submillimeter astronomy in the era of the sma, cambridge, june 14, 2005 star formation and...
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Submillimeter Astronomy in the era of the SMA, Cambridge, June 14, 2005
Star Formation and Protostars at High Angular Resolution with the SMA
Star Formation and Protostars at High Angular Resolution with the SMA
Jes Jørgensen (CfA)
Tyler Bourke, Philip Myers, David Wilner (CfA), Fredrik Schöier (Stockholm), Ewine van Dishoeck (Leiden),
... and the PROSAC team.
Jes Jørgensen (CfA)
Tyler Bourke, Philip Myers, David Wilner (CfA), Fredrik Schöier (Stockholm), Ewine van Dishoeck (Leiden),
... and the PROSAC team.
ACP
Dark Cloud Cores
t = 0Gravitational
collapse
t ~ 104 – 105
yrs
Protostar embedded in ~10,000 AU
envelope
t ~ 105 – 106
yrs
T-Tauri star, disk, outflow
t ~ 106 – 107
yrs
Pre-main sequence star, remnant disk
t > 107 yrs
Main-sequence star, planetary
system
Figure based on Shu (1987); from “NASA Origins”
Low-mass protostarsLow-mass protostars
• Densities ranging from 104 cm-3 to 107-108 cm-3 (H2)
• Temperatures ranging from ~10 K to a few hundred K.
~ 20,000 AU (100”) ~ 200 AU (1”)
PROSACPROSAC
Line + continuum survey (230/345 GHz) of deeply embedded (class 0) protostars 8 protostellar sources from Ph.D. thesis of J. Jørgensen (Leiden
Univ. 2004; Jørgensen et al. 2002, 2004, 2005)... Single-dish survey at JCMT and Onsala 20m telescopes. Follow-up 1, 3 mm interferometric measurements OVRO and BIMA. All tied together by detailed line and continuum rad. transfer models.
3 spectral setups per source: CO, CS, SO, HCO+, H2CO, CH3OH, SiO, ... transitions (and isotopes)
Line + continuum survey (230/345 GHz) of deeply embedded (class 0) protostars 8 protostellar sources from Ph.D. thesis of J. Jørgensen (Leiden
Univ. 2004; Jørgensen et al. 2002, 2004, 2005)... Single-dish survey at JCMT and Onsala 20m telescopes. Follow-up 1, 3 mm interferometric measurements OVRO and BIMA. All tied together by detailed line and continuum rad. transfer models.
3 spectral setups per source: CO, CS, SO, HCO+, H2CO, CH3OH, SiO, ... transitions (and isotopes)
PROtostellar Submillimeter Array Campaign
Jørgensen (PI)Bourke, Di Francesco, Lee, Myers, Ohashi,
Schöier, Takakuwa, van Dishoeck, Wilner, Zhang
In this talk...In this talk...
What is the structure of protostellar envelopes on a few 100 AU scales?
What is the physical structure of circumstellar disks - and their molecular content?
Do low-mass protostars have hot cores, i.e., inner regions with temperatures higher than 100 K and where complex organic molecules might be present?
What is the structure of protostellar envelopes on a few 100 AU scales?
What is the physical structure of circumstellar disks - and their molecular content?
Do low-mass protostars have hot cores, i.e., inner regions with temperatures higher than 100 K and where complex organic molecules might be present?
NGC1333-IRAS2NGC1333-IRAS2SCUBA 850 µm
Tbol ~ 50 K, Lbol ~ 16 L
d ~ 220 pc (Cernis, 1990)
2C2A
2BThree pre/protostellar objects (Looney et al. 2000, Sandell & Knee 2001, Jørgensen et al. 2004)
SCUBA 850 µm SMA 850 µm
NGC1333-IRAS2A dust continuum at 850 µm.
SMA 850 µm
NGC1333-IRAS2A dust continuum at 850 µm.
…the SMA resolves the warm dust in the inner envelope and the circumstellar disk
Envelope (constrained through SCUBA observations; Jørgensen et al. (2002))
Disk (resolved)
NGC1333-IRAS2A dust continuum at 850 µm.
cm through mm measurements from Rodríguez et al. (1999), Reipurth et al. (2002), Jørgensen et al. (2004)
The dust continuum emission follows a power-law F 2.2 from cm through submillimeter wavelengths.
Likely optically thick thermal dust emission from a circumstellar disk with a size of 300 AU and mass of a few 0.01-0.1 M
It is not evident from high-resolution data that the envelope extends all the way to the smallest scales.
The disk material will be dominating a hot core in the protostellar envelope.
The dust continuum emission follows a power-law F 2.2 from cm through submillimeter wavelengths.
Likely optically thick thermal dust emission from a circumstellar disk with a size of 300 AU and mass of a few 0.01-0.1 M
It is not evident from high-resolution data that the envelope extends all the way to the smallest scales.
The disk material will be dominating a hot core in the protostellar envelope.
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
Envelope and disk chemistry
Envelope and disk chemistry
Detections of high excitation transitions of CO, HCN (and H13CN), SO, SO2, CH3OH (and CH3OD), CH3OCH3 and CH3OCHO (tentative) in submm window toward NGC1333-IRAS2A.
Organic molecules toward IRAS2AOrganic molecules toward IRAS2A
500 AU500 AU
...line emission compact (largely unresolved)
Complex organic species detected on small scales in IRAS2A. ...but in the 2” SMA beam: the disk column density is
dominating compared to the hot core. Sulfur species are expected to be enhanced in typical hot
cores (Charnley 1997, Wakelam et al. 2004)
Complex organic species detected on small scales in IRAS2A. ...but in the 2” SMA beam: the disk column density is
dominating compared to the hot core. Sulfur species are expected to be enhanced in typical hot
cores (Charnley 1997, Wakelam et al. 2004)
Envelope and disk chemistry
Envelope and disk chemistry
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
Envelope and disk chemistry
Envelope and disk chemistry
With SO abundance enhancements in hot core
Constant abund. envelope
The SO abundance is almost constant throughout the envelope (consistent with single-dish obs. of S-species).
An abundance enhancement in the innermost envelope is clearly ruled out.
The presence of the high excitation lines of in particular CH3OH suggests that the temperature is high ~ 150 K. Heated layer of circumstellar disk (e.g., Elias 29; Ceccarelli et al. 2002)?
The presence of the high excitation lines of in particular CH3OH suggests that the temperature is high ~ 150 K. Heated layer of circumstellar disk (e.g., Elias 29; Ceccarelli et al. 2002)?
Envelope and disk chemistry
Envelope and disk chemistry
Jørgensen et al., ApJ, submitted
Complex organic species detected on small scales in IRAS2A. ...but in the 2” SMA beam: the disk column density is
dominating compared to the hot core. Sulfur species are expected to be enhanced in typical hot
cores (Charnley 1997, Wakelam et al. 2004)
Complex organic species detected on small scales in IRAS2A. ...but in the 2” SMA beam: the disk column density is
dominating compared to the hot core. Sulfur species are expected to be enhanced in typical hot
cores (Charnley 1997, Wakelam et al. 2004)
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
Low-mass hot cores: Presence of complex organic species on small scales (i.p., IRAS16293: Cazaux et al. (2003), Kuan et al. (2004), Bottinelli et al. (2004)).
...much more to come!
ConclusionsConclusions High-angular resolution interferometric and single-dish
continuum observations of NGC 1333-IRAS2A can be fitted by an extended envelope and a 300 AU (resolved) disk with a mass a few 0.01-0.1 M.
The large size of the disk suggests a rapid build-up of disks in the deeply embedded stages of protostellar evolution.
The molecular content of the disk is non-negligible compared to a candidate hot core. It is not evident from the dust observations/models that warm (T > 100 K) material is present in the envelope around NGC1333-IRAS2A.
No evidence is seen for sulfur enhancements on small-scales. Other species such as CH3OH may have their origin in the circumstellar disk... (don’t forget the outflows, though)
High-angular resolution interferometric and single-dish continuum observations of NGC 1333-IRAS2A can be fitted by an extended envelope and a 300 AU (resolved) disk with a mass a few 0.01-0.1 M.
The large size of the disk suggests a rapid build-up of disks in the deeply embedded stages of protostellar evolution.
The molecular content of the disk is non-negligible compared to a candidate hot core. It is not evident from the dust observations/models that warm (T > 100 K) material is present in the envelope around NGC1333-IRAS2A.
No evidence is seen for sulfur enhancements on small-scales. Other species such as CH3OH may have their origin in the circumstellar disk... (don’t forget the outflows, though)