A5054676844- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Astronomy and Astrophysical Research
- Vehicle emissions and performance
- Galaxies: Formation, Evolution, Phenomena
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Astrophysical Phenomena and Observations
- Spacecraft and Cryogenic Technologies
- Superconducting and THz Device Technology
- Optical Coatings and Gratings
- Phase Equilibria and Thermodynamics
- Space Exploration and Technology
- Gamma-ray bursts and supernovae
- Superconducting Materials and Applications
- Optical Polarization and Ellipsometry
- Solar and Space Plasma Dynamics
- Infrared Target Detection Methodologies
- Planetary Science and Exploration
- Particle accelerators and beam dynamics
- Adaptive optics and wavefront sensing
University of Illinois Urbana-Champaign
2015-2024
National Radio Astronomy Observatory
2013-2024
University of Illinois System
2012-2022
Kagoshima University
2021
Tsinghua University
2019-2021
Institute for Advanced Study
2019-2021
Northwestern University
2021
Center for Astrophysics Harvard & Smithsonian
2019-2021
Instituto Argentino de Radioastronomía
2016-2021
Centro Científico Tecnológico - La Plata
2016-2021
We present the results of a λ = 2.7 mm continuum interferometric survey 24 young stellar objects in 11 fields. The target range from deeply embedded class 0 sources to optical T Tauri sources. This is first subarcsecond dust emission young, systems. These multiarray observations, utilizing high dynamic u-v BIMA array, fully sample spatial scales ranging 04 60'', thus allowing consistent comparison structures variety images show diversity structure and complexity. optically visible stars (DG...
We present λ1.3 mm CARMA observations of dust polarization toward 30 star-forming cores and 8 regions from the TADPOL survey. show maps all sources, compare ~2.5" resolution with ~20" single-dish submillimeter telescopes. Here we do not attempt to interpret detailed B-field morphology each object. Rather, use average orientations derive conclusions in a statistical sense ensemble bearing mind that these can be quite uncertain. discuss three main findings: (1) A subset sources have consistent...
We present an overview of the Large Program, ``Early Planet Formation in Embedded Disks (eDisk)'', conducted with Atacama Millimeter/submillimeter Array (ALMA). The ubiquitous detections substructures, particularly rings and gaps, protoplanetary disks around T Tauri stars raise possibility that at least some planet formation may have already started during embedded stages star formation. In order to address exactly how when is initiated, program focuses on searching for substructures 12...
Investigating Protostellar Accretion is a Cycle 1 JWST program using the NIRSpec+MIRI integral field units to obtain 2.9--28 $\mu$m spectral cubes of five young protostars with luminosities 0.2-10,000 L$_{\odot}$ in their primary accretion phase. This paper introduces NIRSpec 2.9--5.3 data inner 840-9000 au spatial resolutions from 28-300 au. The spectra show rising continuum emission; deep ice absorption; emission H$_{2}$, H~I, and [Fe~II]; CO fundamental series absorption. Maps scattered...
Abstract Investigating Protostellar Accretion (IPA) is a JWST Cycle 1 GO program that uses NIRSpec integral field units and MIRI Medium Resolution Spectrograph to obtain 2.9–28 μ m spectral cubes of young, deeply embedded protostars with luminosities 0.2–10,000 L ⊙ central masses 0.15–12 M . In this Letter, we report the discovery highly collimated atomic jet from Class 0 protostar IRAS 16253−2429, lowest-luminosity source ( bol = 0.2 ) in IPA program. The detected multiple [Fe ii ] lines...
We present the properties of an extensive sample molecular clouds in Large Magellanic Cloud (LMC) mapped at 11 pc resolution CO(1-0) line. identify as regions connected CO emission, and find that distributions cloud sizes, fluxes masses are sensitive to choice decomposition parameters. In all cases, however, luminosity function is steeper than dN/dL \propto L^{-2}, suggesting a substantial fraction mass low-mass clouds. A correlation between size linewidth, while apparent for largest...
ABSTRACT We present a multiplicity study of all known protostars (94) in the Perseus molecular cloud from Karl G. Jansky Very Large Array survey at Ka-band (8 mm and 1 cm) C-band (4 6.6 cm). The observed sample has bolometric luminosity range between 0.1 L ⊙ ∼33 , with median 0.7 . This is based on data, having best resolution ∼0.″065 (15 au) separations out to ∼43″ (10,000 can be probed. overall fraction (MF) found 0.40 ± 0.06 companion star (CSF) 0.71 0.06. MF CSF Class 0 are 0.57 0.09 1.2...
We present results of 1.3 mm dust polarization observations toward 16 nearby, low-mass protostars, mapped with ~2.5" resolution at CARMA. The show that magnetic fields in protostellar cores on scales ~1000 AU are not tightly aligned outflows from the protostars. Rather, data consistent scenarios where and preferentially misaligned (perpendicular), or they randomly aligned. If one assumes emerge along rotation axes circumstellar disks, have disrupted surrounding material, then our imply disks...
The mechanism for producing polarized emission from protostellar disks at (sub)millimeter wavelengths is currently uncertain. Classically, polarization expected non-spherical grains aligned with the magnetic field. Recently, two alternatives have been suggested. One caused by self-scattering dust of sizes comparable to wavelength while other due their short axes along direction radiation anisotropy. latter has recently shown as a likely causing detected in HL Tau 3.1 mm. In this paper, we...
High-resolution Airborne Wide-band Camera (HAWC[Formula: see text]) is the facility far-infrared imager and polarimeter for SOFIA, NASA’s Stratospheric Observatory Infrared Astronomy. It designed to cover portion of infrared spectrum that completely inaccessible ground-based observatories which essential studies astronomical sources with temperatures between tens hundreds degrees Kelvin. Its ability make polarimetric measurements aligned dust grains provides a unique new capability studying...
Spatially resolved polarized millimeter/submillimeter emission has been observed in the disk of HL Tau and two other young stellar objects. It is usually interpreted as coming from magnetically aligned grains, but can also be produced by dust scattering, demonstrated explicitly Kataoka et al. for face-on disks. We extend their work including polarization induced inclination with respect to line sight. Using a physically motivated, semi-analytic model, we show that fraction scattered light...
We present a high angular resolution ($\sim 0.2^{\prime\prime}$), sensitivity ($\sigma \sim 0.2$ mJy) survey of the 870 $\mu$m continuum emission from circumstellar material around 49 pre-main sequence stars in $\rho$ Ophiuchus molecular cloud. Because most millimeter instruments have resided northern hemisphere, this represents largest high-resolution, millimeter-wave disk content Our systems comprises 63 stars; we detect disks associated with 29 single sources, 11 binaries, 3 triple and 4...
Abstract We have conducted a survey of 328 protostars in the Orion molecular clouds with Atacama Large Millimeter/submillimeter Array at 0.87 mm resolution ∼0.″1 (40 au), including observations Very 9 toward 148 ∼0.″08 (32 au). This is largest multiwavelength this by an order magnitude. use dust continuum emission and to measure disk radii masses Class 0, I, flat-spectrum protostars, characterizing evolution these properties protostellar phase. The mean for are <?CDATA...
Abstract While dust disks around optically visible, Class II protostars are found to be vertically thin, when and how settles the midplane unclear. As part of Atacama Large Millimeter/submillimeter Array large program, Early Planet Formation in Embedded Disks, we analyze edge-on, embedded, I protostar IRAS 04302+2247, also nicknamed “Butterfly Star.” With a resolution 0.″05 (8 au), 1.3 mm continuum shows an asymmetry along minor axis that is evidence thick geometrically disk viewed nearly...
Nitrogen-bearing complex organic molecules have been commonly detected in the gas phase but not yet interstellar ices. This has led to long-standing question of whether these form or The James Webb Space Telescope (JWST) offers sensitivity, spectral resolution, and wavelength coverage needed detect them ices investigate their abundance ratios are similar ice. We report first tentative detection CH 3 CN, C 2 H 5 CN simple molecule, N O, based on CN-stretch band toward three (HOPS 153, HOPS...
The structure and composition of simple ices can be modified during stellar evolution by protostellar heating. Key to understanding the involved processes are thermal chemical tracers that diagnose history environment ice. 15.2 $\mu$m bending mode $^{12}$CO$_2$ has proven a valuable tracer ice heating events but suffers from grain shape size effects. A viable alternative is weaker $^{13}$CO$_2$ isotopologue band at 4.39 which now become accessible high S/N with $\textit{James Webb}$ Space...
ABSTRACT Polarization is a unique tool to study the dust grains of protoplanetary discs. around HL Tau was previously imaged using Atacama Large Millimeter/submillimeter Array (ALMA) at Bands 3 (3.1 mm), 6 (1.3 and 7 (0.87 showing that polarization orientation changes across wavelength λ. Band predominantly parallel disc minor axis but appears azimuthally oriented 3, with morphology in between two. We present new ∼0.2 arcsec (29 au) observations Q-Band (7.0 mm) Karl G. Jansky Very (VLA) 4...
Abstract We present 870 μ m polarimetric observations toward 61 protostars in the Orion molecular clouds with ∼400 au (1″) resolution using Atacama Large Millimeter/submillimeter Array. successfully detect dust polarization and outflow emission 56 protostars; 16 of them is likely produced by self-scattering. Self-scattering signatures are seen several Class 0 sources, suggesting that grain growth appears to be significant disks at earlier protostellar phases. For rest protostars, traces...
Abstract We performed radiative transfer calculations and observing simulations to reproduce the 1.3 mm dust-continuum C 18 O (2–1) images in Class I protostar R CrA IRS7B-a, observed with ALMA Large Program “Early Planet Formation Embedded Disks (eDisk).” found that a dust disk model passively heated by central cannot peak brightness temperature of continuum emission (∼195 K), regardless assumptions about opacity. Our calculation suggests viscous accretion heating is required high...
We describe the characteristics of BIMA millimeter wave array at Hat Creek, California. The is an aperture synthesis instrument consisting 9 6-meter diameter antennas which may be deployed in three differenet configurations, with spacings ranging from 7 meters up to 1.3 km. At observing frequency 100 GHz these configurations yield maps angular resolutions 5", 2", and 0.4", over a 2' field. Larger fields mapped by using multiple pointings. For all but oldest telescopes, surface accuracy ≤ 30...
We present dust opacity spectral indexes (beta) of the youngest protostellar systems (so-called Class 0 sources), L1448 IRS 2, 3, and L1157, obtained between 1.3 mm 2.7 continua, using Combined Array for Research in Millimeter-wave Astronomy (CARMA). The unprecedented compact configuration image fidelity CARMA allow a better detection continuum emission from sources, with less serious missing flux problem normally associated interferometry. Through visibility-modeling at both simultaneously,...