1 / 19

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)

ocean-santos
Télécharger la présentation

Ammonia and CCS as diagnostic tools of low-mass protostars

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 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)

  2. de Gregorio-Monsalvo, SOCHIAS 2009 Molecular lines as diagnosis tools of the interestellar medium Physical conditions: - The excitation conditions depend on TK, n H2 and the radiation field. - Molecular clouds: TK~ 10 K → excites lowest rotational transitions - From line intensities: Tex, τ, N Kinematics: - Linewidthsand shapes→ turbulent and systemic motions of the gas Stage of evolution: - Time-dependent chemistry and the spatial distribution of some species (e.g. NH3 (late-type molecule) and CCS (early-type molecule)).

  3. de Gregorio-Monsalvo, SOCHIAS 2009 Why CCS is interesting? “CCS spectral lines are a powerful tool to study YSOs” 1. High density gas tracer: • Structure and physical conditions of the cloud. •Intense in cold quiescent cores. 2. Kinematics: • No splitting in hyperfine structure 3.Evolutionary stage of molecular clouds. • Spatial anticorrelation between CCS and ammonia. •[CCS] / [NH3] indicator of cloud evolution.

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

  5. RESULT: 6 detections in CCS and NH3 (de Gregorio-Monsalvo et al. 2006) de Gregorio-Monsalvo, SOCHIAS 2009 CCS and NH3 survey in low-mass star forming regions (SFRs) GOALS: 1- Find good candidates for interferometric observations. 2- Relation between CCS and physical characteristics and age of star forming regions. • SURVEY: 40 young low-mass star forming • regions using the Robledo-70m (NASA • DSS-63) antenna at 22 GHz (1cm). • SELECTION CRITERIA: Low-mass regions with presence of H2O maser • emission at 22 GHz (traces star formation activity and youth; Furuya 2001)

  6. de Gregorio-Monsalvo, SOCHIAS 2009 Survey conclusions • Dependencies of CCS emission on source and cloud parameters (stadistical study): - No relation with source luminosity, radio continuum and water maser flux densities, nor with molecular outflows parameters (RC, M, , LCO, P, F, Ekin). - CCS emitting regions show NH3 spectrum with narrow v → less turbulence, younger regions • Ammonia linewidths broader than CCS ones: - CCS and ammonia trace different regions

  7. de Gregorio-Monsalvo, SOCHIAS 2009 VLA interferometric observations Observations at ~1.3cm (22 GHz) in CCS, H2O, and NH3 Very Large Array, New Mexico (USA). GOALS : 1- Study physical conditions, kinematics, and interaction with the medium at high-angular resolution. 2- Test the distribution of CCS vs. NH3 in SFRs at small scales SOURCES : B1-IRS, L1448C and L1448-IRS3

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

  9. CCS Vlsr 10000 AU at 350 pc (de Gregorio-Monsalvo et al. 2005) de Gregorio-Monsalvo, SOCHIAS 2009 B1-IRS: CCS emission • CCS emission is clumpy. • Redshifted clumps. • Velocity gradient blue- • shifted towards the • central source

  10. CCS Vlsr 10000 AU at 350 pc (de Gregorio-Monsalvo et al. 2005) (de Gregorio-Monsalvo et al. 2005) de Gregorio-Monsalvo, SOCHIAS 2009 B1-IRS: CCS emission - Strong interaction with the molecular outflow - CCS enhanced via shocked induced chemistry?

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

  12. L1448-IRS3 Blue L1448-IRS2 L1448C Red de Gregorio-Monsalvo, SOCHIAS 2009 L1448 • 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)

  13. de Gregorio-Monsalvo, SOCHIAS 2009 L1448: CCS emission Vlsr H2O L1448-IRS3  Vlsr L1448C  H2O CCS (contours) + IR outflow (gray) H2O masers

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

  15. de Gregorio-Monsalvo, SOCHIAS 2009 L1448: CCS vs. NH3 Again: Spatial anticorrelation at scales of ~5’’ CCS (contours) and NH3(gray; Curiel et al. 1999)

  16. Vlsr Vlsr de Gregorio-Monsalvo, SOCHIAS 2009 L1448: Kinematics CCS (contours + color) CCS (contours) + NH3 (color) Again: CCS and NH3 show a kinematics associated with a strong interaction with the molecular outflows of the region.

  17. de Gregorio-Monsalvo, SOCHIAS 2009 General 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.

  18. de Gregorio-Monsalvo, SOCHIAS 2009 Thank you!

  19. Before Before VLA-D VLA-B Continuum at 1.3 cm Continuum at 1.3 cm + + After After de Gregorio-Monsalvo, SOCHIAS 2009 IRAS 16293-2422 Testing a new observation technique: cross-calibration in spectral line. - Simultaneous observations of CCS (22.35 GHz) and H2O (22.24 GHz). - Self-calibration of H2O masers to correct for atmospheric variations. • No CCS emission, but averaging the central 93 channels, allowed to detect radio continuum emission at ~1.3 cm (left panel). 3-5  3-7  (de Gregorio-Monsalvo et al. in prep.) Improvement of ~30% in the SNR ...cross-calibration on spectral lines is feasible!!!!

More Related