Podcasts about atacama large millimeter array

Disentangling protoplanetary disk gas mass and carbon depletion through combined atomic and molecular tracers by J. A. Sturm et al. on Tuesday 20 September The total disk gas mass and elemental C, N, O composition of protoplanetary disks are crucial ingredients for our understanding of planet formation. Measuring the gas mass is complicated, since H$_2$ cannot be detected in the cold bulk of the disk and the elemental abundances with respect to hydrogen are degenerate with gas mass in all disk models. We present new NOEMA observations of CO, $^{13}$CO, C$^{18}$O and optically thin C$^{17}$O $J$=2-1 lines, and use additional high angular resolution Atacama Large Millimeter Array millimeter continuum and CO data to construct a representative model of LkCa 15. The transitions that constrain the gas mass and carbon abundance most are C$^{17}$O 2-1, N${_2}$H$^+$ 3-2 and HD 1-0. Using these three molecules we find that the gas mass in the LkCa 15 disk is $M_mathrm{g}=0.01 ^{+0.01}_{-0.004} M_{odot}$, a factor of six lower than estimated before. The carbon abundance is C/H = ($3 pm 1.5) times10^{-5}$, implying a moderate depletion of elemental carbon by a factor of 3-9. All other analyzed transitions also agree with these numbers, within a modeling uncertainty of a factor of two. Using the resolved ce{C2H} image we find a C/O ratio of $sim$1, which is consistent with literature values of H$_2$O depletion in this disk. The lack of severe carbon depletion in the LkCa 15 disk is consistent with the young age of the disk, but contrasts with the higher depletions seen in older cold transition disks. Combining optically thin CO isotopologue lines with N$_2$H$^+$ is promising to break the degeneracy between gas mass and CO abundance. The moderate level of depletion for this source with a cold, but young disk, suggests that long carbon transformation timescales contribute to the evolutionary trend seen in the level of carbon depletion among disk populations, rather than evolving temperature effects and presence of dust traps alone. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.09286v1

Disentangling protoplanetary disk gas mass and carbon depletion through combined atomic and molecular tracers by J. A. Sturm et al. on Tuesday 20 September The total disk gas mass and elemental C, N, O composition of protoplanetary disks are crucial ingredients for our understanding of planet formation. Measuring the gas mass is complicated, since H$_2$ cannot be detected in the cold bulk of the disk and the elemental abundances with respect to hydrogen are degenerate with gas mass in all disk models. We present new NOEMA observations of CO, $^{13}$CO, C$^{18}$O and optically thin C$^{17}$O $J$=2-1 lines, and use additional high angular resolution Atacama Large Millimeter Array millimeter continuum and CO data to construct a representative model of LkCa 15. The transitions that constrain the gas mass and carbon abundance most are C$^{17}$O 2-1, N${_2}$H$^+$ 3-2 and HD 1-0. Using these three molecules we find that the gas mass in the LkCa 15 disk is $M_mathrm{g}=0.01 ^{+0.01}_{-0.004} M_{odot}$, a factor of six lower than estimated before. The carbon abundance is C/H = ($3 pm 1.5) times10^{-5}$, implying a moderate depletion of elemental carbon by a factor of 3-9. All other analyzed transitions also agree with these numbers, within a modeling uncertainty of a factor of two. Using the resolved ce{C2H} image we find a C/O ratio of $sim$1, which is consistent with literature values of H$_2$O depletion in this disk. The lack of severe carbon depletion in the LkCa 15 disk is consistent with the young age of the disk, but contrasts with the higher depletions seen in older cold transition disks. Combining optically thin CO isotopologue lines with N$_2$H$^+$ is promising to break the degeneracy between gas mass and CO abundance. The moderate level of depletion for this source with a cold, but young disk, suggests that long carbon transformation timescales contribute to the evolutionary trend seen in the level of carbon depletion among disk populations, rather than evolving temperature effects and presence of dust traps alone. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2209.09286v1

A galaxy group candidate at z~3 7 in the COSMOS field by Nikolaj Bjerregaard Sillassen et al. on Tuesday 13 September We report a galaxy group candidate HPC1001 at $zapprox3.7$ in the COSMOS field. This structure was selected as a high galaxy overdensity at $z>3$ in the COSMOS2020 catalog. It contains ten candidate members, of which eight are assembled in a $10''times10''$ area with the highest sky density among known protoclusters and groups at $z>3$. Four out of ten sources were also detected at 1.2$~$mm with Atacama Large Millimeter Array continuum observations. Photometric redshifts, measured by four independent methods, fall within a narrow range of $3.5

A University of Arizona-led team of astronomers has created a detailed, three-dimensional image of a dying hypergiant star. The team, led by UArizona researchers Ambesh Singh and Lucy Ziurys, traced the distribution, directions and velocities of a variety of molecules surrounding a red hypergiant star known as VY Canis Majoris. Their findings, which they presented on June 13 at the 240th Meeting of the American Astronomical Society in Pasadena, California, offer insights, at an unprecedented scale, into the processes that accompany the death of giant stars. The work was done with collaborators Robert Humphreys from the University of Minnesota and Anita Richards from the University of Manchester in the United Kingdom. Extreme supergiant stars known as hypergiants are very rare, with only a few known to exist in the Milky Way. Examples include Betelgeuse, the second brightest star in the constellation Orion, and NML Cygni, also known as V1489 Cygni, in the constellation Cygnus. Unlike stars with lower masses – which are more likely to puff up once they enter the red giant phase but generally retain a spherical shape – hypergiants tend to experience substantial, sporadic mass loss events that form complex, highly irregular structures composed of arcs, clumps and knots. Located about 3,009 light-years from Earth, VY Canis Majoris – or VY CMa, for short – is a pulsating variable star in the slightly southern constellation of Canis Major. Spanning anywhere from 10,000 to 15,000 astronomical units (with 1 AU being the average distance between Earth and the sun) VY CMa is possibly the most massive star in the Milky Way, according to Ziurys. “Think of it as Betelgeuse on steroids,” said Ziurys, a Regents Professor with joint appointments in UArizona Department of Chemistry and Biochemistry and Steward Observatory, both part of the College of Science. “It is much larger, much more massive and undergoes violent mass eruptions every 200 years or so.” The team chose to study VY CMa because it is one of the best examples of these types of stars. “We are particularly interested in what hypergiant stars do at end of their lives,” said Singh, a fourth-year doctoral student in Ziurys' lab. “People used to think these massive stars simply evolve into supernovae explosions, but we are no longer sure about that.” “If that were the case, we should see many more supernovae explosions across the sky,” Ziurys added. “We now think they might quietly collapse into black holes, but we don't know which ones end their lives like that, or why that happens and how.” Previous imaging of VY CMa with NASA's Hubble Space Telescope and spectroscopy showed the presence of distinct arcs and other clumps and knots, many extending thousands of AU from the central star. In Search of Details on the Deaths of Rare Giant Stars To uncover more details of the processes by which hypergiant stars end their lives, the team set out to trace certain molecules around the hypergiant and map them to preexisting images of the dust, taken by the Hubble Space Telescope. “Nobody has been able to make a complete image of this star,” Ziurys said, explaining that her team set out to understand the mechanisms by which the star sheds mass, which appear to be different from those of smaller stars entering their red giant phase at the end of their lives. “You don't see this nice, symmetrical mass loss, but rather convection cells that blow through the star's photosphere like giant bullets and eject mass in different directions,” Ziurys said. “These are analogous to the coronal arcs seen in the sun, but a billion times larger.” The team used the Atacama Large Millimeter Array, or ALMA, in Chile to trace a variety of molecules in material ejected from the stellar surface. While some observations are still in progress, preliminary maps of sulfur oxide, sulfur dioxide, silicon oxide, phosphorous oxide and sodium chloride were obtained. From these data, the group constructed an image of the gl...

Utilizaron para la detección el radiotelescopio llamado: Atacama Large Millimeter Array, cuyo acrónimo es ALMA. Con el realizaron observaciones de alta resolución de la nube y encontraron que se arremolinaba alrededor de un objeto invisible masivo. Los agujeros negros varían en masa desde aproximadamente cinco veces la masa del sol hasta agujeros negros super-masivos de millones de veces la masa del sol. Se especula que se forman agujeros negros de masa estelar cuando las estrellas muy masivas colapsan al final de su ciclo de vida. Una vez que se ha formado un agujero negro, puede seguir creciendo al absorber masa de su entorno. Percatémonos del relato…

The 2018 Astor Visiting Lecture 14th March 2018 delivered by Professor Adam Leroy, Ohio State University. The Atacama Large Millimeter/sub-millimeter Array (ALMA) is the largest, most complex ground-based telescope ever built. From its perch high in the Chilean Andes, ALMA is now unveiling the birth of planets, stars, and galaxies. I will give a taste of the revolution ushered in by ALMA. This includes resolving the disks that form new Solar systems, finding the seeds of gaseous giant planets, weighing – and maybe even directly imaging – black holes, and watching galaxies form at the edge of the universe. Then, I will show how my colleagues and I are using ALMA to understand the origins of stars in galaxies. As part of ALMA's largest project to date, we are studying all of the stellar nurseries across the nearby universe. We see that the cold clouds of gas and dust that form stars appear to be shaped by violent, dynamic processes that vary from galaxy to galaxy. We also see that the birth of stars from these clouds is both inefficient and terribly destructive.

For all 66 ALMA antennas to move in exact unison, the precision of the dish surface must be less than the width of a strand of hair. Witnessing them whirl in the desert is a magnificent sight. The latest in science, culture, and history from Smithsonian Channel.

In 2014, astronomer David Wilmer aimed the ALMA Array at a young star 450 light years away. What he found proved that planets formed billions of years earlier than what scientists originally... The latest in science, culture, and history from Smithsonian Channel.

Presented by Prof. Jeremy Mould on 7th May 2015.The skies of northern Chile are considered the best in the world for astronomy at visible through millimetre wavelengths. Most of the observatories are in the Norte Chico and Atacama regions. Cerro Paranal Observatory is the largest in the world. The Atacama Large Millimeter Array is an international astronomical facility composed of a group of up to 66 radio antennae working together 5000 meters above sea level in the hghlands (Llano de Chajnantor) of the Andes Mountain Range, 50 kms from San Pedro de Atacama. ALMA is the most global astronomical project. Under development is the LSST - Large Synoptic Survey Telescope. The project, which brings together 19 universities and laboratories is under construction on Cerro Pachon and will be able to view, weekly, the entire visible Universe using a digital camera of 3000 million pixels. Cerro Armazones, 3,060 meters in height, situated in the Atacama desert some 130 km south of Antofagasta, Chile, is the site chosen for the largest telescope in the world -known as European Extremely Large Telescope (E-ELT). Las Campanas observatory is operated by Carnegie Institution of Washington, and its location is 2,500 meters above sea level. It will host the Giant Magellan Telescope. Australian astronomers are participating in its construction.

Presented by Prof. Jeremy Mould on 7th May 2015.The skies of northern Chile are considered the best in the world for astronomy at visible through millimetre wavelengths. Most of the observatories are in the Norte Chico and Atacama regions. Cerro Paranal Observatory is the largest in the world. The Atacama Large Millimeter Array is an international astronomical facility composed of a group of up to 66 radio antennae working together 5000 meters above sea level in the hghlands (Llano de Chajnantor) of the Andes Mountain Range, 50 kms from San Pedro de Atacama. ALMA is the most global astronomical project. Under development is the LSST - Large Synoptic Survey Telescope. The project, which brings together 19 universities and laboratories is under construction on Cerro Pachon and will be able to view, weekly, the entire visible Universe using a digital camera of 3000 million pixels. Cerro Armazones, 3,060 meters in height, situated in the Atacama desert some 130 km south of Antofagasta, Chile, is the site chosen for the largest telescope in the world -known as European Extremely Large Telescope (E-ELT). Las Campanas observatory is operated by Carnegie Institution of Washington, and its location is 2,500 meters above sea level. It will host the Giant Magellan Telescope. Australian astronomers are participating in its construction.

Presented by David J. Wilner on 13 February 2015.Where did the Earth come from? How can we know? How can particles no larger than those in smoke come together to make a planet thousands of kilometers wide? Amazingly, radio telescope observations of material surrounding infant stars are starting to show us signs of planet formation in action. This talk will introduce some of the basic ideas and open questions of planet formation, starting with naked eye observations and proceeding to the latest images from giant radio telescopes, including the new international Atacama Large Millimeter Array of 66 antennas sited at 5000 meters altitude in northern Chile.

Presented by David J. Wilner on 13 February 2015.Where did the Earth come from? How can we know? How can particles no larger than those in smoke come together to make a planet thousands of kilometers wide? Amazingly, radio telescope observations of material surrounding infant stars are starting to show us signs of planet formation in action. This talk will introduce some of the basic ideas and open questions of planet formation, starting with naked eye observations and proceeding to the latest images from giant radio telescopes, including the new international Atacama Large Millimeter Array of 66 antennas sited at 5000 meters altitude in northern Chile.

The Atacama desert in Chile is one of the driest places on earth. It’s also the site of a new telescope called the Atacama Large Millimeter Array.

Jeff Mangum, NRAO astronomer, describes NRAO's newest telescope project, ALMA , as well as his research looking for formaldehyde in nearby galaxies.

We take a multi-faceted approach to study the relativistic cosmic ray (CR) proton population in galaxy clusters. CR protons may be accelerated by structure formation shock waves, injected from radio galaxies into the intra-cluster medium, or result from supernova driven galactic winds. This thesis addresses the following questions: do CR protons exist in galaxy clusters? What is the dynamic and cosmological impact of CRs? How can we observe them? How can we describe CRs and their interactions? The first major part of this thesis investigates the question of the dynamic influence of CRs on the intra-cluster medium and searches for unbiased tracers of their existence using multi-frequency observational results. To this end, I develop an analytical framework to describe the hadronic interactions of CR protons with the ambient thermal plasma. In the second part, a description of CR gas for cosmological applications is presented that is especially suited for hydrodynamical simulations. During the course of this work, I focus on developing a formalism for instantaneously identifying and estimating the strength of structure formation shocks during cosmological simulations to accelerate CRs through diffusive shock acceleration. Since the energetically dominant CR population is trapped by cluster magnetic fields, it can only be observed indirectly through non-thermal radiative processes. CR protons interact hadronically with the ambient plasma and produce mainly neutral and charged pions that successively decay into gamma-rays, secondary electrons, and neutrinos. I develop an analytic formalism which describes the induced radio synchrotron, inverse Compton, and gamma-ray emission. Comparing the expected gamma-ray flux to the upper limits obtained by the gamma-ray observatory EGRET, I am able to constrain the CR proton energy density in nearby cooling core clusters to < 20% relative to the thermal energy density. In this context, I study the hypothesis that the diffuse radio synchrotron emission of galaxy clusters is produced by hadronically originating relativistic electrons and I develop a non-parametric criterion to obtain the minimum energy state for an observed radio synchrotron emission: the excellent agreement between the observed and theoretically expected radio surface brightness profile of the Perseus mini-halo and the small amount of energy density in CR protons needed to account for the observed radio emission makes this hadronic model an attractive explanation of radio mini-halos found in cooling core clusters. To explain the giant radio halo of Coma within the hadronic model of secondary electrons, the CR proton-to-thermal energy density profile has to increase radially up to moderate CR energy densities. Cosmological simulations that self-consistently follow CR acceleration at shock waves predict such an energy density profile: strong shock waves, that occur predominantly in low density regions, are able to efficiently accelerate high-energetic CRs, whereas weak central flow shocks inject only a low-energetic CR population which is strongly diminished by Coulomb interactions. This implies that the dynamic importance of the shock-injected CR energy density is largest in the low-density halo infall regions, but is less important for the weaker shocks occurring in central high-density cluster regions. As an extension of this work, I propose a new method in order to elucidate the content of the radio plasma bubbles located at cool cores of galaxy clusters. Using the Sunyaev-Zel'dovich (SZ) effect, the Atacama Large Millimeter Array and the Green Bank Telescope should be able to infer the dynamically dominant CR component of the plasma bubbles in suitable galaxy clusters within short observation times. Future high-sensitivity multi-frequency SZ observations will be able to infer the energy spectrum of the dynamically dominant electron population. This knowledge can yield indirect indications for an underlying composition of relativistic outflows of radio galaxies because plasma bubbles represent the relic fluid of jets. In the second major part of my thesis, I address the problem of constructing an accurate and self-consistent model for the description of CRs that aims at studying the dynamic influence of CRs on structure formation and galaxy evolution. This will not only allow the production of realistic non-thermal emission signatures of galaxies and clusters of galaxies, but also allow in-vivo studies of dynamic effects driven by relativistic particles and the star formation history. The developed model self-consistently traces relativistic protons originating from various kinds of sources, such as structure formation shock waves and supernovae driven galactic winds, and also accounts for dissipative processes in the relativistic gas component. To this end, I develop a formalism for the identification and accurate estimation of the strength of structure formation shocks during cosmological smoothed particle hydrodynamics simulations. Shocks not only play a decisive role for the thermalization of gas in virializing structures but also for the acceleration of CRs through diffusive shock acceleration. The formalism is applicable both to ordinary non-relativistic thermal gas and to plasmas composed of CRs and thermal gas. I apply these methods to studying the properties of structure formation shocks in high-resolution hydrodynamic simulations of the LambdaCDM model and find that most of the energy is dissipated in weak internal shocks which are predominantly central flow shocks or merger shock waves traversing halo centers. Collapsed cosmological structures are surrounded by external shocks with a much higher Mach number, but they play only a minor role in the energy balance of thermalization. I show that after the epoch of cosmic reionization, the Mach number distribution is significantly modified by an efficient suppression of strong external shock waves due to the associated increase of the sound speed of the diffuse gas.