A5007536754- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Atmospheric Ozone and Climate
- Galaxies: Formation, Evolution, Phenomena
- Molecular Spectroscopy and Structure
- Astro and Planetary Science
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Astrophysics and Cosmic Phenomena
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Adaptive optics and wavefront sensing
- Quantum, superfluid, helium dynamics
- Dark Matter and Cosmic Phenomena
- High-pressure geophysics and materials
- Atomic and Subatomic Physics Research
- Geophysics and Gravity Measurements
- Neutrino Physics Research
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Granular flow and fluidized beds
- Solar and Space Plasma Dynamics
Ames Research Center
2016-2024
Universities Space Research Association
2018-2024
Drexel University
2024
Space Science Institute
2024
University of Cologne
2013-2016
Boston University
2005-2015
Northwestern University
2009-2013
The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey is a new survey of 13CO J = 1 → 0 emission. used the SEQUOIA multipixel array on Five 14 m telescope to cover longitude range l 18°-557 and latitude |b| < 1°, total 75.4 deg2. Using both position-switching On-The-Fly mapping modes, we achieved an angular sampling 22'', better than half telescope's 46'' resolution. survey's velocity coverage -5 135 km s-1 for longitudes ≤ 40° 85 > 40°. At resolution 0.21 s-1,...
In diffuse interstellar clouds the chemistry that leads to formation of oxygen bearing ions OH+, H2O+, and H3O+ begins with ionization atomic hydrogen by cosmic rays, continues through subsequent abstraction reactions involving H2. Given these reaction pathways, observed abundances molecules are useful in constraining both total cosmic-ray rate (zeta_H) molecular fraction, f(H2). We present observations targeting transitions made Herschel Space Observatory along 20 Galactic sight lines...
We use 8.3 um mid-infrared images acquired with the Midcourse Space Experiment satellite to identify and catalog Infrared Dark Clouds (IRDCs) in first fourth quadrants of Galactic plane. Because IRDCs are seen as dark extinction features against diffuse infrared background, we them by determining a model background from then searching for regions high decremental contrast respect this background. IRDC candidates our defined contiguous bounded closed contours 2 sigma threshold. Although most...
Infrared Dark Clouds (IRDCs) contain compact cores which probably host the early stages of high-mass star formation. Many these regions extended, enhanced 4.5 μm emission, so-called "green fuzzies," indicate shocked gas. also 24 presumably from heated dust indicates embedded protostars. Because fuzzies" and point sources both formation, we have developed an algorithm to identify star-forming within IRDCs by searching for simultaneous presence two distinct indicators. We employ this on a...
Using 13CO J = 1 → 0 molecular line emission from the Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey (BU-FCRAO GRS), we have established kinematic distances to 313 infrared dark clouds (IRDCs) by matching morphology of in distinct velocity channels their mid-infrared extinction. The distribution IRDCs shows an enhancement toward Galaxy's most massive and active star-forming structure, so-called 5 kpc ring. typical sizes ~5 pc, peak column densities ~1022...
The "Nessie" Nebula is a filamentary infrared dark cloud (IRDC) with large aspect ratio of over 150:1 (15 × 001 or 80 pc 0.5 at kinematic distance 3.1 kpc). Maps HNC (1–0) emission, tracer dense molecular gas, made the Australia Telescope National Facility Mopra telescope, show an excellent morphological match to mid-IR extinction. Moreover, because line emission from entire nebula has same radial velocity within ±3.4 km s−1, single, coherent and not chance alignment multiple unrelated...
The Orion Molecular Cloud is the nearest massive-star forming region. Massive stars have profound effects on their environment due to strong radiation fields and stellar winds. Stellar feedback one of most crucial cosmological parameters that determine properties evolution interstellar medium in galaxies.
Identified as extinction features against the bright Galactic mid-infrared background, infrared dark clouds (IRDCs) are thought to harbor very earliest stages of star and cluster formation. In order better characterize properties their embedded cores, we have obtained new 24 μm, 60–100 submillimeter continuum data toward a sample 38 IRDCs. The μm Spitzer images reveal that while IRDCs remain dark, many cores associated with emission sources, which suggests they contain one or more...
We present a multiwavelength study of the infrared dark cloud MSXDC G034.43+00.24. Dust emission, traced by millimeter/submmillimeter images obtained with IRAM, JCMT, and CSO telescopes, reveals three compact cores within this masses 170-800 M☉ sizes <0.5 pc. Spitzer 3.6-8.0 μm show slightly extended emission toward these cores, spectral enhancement at 4.5 that probably arises from shocked H2. In addition, broad line widths (ΔV ~ 10 km s-1) HCN (4-3) CS (3-2) detection SiO (2-1), observed...
CS (2-1) measurements toward a large sample of fourth Galactic quadrant infrared dark clouds (IRDCs) were made with the Australia Telescope National Facility Mopra telescope in order to establish their kinematic distances and distribution. Due its critical density, unambiguously separates dense IRDCs from more diffuse giant molecular clouds. The fourth-quadrant show pronounced peak radial galactocentric distribution at R = 6 kpc. first-quadrant IRDC (traced by 13CO emission) also shows peak,...
FEEDBACK is a SOFIA legacy program dedicated to study the interaction of massive stars with their environment. It performs survey 11 galactic high mass star forming regions in 158 $μ$m (1.9 THz) line CII and 63 (4.7 OI. We employ 14 pixel LFA 7 HFA upGREAT instrument spectrally resolve (0.24 MHz) these FIR structure lines. With an observing time 96h, we will cover $\sim$6700 arcmin$^2$ at 14.1$''$ angular resolution for 6.3$''$ OI line. The observations started spring 2019 (Cycle 7). Our aim...
Abstract We present new 13 CO (1−0), C 18 O HCO + and H (1−0) maps from the IRAM 30 m telescope a spectrally resolved [C ii ] 158 μ map observed with SOFIA toward massive DR21 cloud. This traces kinematics low- to high-density gas in cloud, which allows us constrain formation scenario of high-mass star-forming ridge. The molecular line data reveal that subfilaments are systematically redshifted relative dense demonstrate unveils surrounding CO-poor filaments also show this is organized...
We present 74 MHz radio continuum observations of the Galactic center region. These measurements show nonthermal emission arising from molecular clouds that is unaffected by free-free absorption along line sight. focus on one cloud, G0.13--0.13, representative population are spatially correlated with steep spectrum (alpha^{74MHz}_{327MHz}=1.3\pm0.3) This cloud lies adjacent to filaments Arc near l~0.2^0 and a strong source continuum, SiO (2-1) FeI Kalpha 6.4 keV emission. three-way...
Abstract Stratospheric Observatory for Infrared Astronomy [C ii ] 157 μ m, APEX 860 m J = 3−2 CO, and archival James Clerk Maxwell Telescope 2−1 CO 13 observations of the Horsehead Nebula are presented. The photon-dominated region (PDR) between Orion B molecular cloud adjacent IC 434 H is used to study radial velocity structure feedback impacts UV radiation. Multiple west-facing edges superimposed along line sight with velocities that differ by a few kilometers per second. lies in foreground...
We have mapped the G287.84-0.82 cometary globule (with Treasure Chest cluster embedded in it) South Pillars region of Carina (i) [CII], 63micron [OI], and CO(11-10) using upGREAT on SOFIA (ii) J=2-1 transitions CO, 13CO, C18O J=3-2 H2CO APEX telescope Chile. probe morphology, kinematics, physical conditions molecular gas photon dominated regions (PDRs) G287.84-0.82. The [CII] [OI] emission suggest that overall structure pillar red-shifted photo evaporating tails) is consistent with effect...
We present a study of signatures on-going star formation in sample protostellar objects with enhanced 4.5 {\mu}m emission ('green' sources) near the Galactic center. To understand how center region compares to that disk, we used Expanded Very Large Array observe radiatively excited Class II 6.7 GHz CH3OH masers and collisionally I 44 masers, both tracers high-mass formation, toward 34 foreground 'green' sources. find 33\pm15% sources are coincident 44\pm17% masers. For correlation rates...
We present a study of star formation in the Central Molecular Zone (CMZ) our Galaxy through association three indicators: 6.7 GHz CH3OH masers, 22 H2O and enhanced 4.5 micron emission (`green') sources. explore how Galactic center (l < 1.3 deg, |b| 10', where l b are longitude latitude) compares with that disk (6 deg 345 2 deg). Using an automated algorithm, we search for sources toward masers detected Parkes Methanol Multibeam Survey. combine these results maser survey CMZ carried out Mopra...
Context. The [C II ] 158 μm fine-structure line is one of the dominant coolants neutral interstellar medium. It hence brightest far-infrared (FIR) emission lines and can be observed not only in star-forming regions throughout Galaxy, but also diffuse medium distant galaxies. has been suggested to a powerful tracer star formation. Aims. We aim understand origin its relation other tracers gas dust. This includes study heating efficiency as traced by test models heating. Methods. made use...
Abstract Using the upGREAT instrument on board Stratospheric Observatory for Infrared Astronomy, we imaged [C ii ] 157.74 and [O i 63.18 μ m line emission from a bright photodissociation region (PDR) associated with an ionized bubble located in Nessie Nebula, filamentary infrared dark cloud. A comparison Australia Telescope Compact Array data reveals classic structure, uniform progression gas, to photodissociated molecular gas bubble’s interior its exterior. PDR self-absorption features....
Neutrinoless double beta decay is one of the most sensitive probes for new physics beyond Standard Model particle physics. One isotopes under investigation <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mmultiscripts><a:mi>Xe</a:mi><a:mprescripts/><a:none/><a:mn>136</a:mn></a:mmultiscripts></a:math>, which would into <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mmultiscripts><b:mi>Ba</b:mi><b:mprescripts/><b:none/><b:mn>136</b:mn></b:mmultiscripts></b:math>. Detecting...
We analyze a [C II] 158 micron map obtained with the L2 GREAT receiver on SOFIA of emission/reflection nebula illuminated by early B star S1 in rho-OphA cloud core. This data set has been complemented maps CO(3-2), 13CO(3-2) and C18O(3-2), observed as part JCMT Gould Belt Survey, archival HCO^+(4-3) data, well [O I] 63 145 imaging Herschel/PACS. The emission is completely dominated strong PDR from surrounding expanding into dense Oph A molecular west south S1. significantly blue shifted...
Abstract We introduce new analysis methods for studying the star cluster formation processes in Orion A, especially examining scenario of a cloud–cloud collision. utilize CARMA–NRO survey 13CO (1–0) data to compare molecular gas properties young stellar objects from SDSS III IN-SYNC survey. show that increase $v_{\rm {}^{13}CO} - v_{\rm YSO}$ and Σ scatter older YSOs can be signals SOFIA-upGREAT 158 μm [C ii] archival toward northern part A are also compared test whether position velocity...
We present a two-epoch Hubble Space Telescope (HST) study of NGC 2071 IR highlighting HOPS 361-C, protostar producing an arced 0.2 parsec-scale jet. Proper motions for the brightest knots decrease from 350 to 100 km/s with increasing distance source. The [Fe II] and Pa$\beta$ emission line intensity ratio gives velocity jump through each knot 40--50 km/s. A new [O I] 63 \mic\ spectrum, taken German REciever Astronomy at Terahertz frequencies (GREAT) instrument aboard Stratospheric...