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

2. ? ? ? ? ? ? ? ? ? ? ? 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

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

4. 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

5. ? 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 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

6. ? ? ? ? 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? ? ?

7. 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

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

9. 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 =
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

10. 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

11. Ophiuchus Disk Masses Number Mdisk (Msun) 0.02 0.04 0.06 0.08 0.1 0.125 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

12. 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)

13. 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 Bodenheimer & Pollack 1986
Time (Myr)
0.001
0.1
1.0
Grav. Instability formation time
Core acc. formation time

14. 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

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

16. 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

17. 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

18. 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

19. 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

20. 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)

21. 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)

22. 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

23. 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

24. 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

25. 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