ALMA Observations of Circumstellar Disks in the Upper Scorpius OB Association

We present ALMA observations of 106 G-, K-, and M-type stars in the Upper Scorpius OB Association hosting circumstellar disks. With these data, we measure the 0.88 mm continuum and $^{12}$CO $J$ = 3$-$2 line fluxes of disks around low-mass ($0.14-1.66$ $M_{\odot}$) stars at an age of 5-11 Myr. Of the 75 primordial disks in the sample, 53 are detected in the dust continuum and 26 in CO. Of the 31 disks classified as debris/evolved transitional disks, 5 are detected in the continuum and none in CO. The lack of CO emission in approximately half of the disks with detected continuum emission can be explained if CO is optically thick but has a compact emitting area ($\lesssim 40$ au), or if the CO is heavily depleted by a factor of at least $\sim1000$ relative to interstellar medium abundances and is optically thin. The continuum measurements are used to estimate the dust mass of the disks. We find a correlation between disk dust mass and stellar host mass consistent with a power-law relation of $M_{\mathrm{dust}}\propto M_*^{1.67\pm0.37}$. Disk dust masses in Upper Sco are compared to those measured in the younger Taurus star-forming region to constrain the evolution of disk dust mass. We find that the difference in the mean of $\log(M_{\mathrm{dust}}/M_*)$ between Taurus and Upper Sco is $0.64\pm0.09$, such that $M_{\mathrm{dust}}/M_*$ is lower in Upper Sco by a factor of $\sim4.5$.Comment: 18 pages of text, 11 Figures, 5 Tables. Published in Ap

Measurement of Circumstellar Disk Sizes in the Upper Scorpius OB Association with ALMA

We present detailed modeling of the spatial distributions of gas and dust in 57 circumstellar disks in the Upper Scorpius OB Association observed with ALMA at sub-millimeter wavelengths. We fit power-law models to the dust surface density and CO $J$ = 3-2 surface brightness to measure the radial extent of dust and gas in these disks. We found that these disks are extremely compact: the 25 highest signal-to-noise disks have a median dust outer radius of 21 au, assuming an $R^{-1}$ dust surface density profile. Our lack of CO detections in the majority of our sample is consistent with these small disk sizes assuming the dust and CO share the same spatial distribution. Of seven disks in our sample with well-constrained dust and CO radii, four appear to be more extended in CO, although this may simply be due to higher optical depth of the CO. Comparison of the Upper Sco results with recent analyses of disks in Taurus, Ophiuchus, and Lupus suggests that the dust disks in Upper Sco may be $\sim3$ times smaller in size than their younger counterparts, although we caution that a more uniform analysis of the data across all regions is needed. We discuss the implications of these results for disk evolution.Comment: 15 pages of text, 7 figures, 3 tables. Accepted in Ap

Opportunity to Test non-Newtonian Gravity Using Interferometric Sensors with Dynamic Gravity Field Generators

We present an experimental opportunity for the future to measure possible violations to Newton's 1/r^2 law in the 0.1-10 meter range using Dynamic gravity Field Generators (DFG) and taking advantage of the exceptional sensitivity of modern interferometric techniques. The placement of a DFG in proximity to one of the interferometer's suspended test masses generates a change in the local gravitational field that can be measured at a high signal to noise ratio. The use of multiple DFGs in a null experiment configuration allows to test composition independent non-Newtonian gravity significantly beyond the present limits. Advanced and third-generation gravitational-wave detectors are representing the state-of-the-art in interferometric distance measurement today, therefore we illustrate the method through their sensitivity to emphasize the possible scientific reach. Nevertheless, it is expected that due to the technical details of gravitational-wave detectors, DFGs shall likely require dedicated custom configured interferometry. However, the sensitivity measure we derive is a solid baseline indicating that it is feasible to consider probing orders of magnitude into the pristine parameter well beyond the present experimental limits significantly cutting into the theoretical parameter space.Comment: 9 pages, 6 figures; Physical Review D, vol. 84, Issue 8, id. 08200

Molecular outflow launched beyond the disk edge

One of the long-standing problems of star formation is the excess of angular momentum of the parent molecular cloud. In the classical picture, a fraction of angular momentum of the circumstellar material is removed by the magneto-centrifugally driven disk wind that is launched from a wide region throughout the disk. In this work, we investigate the kinematics in the envelope-disk transition zone of the Class I object BHB07-11, in the B59 core. For this purpose, we used the Atacama Large Millimeter/submillimeter Array in extended configuration to observe the thermal dust continuum emission ($\lambda_0 \sim$ 1.3 mm) and molecular lines (CO, C$^{18}$O and H$_2$CO), which are suitable tracers of disk, envelope, and outflow dynamics at a spatial resolution of $\sim 30$ AU. We report a bipolar outflow that was launched at symmetric positions with respect to the disk ($\sim$80~AU in radius), but was concentrated at a distance of 90--130~AU from the disk center. The two outflow lobes had a conical shape and the gas inside was accelerating. The large offset of the launching position coincided with the landing site of the infall material from the extended spiral structure (seen in dust) onto the disk. This indicates that bipolar outflows are efficiently launched within a narrow region outside the disk edge. We also identify a sharp transition in the gas kinematics across the tip of the spiral structure, which pinpoints the location of the so-called centrifugal barrier.Comment: 5 pages, 5 figures, Accepted for publication in A&A Letter

ALMA Observations of the Orion Proplyds

We present ALMA observations of protoplanetary disks ("proplyds") in the Orion Nebula Cluster. We imaged 5 individual fields at 856um containing 22 HST-identified proplyds and detected 21 of them. Eight of those disks were detected for the first time at submillimeter wavelengths, including the most prominent, well-known proplyd in the entire Orion Nebula, 114-426. Thermal dust emission in excess of any free-free component was measured in all but one of the detected disks, and ranged between 1-163 mJy, with resulting disk masses of 0.3-79 Mjup. An additional 26 stars with no prior evidence of associated disks in HST observations were also imaged within the 5 fields, but only 2 were detected. The disk mass upper limits for the undetected targets, which include OB stars, theta1Ori C and theta1Ori F, range from 0.1-0.6 Mjup. Combining these ALMA data with previous SMA observations, we find a lack of massive (>3 Mjup) disks in the extreme-UV dominated region of Orion, within 0.03 pc of O-star theta1Ori C. At larger separations from theta1Ori C, in the far-UV dominated region, there is a wide range of disk masses, similar to what is found in low-mass star forming regions. Taken together, these results suggest that a rapid dissipation of disk masses likely inhibits potential planet formation in the extreme-UV dominated regions of OB associations, but leaves disks in the far-UV dominated regions relatively unaffected.Comment: ApJ, in pres

ALMA Measurements of Circumstellar Material in the GQ Lup System

We present ALMA observations of the GQ Lup system, a young Sun-like star with a substellar mass companion in a wide-separation orbit. These observations of 870 $\mu$m continuum and CO J=3-2 line emission with beam size $\sim0.3''$ ($\sim45$ AU) resolve the disk of dust and gas surrounding the primary star, GQ Lup A, and provide deep limits on any circumplanetary disk surrounding the companion, GQ Lup b. The circumprimary dust disk is compact with a FWHM of $59\pm12$ AU, while the gas has a larger extent with a characteristic radius of $46.5\pm1.8$ AU. By forward-modeling the velocity field of the circumprimary disk based on the CO emission, we constrain the mass of GQ Lup A to be $M_* = (1.03\pm0.05)*(d/156\text{ pc})$ $M_\odot$, where $d$ is a known distance, and determine that we view the disk at an inclination angle of $60.5^\circ\pm0.5^\circ$ and a position angle of $346^\circ \pm1^\circ$. The $3\sigma$ upper limit on the 870 $\mu$m flux density of any circumplanetary disk associated with GQ Lup b of $<0.15$ mJy implies an upper limit on the dust disk mass of $<0.04$ $M_\oplus$ for standard assumptions about optically thin emission. We discuss proposed mechanisms for the formation of wide-separation substellar companions given the non-detection of circumplanetary disks around GQ Lup b and other similar systems.Comment: 11 pages, 4 figure

ALMA Observations of Asymmetric Molecular Gas Emission from a Protoplanetary Disk in the Orion Nebula

We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of molecular line emission from d216-0939, one of the largest and most massive protoplanetary disks in the Orion Nebula Cluster (ONC). We model the spectrally resolved HCO$^+$ (4--3), CO (3--2), and HCN (4--3) lines observed at 0\farcs5 resolution to fit the temperature and density structure of the disk. We also weakly detect and spectrally resolve the CS (7--6) line but do not model it. The abundances we derive for CO and HCO$^+$ are generally consistent with expected values from chemical modeling of protoplanetary disks, while the HCN abundance is higher than expected. We dynamically measure the mass of the central star to be $2.17\pm0.07\,M_\odot$ which is inconsistent with the previously determined spectral type of K5. We also report the detection of a spatially unresolved high-velocity blue-shifted excess emission feature with a measurable positional offset from the central star, consistent with a Keplerian orbit at $60\pm20\,\mathrm{au}$. Using the integrated flux of the feature in HCO$^+$ (4--3), we estimate the total H$_2$ gas mass of this feature to be at least $1.8-8\,M_\mathrm{Jupiter}$, depending on the assumed temperature. The feature is due to a local temperature and/or density enhancement consistent with either a hydrodynamic vortex or the expected signature of the envelope of a forming protoplanet within the disk.Comment: 19 pages, 12 figures, accepted for publication in A

A Machine-Learning Based Microwave Sensing Approach to Food Contaminant Detection

To detect contaminants accidentally included in packaged foods, food industries use an array of systems ranging from metal detectors to X-ray imagers. Low density plastic or glass contaminants, however, are not easily detected with standard methods. If the dielectric contrast between the packaged food and these contaminants in the microwave spectrum is sensible, Microwave Sensing (MWS) can be used as a contactless detection method, which is particularly useful when the food is already packaged. In this paper we propose using MWS combined with Machine Learning (ML). In particular, we report on experiments we did with packaged cocoa-hazelnut spread and show the accuracy of our approach. We also present an FPGA acceleration that runs the ML processing in real-time so as to keep up with the throughput of a production line

Preliminary laboratory multi-scale investigation on performance of pervious concrete pavements and vegetated elements as storm water bio-filters and retention systems

The growing population in urban areas worldwide is having a severe impact on the environment and quality of life of inhabitants. To alleviate the impact on traditional transportation infrastructures, existing and future urban facilities must be more environmentally friendly and sustainable. One solution is to develop new “green transportation infrastructures” (GTI) as part of the urban storm water management system. Although technologies for GTI have been well-investigated, there is limited experience of their potential benefits globally and, specifically, in Italy. This work, funded by the Regione Piemonte in 2015 and supported by different areas of expertise, aimed at promoting new urban storm water systems through the retention, filtration, and restoration of natural soil water content. To this end, a laboratory investigation of porous road pavements (Figure 1), and vegetated boxes (Figure 2 and 3) that filter runoff pollutants from impervious pavements was conducted to examine ecological, hydraulic, and mechanical performance levels. Three different experimental scales (samples, columns, and boxes) for the two GTI technologies were considered. Samples were used to assess the permeability, void content, strength, and pollution reduction potential of different materials used to build full-scale bio-filter systems. The pollutant reduction was determined by the reduction in suspended solids and hydrocarbon concentration, with results confirming that it depends on filter type and permeability. The preliminary results are encouraging and show a high reduction in total suspended solids and hydrocarbon concentrations (from 65% to 99%). Concrete pervious pavements and vegetated bio-filter systems were reproduced in columns and boxes, combining materials and supports for biofilm bacteria (geotextile, plastic caps) to assess the abatement potential of pre-developed biofilm bacteria compared to systems where bacteria are present naturally. Hydraulic parameters (percolation time, void content, outflow rate) were estimated so as to provide basic design parameters for full-scale applications

Inner edges of planetesimal belts: collisionally eroded or truncated?

The radial structure of debris discs can encode important information about their dynamical and collisional history. In this paper we present a 3-phase analytical model to analyse the collisional evolution of solids in debris discs, focusing on their joint radial and temporal dependence. Consistent with previous models, we find that as the largest planetesimals reach collisional equilibrium in the inner regions, the surface density of dust and solids becomes proportional to $\sim r^{2}$ within a certain critical radius. We present simple equations to estimate the critical radius and surface density of dust as a function of the maximum planetesimal size and initial surface density in solids (and vice versa). We apply this model to ALMA observations of 7 wide debris discs. We use both parametric and non-parametric modelling to test if their inner edges are shallow and consistent with collisional evolution. We find that 4 out of 7 have inner edges consistent with collisional evolution. Three of these would require small maximum planetesimal sizes below 10 km, with HR 8799's disc potentially lacking solids larger than a few centimeters. The remaining systems have inner edges that are much sharper, which requires maximum planetesimal sizes $\gtrsim10$ km. Their sharp inner edges suggest they could have been truncated by planets, which JWST could detect. In the context of our model, we find that the 7 discs require surface densities below a Minimum Mass Solar Nebula, avoiding the so-called disc mass problem. Finally, during the modelling of HD 107146 we discover that its wide gap is split into two narrower ones, which could be due to two low-mass planets formed within the disc.Comment: Accepted for publication in MNRAS, 21 pages, 11 figure