Steve BoudreaultSteve Boudreault

ASTRO DEBATA Tuesday 24th of February 2009The formation of brown The formation of brown dwarfs as revealed by dwarfs as revealed by the mass function of IC the mass function of IC 23912391

Collaborators (MPIA) :Collaborators (MPIA) : Coryn Bailer-Jones Coryn Bailer-Jones

Reinhard MundtReinhard MundtThomas HenningThomas Henning

Wei WangWei WangMario GennaroMario Gennaro

(external) :(external) : JosJoséé Caballero, U of Mardid Caballero, U of Mardid

IAC, Canary IslandsIAC, Canary IslandsRay Jayawardhana, U of TorontoRay Jayawardhana, U of Toronto

Postdoctoral researcher at the Postdoctoral researcher at the

Max-Planck-Institut für AstronomieMax-Planck-Institut für Astronomie

Heidelberg, GermanyHeidelberg, Germany

Theoretical Background Theoretical Background

Photometric Survey Photometric Survey

Spectroscopic Follow-up Spectroscopic Follow-up

Future WorkFuture Work

Today, I will talk about …

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 33

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

How to form brown How to form brown dwarfs ? dwarfs ?

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 44

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binaries presence / distribution of binaries

kinematics / spatial distributionkinematics / spatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

Grether & Lineweaver ( 2006 )Grether & Lineweaver ( 2006 ) P < 5 yr (≤ 3AU for BD) & D ≤ P < 5 yr (≤ 3AU for BD) & D ≤ 50pc50pc

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 55

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binariespresence / distribution of binaries

kinematics / spatial distributionkinematics / spatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

( Taurus star-forming region ( Taurus star-forming region ))

Kumar & Schmeja (2007)

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 66

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binaries presence / distribution of binaries

kinematics / spatial distributionkinematics / spatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

M9.5 M9.5

M ~ 15 M ~ 15 MMJJ

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 77

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binaries presence / distribution of binaries

kinematics / spatial distributionkinematics / spatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

Muench et al. (2002)Bouvier et al. (2008)

Briceño et al. (2002)

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 88

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binaries presence / distribution of binaries

kinematics / spatial distributionkinematics / spatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

Bate & Bonnell, 2005, MNRAS, 356, Bate & Bonnell, 2005, MNRAS, 356, 12011201Numerical simulation of compression & Numerical simulation of compression & fragmentation of a molecular cloudfragmentation of a molecular cloud ⇨ ⇨ BDs form via the ejection scenarioBDs form via the ejection scenario

Bonnell et al. 2008, MNRAS, 389, 1556Bonnell et al. 2008, MNRAS, 389, 1556Numerical simulation of compression & Numerical simulation of compression & fragmentation of a molecular cloud fragmentation of a molecular cloud ⇨ ⇨ BDs form like stars in high gas densityBDs form like stars in high gas density

Luhman et al. 2007, Luhman et al. 2007, Protostar and Protostar and Planets VPlanets Vastro-ph/06085461astro-ph/06085461Review of observational signaturesReview of observational signatures

⇨ ⇨ Common formation for BDs and starsCommon formation for BDs and stars

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 99

⇨ ⇨ Compression & fragmentation of molecular cloud (star-Compression & fragmentation of molecular cloud (star-like)like)

⇨ ⇨ ( - )Formation in circumstellar disk planet like ( - )Formation in circumstellar disk planet like ⇨ ⇨ - ( , Interruption of star like accretion ejection - ( , Interruption of star like accretion ejection

)photoevaporation)photoevaporation

Theoretical Background :Theoretical Background : different formation different formation mechanisms of brown dwarfsmechanisms of brown dwarfs

Distinction between these scenarios : Distinction between these scenarios :

presence / distribution of binaries presence / distribution of binaries

kinematics / kinematics / spatial distributionspatial distribution

presence of circumstellar disk presence of circumstellar disk

Mass function (MF)Mass function (MF)

For our project …

⇦

⇦

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1010

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

IC 2391 is an interesting target because … IC 2391 is an interesting target because …

objects in clusters have same metallicity and are objects in clusters have same metallicity and are coevalcoeval

near : distance is 146pc ( Robichon et al., 1999 ) near : distance is 146pc ( Robichon et al., 1999 )

age of 50Myr ( Barrado y Navascués et al, 2004) age of 50Myr ( Barrado y Navascués et al, 2004)

⇨⇨not too young ( extinction due to molecular gaz )not too young ( extinction due to molecular gaz )

⇨⇨not too old ( relaxation time is 104.9Myr, optical not too old ( relaxation time is 104.9Myr, optical data )data )

low reddening : E(low reddening : E(BB--VV) = 0.01 ( Randoch et al., 2001 )) = 0.01 ( Randoch et al., 2001 )

previous study of MF : completness limit of 0.072Mprevious study of MF : completness limit of 0.072M

no radial study of IC 2391 yetno radial study of IC 2391 yet

Why the open cluster IC IC 23912391 ?

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1111

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

35 ESO/WFI fields of 34’x33’35 ESO/WFI fields of 34’x33’

( ~ 10.9 deg( ~ 10.9 deg22 ) )

Fields chosen to …Fields chosen to …

⇨ ⇨ avoid bright starsavoid bright stars

⇨ ⇨ avoid MF gradient due toavoid MF gradient due to

low galactic latitude low galactic latitude b~-b~-6º6º

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1212

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

Wide bands Wide bands RRcc and and JJ

Medium bands at 770, Medium bands at 770, 815, 856 and 914 nm815, 856 and 914 nm

⇨ ⇨ ESO/WFI (optical data)ESO/WFI (optical data)

⇨ ⇨ CTIO/CPAPIRCTIO/CPAPIR (IR data) (IR data)

Those bands were chosen …

⇨to sample spectra of M and

L-dwarfs

⇨to minimize Earth-sky

background

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1313

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

1st selection : 1st selection : - Color-magnitude diagram- Color-magnitude diagram- Isochrones- Isochrones

2nd selection : - Color-color diagram- Isochrones- Red giant colors ( Hauschildt et al. 1999 ) - Color VS Teff for G, K, M and L dwarfs

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1414

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

3rd selection : 3rd selection : - Astrometry- Astrometry (from our 8 years baseline)(from our 8 years baseline)

4th selection : - M [obs] VS M [model] ( from Teff and mass )- Errors on age and distance of IC 2391 - Unresolved binaries

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1515

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

⇨ ⇨ Major : radial variation 0.15 MMajor : radial variation 0.15 M < M < 0.5 < M < 0.5 MM

⇨ Major : no radial variation M ≤ 0.11 M ⇨ Major : no radial variation M ≤ 0.11 M

⇨ Minor⇨ Minor : long spectral baseline = less M-: long spectral baseline = less M-dwarf contaminantsdwarf contaminants

⇨ Minor ⇨ Minor : medium band = less M-giant : medium band = less M-giant contaminantscontaminants

⇨ Minor ⇨ Minor : colour variation with : colour variation with E ( B – V )E ( B – V )

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1616

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

⇨ ⇨ Major : radial variation 0.15 MMajor : radial variation 0.15 M < M < 0.5 < M < 0.5 MM

⇨ Major : no radial ⇨ Major : no radial variation M ≤ 0.11variation M ≤ 0.11 M M

⇨ Minor⇨ Minor : long spectral baseline = less M-: long spectral baseline = less M-dwarf contaminantsdwarf contaminants

⇨ Minor ⇨ Minor : medium band = less M-giant : medium band = less M-giant contaminantscontaminants

⇨ Minor ⇨ Minor : colour variation with : colour variation with E ( B – V )E ( B – V )

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1717

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

⇨ ⇨ Major : radial variation 0.15 MMajor : radial variation 0.15 M < M < 0.5 < M < 0.5 MM

⇨ Major : no radial variation M ≤ 0.11 M⇨ Major : no radial variation M ≤ 0.11 M

⇨ Minor ⇨ Minor : long spectral baseline = less M-: long spectral baseline = less M-dwarf contaminantsdwarf contaminants

⇨ Minor ⇨ Minor : medium band = less M-giant : medium band = less M-giant contaminantscontaminants

⇨ Minor ⇨ Minor : colour variation with : colour variation with E ( B – V )E ( B – V )

Barrado y Navasqués et al. (2004)

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1818

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

⇨ ⇨ Major : radial variation 0.15 MMajor : radial variation 0.15 M < M < 0.5 < M < 0.5 MM

⇨ Major : no radial variation M ≤ 0.11 M ⇨ Major : no radial variation M ≤ 0.11 M

⇨ Minor⇨ Minor : long spectral baseline = less M-: long spectral baseline = less M-dwarf contaminantsdwarf contaminants

⇨ Minor ⇨ Minor : medium band = less M-giant : medium band = less M-giant contaminantscontaminants

⇨ Minor ⇨ Minor : colour variation with : colour variation with E ( B – V )E ( B – V )

Ο Jeffries et al. (2004)

Δ Naylor et al. (2002)

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 1919

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Photometric Survey : Photometric Survey : determination of the determination of the mass function for very low mass stars and brown mass function for very low mass stars and brown dwarfs population in IC 2391 and look for radial dwarfs population in IC 2391 and look for radial dependencedependence

⇨ ⇨ Major : radial variation 0.15 MMajor : radial variation 0.15 M < M < 0.5 < M < 0.5 MM

⇨ Major : no radial variation M ≤ 0.11 M ⇨ Major : no radial variation M ≤ 0.11 M

⇨ Minor ⇨ Minor : long spectral baseline = less M-: long spectral baseline = less M-dwarf contaminantsdwarf contaminants

⇨ Minor ⇨ Minor : medium band = less M-giant : medium band = less M-giant contaminantscontaminants

⇨ Minor⇨ Minor : colour variation with : colour variation with E ( B – V )E ( B – V ) Schlegel et al. (1998)

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2020

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Spectroscopic Follow-up : Spectroscopic Follow-up : improve candidate selection and spectral type determination

CTIO / HYDRA

2 Nights in January 2007

⇨1st lost (bad weather)

⇨2hrs lost (technical)

⇨Ic~18 ( 45 MJ )

FINALLY WE HAD 4HRS !!

( out of 12hrs awarded )

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2121

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Spectroscopic Follow-up : Spectroscopic Follow-up : improve candidate selection and spectral type determination

⇨measurement of EW

⇨SpT determination

⇨68% contamination

⇨MF ???

… but no red giants.

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2222

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Spectroscopic Follow-up : Spectroscopic Follow-up : improve candidate selection and spectral type determination

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2323

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Spectroscopic Follow-up : Spectroscopic Follow-up : improve candidate selection and spectral type determination

FROM PHOTOMETRY : Teff = 2791K M=0.058MFROM PHOTOMETRY : Teff = 2791K M=0.058M 815/20=17.54815/20=17.54

VVrr = 16.25±6.59 km/s = 16.25±6.59 km/s

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2424

Theoretical Background

Photometric Survey

Spectroscopic Follow-up

Future Work

Future Work : Future Work : follow-up on brown dwarfs candidates and survey on other open clusters

⇨ Other clusters : Praesepe (WFI, O2K, LBTC, WFC, ~45MJ)

Coma Ber (O2K, …)

Alessi 5 & ASCC 24 (WFI + O2K, ~20MJ)⇨ VLT/VIMOS for IC2391 (April 2008 --- February 2009)

’ What s next?

⇨ NTT/SofI (J & Ks) for IC2391 (deep fields)

⇨ Numerical simulation … evolution of MF of cluster with σv

Steve BoudreaultSteve Boudreault ASTRO DEBATA, 24.02.2009ASTRO DEBATA, 24.02.2009 2525

CONCLUSIONS AND REVIEW• We are interested in the formation and evolution of BDs

population

⇨ Survey in open cluster to obtain MF of VLMS and BDs• Photometric survey of IC 2391

⇨ MF shows no variation on the BDs and VLMS regime

⇨ if formed by ejection, velocity BDs = velocity VLMS

⇨ if velocity BDs > velocity VLMS and ejection give high velocity

for BDs, then ejection not dominant formation process

• However important contamination : spectroscopic follow-up NEEDEDNEEDED

⇨ Analyses of preliminary spectroscopic follow-up : 32% real members, no red giants and 7 new brown dwarfs … and additional data from VLT next spring• Still a lot of work and projects …

FROM PHOTOMETRY : Teff = 2791K M=0.058MFROM PHOTOMETRY : Teff = 2791K M=0.058M 815/20=17.54815/20=17.54

VVrr = 16.25±6.59 km/s = 16.25±6.59 km/s