We utilize ALMA archival data to estimate the dust disk size of 152 protoplanetary disks in Lupus (1-3 Myr), Chamaeleon I (2-3 Myr), and Upper-Sco (5-11 Myr). We combine our sample with 47 disks from ...Tau/Aur and Oph whose dust disk radii were estimated, as here, through fitting radial profile models to visibility data. We use these 199 homogeneously derived disk sizes to identify empirical disk-disk and disk-host property relations as well as to search for evolutionary trends. In agreement with previous studies, we find that dust disk sizes and millimeter luminosities are correlated, but show for the first time that the relationship is not universal between regions. We find that disks in the 2-3 Myr old Cha I are not smaller than disks in other regions of similar age, and confirm the Barenfeld et al. finding that the 5-10 Myr USco disks are smaller than disks belonging to younger regions. Finally, we find that the outer edge of the solar system, as defined by the Kuiper Belt, is consistent with a population of dust disk sizes which have not experienced significant truncation.
We present a high-resolution (∼0 12, ∼16 au, mean sensitivity of 50 Jy beam−1 at 225 GHz) snapshot survey of 32 protoplanetary disks around young stars with spectral type earlier than M3 in the ...Taurus star-forming region using the Atacama Large Millimeter Array. This sample includes most mid-infrared excess members that were not previously imaged at high spatial resolution, excluding close binaries and objects with high extinction, thereby providing a more representative look at disk properties at 1-2 Myr. Our 1.3 mm continuum maps reveal 12 disks with prominent dust gaps and rings, 2 of which are around primary stars in wide binaries, and 20 disks with no resolved features at the observed resolution (hereafter smooth disks), 8 of which are around the primary star in wide binaries. The smooth disks were classified based on their lack of resolved substructures, but their most prominent property is that they are all compact with small effective emission radii (Reff,95% 50 au). In contrast, all disks with Reff,95% of at least 55 au in our sample show detectable substructures. Nevertheless, their inner emission cores (inside the resolved gaps) have similar peak brightness, power-law profiles, and transition radii to the compact smooth disks, so the primary difference between these two categories is the lack of outer substructures in the latter. These compact disks may lose their outer disk through fast radial drift without dust trapping, or they might be born with small sizes. The compact dust disks, as well as the inner disk cores of extended ring disks, that look smooth at the current resolution will likely show small-scale or low-contrast substructures at higher resolution. The correlation between disk size and disk luminosity correlation demonstrates that some of the compact disks are optically thick at millimeter wavelengths.
A likely planet-induced gap in the disc around T Cha Hendler, Nathanial P; Pinilla, Paola; Pascucci, Ilaria ...
Monthly Notices of the Royal Astronomical Society Letters,
03/2018, Letnik:
475, Številka:
1
Journal Article
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Abstract
We present high-resolution (0.11 × 0.06 arcsec2) 3 mm ALMA observations of the highly inclined transition disc around the star T Cha. Our continuum image reveals multiple dust structures: an ...inner disc, a spatially resolved dust gap, and an outer ring. When fitting sky-brightness models to the real component of the 3 mm visibilities, we infer that the inner emission is compact (≤1 au in radius), the gap width is between 18 and 28 au, and the emission from the outer ring peaks at ∼36 au. We compare our ALMA image with previously published 1.6 μm VLT/SPHERE imagery. This comparison reveals that the location of the outer ring is wavelength dependent. More specifically, the peak emission of the 3 mm ring is at a larger radial distance than that of the 1.6 μm ring, suggesting that millimeter-sized grains in the outer disc are located farther away from the central star than micron-sized grains. We discuss different scenarios to explain our findings, including dead zones, star-driven photoevaporation, and planet-disc interactions. We find that the most likely origin of the dust gap is from an embedded planet, and estimate – for a single planet scenario – that T Cha's gap is carved by a 1.2MJup planet.
Abstract
With the growing numbers of asteroids being discovered, identifying an observationally complete sample is essential for statistical analyses and for informing theoretical models of the ...dynamical evolution of the solar system. We present an easily implemented method of estimating the empirical observational completeness in absolute magnitude,
, as a function of semimajor axis. Our method requires fewer assumptions and decisions to be made in its application, making results more transportable and reproducible among studies that implement it, as well as scalable to much larger data sets of asteroids expected in the next decade with the Vera C. Rubin Observatory’s Legacy Survey of Space and Time. Using the values of
(
a
) determined at high resolution in semimajor axis,
a
, we demonstrate that the observationally complete sample size of the main belt asteroids is larger by more than a factor of 2 compared with using a conservative single value of
, an approach often adopted in previous studies. Additionally, by fitting a simple, physically motivated model of
(
a
) to ∼7 × 10
5
objects in the Minor Planet Database, our model reveals statistically significant deviations between the main belt and the asteroid populations beyond the main belt (Hungarias, Hildas, and Trojans), suggesting potential demographic differences, such as in their size, eccentricity, or inclination distributions.
Abstract
The properties of disks around brown dwarfs and very low mass stars (hereafter VLMOs) provide important boundary conditions on the process of planet formation and inform us about the numbers ...and masses of planets than can form in this regime. We use the
Herschel Space Observatory
PACS spectrometer to measure the continuum and O
i
63
μ
m line emission toward 11 VLMOs with known disks in the Taurus and Chamaeleon I star-forming regions. We fit radiative transfer models to the spectral energy distributions of these sources. Additionally, we carry out a grid of radiative transfer models run in a regime that connects the luminosity of our sources with brighter T Tauri stars. We find that VLMO disks with sizes 1.3–78 au, smaller than typical T Tauri disks, fit well the spectral energy distributions assuming that disk geometry and dust properties are stellar mass independent. Reducing the disk size increases the disk temperature, and we show that VLMOs do not follow previously derived disk temperature–stellar luminosity relationships if the disk outer radius scales with stellar mass. Only 2 out of 11 sources are detected in O
i
despite a better sensitivity than was achieved for T Tauri stars, suggesting that VLMO disks are underluminous. Using thermochemical models, we show that smaller disks can lead to the unexpected O
i
63
μ
m nondetections in our sample. The disk outer radius is an important factor in determining the gas and dust observables. Hence, spatially resolved observations with ALMA—to establish if and how disk radii scale with stellar mass—should be pursued further.
ALMA surveys of nearby star-forming regions have shown that the dust mass in the disk is correlated with the stellar mass, but with a large scatter. This scatter could indicate either different ...evolutionary paths of disks or different initial conditions within a single cluster. We present ALMA Cycle 3 follow-up observations for 14 Class II disks that were low signal-to-noise (S/N) detections or non-detections in our Cycle 2 survey of the ∼2 Myr old Chamaeleon I star-forming region. With five times better sensitivity, we detect millimeter dust continuum emission from six more sources and increase the detection rate to 94% (51/54) for Chamaeleon I disks around stars earlier than M3. The stellar-disk mass scaling relation reported in Pascucci et al. is confirmed with these updated measurements. Faint outliers in the Fmm-M* plane include three non-detections (CHXR71, CHXR30A, and T54) with dust mass upper limits of 0.2 M⊕ and three very faint disks (CHXR20, ISO91, and T51) with dust masses ∼0.5 M⊕. By investigating the SED morphology, accretion property and stellar multiplicity, we suggest for the three millimeter non-detections that tidal interaction by a close companion ( 100 au) and internal photoevaporation may play a role in hastening the overall disk evolution. The presence of a disk around only the secondary star in a binary system may explain the observed stellar SEDs and low disk masses for some systems.
As phenomics data volume and dimensionality increase due to advancements in sensor technology, there is an urgent need to develop and implement scalable data processing pipelines. Current phenomics ...data processing pipelines lack modularity, extensibility, and processing distribution across sensor modalities and phenotyping platforms. To address these challenges, we developed PhytoOracle (PO), a suite of modular, scalable pipelines for processing large volumes of field phenomics RGB, thermal, PSII chlorophyll fluorescence 2D images, and 3D point clouds. PhytoOracle aims to (
) improve data processing efficiency; (
) provide an extensible, reproducible computing framework; and (
) enable data fusion of multi-modal phenomics data. PhytoOracle integrates open-source distributed computing frameworks for parallel processing on high-performance computing, cloud, and local computing environments. Each pipeline component is available as a standalone container, providing transferability, extensibility, and reproducibility. The PO pipeline extracts and associates individual plant traits across sensor modalities and collection time points, representing a unique multi-system approach to addressing the genotype-phenotype gap. To date, PO supports lettuce and sorghum phenotypic trait extraction, with a goal of widening the range of supported species in the future. At the maximum number of cores tested in this study (1,024 cores), PO processing times were: 235 minutes for 9,270 RGB images (140.7 GB), 235 minutes for 9,270 thermal images (5.4 GB), and 13 minutes for 39,678 PSII images (86.2 GB). These processing times represent end-to-end processing, from raw data to fully processed numerical phenotypic trait data. Repeatability values of 0.39-0.95 (bounding area), 0.81-0.95 (axis-aligned bounding volume), 0.79-0.94 (oriented bounding volume), 0.83-0.95 (plant height), and 0.81-0.95 (number of points) were observed in Field Scanalyzer data. We also show the ability of PO to process drone data with a repeatability of 0.55-0.95 (bounding area).
The planets of our Solar System formed within a disk of dust and gas 4.5 billion years ago. While the Solar System’s primordial protoplanetary disk is now gone, we can begin to understand its ...possible properties by looking out to the disks within nearby star-forming regions. To understand planet formation, dust observations are used to constrain the mechanics and evolution of planet formation. The properties of disks around brown dwarfs and very-low mass stars (hereafter VLMOs) provide important boundary conditions on the process of planet formation and inform us about the numbers and masses of planets than can form in this regime. Radiative transfer models are fit to the spectral energy distributions of 11 VLMOs with known disks and find that these VLMOs do not follow previously derived disk temperature-stellar luminosity relationships if the disk outer radius scales with stellar mass. The3 mm continuum observation of the highly inclined transition disk around the star T Cha reveals multiple dust structures: an inner disk, a spatially resolved dust gap, and an outer ring. When compared with previously published 1.6µm VLT/SPHERE imagery, it is found that the location of the outer ring is wavelength dependent. More specifically, the peak emission of the 3 mm ring is at a larger radial distance than that of the 1.6 µm ring, suggesting that millimeter-sized grains in the outer disk are located further away from the central star than micron-sized grains. The most likely origin of the dust gap is from an embedded planet or planets. The dust disksize of 152 protoplanetary disks is estimated from archival ALMA observations. This sample is combined with 47 disks from Tau/Aur and Oph whose dust disk radii were estimated, as here, through fitting radial profile models to visibility data. These 199 homogeneously derived disk sizes are used to identify empirical disk-disk and disk-host property relations as well as to search for evolutionary trends. In agreement with previous studies, we find that dust disk sizes and millimeter luminosities are correlated, but show for the first time that the relationship is not universal between regions. We find that disks in the 2-3 Myr-old are not smaller than disks in other regions of similar age, and confirm the Barenfeld et al. (2017) finding that the 5-10 Myr USco disks are smaller than disks belonging to younger regions. Finally, we find that the outer edge of the Solar System, as defined by the Kuiper Belt, is consistent with a population of dust disk sizes which have not experienced significant truncation.
The properties of disks around brown dwarfs and very low mass stars (hereafter VLMOs) provide important boundary conditions on the process of planet formation and inform us about the numbers and ...masses of planets than can form in this regime. We use the Herschel Space Observatory PACS spectrometer to measure the continuum and O i 63 m line emission toward 11 VLMOs with known disks in the Taurus and Chamaeleon I star-forming regions. We fit radiative transfer models to the spectral energy distributions of these sources. Additionally, we carry out a grid of radiative transfer models run in a regime that connects the luminosity of our sources with brighter T Tauri stars. We find that VLMO disks with sizes 1.3-78 au, smaller than typical T Tauri disks, fit well the spectral energy distributions assuming that disk geometry and dust properties are stellar mass independent. Reducing the disk size increases the disk temperature, and we show that VLMOs do not follow previously derived disk temperature-stellar luminosity relationships if the disk outer radius scales with stellar mass. Only 2 out of 11 sources are detected in O i despite a better sensitivity than was achieved for T Tauri stars, suggesting that VLMO disks are underluminous. Using thermochemical models, we show that smaller disks can lead to the unexpected O i 63 m nondetections in our sample. The disk outer radius is an important factor in determining the gas and dust observables. Hence, spatially resolved observations with ALMA-to establish if and how disk radii scale with stellar mass-should be pursued further.
With the growing numbers of asteroids being discovered, identifying an observationally complete sample is essential for statistical analyses and for informing theoretical models of the dynamical ...evolution of the solar system. We present an easily implemented method of estimating the empirical observational completeness in absolute magnitude, H_lim, as a function of semi-major axis. Our method requires fewer assumptions and decisions to be made in its application, making results more transportable and reproducible amongst studies that implement it, as well as scalable to much larger datasets of asteroids expected in the next decade with the Vera C.~Rubin Observatory's Legacy Survey of Space and Time (LSST). Using the values of H_lim(a) determined at high resolution in semimajor axis, a, we demonstrate that the observationally complete sample size of the main belt asteroids is larger by more than a factor of 2 compared to using a conservative single value of H_lim, an approach often adopted in previous studies. Additionally, by fitting a simple, physically motivated model of H_lim(a) to 7e5 objects in the Minor Planet Database, our model reveals statistically significant deviations between the main belt and the asteroid populations beyond the main belt (Hungarias, Hildas and Trojans), suggesting potential demographic differences, such as in their size, eccentricity or inclination distributions.
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