Spatially Resolved Millimeter Observations of Pre-Main Sequence Binaries Jenny Patience Thanks Merci

? ? ? ? ? ? ? ? ? ? ? Outstanding Questions Are binary stars likely sites of planet formation? How do disk properties vary with mass and environment? ? ? ? ? ? ? ? ? • These observations probe the size scales and timescales important for disks

Background - Binaries Binary Frequency in Different Samples People ~1%

Entire disk few arcsecond resolution Approach • Millimeter Interferometry (E. Jensen (Swarthmore), L. Prato (Lowell), R. Akeson(MSC)) Entire disk few arcsecond resolution Separate binary components Sample: Class I and II Binaries Cool Outer Disks • Interferometer - Angular resolution limit determined by the longest baseline l/Bmax = 1”.3 at 3mm OVRO Interferometer Adjustable, Bmax = 440m • Single Aperture - Angular resolution limit set by the telescope diameter IRAM 30m, l/D ~ 11” - cannot resolve many multiple sources (1mm) confusion with the cloud emission l/D

? OVRO Interferometer Project - Outer Disks in Young Binaries Class I Sample: Binaries in Ophiuchus (Class I/II) and Taurus (Class I) Separation resolvable w/OVRO 1”.5-4” beam (100’s - 1000 AU) Flux detectable based on 1mm (Haisch et al. 2004, Duchene et al. 2003, Simon et al. 1995, Motte & Andre 2001, Andre & Montmerle 1994) ? Class I Class II Class 0 Material around each star + extended envelope Is there disk material around each star? Primary disk, but little/no Secondary disk material

? ? ? ? Previous Observations • Ophiuchus Class 0 systems show a disk around each binary component (Wooten 1989) (Looney et al. 2000) • Taurus Class II systems show a strong bias for primary disks (Jensen & Akeson 2003) ? ? • What happens to disks during the Class I/II stage in Ophiuchus and Class I stage in Taurus? ? ?

Ophiuchus Continuum Images IRS 43 L1689SNO2 Class I Targets SR 24 Elias 30 Class II Targets Millimeter emission dominated by primary Circumsecondary disk masses very limited even at Class I stage IR excesses, Ha indicate there is hotter, inner disk material and accretion

Ophiuchus Spectral Line Results • IRS43 Primary rotating gas disk • SR 24 Secondary CO emission, but no continuum IRS 43 SR 24

Dust Opacity Scaling Solve for power law index b k(v) = ko ( v / vo)b Assign previously measured 1.3mm (240 GHz) flux to primary and combine with new 3mm (112 GHz) flux: log(F240GHz / F112GHz) log(240 GHz / 112 GHz) b = - 2 values range from 0.0 ± 0.2 to 1.6 ± 0.4 within range of previous measurements of T Tauri stars lower than ~2 expected from interstellar dust grains Possible explanations: grain growth, differences in composition/structure of grains

Disk Masses Disk masses are calculated from the 3mm flux and the value of b F3mm (mJy) D2 (pc) 6.4x107 T (K) k MD (Msun) = k(112GHz) = 0.01 (112 GHz / 1000 GHz)b This assumes that the material is optically thin Optically thin Optically thick

Ophiuchus Disk Masses Number Mdisk (Msun) 0.02 0.04 0.06 0.08 0.1 0.12 5 10 15 20 25 0.02 0.04 0.06 0.08 0.1 0.12 Mdisk (Single) Mdisk (Binary) Number Mdisk (Msun) L1689SNO2 IRS 43 SR 24 Elias 30 Minimum Mass Solar Nebula Disk masses shown with T=15-30K Comparable to disk masses measured for Taurus members based on single dish data Comparable to Minimum Mass Solar Nebula Sufficient material for planet formation

Evolution of Dust Disks in Ophiuchus Binaries Class 0 (2 disks) What is the dissipation timescale for the secondary disk ? Class I (1 disk) Class II (1 disk)

Theoretical Planet Formation Timescales Majority of secondary disk mass dissipated by Class I stage How does this compare to planet formation timescales? 2 categories of giant planet formation models: Gravitational Instability Core formation by accumulation Faster Favored Boss 1997 Bodenheimer & Pollack 1986 Time (Myr) 0.001 0.1 1.0 Grav. Instability formation time Core acc. formation time

Ages of Class I/II Stars Stellar Ages difficult to determine Class II ages from comparison with theoretical evolutionary tracks Stellar spectra determine temperature and luminosity Typical ages ~1-few Myr Class I ages often estimated statistically Difficult to detect photospheric features, but some detected 10-15% as many Class I objects as Class II objects Lifetime based on comparison with models Lifetime based on statistics 1 Myr 1 Myr

Implications for Planet Formation Time (Myr) 0.001 0.1 1.0 Grav. Instability formation time Core acc. formation time

Implications for Planet Formation Oph Class I (IRS 43) R~18,000 Oph Class I lifetime (statistical) Oph Class II/III R~1000 Time (Myr) 0.001 0.1 1.0 Grav. Instability formation time Core acc. formation time Oph: Luhman & Reike 1999, Greene & Lada 2002

Implications for Planet Formation Oph Class I (IRS 43) R~18,000 Tau Class I/II R~30,000 Tau Class I lifetime (statistical) Oph Class I lifetime (statistical) Oph Class II/III R~1000 Time (Myr) 0.001 0.1 1.0 Grav. Instability formation time Core acc. formation time Oph: Luhman & Reike 1999, Greene & Lada 2002, Tau: White & Hillenbrand 2004 • If Class I systems are younger, then there may not have been sufficient time to form giant planets through the gradual accumulation of planetesimals in the secondary disks

Comparison with Radial Velocity Planets Ophiuchus OVRO results show little disk material around secondaries relative to primaries -- how does this compare to the frequency of planets around secondaries relative to primaries? 4 planets = 4% 111 primaries CCDM catalogue 889 r.v. targets 25 secondaries 1 planet = 4% (Nidever et al. 2002) 60” cutoff contains 65 planet stars A few additional primary and secondary host stars among the planet stars not listed in Nidever et al. 2002 • Frequency of planets around secondaries appears similar to primaries despite differences in disk masses at earlier stages, but small number statistics

Binary Formation Models Scale-free Fragmentation (Clarke 2000) Accretion after Fragmentation (Bate & Bonnell 1997, Bate 2000) Disk-assisted Small-N Capture (McDonald & Clarke 1995) Disruptive to disks, stronger effect for smaller separations More massive star has more massive disk Disk mass ratio is a function of stellar mass ratio

Comparison with Binary Formation Models • Class II systems have known stelar mass ratio • Disk mass ratio expected to be similar to stellar mass Ratio (e.g. Bate 2000) • Dashed lines evolution of 50 AU binary from 105-5x106 yrs (Armitage et al. 1999)

Taurus Continuum Images • 4 Taurus Class I binaries observed, 3 detected • Both circumprimary and circumsecondary disks detected Secondary disk lifetimes longer for Taurus systems IRAS04113 IRAS04191 IRAS04325 A disk dominant A and B disk similar B disk dominant In some cases accretion onto secondary is favored (e.g. low eccentricity, moderate mass ratio - Artymowicz & Lubow 1996 accretion of high angular momentum material - Bate & Bonnell 1997)

Taurus Continuum Results • Possible explanations Secondary star actually more massive Small statistics skewed initial results • Follow-up program to obtain spectra of each component (with L. Prato, Lowell) IRAS04113 M3 Spectral Type M0-1.5 Spectral Type

Upcoming Improvements • CARMA/ALMA mm arrays CARMA photo: A. West ALMA site • CARMA/ALMA will have resolution sensitivity to investigate the peak of the binary distribution OVRO 3mm Future CARMA/ALMA

CARMA Observations of Perseus • 3mm Observations of Class 0/I Members of NGC 1333 10” 10” 10” 10” CARMA 3mm map CSO 350µm Map of NGC 1333 CARMA 3mm maps

Summary and Conclusions Ophiuchus: • Primary dominates mm emission for both Class I and Class II sources • Circumprimary disk masses comparable to other single/binary T Tauri stars and the Minimum Mass Solar Nebula • Circumsecondary disk masses very limited even at early evolutionary stage may be difficult to form planets around these stars • Dust opacity index consistent with grain growth Taurus: • Secondary disks often detected in Class I binaries, unlike Ophiuchus results