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How do massive stars form ? A comparison of model tracks with Herschel data. Michael D Smith CAPS University of Kent Available at: http://astro.kent.ac.uk/mds/capsule.pdf October 2013. L ate stage: Rosette in optical . AFGL 2591. Rosette Nebula, Travis Rector, KPNO.

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how do massive stars form a comparison of model tracks with herschel data

How do massive stars form?Acomparison of model tracks with Herschel data

Michael D Smith

CAPS

University of Kent

Available at: http://astro.kent.ac.uk/mds/capsule.pdf

October 2013

l ate stage rosette in optical
Late stage: Rosette in optical

AFGL 2591

Rosette Nebula, Travis Rector, KPNO

slide4

Near-Infrared Interferometry: Preibisch, Weigelt et al.

S140 IRS 3

S140 IRS 1

R Mon

IRAS 23151+5912

AFGL 2591

K3-50 A

Mon R2

numerical telescope k band imaging
Numerical telescope: K-band imaging

reflected

shock

AFGL 2591

total

approach 1 hmcs to uchii to hii
Approach 1: HMCs to UCHii to Hii

AdaptedfromGorti & Hollenbach 2002

approach 2 irdcs alma to herschel cool cores
Approach 2: IRDCs, ALMA, to Herschel cool cores

IRDCs: initial states imprinted - SDC335

Accelerated accretion

Peretto et al 2013, 555, A112

a) Mid-infrared Spitzer composite image (red: 8 μm; green: 4.5 μm; blue: 3.6 μm)

b) ALMA-only image of the N2H+(1−0) integrated intensity,

c) ALMA N2H+(1−0) velocity field

approach 3 two stage stitch up
Approach 3: two stage stitch-up

Molinari et al 2008

noted: lack of diagnostic tools.

Stage 1: Accretion phase

Stage 2: Clean up,

cluster forms + sweep out

Early protostar: Accelerated accretion

model (Mckee & Tan 2003)

Clump mass and final star mass

simply related):

Accelerated accretion

approach 3 two stage stitch up1
Approach 3: two stage stitch-up

Molinari et al 2008 tracks from SED to mm dust masses

Diagnostic tools:

Accelerated accretion

Lbol-Mclump-Tbol

Lbol/Lsolar

Mclump/Msolar

alternative evolutions
Alternative evolutions

Dark cloud fragments into cores/envelopes.

Envelope accretion: from fixed bound envelope, bursts etc

Global collapse.

Accretion evolutions: from clumps, competitive, turbulent. Cores and protostars grow simultaneously

Mergers, harrassment, cannabolism, disintegration

issues for massive stars
Issues for Massive Stars

Global collapse or fragmentation?

Most massive? Radiation feedback problem + solutions

Environment? Cluster-star evolutions? Which forms first?

Efficiency problem.

IMF: Feedback- radiation and outflow phases? EUV problem

Separate accretion luminosity from Interior luminosity?

Bursts? Luminosity problem: under-luminous?

Two phases; accretion followed by clean-up? Dual evolution?

recent simulations
Recent Simulations

Krumholz et al. 2007 , 2009 ; Peters et al. 2010a , 2011 ; Kuiper et al. 2010a , 2011 , 2012 ; Cunningham et al. 2011 ; Dale & Bonnell2011

Kuiper & Yorke 2013: 2D RHD, core only: spherical solid-body rotation + protostellar structure.

Conclusion: diverse, depends on disk formation, bloating and feedback coordination.

objective model for massive stars
Objective: Model for Massive Stars

Piece together evolutionary algorithms for the protostellar structure, the environment, the inflow and the radiation feedback.

The framework requires the accretion rate from the clump to be specified.

We investigate constant, decelerating and accelerating accretion rate scenarios.

We consider both hot and cold accretion, identified with spherical free-fall and disk accretion, respectively.

objective model for massive stars1
Objective: Model for Massive Stars

Piece together evolutionary algorithms for the protostellar structure, the environment, the inflow and the radiation feedback.

The framework requires the accretion rate from the clump to be specified.

We investigate constant, decelerating and accelerating accretion rate scenarios.

We consider both hot and cold accretion, identified with spherical free-fall and disk accretion, respectively.

cold or hot accretion
Cold or Hot Accretion?

Kuiper & Yorke 2013 ApJ 772

Hosokawa, Omukai, Yorke 2009, 2010

the protostar radius
The protostar: radius

Stellar radius as mass accumulates

(I) adiabatic, (II) swelling/bloating,

(III) Kelvin–Helmholtz contraction, and (IV) main sequence

Hot accretion Cold accretion

the protostar luminosity
The protostar: luminosity

Origin Luminosity as mass accumulates (cold)

the protostar adaption
The protostar: adaption

Assumed mass accretion rates + interpolation scheme

the low mass scheme construction
The Low-Mass Scheme: Construction

Clump Envelope Accretion Disk Protostars

  • mass conservation
  • prescribed accretion rate
  • bifurcation coefficient
  • jet speed ~ escape speed

Bipolar Outflow Jets

  • Evolution:
  • systematic and simultaneous
  • ProtostarL(Bolometric)
  • Jet L(Shock)
  • Outflow Momentum (Thrust)
  • Clump/Envelope Mass
  • Class Temperature
  • Disk Infrared excess
the capsule scheme construction
The Capsule Scheme: Construction

Lyman Flux

Radio: H II region

Radiative Flux

Clump Envelope Accretion Disc Protostar

Bipolar Outflow Jets

thermal radio jets

H2 shocks

the clump mass isotherms herschel data
The clump mass, isotherms + Herschel data

Origin Luminosity as clump mass declines

Constant slow accretion Accelerated accretion

( Data: Elia et al 2010), Hi-GAL

Accelerated accretion Power Law deceleration (Data: Molinari et al 2008)

bolometric temperature
Bolometric Temperature

Origin Distance dotted line = accelerated accretion

Herschel: <20K: 0.463 <30K: 0.832 <50K: 0.950

bolometric temperature1
Bolometric Temperature

Clump = cluster x 2

Clump = cluster x 6

l bol m clump t bol results
Lbol-Mclump-Tbol results

Accelerated accretion is not favoured

Source counts as a function of the bolometric temperature can distinguish the accretion mode.

Accelerated accretion yields a relatively high number of low-temperature objects.

On this basis, we demonstrate that evolutionary tracks to fit Herschel Space Telescope data require the generated stars to be three to four times less massive than in previous interpretations.

This is consistent with star formation efficiencies of 10-20%

the clump mass isotherms herschel data1
The clump mass, isotherms + Herschel data

Or Luminosity as clump mass declines: massive clumps

the lyman flux atca 18 ghz data
The Lyman Flux (ATCA 18 GHz data)

N(Ly), Lyman Continuum photons/s

Sanchez-Monge et al., 2013, A&A 550, A21

Orig Accelerated accretion

Lbol/LsunBolometric Luminosity

the lyman flux
The Lyman Flux

Origin D COLD accretion + Hot Spots (75%, 5% area)

Distributed accretion Accretion hotspots

Orig Constant accretion rate

the lyman flux summary
The Lyman Flux: summary

Neither spherical nor disk accretion can explain the high radio luminosities of many protostars.

Nevertheless, we discover a solution in which the extreme ultraviolet flux needed to explain the radio emission is produced if the accretion flow is via free-fall on to hot spots covering less than 20% of the surface area.

Moreover, the protostar must be compact, and so has formed through cold accretion.

This suggest that massive stars form via gas accretion through disks which, in the phase before the star bloats, download their mass via magnetic flux tubes on to the protostar.

jet speed keplerian speed
Jet speed = keplerian speed

Or Different constant accretion rates………..

what next
Michael D. Smith - Accretion DiscsWhat next?
  • Disk – planet formation
  • Binary formation, mass transfer etc
  • Mass outflows v. radiation feedback
  • Feedback routes
  • Outbursts
  • Thermal radio jets
  • ???
thanks for listening
Thanks For Listening!

ANY QUESTIONS?

low mass protostellar tracks
Low-Mass ProtostellarTracks
  • X-Axis: Luminosity
  • Y-Axis: Jet Power
  • Tracks/Arrows: the scheme
  • Diagonalline:
  • Class 0/I border
  • Data: ISO FIR + NIR (Stanke)
  • Above: Class 0
  • Under: Class 1
disk evolution
Michael D. Smith - Accretion DiscsDisk evolution
  • Column density as function of radius and time: (r,t)
  • Assume accretion rate from envelope
  • Assume entire star (+ jets) is supplied through disc
  • Angular momentum transport:
  • - turbulent viscosity: `alpha’ prescription
  • - tidal torques: Toomre Q parameterisation
  • Class 0 stage: very abrupt evolution?? Test……
  • …to create a One Solar Mass star
the envelope disc connection slow inflow
Michael D. Smith - Accretion DiscsThe envelope-disc connection; slow inflow

50,000 yr: blue

500,000 yr: green

2,000,000 yr: red

Peak accretion at 100,000 yr

Accrate 3.5 x 10-6Msun/yr

Viscosity alpha = 0.1

the envelope disc connection slow inflow low alpha
Michael D. Smith - Accretion DiscsThe envelope-disc connection; slow inflow; low alpha

Peak accretion at 200,000 yr

Accrate 3.5 x 10-6Msun/yr

Viscosity alpha = 0.01

50,000 yr: blue

500,000 yr: green

2,000,000 yr: red