A herschel and_apex_census_of_the_reddest_sources_in_orion_searching_for_the_youngest_protostars
How do massive stars form ? A comparison of model tracks with Herschel data
description
Transcript of How do massive stars form ? A comparison of model tracks with Herschel data
![Page 1: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/1.jpg)
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
September 2013
![Page 2: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/2.jpg)
Late stage: Rosette in optical
AFGL 2591
Rosette Nebula, Travis Rector, KPNO
![Page 3: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/3.jpg)
Early emerging: near-infrared, with outflows
Li e
t al
2008
ApJ
L 67
9, L
101
![Page 4: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/4.jpg)
K3-50 AIRAS 23151+5912
AFGL 2591Mon R2
R MonS140 IRS 1S140 IRS 3
Near-Infrared Interferometry: Preibisch, Weigelt et al.
![Page 5: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/5.jpg)
Numerical telescope: K-band imaging
reflected
shock
totalAFGL 2591
![Page 6: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/6.jpg)
● 6
Approach 1: HMCs to UCHii to Hii
●Ad
apte
d fro
m G
orti
& Ho
llenb
ach
2002
![Page 7: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/7.jpg)
● 7
Approach 2: IRDCs, ALMA, to Herschel cool cores
IRDCs: initial states imprinted - SDC335
Accelerated accretion
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
Pere
tto e
t al
2013
, 555
, A11
2
![Page 8: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/8.jpg)
● 8
Approach 3: two stage stitch-upMolinari et al 2008 noted: lack of diagnostic tools.
Stage 1: Accretion phaseStage 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
![Page 9: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/9.jpg)
● 9
Approach 3: two stage stitch-upMolinari et al 2008 tracks from SED to mm dust massesDiagnostic tools:
Accelerated accretionLbol-Mclump-Tbol
L bol/L
sola
r
Mclump/Msolar
![Page 10: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/10.jpg)
● 10
Alternative evolutionsDark 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
![Page 11: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/11.jpg)
● 11
Issues for Massive StarsMost massive? Radiation feedback problem
Environment? Cluster-star evolutions? Efficiency problem.
Global collapse or fragmentation?
IMF: Feedback - radiation and outflow phases? EUV problemSeparate accretion luminosity from Interior luminosity?
Bursts? Luminosity problem
Two phases; accretion followed by clean-up? Dual evolution?
![Page 12: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/12.jpg)
● 12
Krumholz et al. 2007 , 2009 ; Peters et al. 2010a , 2011 ; Kuiper et al. 2010a , 2011 , 2012 ; Cunningham et al. 2011 ; Dale & Bonnell 2011Kuiper & Yorke 2013: 2D RHD, core only: spherical solid-body rotation + protostellar structure.Conclusion: diverse, depends on disk formation, bloating and feedback coordination.
Recent Simulations
![Page 13: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/13.jpg)
● 13
Objective: Model for Massive StarsPiece 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.
![Page 14: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/14.jpg)
● 14
Objective: Model for Massive StarsPiece 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.
![Page 15: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/15.jpg)
● 15
Cold or Hot Accretion?
Kuip
er &
York
e 20
13 A
pJ 7
72
Hoso
kawa
, Om
ukai
, Yor
ke 2
009,
20
10
![Page 16: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/16.jpg)
● 16
The protostar: radiusStellar radius as mass accumulates (I) adiabatic, (II) swelling/bloating, (III) Kelvin–Helmholtz contraction, and (IV) main sequence
Hot accretion Cold accretion
![Page 17: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/17.jpg)
● 17
The protostar: luminosityOrigin Luminosity as mass accumulates (cold)
![Page 18: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/18.jpg)
● 18
The protostar: adaptionAssumed mass accretion rates + interpolation scheme
![Page 19: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/19.jpg)
● mass conservation● prescribed accretion rate● bifurcation coefficient● jet speed ~ escape speed
The Low-Mass Scheme: Construction● Clump Envelope Accretion Disk Protostars
● Bipolar Outflow Jets ● Evolution:
● systematic and simultaneous
• Protostar L(Bolometric)
• Jet L(Shock)
• Outflow Momentum (Thrust)
• Clump/Envelope Mass
• Class Temperature
• Disk Infrared excess
![Page 20: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/20.jpg)
The Capsule Scheme: Construction
● Clump Envelope Accretion Disc Protostar
Bipolar Outflow Jets
Lyman Flux
thermal radio jets
H2 shocks
Radiative Flux
Radio: H II region
![Page 21: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/21.jpg)
● 21
Capsule Flow Chart
![Page 22: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/22.jpg)
Origin Luminosity as clump mass declines
● 22
The clump mass, isotherms + Herschel data
Accelerated accretion Power Law deceleration (Data: Molinari et al 2008)
Constant slow accretion Accelerated accretion ( Data: Elia et al 2010), Hi-GAL
![Page 23: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/23.jpg)
Origin Distance dotted line = accelerated accretion
● 23
Bolometric Temperature
Herschel: <20K: 0.463 <30K: 0.832 <50K: 0.950
![Page 24: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/24.jpg)
● 24
Bolometric Temperature
Clump = cluster x 6
Clump = cluster x 2
![Page 25: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/25.jpg)
● 25
Lbol-Mclump-Tbol resultsWe find that accelerated accretion is not favoured on the basis of the often-used diagnostic diagram which correlates the bolometric luminosity and clump mass. Instead, source counts as a function of the bolometric temperature can distinguish the accretion mode.Specifically, 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%
![Page 26: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/26.jpg)
Or Luminosity as clump mass declines: massive clumps
● 26
The clump mass, isotherms + Herschel data
![Page 27: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/27.jpg)
● 27
The Lyman Flux (ATCA 18 GHz data)
Orig Accelerated accretion
N(Ly
), Lym
an C
ontin
uum
pho
tons
/s
Lbol /Lsun Bolometric LuminositySa
nche
z-M
onge
et a
l., 2
013,
A&A
550
, A2
1
![Page 28: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/28.jpg)
Origin D COLD accretion + Hot Spots (75%, 5% area)Distributed accretion Accretion hotspots
● 28
The Lyman Flux
Orig Constant accretion rate
![Page 29: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/29.jpg)
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.
● 29
The Lyman Flux: summary
![Page 30: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/30.jpg)
Or Different constant accretion rates………..
● 30
Jet speed = keplerian speed
![Page 31: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/31.jpg)
● Michael D. Smith - Accretion Discs
● 31
What next?● Disk – planet formation● Binary formation, mass transfer etc● Mass outflows v. radiation feedback● Feedback routes● Outbursts ● Thermal radio jets● ???
![Page 32: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/32.jpg)
Thanks For Listening!
ANY QUESTIONS?
![Page 33: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/33.jpg)
● X-Axis: Luminosity● Y-Axis: Jet Power● Tracks/Arrows: the
scheme● Diagonal line: ● Class 0/I border
● Data: ISO FIR + NIR (Stanke)
● Above: Class 0● Under: Class 1
Low-Mass Protostellar Tracks
![Page 34: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/34.jpg)
● Michael D. Smith - Accretion Discs
● 34
Disk 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
![Page 35: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/35.jpg)
● Michael D. Smith - Accretion Discs
● 35
The envelope-disc connection; slow inflow
● Peak accretion at 100,000 yr● Acc rate 3.5 x 10-6 Msun/yr● Viscosity alpha = 0.1
● 50,000 yr: blue● 500,000 yr: green
● 2,000,000 yr: red
![Page 36: How do massive stars form ? A comparison of model tracks with Herschel data](https://reader033.fdocuments.us/reader033/viewer/2022051219/56816034550346895dcf5783/html5/thumbnails/36.jpg)
● Michael D. Smith - Accretion Discs
● 36
The envelope-disc connection; slow inflow; low alpha
● Peak accretion at 200,000 yr● Acc rate 3.5 x 10-6 Msun/yr● Viscosity alpha = 0.01
● 50,000 yr: blue● 500,000 yr: green
● 2,000,000 yr: red