Ammonia and CCS as diagnostic tools of low-mass protostars

Ammonia and CCS as diagnostic tools of low-mass protostars

Ammonia and CCS as diagnostic tools of low-mass protostars

Itziar de Gregorio-MonsalvoItziar de Gregorio-Monsalvo

(ESO /ALMA fellow in Chile)

Collaborators: J.F. Gómez (IAA, Spain) C.J. Chandler (NRAO, USA)

T.B.H. Kuiper (JPL-Caltech, USA) J.M. Torrelles (IEEC, Spain) G. Anglada (IAA, Spain)

Collaborators: J.F. Gómez (IAA, Spain) C.J. Chandler (NRAO, USA)

T.B.H. Kuiper (JPL-Caltech, USA) J.M. Torrelles (IEEC, Spain) G. Anglada (IAA, Spain)

Physical conditions:Physical conditions: - The excitation conditions depend on T- The excitation conditions depend on TKK, n , n H2H2 and the radiation field. and the radiation field.

- Molecular clouds:- Molecular clouds: TTKK ~ 10 K ~ 10 K → → excites lowest rotational transitions excites lowest rotational transitions

- From line intensities: T- From line intensities: Texex, , ττ, N, N

Kinematics:Kinematics: - - LinewidthsLinewidths and shapesand shapes→ turbulent and systemic motions of the gas→ turbulent and systemic motions of the gas

Stage of evolution:Stage of evolution: - - Time-dependent chemistryTime-dependent chemistry and the spatial distribution of some species and the spatial distribution of some species

(e.g. NH(e.g. NH33 (late-type molecule) and CCS (early-type molecule)). (late-type molecule) and CCS (early-type molecule)).

de Gregorio-Monsalvo, SOCHIAS 2009

Molecular lines as diagnosis tools of the Molecular lines as diagnosis tools of the interestellar mediuminterestellar medium

Why CCS is interesting?Why CCS is interesting? ““CCS spectral lines are a powerful tool to study YSOs”CCS spectral lines are a powerful tool to study YSOs”

1. 1. High density gas tracer:High density gas tracer: • • Structure and physical conditions of the cloud.Structure and physical conditions of the cloud. • • Intense in cold quiescent cores.Intense in cold quiescent cores.

2. 2. Kinematics:Kinematics: • • No splitting in hyperfine structureNo splitting in hyperfine structure

3.3. Evolutionary stage of molecular clouds.Evolutionary stage of molecular clouds. • • Spatial anticorrelation between CCS and ammonia. Spatial anticorrelation between CCS and ammonia.

•• [CCS] / [NH3] indicator of cloud evolution.[CCS] / [NH3] indicator of cloud evolution.


• • Evolutionary effect: Star formation phenomena destroy CCS Evolutionary effect: Star formation phenomena destroy CCS BUT favor ammonia production. BUT favor ammonia production.

Why CCS is interesting?Why CCS is interesting?

What about (more evolved) star-forming regions at higher resolution?What about (more evolved) star-forming regions at higher resolution?


(Hirota et al. 2002)(Hirota et al. 2002)

B68

(Lai et al. 2003)(Lai et al. 2003)

L1521E

Previous works: Starless cores, single-dish observations.Starless cores, single-dish observations.

GOALS:GOALS: 1- Find good candidates for interferometric observations. 1- Find good candidates for interferometric observations. 2- Relation between CCS and physical characteristics and age of 2- Relation between CCS and physical characteristics and age of star forming regions. star forming regions.

CCS and NHCCS and NH33 survey in low-mass star forming survey in low-mass star forming

regions (SFRs)regions (SFRs)

SELECTION CRITERIA:SELECTION CRITERIA: Low-mass regions with presence of Low-mass regions with presence of HH22O maser O maser

emission at 22 GHz (traces star formation activity and youth; Furuya 2001)emission at 22 GHz (traces star formation activity and youth; Furuya 2001)

SURVEY: SURVEY: 40 young low-mass star forming 40 young low-mass star forming regions using the Robledo-70m (NASA regions using the Robledo-70m (NASA DSS-63) antenna at 22 GHz (1cm).DSS-63) antenna at 22 GHz (1cm).


RESULT: RESULT: 6 detections in CCS and NH6 detections in CCS and NH3 3 (de Gregorio-Monsalvo et al. 2006)

Survey conclusionsSurvey conclusions

• • Dependencies of CCS emission on source and cloud parameters (stadistical Dependencies of CCS emission on source and cloud parameters (stadistical study):study): - No relation with source luminosity, radio continuum and water maser - No relation with source luminosity, radio continuum and water maser

flux densities, nor with molecular outflows parameters (Rflux densities, nor with molecular outflows parameters (RCC, M, , M, , L, LCOCO, ,

P, F, EP, F, Ekinkin).).

- CCS emitting regions show NH- CCS emitting regions show NH33 spectrum with narrow spectrum with narrow v

→ → less turbulence, younger regionsless turbulence, younger regions

• • Ammonia linewidths broader than CCS ones:Ammonia linewidths broader than CCS ones: - CCS and ammonia trace different regions- CCS and ammonia trace different regions


Observations at ~1.3cm (22 GHz) in CCS, H2O, and NH3

VLA interferometric observationsVLA interferometric observations

GOALSGOALS : : 1- Study physical conditions, kinematics, and interaction with the 1- Study physical conditions, kinematics, and interaction with the medium medium at high-angular resolution.at high-angular resolution.

2- Test the distribution of CCS vs. NH2- Test the distribution of CCS vs. NH3 3 in SFRs at small scales in SFRs at small scales

SOURCESSOURCES : : B1-IRS, L1448C and L1448-IRS3B1-IRS, L1448C and L1448-IRS3


Very Large Array, New Mexico (USA).

B1-IRSB1-IRS• Class 0 source in Perseus (350 pc; Bachiller et al. 1990).

• CO (1-0) outflow (Hirano et al. 1997).

• 2MASS source at the tip of the CO outflow (reflection nebula in K-band).• H2O masers in an elongated structure. Unbound motions, probably tracing a jet .• Lack of velocity gradient ( Outflow lies near the plane of the sky ).


(Hirano et al. 1997)

2MASS + H2O masers

(de Gregorio-Monsalvo et al. 2005)

CO(1-0)

B1-IRS: CCS emissionB1-IRS: CCS emission

• CCS emission is clumpy.CCS emission is clumpy.

• Redshifted clumps. Redshifted clumps.

• Velocity gradient blue-Velocity gradient blue- shifted towards the shifted towards the central sourcecentral source


CCS

10000 AU at 350 pc


Vlsr

B1-IRS: CCS emissionB1-IRS: CCS emission

- Strong interaction with the molecular outflow - Strong interaction with the molecular outflow - CCS enhanced via shocked induced chemistry?- CCS enhanced via shocked induced chemistry?



CCS

10000 AU at 350 pc


Vlsr

B1-IRS: Ammonia vs CCSB1-IRS: Ammonia vs CCS

- Spatial anticorrelation at scales of ~5’’- Useful for testing future theoretical chemical models

NH3CCS



L1448L1448

L1448C

L1448-IRS3

L1448-IRS2

Red

Blue

• Located in Perseus molecular cloud (250 pc; Enoch et al. 2006).

• L1448-C (Class 0 source) and L1448-IRS3 (Class0/I source).

• Spectacular molecular outflow (Bachiller et al. 1990)


CCS (contours) + IR outflow (gray)

L1448-IRS3

L1448C H2O

H2O

H2O masers

Vlsr

Vlsr


L1448: CCS emissionL1448: CCS emission

• CCS emission is clumpy.CCS emission is clumpy.

• Strong interaction between CCSStrong interaction between CCS clumps and the outflows.clumps and the outflows.

Again, the CCS seems to be enhanced in shocked regions


CCS (contours) + IR outflow (gray)

L1448: CCS emissionL1448: CCS emission

(de Gregorio-Monsalvo et al. in prep.)

L1448-IRS3

L1448C

Again: Spatial anticorrelation at scales of ~5’’

CCS (contours) and NH3(gray; Curiel et al. 1999)


L1448: CCS vs. NHL1448: CCS vs. NH33

L1448: Kinematics L1448: Kinematics

CCS (contours + color) CCS (contours) + NH3 (color)

VlsrVlsr

Again: CCS and NH3 show a kinematics associated with a strong interaction with the molecular outflows of the region.


General ConclusionsGeneral Conclusions

1. CCS and NH3 survey in low-mass SFRs → six sources show CCS and NH3

2. Statistical study: - No relation between the characteristic of the central sources or the molecular outflows and the presence of CCS.

- Relation with ammonia linewidth supports that the CCS-emiting regions might be younger.

3. We observed a spatial anticorrelation between NH3 and CCS at scales of 5’’ → a combination of both is needed to trace the full column density of dense material and to understand the kinematics of the young SFRs.

4. CCS kinematical patterns suggests a strong interaction between the gas traced by CCS and the molecular outflow of the region → a shocked induced chemistry could be responsible for a local CCS abundance enhancement.



Thank you!Thank you!

IRAS 16293-2422IRAS 16293-2422

Improvement of ~30% in the SNR ...cross-calibration on spectral lines is feasible!!!!Improvement of ~30% in the SNR ...cross-calibration on spectral lines is feasible!!!!

Testing a new observation technique: cross-calibration in spectral line.Testing a new observation technique: cross-calibration in spectral line. - Simultaneous observations of CCS (22.35 GHz) and H- Simultaneous observations of CCS (22.35 GHz) and H22O (22.24 GHz). O (22.24 GHz).

- Self-calibration of H2O masers to correct for atmospheric variations.- Self-calibration of H2O masers to correct for atmospheric variations.

(de Gregorio-Monsalvo et al. in prep.)

• No CCS emission, but averaging the central 93 channels, allowed to detectNo CCS emission, but averaging the central 93 channels, allowed to detect radio continuum emission at ~1.3 cm (left panel).radio continuum emission at ~1.3 cm (left panel).

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BeforeBefore

AfterAfter++

BeforeBefore

AfterAfter

VLA-D VLA-B

Continuumat 1.3 cm

Continuumat 1.3 cm

3-5

3-7


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Ammonia and CCS as diagnostic tools of low-mass protostars