1 / 17

Multiplicity among embedded protostars

Multiplicity among embedded protostars. Gaspard Duch êne (Grenoble) J. Bouvier, S. Bontemps, P. André, F. Motte, A. Djupvik, A. Ghez. Multiplicity in Star Formation - Toronto - 16-18 May 2007. General background. Multiplicity well studied for ages  10 6 yrs. Large excess in some

hermione-holloway
Download Presentation

Multiplicity among embedded 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. Multiplicity among embedded protostars Gaspard Duchêne (Grenoble) J. Bouvier, S. Bontemps, P. André, F. Motte, A. Djupvik, A. Ghez Multiplicity in Star Formation - Toronto - 16-18 May 2007

  2. General background • Multiplicity well studied for ages  106 yrs Large excess in some young populations Scaled MF from VB surveys Apparent dependence on environment T Tauri stars open clusters field Multiplicity in Star Formation - Toronto - 16-18 May 2007

  3. General background • Interpretation still ambiguous: Scaled MF from VB surveys ? Multiplicity in Star Formation - Toronto - 16-18 May 2007

  4. General background • Interpretation still ambiguous: Tracer of different initial states ? Scaled MF from VB surveys  Physics of core fragmentation Higher cloud mass Multiplicity in Star Formation - Toronto - 16-18 May 2007

  5. General background • Interpretation still ambiguous: Tracer of different initial states ? Scaled MF from VB surveys  Physics of core fragmentation Denser clusters Tracer of a different early evolution ? Stellar dynamics Multiplicity in Star Formation - Toronto - 16-18 May 2007

  6. General background • Need to survey even younger systems: • Embedded protostars ! Class 0 age ~ 104 yrs, radio Scaled MF from VB surveys ? Class I age ~ 105 yrs, IR Reipurth (2000) 80-85% MF Multiplicity in Star Formation - Toronto - 16-18 May 2007

  7. This work : basic presentation • Objective: survey of protostars with deep, high resolution, NIR imaging • Several SFRs • Taurus vs. Orion • Focus on • Class I • Flat Spectrum (FS) FS Class I Kaas et al. (2004) Multiplicity in Star Formation - Toronto - 16-18 May 2007

  8. This work : basic presentation • Observations: • Seeing-limited: CFHT-IR (0.6”) JHK • Diffraction-limited: VLT-NACO (0.07”) HKL’ CFHT-IR VLT-NACO ~7 mag ~7 mag 1’’ 10’’ 0.1’’ 1’’ 10’’ Duchene et al. (2007) Duchene et al. (2004) Multiplicity in Star Formation - Toronto - 16-18 May 2007

  9. Additional sample • When available, we also added older HST/NICMOS images to our survey • Somewhat poorer resolution (0.15’’) • Higher PSF stability • Higher sensitivity (fainter targets) 0.24’’ Padgett et al. (1999) Multiplicity in Star Formation - Toronto - 16-18 May 2007

  10. This work : sample • Overview of our sample: Multiplicity in Star Formation - Toronto - 16-18 May 2007

  11. This work : sample • Sample represents ~40% of all known Class Is and FSs in each cloud • Magnitude bias • Population distributed in all clouds • Not densely clustered (except in Serpens) • Serpens and Orion: higher luminosities Multiplicity in Star Formation - Toronto - 16-18 May 2007

  12. New tight systems IRAS 04361+2547 ? VLT-NACO Ks HST-NICMOS H Terebey et al. (1998) 0.31’’ Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16-18 May 2007

  13. Results : multiplicity rates • 110-1400 AU: 27 +/- 6 % (Tau+Oph) • 14-1400 AU: 45 +/- 8 % (Tau+Oph) • 45-1400 AU: 30 +/- 6 % (all clouds) • consistent with Reipurth et al. (2004) • Factor ~1.5 excess over field stars • No cloud-to-cloud difference • First evidence for high early MF in Orion ! Multiplicity in Star Formation - Toronto - 16-18 May 2007

  14. Results : multiplicity rates • Dependence on evolutionary stage? NO! • Class I vs. FS sources: • No significant difference • Objects with extended envelope: • Supposedly younger than other ClassI objects • Seeing-limited observations suggested a trend… • … but diffraction-limited observations proved otherwise Multiplicity in Star Formation - Toronto - 16-18 May 2007

  15. Results : other properties • Masses unknown from luminosity and IR fluxes • Need HR spectroscopy for mass ratios • High-order multiples: 5 triples overall • Not more than found among T Tauri stars or, probably, field stars • No unstable multiple system • Already destroyed or never existed Multiplicity in Star Formation - Toronto - 16-18 May 2007

  16. Results: other properties • Same MF in all clouds but differences in the distribution of separations Orion is different from other clouds at the 2.7  level (99.3%) Taurus All Orion companions Needs confirmation with larger samples Ophiuchus Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16-18 May 2007

  17. Overview and implications • High multiplicity rate of Class I and FS sources in all clouds • Even in the Orion molecular cloud ! • No many-star systems left by ~105 yrs • Consistent with quasi-universal scenario • Small-scale physics dominates fragmentation and/or early dynamical evolution Multiplicity in Star Formation - Toronto - 16-18 May 2007

More Related