A5059578918- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Gamma-ray bursts and supernovae
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Scientific Computing and Data Management
- Distributed and Parallel Computing Systems
- Astronomical Observations and Instrumentation
- Environmental Monitoring and Data Management
- Astrophysical Phenomena and Observations
- Isotope Analysis in Ecology
- Solar and Space Plasma Dynamics
- Nuclear Physics and Applications
- Advanced Chemical Physics Studies
- Space Exploration and Technology
- Methane Hydrates and Related Phenomena
- Superconducting and THz Device Technology
- Radio Astronomy Observations and Technology
- Advanced Combustion Engine Technologies
- Soil Moisture and Remote Sensing
- Galaxies: Formation, Evolution, Phenomena
- Advanced Data Storage Technologies
University of Illinois Urbana-Champaign
2008-2019
National Center for Supercomputing Applications
2017-2019
NASA Astrobiology Institute
2012-2015
University of Hawaii System
2013-2015
University of Hawaiʻi at Mānoa
2012-2015
University of Hawaii at Hilo
2012-2015
Large Synoptic Survey Telescope Corporation
2015
Ames Research Center
2012
(Abridged) We describe here the most ambitious survey currently planned in optical, Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST have unique capability faint time domain. The design is driven four main themes: probing dark energy matter, taking an inventory Solar System, exploring transient optical sky, mapping Milky Way. wide-field ground-based system sited at Cerro Pach\'{o}n northern Chile. telescope 8.4 m...
The Large Synoptic Survey Telescope (LSST) is a large-aperture, wide-field, ground-based survey system that will image the sky in six optical bands from 320 to 1050 nm, uniformly covering approximately $18,000$deg$^2$ of over 800 times. LSST currently under construction on Cerro Pachón Chile, and expected enter operations 2022. Once operational, explore wide range astrophysical questions, discovering "killer" asteroids examining nature Dark Energy. generate average 15 TB data per night,...
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...
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,...
Variations in molecular cloud environments have the potential to affect composition and structure of circumstellar disks therein. To this end, comparative analyses nearby star-forming regions are essential informing theoretical work. In particular, Ophiuchus clouds ideal for comparison as they more compact with much higher extinction than Taurus, low-mass exemplar, experience a moderate amount external radiation. We carried out study collection 136 young stellar objects <1 Myr old region,...
We present a study of dense molecular gas kinematics in seventeen nearby protostellar systems using single-dish and interferometric line observations. The non-axisymmetric envelopes around sample Class 0/I protostars were mapped the N2H+ (J=1-0) tracer with IRAM 30m, CARMA PdBI as well NH3 (1,1) VLA. emission is used to construct line-center velocity linewidth maps for all sources examine kinematic structure on spatial scales from 0.1 pc ~1000 AU. direction large-scale gradients mapping...
We use archived Infrared Array Camera images from the Spitzer Space Telescope to show that many Class 0 protostars exhibit complex, irregular, and non-axisymmetric structure within their dusty envelopes. Our 8 μm extinction maps probe some of densest regions in these protostellar Many systems are observed have highly irregular morphologies on scales ≳1000 AU, with a quarter sample exhibiting filamentary or flattened dense structures. Complex envelope is spatially distinct outflow cavities,...
We present a 1.3 mm dust continuum survey toward nine Class 0 protostars and two I in the Perseus molecular cloud, using CARMA with resolution of ∼03 (70 AU). This sample approximately doubles number observed spatial resolutions <100 AU at millimeter wavelengths, enabling presence large protostellar disks proto-binary systems to be probed. have detected flattened structures radii >100 around sources (L1448 IRS2 Per-emb-14), these may strong disk candidates. Marginally resolved within 30°...
We present dual-wavelength observations and modeling of the nearly edge-on Class 0 young stellar object L1157-mm. Using Combined Array for Research in Millimeter-wave Astronomy, a spherical structure is seen from circumstellar envelope at size scale 10^2 to 10^3 AU both 1 mm 3 dust emission. Radiative transfer performed compare data with theoretical models, including power-law model Terebey-Shu-Cassen model. Bayesian inference applied parameter estimation information criteria used selection....
We present an interferometric kinematic study of morphologically complex protostellar envelopes based on observations the dense gas tracers N2H+ and NH3. The strong asymmetric nature most in our sample leads us to question common interpretation velocity gradients as rotation, given possibility projection effects observed velocities. Several "idealized" sources with well-ordered fields envelope structures are now analyzed more detail. compare data position-velocity diagrams models for...
We present a study on the spatial distribution of N2D+ and N2H+ in 13 protostellar systems. Eight thirteen objects observed with IRAM 30 m telescope show relative offsets between peak (J = 2 → 1) 1 0) emission. highlight case L1157 using interferometric observations from Submillimeter Array Plateau de Bure Interferometer 3 2) transitions, respectively. Depletion is clearly inside radius ∼2000 AU (7'') emission resolved into two peaks at radii ∼1000 (35), depletion region N2D+. Chemical...
We present observations of three Class 0/I protostars (L1157-mm, CB230 IRS1, and L1165-SMM1) using the Karl G. Jansky Very Large Array (VLA) two (L1165-SMM1 IRS1) with Combined for Research in Millimeter-wave Astronomy (CARMA). The VLA were taken at wavelengths λ = 7.3 mm, 1.4 cm, 3.3 4.0 6.5 cm a best resolution ∼006 (18 AU) mm. L1165-SMM1 CARMA 1.3 mm ∼03 (100 IRS1 3.4 ∼3'' (900 AU). find that have probable binary companions separations from detections secondary peaks multiple wavelengths....
Using interferometric data from BIMA observations, combined with detailed modeling in Fourier space of the physical structures predicted by models, we constrain circumstellar envelope parameters for four Class 0 young stellar objects, as well their embedded disks. The envelopes these objects are still undergoing collapse, and theoretical collapse models can be compared to observations. Since it has been suggested a previous study that both Larson-Penston Shu similarity solutions...
We present a time series of synoptic images the linearly-polarized v=1, J=1-0 SiO maser emission toward Mira variable, TX Cam. These data comprise 43 individual epochs at an approximate biweekly sampling over optical pulsation phase range 0.68 to 1.82. The have angular resolution ~500 microarcsec and were obtained using Very Long Baseline Array (VLBA), operating in GHz band spectral-line, polarization mode. previously published total intensity for this range; paper serves image sequence...
Clumpy structure in the debris disk around Vega has been previously reported at millimeter wavelengths and attributed to concentrations of dust grains trapped resonances with an unseen planet. However, recent imaging similar higher sensitivity disputed observed structure. We present three new millimeter-wavelength observations that help resolve puzzling contradictory observations. have system Submillimeter Array (SMA) a wavelength 880 um angular resolution 5"; Combined for Research...
We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r=6.28 AU) until it moved into solar conjunction in mid-2013 June using UH2.2m, and Gemini North 8-m telescopes on Mauna Kea, Lowell 1.8m Flagstaff, Calar Alto 1.2m telescope Spain, VYSOS-5 Loa Hawaii data from CARA network. Additional pre-discovery Pan STARRS1 survey extends light curve back to 2011 September 30 (r=9.4 AU). The images showed a similar tail morphology...
The Large Synoptic Survey Telescope (LSST) is an ambitious astronomical survey with a similarly Data Management component. for LSST includes processing on both nightly and yearly cadences to generate transient alerts, deep catalogs of the static sky, forced photometry light-curves billions objects at hundreds epochs, spanning least decade. algorithms running in these pipelines are individually sophisticated interact subtle ways. This paper provides overview those pipelines, focusing more...
The bipolar jet HH 212 is one of the finest collimated jets known. It has up to now been detected only in near-infrared H2 emission, but here we present deep optical images that show two major bow shocks are weakly [S ii] as expected for a bona fide Herbig–Haro jet. We also widefield reveal more located symmetrically north and south around source along main axis. Additionally, examination Spitzer 4.5 μm reveals yet another bright shock further axis; no corresponding seen south. In total,...
We present new Hα and Hβ images of the HH 1/2 system, we find that Hα/Hβ ratio has high values in ridges along leading edges 1 bow shock brighter condensations 2. These have = 4 → 6, which is consistent with collisional excitation from n to 3 levels hydrogen a gas temperatures T 1.5 10 × 104 K. This therefore first direct evidence excitation/ionization region just behind Herbig–Haro fronts detected.
The luminous Class I protostar HBC 494, embedded in the Orion A cloud, is associated with a pair of reflection nebulae, Re50 and Re50N, which appeared sometime between 1955 1979. We have found that dramatic brightening Re50N has taken place 2006 2014. This could result if source undergoing FUor eruption. However, near-infrared spectrum shows featureless very red continuum, contrast to strong CO bandhead absorption displayed by FUors. Such heavy veiling, high luminosity protostar, indicative...
The little-studied Herbig Be star V1818 Ori is located in the direction of southern L1641 cloud and Mon R2 star-forming complex, most likely associated with latter at a distance ∼900 pc. A high-resolution spectrum consistent spectral type around B7 V, lines Hα, red Ca ii triplet, several forbidden emission. An All Sky Automated Survey V-band light curve spanning 9 yr reveals major variability deep absorption episodes reminiscent UX Orionis stars. We have searched for additional young stars...
We present new Hubble Space Telescope (HST) narrow band images of the bright Herbig–Haro (HH) objects HH 1 and 2 in light Hα, Hβ, [O i] 6300, ii] 3726+28, iii] 5007 [S 6716+30 emission lines. The resulting line ratio maps give an improved picture physical structure these objects, showing presence spatially limited, high excitation/ionization ridges. find that has a morphology could be interpreted terms single, asymmetric bow shock, many clumps fall two bow-shaped structures different...
A detailed imaging and spectroscopic analysis is presented of the little-studied T Tauri star PR Ori its associated Herbig–Haro flow HH 305, located on outskirts L1641-N cluster in Orion. shown to be a multiple system, where component close 0077 binary, B component, at distance 350, driver large flow. low-luminosity source, here called C, 93 southeast spectroscopically straddling stellar/brown dwarf boundary. The corresponding separations projection are 32, 1450, 3900 au, respectively....