Resolving Debris Disks with (Sub)Millimeter Interferometry

September 19, 2005 STScI Workshop: Nearby Resolved Debris Disks 1

Resolving Debris Disks with (Sub)Millimeter Interferometry

David J. Wilner (Harvard-Smithsonian CfA)

• Why (Sub)Millimeter?• Interferometry & Limitations• A Few Examples• Future Prospects


Why Millimeter and Submillimeter? • (Sub)millimeter: thermal emission from dust particles

– sample low temperature dust – favorable contrast with stellar photosphere– sample large dust

G2V star HD107146

Williams et al. 2004

excess>25 m

T=51 K

T=100 K


scattered light emitted light

spatial resolutioncontrast with star

temperature dependence

optical/near-ir far-ir/submmmid-ir

Observational Probes of Structure

Williams et al. 2004

HST Ardila et al. 2005

JCMT Williams et al. 2004


(Sub)Millimeter Interferometry• way to achieve high angular resolution

– obtain ~1 arcsec (/1.3mm)(D/300 m)

• excellent control of systematics for weak continuum

BIMA

IRAM PdBI

SMA

OVRO


Limitations: Sensitivity• nearby debris disks: 10’s of mJy (850 m)• interferometer sensitivity: rms ~1 mJy in ~8 hours

– modest collecting area (SMA ~ JCMT, PdBI ~ IRAM 30m)– modest bandwidths (~2 GHz) vs. bolometers (~50 GHz)– room for improvement in detectors (not quantum limited)– problematic atmosphere: transparency & seeing


Limitations: Imaging Capability• (Sub)millimeter fields of view are small (<1 arcmin)• measure Fourier components of source brightness

– this is not direct imaging...– sampling is limited (“uv coverage”)

with small N (<9) arrays– largest structures not sampled


Large dust Small dust• structure depends on =Frad/Fgrav

– smallest particles blown out quickly– small particles drop of out resonances– large particles stay in resonances

• Vega (Su et al. 2005) – mid-ir & far-ir smooth;

submm clumpy

large

small

Moro-Martin & Malhotra 2003

Holland et al. 1998


Vega: 1.3 mm Interferometry

PdBI: Wilner et al. 2002 OVRO: Koerner et al. 2001

• angular resolution: 2 to 5 arcsec• stellar photosphere provides calibration check• dust blobs are robust, spatially extended• motivates dynamical modeling


• structure created when resonances filled by – inward migration of dust due to P-R drag– outward migration of planet traps planetesimals (like Neptune)

Dynamical Scenarios

Wilner et al. 2002

Wyatt 2003


HD107146: 3 mm Interferometry

• OVRO resolves dust (Carpenter et al. 2005)


HD107146 (cont.)

• predictions for SMA


Future Prospects: SMA, CARMA, ALMA• good sites

• SMA– access to

850, 450 m

• CARMA: – 1.3 mm– larger bw– larger N (15 to 23)


Atacama Large Millimeter Array

• very large array (n= >50 x 12 m + 12 x 7 m), North America, Europe, and Japan: ~$1B

• best possible site, Atacama at 5000 m, sensitivity 100x, high fidelity imaging

2012?


Summary

• (Sub)millimeter: key spectral regime for debris disk structure

• interferometry: (only) way to obtain high angular resolution, but limited: sensitivity, imaging, small fields of view

• examples: IRAM/OVRO results are few but intriguing

• future prospects: SMA, CARMA will provide new data; ALMA will qualitatively change the debris disk field


END


JCMT 850 m SCUBA Images

• “Fantastic Four”: ring morphologies, cleared interiors, offset peaks (Holland et al. 1998, Greaves et al. 1998, etc., ...)

• sculpting by planets? only viable explanation

• submillimeter probes outer cold regions, long orbital periods


Eridani: 350 m CSO Image

Wilner, Dowell, et al.


Debris Disk Evolution

• Sptizer A star data: 24 m excess declines, scatter (“outbursts”) present at all ages (Rieke et al. 2004)

• compatible? with collisionally dominated planetismal disks (Dominik & Decin 2003, Kenyon & Bromley 2004)

~1/t

Resolving Debris Disks with (Sub)Millimeter Interferometry

Documents

Transcript of Resolving Debris Disks with (Sub)Millimeter Interferometry