PROTOPLANETARY DISK STRUCTURES IN OPHIUCHUS. II. EXTENSION TO FAINTER SOURCES
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
We present new results from a significant extension of our previous high angular resolution (0.''3 {approx} 40 AU) submillimeter array survey of the 340 GHz (880 {mu}m) thermal continuum emission from dusty circumstellar disks in the {approx}1 Myr old Ophiuchus star-forming region. An expanded sample is constructed to probe disk structures that emit significantly lower millimeter luminosities (hence dust masses), down to the median value for T Tauri stars. Using a Monte Carlo radiative transfer code, the millimeter visibilities and broadband spectral energy distribution for each disk are simultaneously reproduced with a two-dimensional parametric model for a viscous accretion disk that has a surface density profile {Sigma} {proportional_to} (R/R{sub c}){sup -}{gamma}exp [- (R/R{sub c}){sup 2-}{gamma}]. We find wide ranges of characteristic radii (R{sub c} = 14-198 AU) and disk masses (M{sub d} = 0.004-0.143 M{sub sun}), but a narrow distribution of surface density gradients ({gamma} = 0.4-1.1) that is consistent with a uniform value ({gamma}) = 0.9 {+-} 0.2 and independent of mass (or millimeter luminosity). In this sample, we find a correlation between the disk luminosity/mass and characteristic radius, such that fainter disks are both smaller and less massive. We suggest that this relationship is an imprint of the initial conditions inherited by the disks at their formation epoch, compare their angular momenta with those of molecular cloud cores, and speculate on how future observations can help constrain the distribution of viscous evolution timescales. No other correlations between disk and star properties are found. The inferred disk structures are briefly compared with theoretical models for giant planet formation, although resolution limitations do not permit us to directly comment on material inside R {approx} 20 AU. However, there is some compelling evidence for the evolution of dust in the planet formation region: 4/17 disks in the sample show resolved regions of significantly reduced millimeter optical depths within {approx}20-40 AU of their central stars.
- OSTI ID:
- 21471267
- Journal Information:
- Astrophysical Journal, Vol. 723, Issue 2; Other Information: DOI: 10.1088/0004-637X/723/2/1241; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
ANGULAR MOMENTUM
DUSTS
EMISSION
ENERGY SPECTRA
GOLD 198
INTERSTELLAR GRAINS
LUMINOSITY
MONTE CARLO METHOD
PLANETS
PROTOPLANETS
RADIANT HEAT TRANSFER
STAR ACCRETION
T TAURI STARS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BINARY STARS
CALCULATION METHODS
DAYS LIVING RADIOISOTOPES
ENERGY TRANSFER
ERUPTIVE VARIABLE STARS
EVOLUTION
GOLD ISOTOPES
HEAT TRANSFER
HEAVY NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
NUCLEI
ODD-ODD NUCLEI
OPTICAL PROPERTIES
PARTICLES
PHYSICAL PROPERTIES
RADIOISOTOPES
SPECTRA
STAR EVOLUTION
STARS
VARIABLE STARS