A5029381451- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Molecular Spectroscopy and Structure
- Astronomical Observations and Instrumentation
- Spectroscopy and Laser Applications
- Gastrointestinal disorders and treatments
- Solar and Space Plasma Dynamics
- Space Exploration and Technology
- Space Satellite Systems and Control
- Geophysics and Gravity Measurements
- Ionosphere and magnetosphere dynamics
- Atomic and Molecular Physics
- X-ray Spectroscopy and Fluorescence Analysis
- Advanced Thermodynamic Systems and Engines
- Radio Astronomy Observations and Technology
- Particle Detector Development and Performance
- Flow Measurement and Analysis
- Advanced X-ray Imaging Techniques
Chalmers University of Technology
2013-2024
The University of Tokyo
2023
Universidad de Guanajuato
2023
National Astronomical Observatory of Japan
2018-2020
National Institutes of Natural Sciences
2019-2020
Universidad Nacional Autónoma de México
2005-2015
Kagoshima University
2010-2013
Swedish Institute of Space Physics
2012
Center for Astrophysics Harvard & Smithsonian
2006-2008
The initial conditions found in infrared dark clouds (IRDCs) provide insights on how high-mass stars and stellar clusters form. We have conducted high-angular resolution high-sensitivity observations toward thirty-nine massive IRDC clumps, which been mosaicked using the 12m 7m arrays from Atacama Large Millimeter/submillimeter Array (ALMA). targets are 70 $\mu$m (220-4900 $M_\odot$), dense ($>$10$^4$ cm$^{-3}$), cold ($\sim$10-20K) clumps located at distances between 2 6 kpc. identify an...
We present the dynamical properties of 294 cores embedded in twelve IRDCs observed as part ASHES Survey. Protostellar have higher gas masses, surface densities, column and volume densities than prestellar cores, indicating core mass growth from to protostellar phase. find that ~80% with virial parameter ($\alpha$) measurements are gravitationally bound ($\alpha$< 2). also an anti-correlation between massive having on average lower parameters. more 1.2 1.5, respectively. The non-thermal...
Abstract Massive infrared dark clouds (IRDCs) are considered to host the earliest stages of high-mass star formation. In particular, 70 μ m IRDCs colder and more quiescent clouds. At a scale about 5000 au using formaldehyde (H 2 CO) emission, we investigate kinetic temperature dense cores in 12 obtained from pilot Atacama Large Millimeter/submillimeter Array Survey High-mass clumps Early Stages (ASHES). Compared 1.3 mm dust continuum other molecular lines, such as C 18 O deuterated species,...
A survey of the Milky Way disk and Magellanic System at wavelengths 21-cm atomic hydrogen (HI) line three 18-cm lines OH molecule will be carried out with Australian Square Kilometre Array Pathfinder telescope. The study distribution HI emission absorption unprecedented angular velocity resolution, as well molecular thermal emission, absorption, maser lines. area to covered includes Galactic plane (|b|< 10deg) all declinations south delta = +40deg, spanning longitudes 167deg through 360deg...
Abstract Fragmentation during the early stages of high-mass star formation is crucial for understanding clusters. We investigated fragmentation within 39 star-forming clumps as part Atacama Large Millimeter/submillimeter Array Survey 70 μ m Dark High-mass Clumps in Early Stages (ASHES) survey. Considering projection effects, we have estimated core separations 839 cores identified from continuum emission and found mean values between 0.08 0.32 pc each clump. find compatibility observed masses...
(Abridged) ASHES has been designed to systematically characterize the earliest stages and constrain theories of high-mass star formation. A total 12 massive (>500 $M_{\odot}$), cold (<15 K), 3.6-70 $\mu$m dark prestellar clump candidates, embedded in IRDCs, were carefully selected pilot survey be observed with ALMA. We mosaiced each (~1 arcmin^2) dust line emission 12m/7m/TP arrays at 224 GHz, resulting ~1.2" resolution (~4800 AU). As first paper series, we concentrate on reveal...
We present a study of outflows at extremely early stages high-mass star formation obtained from the ALMA Survey 70 $\mu \rm m$ dark High-mass clumps in Early Stages (ASHES). Twelve massive 3.6$-$70 prestellar clump candidates were observed with Atacama Large Millimeter/submillimeter Array (ALMA) Band 6. Forty-three are identified toward 41 out 301 dense cores using CO and SiO emission lines, yielding detection rate 14%. discover 6 episodic molecular associated low- to cores, indicating that...
Context. This is the first publication from DEATHSTAR project. The overall goal of project to reduce uncertainties observational estimates mass-loss rates evolved stars on Asymptotic Giant Branch (AGB). Aim. aim in this constrain sizes 12 CO emitting region circumstellar envelopes around 42 mostly southern AGB stars, which 21 are M-type and C-type, using Atacama Compact Array (ACA) at Large Millimeter/submillimeter Array. symmetry outflows also investigated. Methods. Line emission J = 2→1...
Abstract With a mass of ∼1000 M ⊙ and surface density ∼0.5 g cm −2 , G023.477+0.114, also known as IRDC 18310-4, is an infrared dark cloud (IRDC) that has the potential to form high-mass stars been recognized promising prestellar clump candidate. To characterize early stages star formation, we have observed G023.477+0.114 part Atacama Large Millimeter/submillimeter Array (ALMA) Survey 70 μ m Dark High-mass Clumps in Early Stages. We conducted ∼1.″2 resolution observations with ALMA at 1.3 mm...
Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB), when an efficient mass-loss process removes a significant fraction of their initial mass. A substantial increase in rate at end AGB is observed for least some unknown reasons. This creates post-AGB objects that are completely enshrouded thick dusty envelopes might be associated with binary interactions. We $J=2-1$ line $^{13}$CO, C$^{17}$O, C$^{18}$O Atacama Large Millimeter / submillimeter Array (ALMA)...
Low- and intermediate-mass stars evolve through the asymptotic giant branch (AGB) when an efficient mass-loss process removes a significant fraction of their initial mass. For most sources, this relies on interplay between convection, stellar pulsations, dust formation. However, predicting history given star from first principles is complex not yet feasible at present. At end AGB, least some experience substantial increase in rate for unknown reasons, leading to creation post-AGB objects...
Aims. Polarisation observations of circumstellar dust and molecular (thermal maser) lines provide unique information about properties magnetic fields in envelopes evolved stars.
Abstract Studying the physical and chemical properties of cold dense molecular clouds is crucial for understanding how stars form. Under typical conditions infrared dark clouds, CO removed from gas phase trapped onto surface dust grains by so-called depletion process. This suggests that CO-depletion factor ( f D ) can be a useful indicator identifying regions (i.e., prestellar cores). We have used 1.3 mm continuum C 18 O (2–1) data observed at resolution ∼5000 au in ALMA Survey 70 μ m Dark...
Abstract PeVatrons are the most powerful naturally occurring particle accelerators in Universe. The identification of counterparts associated to astrophysical objects such as dying massive stars, molecular gas, star-forming regions, and star clusters is essential clarify underlying nature PeV emission, i.e., hadronic or leptonic. We present 12,13CO (J = 2→1) observations made with 1.85 m radio-telescope Osaka Prefecture University toward Cygnus OB7 cloud, which contains PeVatron candidate...
The very late thermal pulse (VLTP) affects the evolution of $\sim$20\% 1--8\,$\mathrm M_\odot$ stars, repeating last phases red giant within a few years and leading to formation new, but hydrogen-poor nebula old planetary (PN). strong dust in latter obscures optical near-infrared radiation star. We aimed determine reheating timescale central star Sakurai's object, which is an important constraint for poorly understood VLTP evolution. observed radio continuum emission object almost 20 from...
MWC 349A is the brightest radio continuum star in centimeter domain. The thermal emission believed to originate an ionized bipolar flow that photoevaporates from surfaces of a neutral Keplerian disk. In this work we present high angular resolution observations taken with Very Large Array (VLA) at wavelengths 7 mm 90 cm allow study structures over 2 orders magnitude size object. image shows intermediate equatorial region ~004 wide, no free-free emission, could be photoevaporating disk around...
(Abridged) The evolution of low- and intermediate-initial-mass stars beyond the asymptotic giant branch (AGB) remains poorly understood. High-velocity outflows launched shortly after AGB phase are thought to be primary shaping mechanism bipolar multipolar planetary nebulae (PNe). However, little is known about launching driving for these jets, whose momentum energy often far exceed that can provided by radiation pressure alone. Here, we report direct evidence a magnetically collimated jet...
Abstract We present a study of the chemistry toward 294 dense cores in 12 molecular clumps, using data obtained from ALMA Survey 70 μ m dark High-mass clumps Early Stages. identified 97 protostellar and 197 prestellar core candidates, based on detection outflows transitions high upper-energy levels ( E u / k > 45 K). The rate N 2 D + emission is 38%, which higher than 9% for cores, indicating that does not exclusively trace cores. rates DCO are 35% 49% those , implying appears more...
Context. The mass loss experienced on the asymptotic giant branch (AGB) at end of lives low- and intermediate-mass stars is widely accepted to rely radiation pressure acting newly formed dust grains. Dust formation happens in extended atmospheres these stars, where density, velocity, temperature distributions are strongly affected by convection, stellar pulsation, heating cooling processes. interaction between processes how that affects growth complex. Hence, characterising empirically...
We present deep XMM–Newton European Photon Imaging Camera observations of the Wolf–Rayet (WR) bubble NGC 6888 around star WR 136. The complete X-ray mapping nebula confirms distribution hot gas in three maxima spatially associated with caps and north-west blowout hinted at by previous Chandra observations. global emission is well described a two-temperature optically thin plasma model (T1 = 1.4 × 106 K, T2 8.2 K) luminosity LX 7.8 1033 erg s−1 0.3–1.5 keV energy range. rms electron density...
We present a spatio-kinematical analysis of the CO~($J$=2$\rightarrow$1) line emission, observed with Atacama Large Millimter/submillimter Array (ALMA), outflow associated most massive core, ALMA1, in 70 $\mu$m dark clump G010.991$-$00.082. The position-velocity (P-V) diagram molecular exhibits peculiar $\mathsf{S}$-shaped morphology that has not been seen any other star forming region. propose model for bipolar consists decelerating high-velocity component surrounded by slower whose...
NGC 4395 is a dwarf galaxy at distance of about 4.3 Mpc (scale: ~0.021 pc mas$^{-1}$). It hosts an intermediate-mass black hole (IMBH) with mass between ~10$^4$ and ~10$^5$ solar masses. The early radio observations the very long baseline interferometry (VLBI) network, High Sensitivity Array (HSA), 1.4 GHz in 2005 showed that its nucleus has sub-mJy outflow-like feature (E) extending over 15 mas. To probe possibility E as continuous jet base physically coupled accretion disc, we performed...
In a born-again planetary nebula (PN), processed H-deficient material has been injected inside the old, H-rich as result of very late thermal pulse (VLTP) event. Long-slit spectra have used to unveil chemical and physical differences between these two structures, but ejection shaping processes still remain unclear. To peer into morpho-kinematics ejecta in PN A 58, we present first integral field spectroscopic observations obtained with GTC MEGARA. We detect emission from H α , He I [O III ],...