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Ammonia and CCS as diagnostic tools of low-mass protostars Ammonia and CCS as diagnostic tools of low-mass protostars Itziar de Gregorio-Monsalvo (ESO.

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Presentation on theme: "Ammonia and CCS as diagnostic tools of low-mass protostars Ammonia and CCS as diagnostic tools of low-mass protostars Itziar de Gregorio-Monsalvo (ESO."— Presentation transcript:

1 Ammonia and CCS as diagnostic tools of low-mass protostars Ammonia and CCS as diagnostic tools of low-mass protostars Itziar 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)

2 Physical conditions: - The excitation conditions depend on T K, n H2 and the radiation field. - The excitation conditions depend on T K, n H2 and the radiation field. - Molecular clouds: - Molecular clouds: T K ~ 10 K → excites lowest rotational transitions T K ~ 10 K → excites lowest rotational transitions - From line intensities: T ex, τ, N Kinematics: Kinematics: - Linewidths and shapes→ turbulent and systemic motions of the gas - Linewidths and shapes→ turbulent and systemic motions of the gas Stage of evolution: Stage of evolution: - Time-dependent chemistry and the spatial distribution of some species (e.g. NH 3 (late-type molecule) and CCS (early-type molecule)). - Time-dependent chemistry and the spatial distribution of some species (e.g. NH 3 (late-type molecule) and CCS (early-type molecule)). de Gregorio-Monsalvo, SOCHIAS 2009 Molecular lines as diagnosis tools of the interestellar medium

3 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. High density gas tracer: 1. 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. Kinematics: 2. Kinematics: No splitting in hyperfine structure No splitting in hyperfine structure 3.Evolutionary stage of molecular clouds. 3. Evolutionary stage of molecular clouds. Spatial anticorrelation between CCS and ammonia. Spatial anticorrelation between CCS and ammonia. [CCS] / [NH3] indicator of cloud evolution. de Gregorio-Monsalvo, SOCHIAS 2009

4 Evolutionary effect: Star formation phenomena destroy CCS BUT favor ammonia production. Evolutionary effect: Star formation phenomena destroy CCS BUT favor ammonia production. Why CCS is interesting? What about (more evolved) star-forming regions at higher resolution? de Gregorio-Monsalvo, SOCHIAS 2009 (Hirota et al. 2002) B68 (Lai et al. 2003) L1521E Starless cores, single-dish observations. Previous works: Starless cores, single-dish observations.

5 GOALS: 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 NH 3 survey in low-mass star forming regions (SFRs) SELECTION CRITERIA: Low-mass regions with presence of H 2 O maser emission at 22 GHz (traces star formation activity and youth; Furuya 2001) SURVEY: 40 young low-mass star forming regions using the Robledo-70m (NASA DSS-63) antenna at 22 GHz (1cm). de Gregorio-Monsalvo, SOCHIAS 2009 RESULT: 6 detections in CCS and NH 3 RESULT: 6 detections in CCS and NH 3 (de Gregorio-Monsalvo et al. 2006)

6 Survey conclusions Dependencies of CCS emission on source and cloud parameters (stadistical study): Dependencies of CCS emission on source and cloud parameters (stadistical 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 (R C, M, , L CO, flux densities, nor with molecular outflows parameters (R C, M, , L CO, P, F, E kin ). P, F, E kin ). - CCS emitting regions show NH 3 spectrum with narrow  - CCS emitting regions show NH 3 spectrum with narrow  v → less turbulence, younger regions → less 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 de Gregorio-Monsalvo, SOCHIAS 2009

7 Observations at ~1.3cm (22 GHz) in CCS, H 2 O, and NH 3 VLA interferometric observations GOALS : 1- Study physical conditions, kinematics, and interaction with the medium at high-angular resolution. medium at high-angular resolution. 2- Test the distribution of CCS vs. NH 3 in SFRs at small scales 2- Test the distribution of CCS vs. NH 3 in SFRs at small scales SOURCES : B1-IRS, L1448C and L1448-IRS3 de Gregorio-Monsalvo, SOCHIAS 2009 Very Large Array, New Mexico (USA).

8 B1-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). H 2 O masers in an elongated structure. Unbound motions, probably tracing a jet. Lack of velocity gradient ( Outflow lies near the plane of the sky ). de Gregorio-Monsalvo, SOCHIAS 2009 (Hirano et al. 1997) 2MASS + H2O masers (de Gregorio-Monsalvo et al. 2005) CO(1-0)

9 B1-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 source central source de Gregorio-Monsalvo, SOCHIAS 2009 CCS AU at 350 pc (de Gregorio-Monsalvo et al. 2005) Vlsr

10 B1-IRS: CCS emission - Strong interaction with the molecular outflow - CCS enhanced via shocked induced chemistry? de Gregorio-Monsalvo, SOCHIAS 2009 (de Gregorio-Monsalvo et al. 2005) CCS AU at 350 pc (de Gregorio-Monsalvo et al. 2005) Vlsr

11 B1-IRS: Ammonia vs CCS - Spatial anticorrelation at scales of ~5’’ - Useful for testing future theoretical chemical models NH3 CCS (de Gregorio-Monsalvo et al. 2005) de Gregorio-Monsalvo, SOCHIAS 2009

12 L1448 L1448 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) de Gregorio-Monsalvo, SOCHIAS 2009

13 CCS (contours) + IR outflow (gray) L1448-IRS3 L1448C   H2OH2O H2OH2O H 2 O masers Vlsr de Gregorio-Monsalvo, SOCHIAS 2009 L1448: CCS emission L1448: CCS emission

14 CCS emission is clumpy. CCS emission is clumpy. Strong interaction between CCS Strong interaction between CCS clumps and the outflows. clumps and the outflows. Again, the CCS seems to be enhanced in shocked regions de Gregorio-Monsalvo, SOCHIAS 2009 CCS (contours) + IR outflow (gray) L1448: CCS emission L1448: CCS emission (de Gregorio-Monsalvo et al. in prep.) L1448-IRS3 L1448C  

15 Again: Spatial anticorrelation at scales of ~5’’ CCS (contours) and NH 3 (gray; Curiel et al. 1999) de Gregorio-Monsalvo, SOCHIAS 2009 L1448: CCS vs. NH 3 L1448: CCS vs. NH 3

16 L1448: Kinematics L1448: Kinematics CCS (contours + color) CCS (contours) + NH 3 (color) Vlsr Again: CCS and NH 3 show a kinematics associated with a strong interaction with the molecular outflows of the region. de Gregorio-Monsalvo, SOCHIAS 2009

17 General Conclusions 1. CCS and NH 3 survey in low-mass SFRs → six sources show CCS and NH 3 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 NH 3 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. de Gregorio-Monsalvo, SOCHIAS 2009

18 Thank you!

19 IRAS Improvement of ~30% in the SNR...cross-calibration on spectral lines is feasible!!!! Testing a new observation technique: cross-calibration in spectral line. - Simultaneous observations of CCS (22.35 GHz) and H 2 O (22.24 GHz). - Simultaneous observations of CCS (22.35 GHz) and H 2 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 detect radio continuum emission at ~1.3 cm (left panel). No CCS emission, but averaging the central 93 channels, allowed to detect radio continuum emission at ~1.3 cm (left panel). +BeforeAfter +BeforeAfter VLA-D VLA-B Continuum at 1.3 cm Continuum at 1.3 cm 3-5  3-7  de Gregorio-Monsalvo, SOCHIAS 2009


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