A5007990574- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Molecular Spectroscopy and Structure
- Atmospheric Ozone and Climate
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Solid-state spectroscopy and crystallography
- Molecular spectroscopy and chirality
- Advanced NMR Techniques and Applications
- Spectroscopy and Laser Applications
- Galaxies: Formation, Evolution, Phenomena
- Solar and Space Plasma Dynamics
- Bee Products Chemical Analysis
- Advanced Combustion Engine Technologies
- Spacecraft and Cryogenic Technologies
- Enzyme Structure and Function
- Machine Learning in Healthcare
- Advanced Graph Neural Networks
- Remote Sensing in Agriculture
- Leaf Properties and Growth Measurement
- Explainable Artificial Intelligence (XAI)
- Atomic and Molecular Physics
- Neural Networks and Applications
Herzberg Institute of Astrophysics
2022
University of Victoria
2016-2021
University of Alberta
2020
National Radio Astronomy Observatory
2016
University of Louisville
2016
University of Louisville Hospital
2014
We present an overview of the first data release (DR1) and first-look science from Green Bank Ammonia Survey (GAS). GAS is a Large Program at Telescope to map all Gould Belt star-forming regions with $A_V \gtrsim 7$ mag visible northern hemisphere in emission NH$_3$ other key molecular tracers. This includes for four clouds: B18 Taurus, NGC 1333 Perseus, L1688 Ophiuchus, Orion A North Orion. compare dust continuum Herschel, find that two tracers correspond closely. over 60\% lines-of-sight...
We measure chemical abundance ratios and radial velocities in four massive (i.e., young) [alpha/Fe]-rich red giant stars using high-resolution high-S/N spectra from ESPaDOnS fed by Gemini-GRACES. Our differential analysis ensures that our abundances are on the same scale as Alves-Brito et al. (2010) study of bulge, thin thick disk giants. confirm program have enhanced [alpha/Fe] slightly metal poor. Aside lithium enrichment one object, exhibit no anomalies when compared to similar...
Recent observations of global velocity gradients across and along molecular filaments have been interpreted as signs gas accreting onto these filaments, potentially feeding star-forming cores proto-clusters. The behavior in however, has not studied detail, particularly on small scales (< 0.1 pc). In this paper, we present MUFASA, an efficient, robust, automatic method to fit ammonia lines with multiple components, generalizable other species. We also CRISPy, a Python package identify...
We use gas temperature and velocity dispersion data from the Green Bank Ammonia Survey core masses sizes James Clerk Maxwell Telescope Gould Belt to estimate virial states of dense cores within Orion A molecular cloud. Surprisingly, we find that almost none are sufficiently massive be bound when considering only balance between self-gravity thermal non-thermal motions present in gas. Including additional pressure binding imposed by weight ambient cloud material smaller terms, however,...
We present initial results from the K-band focal plane array Examinations of Young STellar Object Natal Environments (KEYSTONE) survey, a large project on 100-m Green Bank Telescope mapping ammonia emission across eleven giant molecular clouds at distances $0.9-3.0$ kpc (Cygnus X North, Cygnus South, M16, M17, MonR1, MonR2, NGC2264, NGC7538, Rosette, W3, and W48). This data release includes NH$_3$ (1,1) (2,2) maps for each cloud, which are modeled to produce kinetic temperature, centroid...
We present the observation and analysis of newly discovered coherent structures in L1688 region Ophiuchus B18 Taurus. Using data from Green Bank Ammonia Survey (GAS), we identify regions high density near-constant, almost-thermal, velocity dispersion. Eighteen are revealed, twelve six B18, each which shows a sharp "transition to coherence" dispersion around its periphery. The identification these provides chance study molecular clouds statistically. identified have typical radius 0.04 pc...
Abstract Dynamical studies of dense structures within molecular clouds often conclude that the most massive clumps contain too little kinetic energy for virial equilibrium, unless they are magnetized to an unexpected degree. This raises questions about how such a state might arise, and it persist long enough represent population clumps. In effort reexamine origins this conclusion, we use ammonia line data from Green Bank Ammonia Survey Planck-calibrated dust emission Herschel estimate masses...
We present observations of the Cepheus Flare obtained as part James Clerk Maxwell Telescope (JCMT) Gould Belt Legacy Survey (GBLS) with SCUBA-2 instrument. produce a catalogue sources found by SCUBA-2, and separate these into starless cores protostars. determine masses densities for each our sources, using source temperatures determined Herschel Survey. compare properties in four different molecular clouds: L1147/58, L1172/74, L1251 L1228. find that core mass functions region typically show...
Abstract We use Green Bank Ammonia Survey observations of NH 3 (1, 1) and (2, 2) emission with 32″ FWHM resolution from a ∼10 pc 2 portion the Cepheus-L1251 molecular cloud to identify hierarchical dense gas structures. Our dendrogram analysis data results in 22 top-level structures, which reside within 13 lower-level parent The structures are compact <?CDATA $(0.01\,\mathrm{pc}\lesssim {R}_{\mathrm{eff}}\lesssim 0.1\,\mathrm{pc})$?> spatially correlated highest H column density portions...
The role played by magnetic field during star formation is an important topic in astrophysics. We investigate the correlation between orientation of star-forming cores (as defined core major axes) and ambient directions 1) a 3D MHD simulation, 2) synthetic observations generated from simulation at different viewing angles, 3) nearby molecular clouds. find that results on relative alignment background slightly disagree with those measured fully data, which partly because identified projected...
ABSTRACT Although surveys of infall motions in dense cores have been carried out for years, few focused on mapping across using multiple spectral-line observations. To fill this gap, we present IRAM 30 m telescope maps N 2 H + (1–0), DCO (2–1), (3–2), and HCO (3–2) emission toward two prestellar (L492 L694-2) one protostellar core (L1521F). We find that the measured velocity varies with position each choice molecular line, likely as a result radial variations chemistry dynamics....
Understanding the chemical processes during starless core and prestellar evolution is an important step in understanding initial stages of star disk formation. This project a study deuterated ammonia, o-NH$_2$D, L1251 star-forming region toward Cepheus. Twenty-two dense cores (twenty which are or prestellar, two have protostar), previously identified by p-NH$_3$ (1,1) observations, were targeted with 12m Arizona Radio Observatory telescope on Kitt Peak. o-NH$_2$D J$_{\rm{K_a} \rm{K_c}}^{\pm}...
Abstract Understanding the early stages of star formation is a research field ongoing development, both theoretically and observationally. In this context, molecular data have been continuously providing observational constraints on gas dynamics at different excitation conditions depths in sources. We investigated Barnard 59 core, only active site Pipe Nebula, to achieve comprehensive view kinematic properties source. This information was derived by simultaneously fitting ammonia inversion...
We perform a virial analysis of starless dense cores in three nearby star-forming regions : L1688 Ophiuchus, NGC 1333 Perseus, and B18 Taurus. Our takes advantage comprehensive kinematic information for the gas all these made publicly available through Green Bank Ammonia Survey Data Release 1, which used to estimate internal support against collapse. combine this with ancillary data other important properties cores, including continuum from James Clerk Maxwell Telescope Gould Belt core...
We present deep radio continuum observations of the star-forming core Serpens South Infrared Dark Cloud with Karl G. Jansky Very Large Array (VLA). Observations were conducted in two bands centered at 7.25 GHz (4.14 cm) and 4.75 (6.31 an rms 8.5 11.1 microJy/beam, respectively. also use 2MASS, Spitzer Herschel data to put our context young stellar populations characterized by near far infrared observations. Within a 5 arcmin x region interest around central cluster, we detect roughly...
In the absence of two emission lines H α and [N ii] (6584 Å) in a BPT diagram, we show that other spectral information is sufficiently informative to distinguish active galactic nucleus (AGN) galaxies from star-forming galaxies. We use pattern recognition methods sample galaxy spectra Sloan Digital Sky Survey that, this survey, flux equivalent width [O iii] (5007 β, along with 4000 Å break, can be used classify diagram. This method provides higher accuracy predictions than those which...
We present Herschel SPIRE and PACS maps of the Cepheus Flare clouds L1157, L1172, L1228, L1241, L1251, observed by Gould Belt Survey (HGBS) nearby star-forming molecular clouds. Through modified blackbody fits to data, we determine typical cloud column densities 0.5-1.0 $\times$ 10$^{21}$ cm$^{-2}$ temperatures 14-15 K. Using getsources identification algorithm, extract 832 dense cores from data at 160-500 $\mu$m. From placement in a mass vs. size diagram, consider 303 be candidate...
When multiple star-forming gas structures overlap along the line of sight and emit optically thin emission at significantly different radial velocities, can become non-Gaussian often exhibits two distinct peaks. Traditional line-fitting techniques fail to account adequately for these double-peaked profiles, providing inaccurate measurements cloud kinematics. We present a new method, called Convnet Line-fitting Of Velocities in Emission-line Regions (CLOVER), distinguishing between...