Multiplicity among embedded protostars Gaspard Duchne Grenoble J

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

General background Multiplicity well studied for ages 106 yrs Scaled MF from VB surveys T Tauri stars open clusters Multiplicity in Star Formation - Toronto - 16 -18 May 2007 field

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

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

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

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

General background Need to survey even younger systems: Embedded protostars ! Scaled MF from VB surveys ? Multiplicity in Star Formation - Toronto - 16 -18 May 2007

General background Need to survey even younger systems: Embedded protostars ! Class 0 age ~ 104 yrs, radio Class I age ~ 105 yrs, IR Scaled MF from VB surveys ? Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

This work : basic presentation Objective: survey of protostars with deep, high resolution, NIR imaging Several SFRs Taurus vs. Orion Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

This work : basic presentation Observations: Seeing-limited: CFHT-IR (0. 6”) JHK CFHT-IR ~7 mag 1’’ Duchene et al. (2004) 10’’ Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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 1’’ Duchene et al. (2004) 10’’ 0. 1’’ 10’’ Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

This work : sample Overview of our sample: Taurus Ophiuchus Serpens Orion CFHT-IR Class I FS 12 10 16 25 - VLT-NACO Class I FS 11 5 12 10 2 6 4 8 Multiplicity in Star Formation - Toronto - 16 -18 May 2007

This work : sample Sample represents 30 -50% of all known Class Is and FSs in each cloud Magnitude bias Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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) Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

New tight systems Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16 -18 May 2007

New tight systems IRAS 04361+2547 ? VLT-NACO Ks HST-NICMOS H Terebey et al. (1998) Duchene et al. (2007) 0. 31’’ Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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) Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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 Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

Results : multiplicity rates Dependence on evolutionary stage? Multiplicity in Star Formation - Toronto - 16 -18 May 2007

Results : multiplicity rates Dependence on evolutionary stage? Class I vs. FS sources: No significant difference Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

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

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

Results : other properties Masses unknown from luminosity and IR fluxes Need HR spectroscopy for mass ratios Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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 Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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

Results: other properties Same MF in all clouds but differences in the distribution of separations Taurus Ophiuchus Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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 Ophiuchus Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16 -18 May 2007 All Orion companions

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%) Needs confirmation with larger samples Taurus Ophiuchus Duchene et al. (2007) Multiplicity in Star Formation - Toronto - 16 -18 May 2007 All Orion companions

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 Multiplicity in Star Formation - Toronto - 16 -18 May 2007

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