A5080147217- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Atmospheric Ozone and Climate
- Astronomical Observations and Instrumentation
- Molecular Spectroscopy and Structure
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Atomic and Molecular Physics
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- Advanced Combustion Engine Technologies
- Quantum, superfluid, helium dynamics
- Particle physics theoretical and experimental studies
- Atmospheric chemistry and aerosols
- Particle accelerators and beam dynamics
- Ionosphere and magnetosphere dynamics
- High-pressure geophysics and materials
- GNSS positioning and interference
Center for Astrophysics Harvard & Smithsonian
2022-2024
National Radio Astronomy Observatory
2022-2024
Max Planck Institute for Radio Astronomy
2019-2024
Indian Institute of Science Bangalore
2023
Max Planck Institute for Astronomy
2016-2020
Max Planck Society
2015
Context: The past decade has witnessed a large number of Galactic plane surveys at angular resolutions below 20". However, no comparable high-resolution survey exists long radio wavelengths around 21cm in line and continuum emission. Methods: Employing the Very Large Array (VLA) C-array configuration program, we observe HI line, four OH lines, nineteen Halpha recombination lines as well emission from 1 to 2GHz full polarization over part first quadrant. Results: Covering longitudes 14.5...
Galactic plane radio surveys play a key role in improving our understanding of wide range astrophysical phenomena. Performing such survey using the latest interferometric telescopes produces large data rates necessitating shift towards fully or quasi-real-time analysis with being stored for only time required to process them. We present here overview and setup 3000 hour Max-Planck-Institut fuer Radioastronomie (MPIfR) MeerKAT Plane (MMGPS). The is unique by operating commensal mode,...
There is a considerable deficiency in the number of known supernova remnants (SNRs) Galaxy compared to that expected. Searches for extended low-surface brightness radio sources may find new Galactic SNRs, but confusion with much larger population HII regions makes identifying such features challenging. SNRs can, however, be separated from using their significantly lower mid-infrared (MIR) continuum intensity ratios. We use combination high-resolution 1-2 GHz data The HI, OH, Recombination...
With the $Karl~G.~Jansky$ Very Large Array (VLA) in C-configuration, we observed a large portion of first Galactic quadrant ($l=14.0-67.4^\circ $ and $\lvert b \rvert \leq 1.25^\circ $) achieving an angular resolution $\leq 40^{\prime\prime}$. At $L$ Band, WIDAR correlator at VLA was set to cover 21~cm HI line, four OH transitions, series H$n\alpha$ radio recombination lines (RRLs; $n=151$ 186), eight 128~MHz wide continuum spectral windows (SPWs) simultaneously. The emission shows clear...
Surveys of the Milky Way at various wavelengths have changed our view star formation in Galaxy considerably recent years. In this paper we give an overview GLOSTAR survey, a new survey covering large parts (145 square degrees) northern Galactic plane using Karl G. Jansky Very Large Array (JVLA) frequency range 4-8 GHz and Effelsberg 100-m telescope. This provides for first time radio all angular scales down to 1.5 arcsecond, similar complementary near-IR mid-IR galactic surveys. We outline...
We carried out a large program with the Karl G. Jansky Very Large Array (VLA): "THOR: The HI, OH, Recombination line survey of Milky Way". observed significant portion Galactic plane in first quadrant Way 21cm HI line, 4 OH transitions, 19 radio recombination lines, and continuum from 1 to 2 GHz. In this paper we present catalog sources half (l=14.0-37.9deg l=47.1-51.2deg, |b|<1.1deg) at spatial resolution 10-25", spatially varying noise level ~0.3-1 mJy/beam. contains ~4400 sources. Around...
Radio continuum surveys of the Galactic plane can find and characterize HII regions, supernova remnants (SNRs), planetary nebulae (PNe), extragalactic sources. A number at high angular resolution (<25") different wavelengths exist to study interstellar medium (ISM), but no comparable high-resolution high-sensitivity survey exists long radio around 21cm. We observed a large fraction in first quadrant Milky Way (l=14.0-67.4deg |b| < 1.25deg) with Karl G. Jansky Very Large Array (VLA)...
We introduce the histogram of oriented gradients (HOG), a tool developed for machine vision that we propose as new metric systematic characterization spectral line observations atomic and molecular gas study cloud formation models. In essence, HOG technique takes input extended spectral-line from two tracers provides an estimate their spatial correlation across velocity channels. characterized using synthetic H I 13 CO ( J = 1 → 0) emission numerical simulations magnetohydrodynamic (MHD)...
We present a study of the filamentary structure in emission from neutral atomic hydrogen (H I ) at 21 cm across velocity channels 40′′ and 1.5-km s −1 resolution position-position-velocity cube, resulting combination single-dish interferometric observations The H /OH/recombination-line survey inner Milky Way. Using Hessian matrix method with tools circular statistics, we find that majority structures are aligned Galactic plane. Part this trend can be assigned to long coherent several...
Context. The properties of the population Galactic supernova remnants (SNRs) are essential to our understanding dynamics interstellar medium (ISM) in Milky Way. However, completeness catalog SNRs is expected be only ~30%, with on order 700 yet detected. Deep interferometric radio continuum surveys plane help rectifying this apparent deficiency by identifying low surface brightness and compact that have not been detected previous surveys. routinely confused H II regions, which can similar...
Class II methanol (CH$_{3}$OH) masers are amongst the clearest signposts of recent high-mass star formation (HMSF). A complete catalogue outlines distribution in Galaxy, number young star-forming cores, and physical conditions their environment. The Global View on Star Formation (GLOSTAR) survey, which is a blind survey radio regime 4$-$8 GHz, maps Galactic mid-plane continuum, 6.7 GHz line, 4.8 formaldehyde several recombination lines. We present analysis observations CH$_{3}$OH maser...
The nearby Eta Chamaeleontis association is a collection of 4-10 Myr old stars with disk fraction 35-45%. In this study, the broad wavelength coverage VLT/X-Shooter used to measure stellar and mass accretion properties 15 low in association. For each star, observed spectrum fitted non-accreting template an obtained from assuming plane-parallel hydrogen slab. Five eight IR excess show UV emission, indicating ongoing accretion. rates measured here are similar those previous measurements but...
Molecular clouds form from the atomic phase of interstellar medium. However, characterizing transition between and molecular medium (ISM) is a complex observational task. Here we address cloud formation processes by combining H I self absorption (HISA) with line data. Column density probability functions (N-PDFs) are common tool for examining clouds. One scenario proposed numerical simulations that N-PDF evolves log-normal shape at early times to power-law-like later times. To date,...
Abstract We combine a new Galactic plane survey of hydrogen radio recombination lines (RRLs) with far-infrared surveys ionized nitrogen, N + , to determine nitrogen abundance across radius. RRLs were observed the NASA Deep Space Network Station 43 70 m antenna and Green Bank Telescope in 108 sight spanning −135°< l < 60°, at b = 0°. These positions also [N ii ] 122 μ 205 Herschel Observatory. Combining RRL observations 41 samples high signal-to-noise ratio, we studied distribution...
Context. The derived physical parameters for young HII regions are normally determined assuming the emission region to be optically thin. However, this assumption is unlikely hold such as hyper-compact HII(HCHII) and ultra-compact HII(UCHII) leads underestimation of their properties. This can overcome by fitting SEDs over a wide range radio frequencies. Aims. two primary goals study (1) determine properties from in search potential HCHII regions, (2) use these investigate evolution. Method....
Abstract The HyGAL Stratospheric Observatory for Infrared Astronomy legacy program surveys six hydride molecules—ArH + , OH H 2 O SH, OH, and CH—and two atomic constituents—C O—within the diffuse interstellar medium (ISM) by means of absorption-line spectroscopy toward 25 bright Galactic background continuum sources. This detailed spectroscopic study is designed to exploit unique value specific hydrides as tracers probes different phases ISM, demonstrated recent studies with Herschel Space...
As part of the GLOSTAR survey we have used VLA in its B-configuration to observe Galactic plane between longitudes 28d and 36d latitudes from -1d +1d at C-band (4--8 GHz). To reduce contamination extended sources that are not well recovered by our coverage (u, v)-plane discarded short baselines sensitive emission on angular scales $<4"$. The resulting radio continuum images an resolution 1.0", sensitivity $\sim60 \mu$Jy~beam$^{-1}$; making it most covering a large area with this resolution....
Context. Cygnus X is one of the closest and most active high-mass star-forming regions in our Galaxy, making it best laboratories for studying massive star formation. Aims. We aim to investigate properties molecular gas structures on different linear scales with 4.8 GHz formaldehyde (H 2 CO) absorption line X. Methods. As part GLOSTAR Galactic plane survey, we performed large-scale (7º×3º) simultaneous H CO (1 1,0 –1 1,1 ) spectral radio continuum imaging observations toward at λ ~6 cm Karl...
The Cygnus X complex is covered by the Global View of Star Formation in Milky Way (GLOSTAR) survey, an unbiased radio-wavelength Galactic plane 4--8 GHz continuum radiation and several spectral lines. GLOSTAR survey observed 6.7~GHz transition methanol (CH$_3$OH), exclusive tracer high-mass young stellar objects. Using Very Large Array both B D configurations, we area Cygnus~X $7^{\rm o}\times3^{\rm o}$ size simultaneously line continuum, allowing cross-registration. We detected thirteen...
As part of the GLObal view STAR formation in Milky Way (GLOSTAR) survey, we present high-resolution continuum source catalog for regions ( ℓ = 2° −28°, 36° −40°, 56° −60°, and | b < 1.0°), observed with Karl G. Jansky Very Large Array (VLA) its B-configuration. The images were optimized to detect compact sources on angular scales up 4″, have a typical noise level 1 σ ~ 0.08 mJy beam −1 an resolution 1″, which makes GLOSTAR currently highest as well most sensitive radio survey northern...
Context. The GLObal view on STAR formation in the Milky Way (GLOSTAR) survey studies star with Very Large Array (VLA) and Effelsberg 100 meter radio telescope Galactic plane between −2° < ℓ 60° | b 1°, Cygnus X region (76° 83° −1° 2°), unprecedented sensitivity both flux density (1 σ ~50 μJy beam −1 ) capability of detecting emission angular scales range from 1.″0 to largest structures Galaxy order a few degrees size. Aims. Here, we provide complete GLOSTAR-VLA D-configuration source...
Context. The hydroxyl radical (OH) is present in the diffuse molecular and partially atomic phases of interstellar medium (ISM), but its abundance relative to hydrogen not clear. Aims. We aim evaluate OH with respect using absorption against cm-continuum sources over first Galactic quadrant. Methods. This study part H I /OH/Recombination line survey inner Milky Way (THOR). THOR a Karl G. Jansky Very Large Array (VLA) large program atomic, ionized gas range 15° ≤ l 67° | b |≤ 1°. It...
The Central Molecular Zone (CMZ), a $\sim$200 pc sized region around the Galactic Centre, is peculiar in that it shows star formation rate (SFR) suppressed with respect to available dense gas. To study SFR CMZ, young stellar objects (YSOs) can be investigated. Here we present radio observations of 334 2.2 $μ$m infrared sources have been identified as YSO candidates. Our goal investigate presence centimetre wavelength continuum counterparts this sample candidates which use constrain current...
The dynamics of ionized gas around the W33 Main ultracompact HII region is studied using observations hydrogen radio recombination lines and a detailed multiwavelength characterization massive star-forming performed. We used Giant Meterwave Radio Telescope (GMRT) to observe H167$\alpha$ line at 1.4 GHz an angular resolution 10 arcsec, Karl. G. Jansky Very Large Array (VLA) data acquired in GLOSTAR survey study gas. also observed continuum 610 MHz with GMRT 4$-$8 characterize nature emission....