Star and Planet Formation Neal Evans The University of Texas at Austin.

Star and Planet FormationStar and Planet Formation

Neal EvansNeal Evans

The University of Texas at AustinThe University of Texas at Austin

Antennae: galaxy Antennae: galaxy merger. merger. Visible (HST) Visible (HST)

showsshows copious star copious star formation, but formation, but misses the main misses the main show. Most intense show. Most intense star formation in star formation in obscured region obscured region traced by CO.traced by CO.

Whitmore et al. (1999)Whitmore et al. (1999)Wilson et al. (2000)Wilson et al. (2000)

CO(1-0): OVRO

Star Formation in GalaxiesStar Formation in Galaxies

New Views are ComingNew Views are Coming

The Archive is open:The Archive is open:http://ssc.spitzer.caltech.edu/http://ssc.spitzer.caltech.edu/

Star Formation/Galaxy Star Formation/Galaxy FormationFormation

Key part of galaxy formationKey part of galaxy formation Properties of molecular clouds in other Properties of molecular clouds in other

galaxiesgalaxies Connect studies of distant galaxies to MWConnect studies of distant galaxies to MW

• Collective, clustered, massive SFCollective, clustered, massive SF• Molecular line probes of high densityMolecular line probes of high density• Dust continuum emissionDust continuum emission

Insights into high-z starburstsInsights into high-z starbursts

Star Formation traced by HCNStar Formation traced by HCN

4 6 8 104

6

8

10

12

Slope is close to 1

Is this correlation still correct for smaller and larger scale ??

CO 1-0 on galaxiesSolomon et al. 1997

HCN 1-0 on galaxiesGao & Solomon, 2003

log[L

IR

] (LSUN

)

log[L'Molecule

] (K km/s pc-2)

Relation between LRelation between LIRIR and and

LLCOCO becomes non-linear becomes non-linear

for very high Lfor very high LIRIR..

Stays linear for LStays linear for LHCNHCN..

J. Wu et al. Data from Gao J. Wu et al. Data from Gao and Solomon 2003.and Solomon 2003.

Relation Same for Cores in MWRelation Same for Cores in MW

J Wu et al. In prep.J Wu et al. In prep.

LLHCNHCN or L or LCSCS for cores in for cores in

MW also linear with LMW also linear with LIRIR..

(For L(For LIRIR > 10 > 1044 L Lsunsun) )

These points are for These points are for HCN 3-2 and CS 5-4.HCN 3-2 and CS 5-4.

Same line as HCN 3-2 Same line as HCN 3-2 in galaxies. Parallel to in galaxies. Parallel to HCN 1-0 relation for HCN 1-0 relation for starbursts.starbursts.

Checking HCN 1-0 in Checking HCN 1-0 in MW.MW.-4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12

0

5

10

15

?

?

APM08279

Galactic CO clouds y=0.96X+1.19(Mooney & Solomon,1988)

Cloverleaf

y=1.31X-1.19

y=0.97X+3.10

y=0.98X+3.81

Gao galaxy sample HCN1-0 Solomon galaxy sample CO 1-0 Paglione Galaxy sample HCN 3-2 (Stars) High Z CO 1-0 galaxies Galactic massive cores HCN 3-2 Galactic massive cores CS 5-4

log[L

IR

] (LSUN

)

log[L'Molecule

] (K km/s pc-2)

What probes can we use?What probes can we use?

DustDust Extinction of background starsExtinction of background stars

• Probe NProbe Ndd(b), B(b), Bperpperp

Emission in infrared to millimeterEmission in infrared to millimeter• Probe TProbe Tdd( r), N( r), Ndd(b), B(b), Bperpperp

Problem: need to know dust propertiesProblem: need to know dust properties MoleculesMolecules

Emission or absorption (infrared to radio)Emission or absorption (infrared to radio)• Probe TProbe TKK( r), n( r), v( r), B( r), n( r), v( r), Bparpar

Problem: chemistryProblem: chemistry

Studies of High Mass RegionsStudies of High Mass Regions

Many Detailed Studies Many Detailed Studies Ho, Zhang, …Ho, Zhang, …

SurveysSurveys van der Tak et al. (2000) (14 sources)van der Tak et al. (2000) (14 sources) Beuther et al. (2002) (69 sources)Beuther et al. (2002) (69 sources) Survey of water masers for CSSurvey of water masers for CS

• CS survey Plume et al. (1991, 1997)CS survey Plume et al. (1991, 1997) Dense: <log n> = 5.9Dense: <log n> = 5.9

• Maps of 51 in 350 micron dust emissionMaps of 51 in 350 micron dust emission Mueller et al. 2002Mueller et al. 2002

• Maps of 63 in CS J = 5–4 emissionMaps of 63 in CS J = 5–4 emission Shirley et al. 2003Shirley et al. 2003

Luminosity versus MassLuminosity versus Mass

Mueller et al. (2002)Mueller et al. (2002)

Log Luminosity vs. Log MLog Luminosity vs. Log M

red line: masses of densered line: masses of densecores from dustcores from dustLog L = 1.9 + log MLog L = 1.9 + log M

blue line: masses of GMCsblue line: masses of GMCsfrom COfrom COLog L = 0.6 + log MLog L = 0.6 + log M

L/M much higher for dense L/M much higher for dense cores than for whole cores than for whole GMCs.GMCs.

Linewidth versus SizeLinewidth versus Size

Shirley et al. 2003Shirley et al. 2003

Correlation is weak. Correlation is weak.

Linewidths are 4-5 Linewidths are 4-5 times larger than in times larger than in samples of lower samples of lower mass cores.mass cores.

Massive clusters form Massive clusters form in regions of high in regions of high turbulence, pressure.turbulence, pressure.

Cumulative Mass FunctionCumulative Mass Function

Shirley et al. 2003Shirley et al. 2003

Incomplete below 10Incomplete below 1033 M Msunsun..

Fit to higher mass bins gives slope Fit to higher mass bins gives slope of about –0.93. of about –0.93. Steeper than that of CO clouds or Steeper than that of CO clouds or clumps (–0.5 on this plot).clumps (–0.5 on this plot).Similar to that of clusters, Similar to that of clusters, associations (Massey et al. 1995) associations (Massey et al. 1995) in our Galaxy and in Antennae in our Galaxy and in Antennae (Fall et al. 2004).(Fall et al. 2004).

Massive Cores: Gross Massive Cores: Gross PropertiesProperties

Massive, Dense, TurbulentMassive, Dense, Turbulent Mass distribution closer to clusters, stars than GMCMass distribution closer to clusters, stars than GMC Much more turbulent than low mass coresMuch more turbulent than low mass cores

A model for starbursts?A model for starbursts? Luminosity correlates well with core massLuminosity correlates well with core mass Less scatter than for GMCs as a wholeLess scatter than for GMCs as a whole L/M much higher than for GMCs as a wholeL/M much higher than for GMCs as a whole L/ML/Mdustdust ~ 1.4 x 10 ~ 1.4 x 1044 L Lsunsun/M/Msunsun ~ high-z starbursts ~ high-z starbursts L/L(HCN) similar to starburstsL/L(HCN) similar to starbursts Starburst: all gas like dense cores?Starburst: all gas like dense cores?

Hints of DynamicsHints of Dynamics

J. Wu et al. (2003)J. Wu et al. (2003)

A significant fraction of the massive core A significant fraction of the massive core sample show self-reversed, blue-skewed sample show self-reversed, blue-skewed line profiles in lines of HCN 3-2. line profiles in lines of HCN 3-2. Of 18 double-peaked profiles, 11 are blue, 3 Of 18 double-peaked profiles, 11 are blue, 3 are red.are red.

Suggests inflow motions of overall core.Suggests inflow motions of overall core.

VVinin ~ 1 to 4 km/s over radii of 0.3 to 1.5 pc. ~ 1 to 4 km/s over radii of 0.3 to 1.5 pc.

Open Questions for ALMAOpen Questions for ALMA

Studies of gas, dust, high n tracers in galaxiesStudies of gas, dust, high n tracers in galaxies Detailed structure of massive coresDetailed structure of massive cores

Can we separate into fragments/clusters?Can we separate into fragments/clusters?• Simulations predicting propertiesSimulations predicting properties• Understand IMF?Understand IMF?• See SMA early results as preview for ALMASee SMA early results as preview for ALMA

Can we study dynamics?Can we study dynamics?• Test inward motion hints in single-dish spectraTest inward motion hints in single-dish spectra• Separate dynamics of fragmentsSeparate dynamics of fragments

Evolution of dust, ice, gas-phase chemistryEvolution of dust, ice, gas-phase chemistry• Combine ALMA with Spitzer, SOFIA, Herschel, …Combine ALMA with Spitzer, SOFIA, Herschel, …

What do we need?What do we need?

High resolutionHigh resolution High dynamic range, image fidelityHigh dynamic range, image fidelity

Bright, but complex, sourcesBright, but complex, sources Flexible correlatorFlexible correlator

Very rich spectrum, need many diagnosticsVery rich spectrum, need many diagnostics Full complement of receiversFull complement of receivers For exgal clouds, excellent sensitivityFor exgal clouds, excellent sensitivity

Low Mass vs. High MassLow Mass vs. High Mass

Low Mass star formationLow Mass star formation ““Isolated” (time to form < time to interact)Isolated” (time to form < time to interact) Low turbulence (less than thermal support)Low turbulence (less than thermal support) Nearby (~ 100 pc)Nearby (~ 100 pc)

High Mass star formationHigh Mass star formation ““Clustered” Clustered” Time to form may exceed time to interactTime to form may exceed time to interact Turbulence >> thermalTurbulence >> thermal More distant (>400 pc)More distant (>400 pc)

High vs. Low Early ConditionsHigh vs. Low Early ConditionsPropertyProperty LowLow HighHigh

pp ~1.8~1.8 ~1.8~1.8

nnff (median) (median) 2 x 102 x 1055 1.5 x 101.5 x 1077

LinewidthLinewidth 0.370.37 5.85.8

n( r) = nn( r) = nff (r/r (r/rff))–p –p ; r; rff = 1000 AU = 1000 AU

Even “Isolated” SF ClustersEven “Isolated” SF Clusters

Myers 1987Myers 1987

Taurus Molecular CloudTaurus Molecular CloudPrototypical region of Prototypical region of ““Isolated” star formationIsolated” star formation

But Not Nearly as MuchBut Not Nearly as Much

1 pc1 pcOrion Nebula ClusterOrion Nebula Cluster>1000 stars>1000 stars2MASS image2MASS image

Taurus Cloud at same scaleTaurus Cloud at same scale4 dense cores, 4 obscured stars4 dense cores, 4 obscured stars~15 T Tauri stars~15 T Tauri stars

The Basic FeaturesThe Basic Features

T. GreeneT. Greene

EnvelopeEnvelopeDiskDiskProtostarProtostarJet/wind/outflowJet/wind/outflow

Studies of the EnvelopeStudies of the Envelope

All quantities vary along line of sightAll quantities vary along line of sight Dust temperature, TDust temperature, Tdd( r)( r)

• Heating from outside, later insideHeating from outside, later inside

Gas temperature, TGas temperature, TKK( r)( r)• Gas-dust collisions, CRs, PE heatingGas-dust collisions, CRs, PE heating

Density, n(r), predicted to varyDensity, n(r), predicted to vary Velocity, v(r), connected to densityVelocity, v(r), connected to density Abundance, X(r), varies Abundance, X(r), varies

• Photodissociation, freeze-out, desorptionPhotodissociation, freeze-out, desorption

nd(r), Lκν

Physical Model( ), ( )n r v r

Physical Model( ), ( )n r v r

TD( )r SimulateObservations

Sν(λ)( )I b

ObservationsObservations

Dust

( ), n r TK( )r( )v r

( )X r SimulateObs. T A ( , )v b

Gas

Chemistry

TD( ) r toTK( )r

MonteCarlo nJ( )r

Gas todust

Combined Modeling of Dust and Gas

Iterate

RadiativeTransfer

An Evolutionary ModelAn Evolutionary Model

A physical model from theoryA physical model from theory Sequence of Bonnor-Ebert spheres of increasing nSequence of Bonnor-Ebert spheres of increasing ncc

e.g., Shu (1977) “Inside-out collapse”e.g., Shu (1977) “Inside-out collapse”

Calculate luminosity of central star+diskCalculate luminosity of central star+disk Dust temperature through envelopeDust temperature through envelope Gas temperatureGas temperature Chemical abundances Chemical abundances

Follow gas as it falls, using evolving conditionsFollow gas as it falls, using evolving conditions

Line Profiles including all effectsLine Profiles including all effects

Theory gives n(r,t), v(r,t)Theory gives n(r,t), v(r,t)

C. YoungC. Young

QuickTime™ and aGIF decompressor

are needed to see this picture.

t<0: Series of Bonnor-Ebert spherest<0: Series of Bonnor-Ebert spherest>0: Inside-out collapse model (Shu 1977)t>0: Inside-out collapse model (Shu 1977)

L(t) from Accretion, L(t) from Accretion, ContractionContraction

L(t) calculated.L(t) calculated.First accretion.First accretion.First onto large (5 AU) surfaceFirst onto large (5 AU) surface(first hydrostatic core). (first hydrostatic core). Then onto PMS star with Then onto PMS star with R = 3 RR = 3 Rsunsun, after 20,000 to , after 20,000 to

50,000 yr. And onto disk. 50,000 yr. And onto disk. Prescriptions from Adams and Prescriptions from Adams and Shu.Shu.Contraction luminosity and Contraction luminosity and deuterium burning dominates deuterium burning dominates after t ~100,000 yr.after t ~100,000 yr.

C. Young and Evans, in prep.C. Young and Evans, in prep.

Evolution of Dust TracersEvolution of Dust Tracers



C. Young and Evans, in prep.C. Young and Evans, in prep.

Assumes distance of 140 pc and typical telescope properties.Assumes distance of 140 pc and typical telescope properties.

Calculate Gas TemperatureCalculate Gas Temperature

C. Young andC. Young andJ. Lee et al.J. Lee et al.

Use gas energetics code (Doty) with gas-dust collisions, cosmic rays, photoelectric Use gas energetics code (Doty) with gas-dust collisions, cosmic rays, photoelectric heating, gas cooling. Calculate Theating, gas cooling. Calculate TKK( r, t).( r, t).



Calculate AbundancesCalculate Abundances

J. Lee et al. In prepJ. Lee et al. In prep

Chemical code by E. BerginChemical code by E. Bergin198 time steps of varying 198 time steps of varying length, depending on need.length, depending on need.Medium sized network with Medium sized network with 80 species, 800 reactions. 80 species, 800 reactions. Follows 512 gas parcels.Follows 512 gas parcels.

Includes freeze-out onto Includes freeze-out onto grains and desorption due grains and desorption due to thermal, CR, photo to thermal, CR, photo effects. No reactions on effects. No reactions on grains. Assume binding grains. Assume binding energy on silicates for this energy on silicates for this case.case.



Calculate Line ProfilesCalculate Line Profiles

J. Lee et al. In prep

Line profiles calculated from Line profiles calculated from Monte Carlo plus virtual Monte Carlo plus virtual telescope codes. Includes telescope codes. Includes collisional excitation, trapping.collisional excitation, trapping.Variations in density, Variations in density, temperature, abundance, temperature, abundance, velocity are included.velocity are included.

Assumes distance of 140 pc Assumes distance of 140 pc and typical telescope and typical telescope properties.properties.




A Closer LookA Closer Look


Lines of HCN (J = 1–0).Lines of HCN (J = 1–0).Shown for four times. Shown for four times. Top plot with 50” resolution.Top plot with 50” resolution.Bottom plot with 5” resolution.Bottom plot with 5” resolution.

ALMA will probe the desorption ALMA will probe the desorption wave.wave.

Evidence for InfallEvidence for Infall

Good evidence in a few.Good evidence in a few.(e.g., Zhou et al. 1993)(e.g., Zhou et al. 1993)

Surveys indicate infall is Surveys indicate infall is common at early stages.common at early stages.Gregersen et al. 1997, 2000Gregersen et al. 1997, 2000Mardones et al. 1997Mardones et al. 1997

Observing Infall with ALMAObserving Infall with ALMA

A key observation is to A key observation is to observe the infalling gas in observe the infalling gas in redshiftedredshifted absorptionabsorption against against the background protostarthe background protostar

Very high spectral resolution Very high spectral resolution (<0.1 km/s) is required(<0.1 km/s) is required

High sensitivity to observe in High sensitivity to observe in absorption against disk.absorption against disk.

Low Mass Cores: Gross Low Mass Cores: Gross PropertiesProperties

Molecular cloud necessary, not sufficientMolecular cloud necessary, not sufficient High density (n>10High density (n>1044 cm cm–3–3)) Low turbulenceLow turbulence

Centrally peaked density distributionCentrally peaked density distribution Power law slope ~ high massPower law slope ~ high mass Fiducial density ~ 100 times lowerFiducial density ~ 100 times lower

Complex chemistry, dynamics even in 1DComplex chemistry, dynamics even in 1D Evidence for infall seen, but hard to studyEvidence for infall seen, but hard to study Outflow starts early, strong effect on linesOutflow starts early, strong effect on lines Rotation on small scalesRotation on small scales

Open QuestionsOpen Questions

Initial conditions Initial conditions Cloud/core interactionCloud/core interaction Trace conditions in core closer to centerTrace conditions in core closer to center Inward motions before point source?Inward motions before point source?

Timescales for stagesTimescales for stages Establish existence and nature of infallEstablish existence and nature of infall

Inverse P-Cygni profiles against disksInverse P-Cygni profiles against disks Chemo-dynamical studiesChemo-dynamical studies

Envelope-Disk transitionEnvelope-Disk transition Inner flow in envelopeInner flow in envelope

Outflow dynamicsOutflow dynamics Nature of interaction with ambient mediumNature of interaction with ambient medium

Sub-stellar ObjectsSub-stellar Objects

Brown dwarfs, free-floating planets, …Brown dwarfs, free-floating planets, … BDs clearly exist, clearly have disks, accretion,BDs clearly exist, clearly have disks, accretion,

…… How do these form?How do these form?

Ejection from multiples, clustersEjection from multiples, clusters Formation like starsFormation like stars

Properties of disksProperties of disks Do they form in low-mass, dense envelopes?Do they form in low-mass, dense envelopes? Low end of core mass functionLow end of core mass function

Planet FormationPlanet Formation

Best studied around isolated starsBest studied around isolated stars Origin and evolution of diskOrigin and evolution of disk Gaps, rings, …Gaps, rings, … Debris disks as tracers of planet formationDebris disks as tracers of planet formation Chemistry in disks Chemistry in disks

Evolution of dust, ices, gasEvolution of dust, ices, gas

Planet FormationPlanet Formation

SMM image of VegaSMM image of VegaJACH, Holland et al.JACH, Holland et al.

SMM image of Vega shows dust peaks off SMM image of Vega shows dust peaks off center from star (*). Fits a model with a center from star (*). Fits a model with a Neptune like planet clearing a gap. Neptune like planet clearing a gap. This is with 15-m at 850 microns and 15” This is with 15-m at 850 microns and 15” resolution.resolution.

ALMA can do at higher resolution. ALMA can do at higher resolution.

Model by Wyatt (2003), ApJ, 598, 1321Model by Wyatt (2003), ApJ, 598, 1321

With higher resolutionWith higher resolution

Vega also observed by Wilner et al. (2003). Model of resonance with planet. Vega also observed by Wilner et al. (2003). Model of resonance with planet.

Predicts motion of dustPredicts motion of dust



Model and Animation by Marc Model and Animation by Marc KuchnerKuchner

ALMA ResolutionALMA ResolutionSimulation Contains:Simulation Contains:* 140 AU disk* 140 AU disk* inner hole (3 AU)* inner hole (3 AU)* gap 6-8 AU* gap 6-8 AU* forming giant planets at:* forming giant planets at: 9, 22, 46 AU with local9, 22, 46 AU with local over-densitiesover-densities* ALMA with 2x over-density* ALMA with 2x over-density* ALMA with 20%* ALMA with 20% under-densityunder-density* Each letter 4 AU wide,* Each letter 4 AU wide, 35 AU high35 AU highObserved with 10 km arrayObserved with 10 km arrayAt 140 pc, 1.3 mmAt 140 pc, 1.3 mm

Observed Model Observed Model L. G. MundyL. G. Mundy

Chemistry of Planet-forming Chemistry of Planet-forming DisksDisks

QuickTime™ and aTIFF (LZW) decompressor


Qi et al. 2004Qi et al. 2004

LkCa15 with OVRO.LkCa15 with OVRO.Trace the composition Trace the composition changes with evolution.changes with evolution.

ALMA will have resolution ALMA will have resolution and sensitivity to do this and sensitivity to do this kind of study in many kind of study in many disks.disks.

The Icy ComponentThe Icy Component

Boogert et al. ApJS, submittedBoogert et al. ApJS, submitted

Spitzer IRS plus Keck/NIRSPEC or VLT/ISAACSpitzer IRS plus Keck/NIRSPEC or VLT/ISAAC

Rich spectrum of ices:Rich spectrum of ices:COCO22, H, H22O, CHO, CH33OH, OCNOH, OCN––

and others.and others.

Can study ice evolution Can study ice evolution in regions forming sun-in regions forming sun-like stars. Little like stars. Little processing at T>50 K, processing at T>50 K, some evidence for lower some evidence for lower temperature processing.temperature processing.

Open QuestionsOpen Questions

How the disk initially forms How the disk initially forms Timescales for disk evolutionTimescales for disk evolution How planets form in the diskHow planets form in the disk

Core accretion or Gravitational InstabilityCore accretion or Gravitational Instability

How unusual the solar system isHow unusual the solar system is Systems with giant planets out where ours areSystems with giant planets out where ours are

Evolution of dust, ice, gas in diskEvolution of dust, ice, gas in disk Building blocks for planetsBuilding blocks for planets

RequirementsRequirements

Maximum Spatial resolutionMaximum Spatial resolution Image fidelity (gaps will be hard to see)Image fidelity (gaps will be hard to see)

Best sensitivity Best sensitivity Especially for debris disksEspecially for debris disks

Flexible correlator, receiver bands Flexible correlator, receiver bands ChemistryChemistry

In the ALMA era…In the ALMA era…

Spitzer 2003

SOFIA 2005SOFIA 2005

Herschel 2007

JWST 2011

AT-25 2012AT-25 2012

SAFIR ~2015SAFIR ~2015

SMA, CARMA, eVLA, SMA, CARMA, eVLA, LMT, GBT, APEX, ASTE, LMT, GBT, APEX, ASTE, JCMT, CSO, …JCMT, CSO, …

Making the most of ALMAMaking the most of ALMA

Complementary ObservatoriesComplementary Observatories User-friendly systemUser-friendly system

Low barriers to those from other wavelengthsLow barriers to those from other wavelengths Proposals, planning tools, reduction, analysisProposals, planning tools, reduction, analysis

Scientific support staffScientific support staff Broad wavelength experienceBroad wavelength experience

Financial support tied to timeFinancial support tied to time

A Closer LookA Closer Look

J. Lee et al. In prep

A few abundance profiles at A few abundance profiles at t=100,000 yr.t=100,000 yr.

Vertical offset for convenienceVertical offset for convenience(except CO and HCN).(except CO and HCN).

Big effect is CO desorption, which Big effect is CO desorption, which affects most other species. affects most other species. Secondary peaks related to Secondary peaks related to evaporation of other species.evaporation of other species.

Bolocam map of OphiuchusBolocam map of Ophiuchus

K. Young et al. In prep

Bolocam map (1.2 mm) Bolocam map (1.2 mm) of region in Spitzer of region in Spitzer survey. Covers very survey. Covers very large area (> 10 sq. large area (> 10 sq. deg.) compared to any deg.) compared to any previous map. previous map. Rms noise ~ 50 mJy, Rms noise ~ 50 mJy, with about half the with about half the data.data.

Early Results from SpitzerEarly Results from Spitzer

Based on validation data (about 1%)Based on validation data (about 1%) Observed two small cores (IRAC/MIPS)Observed two small cores (IRAC/MIPS)

One (L1228) with a known infrared sourceOne (L1228) with a known infrared source One (L1014) withoutOne (L1014) without

Observed a few IRS targetsObserved a few IRS targets B5 IRSB5 IRS HH46/47 IRS (with ERO team)HH46/47 IRS (with ERO team)

A Typical Starless CoreA Typical Starless Core

L1014 distance ~ 200 pc, but L1014 distance ~ 200 pc, but somewhat uncertain. somewhat uncertain.

R-band image from DSSR-band image from DSS

A Surprise from SpitzerA Surprise from Spitzer

Three Color Composite:Three Color Composite:Blue = 3.6 micronsBlue = 3.6 micronsGreen = 8.0 micronsGreen = 8.0 micronsRed = 24 micronsRed = 24 microns

R-band image from DSS atR-band image from DSS atLower left.Lower left.

We see many stars throughWe see many stars throughthe cloud not seen in R.the cloud not seen in R.The central source is NOT The central source is NOT a background star. a background star.

L1014 is not “source-less”.L1014 is not “source-less”.Larger size in red is PSF.Larger size in red is PSF.

C. Young et al. ApJS, submitted

Source Peaks on mm EmissionSource Peaks on mm Emission

Left: 8 micron on 1.2 mm MAMBO dust continuum emission (Kauffmann & Bertoldi)Left: 8 micron on 1.2 mm MAMBO dust continuum emission (Kauffmann & Bertoldi)Right: 24 micron on 850 micron SCUBA data (Visser et al. 2002)Right: 24 micron on 850 micron SCUBA data (Visser et al. 2002)

Both long-waveBoth long-wavemaps are 3-sigma maps are 3-sigma contours.contours.


ModelsModels


Model of SED for d = 200 pc.Model of SED for d = 200 pc.Central object has very low Central object has very low luminosity: 0.09 Lluminosity: 0.09 Lsunsun..

Requires BB plus diskRequires BB plus disk(red line) in an envelope.(red line) in an envelope.M(envelope) about 2 MM(envelope) about 2 Msunsun..

Cannot be a stellar-mass Cannot be a stellar-mass object with significant object with significant accretion. Probably sub-accretion. Probably sub-stellar at this point.stellar at this point.

Alternative model: more Alternative model: more distant (2.6 kpc) object lined distant (2.6 kpc) object lined up by chance with peak of a up by chance with peak of a foreground core (dashed line)foreground core (dashed line)

Lessons from L1014Lessons from L1014

““Starless” cores may not beStarless” cores may not be Or may have substellar objectsOr may have substellar objects 1 out of 1 has a source (will soon have more)1 out of 1 has a source (will soon have more)

Very low luminosity sources may existVery low luminosity sources may exist Must be low mass and low accretionMust be low mass and low accretion Caveat: possible background sourceCaveat: possible background source

HH46/H47 Cloud HH46/H47 Cloud

QuickTime™ and aMPEG-4 Video decompressor


NASA/JPL-Caltech

Star and Planet Formation Neal Evans The University of Texas at Austin.

Documents

Transcript of Star and Planet Formation Neal Evans The University of Texas at Austin.