −100 −100 −100
−60 −150 −150 −150
60 40 20 0 −20−40−60 100 0 −100 100 0 −100 100 0 −100
∆α[Arcsec]
Fig.3.Overviewoftheentiresetofoutflowstracedbythe12CO3−2observationswiththeJCMTandAPEX.ContourlevelsaregiveninTableA.1
andthesourceislocatedat(0,0)ineachmap,withtheexceptionofthemapsofNGC1333-IRAS4AandNGC1333-IRAS4B,andSer-SMM3
andSer-SMM4,whicharelocatedinthesamemapsandcenteredonNGC1333-IRAS4AandSer-SMM3,respectively.Thecircleineachplot
correspondstoaregionof5000AUradiusatthedistanceofeachsource.Velocityrangesoverwhichtheintegrationwasdoneareprovidedin
TableA.1.
The upper level column density per statistical weight in a 7
singlepixel(4(cid:48).(cid:48)5×4(cid:48).(cid:48)5forCO6−5,7(cid:48).(cid:48)5×7(cid:48).(cid:48)5forCO3−2)is Class0
6
calculatedas ClassI
(cid:82) s5
Nu = βν2 TmbdV· (1) rce
g A g u4
u ul u o
s
Theconstantβis8πk/hc3=1937cm−2 (GHz2 Kkm)−1.There- of3
mainingparametersareforthespecifictransition,whereνisthe o.
frequency,A istheEinsteinAcoefficientandg =2J+1. N2
ul u
ThetotalCOcolumndensityinapixel,N ,is
total 1
N
Ntotal = guQ(T)eEu/kTex; (2) 03.5 4 4.5 5
u log(R [AU])
CO(6 5)
Q(T) is the partition function corresponding to a specific exci- −
tation temperature, Tex, which is assumed to be 75 K for both Fig.4. Histogram of total RCO (blue- and red-shifted outflows com-
CO 3−2 and CO 6−5 observations (van Kempen et al. 2009b; bined) is shown for Class 0 (red) and Class I (blue) sources. (RCO is
notcorrectedforinclination.)
Yıldız et al. 2012, 2013). Changing T by ±30 K changes the
ex
inferredcolumndensitiesbyonly10–20%.
Themassiscalculatedas
(cid:34) (cid:35) atom. A is the surface area of one pixel j. The sum is over all
H (cid:88)
M =µ m A 2 N (3) outflowpixels.
outflow H2 H 12CO total,j The mass may be underestimated if the 12CO line emission
j
is optically thick. 13CO data exist toward most outflows (see
where the factor µ = 2.8 includes the contribution of helium above) but the S/N of these data is typically too low to prop-
(Kauffmann et al.H22008) and m is the mass of the hydrogen erly measure the opacity in the line wings, except for at the
H
A109,page8of29
U.A.Yıldızetal.:Mechanicalandradiativefeedback
105 CCllaassss0I FCO(32)−100 CCllaassss 0I MCO(32)−100
AU] /(65)− /(65)−
[ O O
CO FC10-1 MC10-1
R 104
10-5 10-4 10-3 10-4 10-3 10-2 10-1
FCO(6−5)[M⊙kms−1yr−1] MCO(6−5)[M⊙]
Fig.6.Outflowforces(left)andoutflowmasses(right),calculatedfrom
103 104 CO 6−5 and 3−2 emission are compared for Class 0 and I sources.
Greenlinesareforaratioof1.
R [AU]
10K
Fig.5.R isplottedagainstR ,theradiusofthemodeledenvelope are then summed and the sum is over all pixels j in the map
CO 10K
within 10 K radius. The black line is for R = R , showing that with outflow emission. The outflow force is calculated for the
CO 10K
almostallsourcesfollowRCO>R10KandthatRCOislargerforClass0 red- and blue-shifted outflow lobes separately. This method is
thanClassIsources. formulatedas:
V (cid:80) (cid:104)(cid:82) M(V(cid:48))V(cid:48)dV(cid:48)(cid:105)
F =c max j j, (4)
source position where the signal naturally is the strongest. The CO i RCO
13CO line wings do not extend beyond the inner velocity lim- where c is the inclination correction (Table 1), and R is
i CO
its. NGC1333-IRAS4A is one of the few sources where line the projected size of the red- or blue-shifted outflow lobe. The
wings are detected in 13CO at the outflow positions (Fig. 11 in outflow force is computed separately from the CO 3−2 and
Yıldızetal.2012),anditisclearthatatthevelocityrangescon- 6−5mapsofthesamesource(seeTables2and3).
sidered here, the line emission is optically thin (τ < 1); the Thedifferenceinoutflowforcebetweentheredandblueout-
same is true for the outflows studied by van der Marel et al. flowlobesrangesfrom∼1uptoafactorof10.Forsourceswith
(2013) in CO 3−2 emission in Ophiuchus (their Fig. 4), where alowoutflowforcesuchasOphIRS63(<10−5 M yr−1kms−1)
(cid:12)
deep pointed observations of 13CO 3−2 were required to mea- this is a result of differences in the inferred outflow mass per
suretheopacity.Thatstudyconcludedthattheopacitydoesnot lobe,which,inthesespecificcases,isprimarilyaresultoflow
playasignificantrolewhendeterminingtheoutflowparameters. S/N.Inthesecases,theoveralluncertaintyontheoutflowforce
Similarly, Dunham et al. (2014) conclude that CO 3−2 may be is high, up to a factor of 10. In other cases, such as HH46 as
optically thick at velocities less than 2 km s−1 offset from the mentionedabove,thereisarealasymmetrybetweenthediffer-
source velocity, velocities which are excluded from our analy- entlobeswhichiscausedbyadifferenceinthesurroundingen-
sisbecauseoftheriskofcloudcontamination.Potentiallymore vironment.Inthefollowing,onlythesumoftheoutflowforces
problematic is the missing mass at low velocities. The missing ofbothlobesasmeasuredfromeachoutflowlobewillbeused.
massismovingclosetothesystemicvelocityanditisnotpossi- Figure 6 shows how the outflow forces and outflow masses
bletodisentanglethismassfromthesurroundingcloudmaterial, calculated from CO 3−2 and 6−5 differ. For strong outflows,
an effect which may introduce a typical uncertainty of a factor there is a factor of a few difference in the two calculations,
of2−3(Downes&Cabrit2007).However,thecorrectionfactors withdifferencesuptoanorderofmagnitudefortheweakerout-
derived by the same authors and implemented here account for flow sources. Although the CO 6−5 emission suffers less from
that missing mass. 12CO 6−5 emission will be less affected by opacity effects and so recovers more emission/mass at lower
this confusion than the 12CO 3−2 emission, simply because of velocities, this effect is overwhelmed by the lower S/N of the
thedifferentexcitationconditionsrequired. CO 6−5 emission. The fact that the masses and outflow forces
derived from the 6−5 data are systematically lower than those
fromthe3−2dataislikelyduetothesameeffect(vanderMarel
3.2.2. Outflowforce
et al. 2013). Moreover, if CO 6−5 traces slightly warmer gas
One of the most important outflow parameters is the outflow than CO 3−2 (Yıldız et al. 2013) then the mass traced by this
force, F . The best method for computing the outflow force linewillbelowerthanthattracedbyCO3−2.Botheffectswork
CO
isstilldebatedandtheresultssufferfromill-constrainedobser- tosystematicallylowertheCO6−5masses,whichinturnleads
vational parameters, such as inclination, i. van der Marel et al. toloweroutflowforces.
(2013)compare sevendifferentmethods proposedinthe litera- Figure 7 displays F from CO 6−5 for Class 0 and
CO
ture to calculate outflow forces. The “separation method” (see Class I sources separately. Generally, Class 0 sources have
below)intheirpaperisfoundtobethepreferredmethod,which higher outflow forces and are thus more powerful than their
islessaffectedbytheobservationalbiases.Themethodcanalso ClassIcounterparts(Bontempsetal.1996).TheClassIsource
be applied to low spatial resolution observations or incomplete withanexceptionallyhighoutflowforceisHH46.
maps.Uncertaintiesareestimatedtobeafactorof2−3.
In the following, the outflow force is calculated separately
3.3. Otheroutflowparameters
for the blue- and red-shifted lobes, only including emission
abovethe3σlevel.Themassiscalculatedforeachchannelsep- Other outflow parameters that characterize the outflow activity
arately and multiplied by the central velocity of that particular are the dynamical age, t , mass outflow rate, M˙ , and ki-
dyn outflow
channel.TheintegralrunsovervelocitiesfromV toV .They neticluminosity,L .
in out kin
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A&A576,A109(2015)
5
3.4. Correlations
Class0
ClassI
Most previous studies of the outflow force were done using
4
CO 1−0, 2−1, or 3−2 (e.g., Cabrit & Bertout 1992; Bontemps
ces3 et al. 1996; Hogerheijde et al. 1998; Hatchell et al. 2007;
ur vanKempenetal.2009c;Dunhametal.2014).Theopacityde-
o
s creases with excitation, as suggested by, e.g., the observations
o.of2 reportedinDunhametal.(2014),butwithouttargeted,deepsur-
N
veys of 13CO, it is difficult to quantify how much the CO col-
1 umndensityisunderestimated.Furthermore,cloudorenvelope
emission may contribute to the emission at the lowest outflow
velocities at which the bulk of the mass is flowing. With our
0
−6.0 −5.5 −5.0 −4.5 −4.0 −3.5 −3.0 −2.5
log(F [M kms−1yr−1]) CO 6−5 observations, some of the above-mentioned issues can
CO(6−5) ⊙ be avoided, or their effects can be lessened. Thus, it is impor-
Fig.7.HistogramsofcalculatedtotaloutflowforceF areshownfor tant to revisit the correlations of outflow force with bolometric
CO
Class0(red)andClassI(blue)sources. luminosityandenvelopemassusingthesenewmeasurements.
In Fig. 8, F is plotted against L , M , and M ,
CO bol env outflow
where the F and M values are taken from the
Table4.Medianvaluesoftheoutflowparameters. CO outflow
CO 6−5 data.The best fitbetween F and L is shownwith
CO bol
thegreenlinecorrespondingto
M M˙ F L
outflow CO kin
[M(cid:12)] [M(cid:12)yr−1] [M(cid:12)kms−1yr−1] [L(cid:12)] log(FCO)=−(4.71±0.02)+(1.13±0.37)log(Lbol). (8)
CO6−5
Outflows from Class 0 and Class I sources are well-separated;
Class0 9.8×10−3 1.5×10−5 6.9×10−4 6.0×10−1
Class 0 sources show more powerful outflows compared to
ClassI 3.4×10−4 8.4×10−6 2.8×10−5 1.2×10−1
Class I sources of similar luminosity. The Pearson correlation
Total 2.2×10−3 1.0×10−5 1.4×10−4 1.9×10−1 coefficientsarer = 0.62,0.83,and0.64forallsources,Class0,
CO3−2 and Class I sources, corresponding to confidences of 2.9, 2.9,
Class0 7.2×10−2 5.4×10−5 2.9×10−3 2.9×100 and1.9σ,respectively.
ClassI 3.1×10−3 3.0×10−5 1.4×10−4 1.4×100 ThebestfitbetweenF andM isdescribedas
CO env
Total 1.7×10−2 3.3×10−5 5.2×10−4 1.9×100
log(F )=−(3.95±0.37)+(1.24±0.21)log(M ) (9)
CO env
and Pearson correlation coefficients are r = 0.81, 0.82, and
Assuming that the outflow moves with a constant velocity 0.56 (3.8, 2.8 and 1.7σ) for all sources, Class 0, and Class I,
overtheextentoftheoutflow,thedynamicalageisdetermined respectively. Since early Class 0 sources have higher accretion
as rates their outflow force is much higher than for the Class I
sources (see, e.g., Bontemps et al. 1996, for a full discussion).
t = RCO· (5) Finally,asexpected,astrongcorrelationisfoundbetween FCO
dyn Vmax and Moutflow with a Pearson correlation coefficient of r = 0.92
forallsources(4.3σ),notsurprisinglysince F isnearlypro-
CO
Thisageisalowerlimitontheageoftheprotostar(Curtisetal. portionaltoMoutflow.Thebestfitisdescribedas
2010)iftheoutflowingmaterialisdecelerated,e.g.,throughin-
log(F )=−(1.71±0.02)+(0.88±0.62)log(M ). (10)
teractions with the ambient surrounding material. On the other CO CO
hand,theoutflowmaybesignificantlyyoungersincetheveloc-
Previously, Bontemps et al. (1996) surveyed 45 sources using
itiesofthecentraljetthatdrivesthemolecularoutflowaretypi-
CO2–1observationswithsmall-scalemaps.InFig.8,theblue
callyhigherthan100kms−1andwhatisobservedinthesecolder and green dashed lines of F vs. L and M show the fit
CO bol env
low-J CO lines may just be the outer shell which is currently
results from their Figs. 5 and 6 (Bontemps et al. 1996). Since
undergoing acceleration, not deceleration. See, e.g., Downes &
their number of Class I sources is higher than Class 0 sources,
Cabrit(2007)foramorecompletediscussion.Theoutflowmass thefitwasonlydoneforClassIsourcesinF vs.L .InFig.8,
CO bol
lossrateiscomputedaccordingto
thebluesolidlineonlyshowsthefitforClassIsourcesandthe
correlationisdescribedby,
M
M˙outflow = toutflow· (6) log(FCO)=−(5.14±0.29)+(0.98±0.55)log(Lbol). (11)
dyn
In the F vs. M plot, the fits are shown as green lines
CO env
Thekineticluminosityisgivenby
for the entire sample. The Bontemps et al. (1996) sample is
weighted toward lower luminosities (<10 L ), where our F
bol CO
L = 1F V · (7) measurements from the CO 6−5 data follow their relation for
kin 2 CO max Class I sources obtained from 2–1 data, but with a shift to a
factor of a few higher values of F . However, given the scat-
CO
OutflowparametersofF ,M˙,andL withinclinationcorrec- ter in the results for low L sources, this difference is hardly
CO kin bol
tions are presented in Tables 2 and 3. However, M , R , significant.
outflow CO
t , and V are not corrected for inclination, since they are Examiningthesameoutflowparametersmeasuredusingthe
dyn max
measuredquantities.Themedianvaluesoftheresultsaregiven CO 3−2 transition, and their correlation with the same outflow
inTable4. parameters,asimilarpicturearises(Fig.A.4).However,forthe
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