Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory
Santiago, Chile
Tel: +56 2 467 6258
Cell: +56 9 75871963
Email: vfoncea@alma.cl
After more than two years of work, today was launched the first Chilean Virtual Observatory (ChiVO), an astro-informatic platform for the administration and analysis of massive data coming from the observatories built across the country. Its implementation will provide advanced computing tools and research algorithms to the Chilean astronomical community.
“This project is a major contribution for Chilean astronomers -said Diego Mardones, an astronomer at Universidad de Chile- because besides being an excellent tool for exploring the huge quantity of astronomical data that will be generated in our country in the coming years, it opens new opportunities of interdisciplinary research.”
ChiVO main team. Left to right: Paulina Troncoso, Astronomer; Ricardo Contreras, U. of Concepción; Jorge Ibsen, ALMA; Mauricio Solar, ChiVO’s director, U. Técnica Federico Santa María (UFSM); Paola Arellano, REUNA; Victor Parada, U. of Santiago; Marcelo Mendoza, ChiVO’s alternate director, UFSM; Diego Mardones, U. of Chile; Mauricio Araya, UFSM; María; Guillermo Cabrera, U. of Chile.
The project led by Universidad Técnica Federico Santa María (UTFSM) is a successful collaboration with four other universities in Chile (Universidad de Chile, Universidad Católica, Universidad de Concepción y Universidad de Santiago) and was funded by FONDEF, the Chilean Scientific and Technological Development Fund. Furthermore, both the Atacama Large Millimeter/submillimeter Array (ALMA) and REUNA, the National Universities Network, are associated to the project. Thanks to ChiVO, Chile will become a member of the International Virtual Observatories Alliance (IVOA) and it will be accessible for all astronomers making their research in the country through its website http://www.chivo.cl.
For the project’s director, Mauricio Solar, “this innovation will allow astronomical data to be processed in Chile using high-quality, local human capital and integrating Chilean astro-informatics with the international community at the highest levels of development.”
With new telescopes being constructed in Chile, the amount of astronomical data generated will only increase. As an example, once ALMA is operating at full capacity, it will produce close to 250 terabytes of data each year. ChiVO will enable Chilean astronomers to access this data with high transfer rates, provide the infrastructure for high storage capacity and access the analysis of the data.
“ChiVO and the services provided by it will be a key tool for the Chilean astronomical community, added Jorge Ibsen, director of ALMA’s Department of Computing. “ALMA is proud to be part of this project that will boost the usage of the astronomical data generated in the country.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
Experts from 33 countries will attend the global Astronomical Data Analysis Software & Systems (ADASS) conference, which brings together astronomy and computer science. Organized by the Atacama Large Millimeter/submillimeter Array (ALMA), the European Southern Observatory (ESO) and the Universidad Técnica Federico Santa María (UTFSM), from October 22 to 26 for the first time in Chile, ADASS will seek to develop astronomy and other industries, providing an opportunity to promote local talent to the rest of the world.
Chile is a privileged setting for astronomic observation and data collection, generating an enormous amount of public data. The ALMA observatory alone generates a terabyte of data per day; the LSST will reach 30 terabytes per night by 2022 and the SKA 360 terabytes per hour by 2030.
LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.
This evolution implies a never seen before data storage and analysis challenge, and Chile is in a position to lead this progress with the support of data, communication and technology platforms and expert human capital with the support of this potent cloud computing era. Herein lies the importance of Chile’s debut as Latin American headquarters for the International Astronomical Data Analysis Software & Systems-ADASS Conference, which after 27 years in practice, has chosen the country as its meeting location.
Invited speakers. Credit: ADASS 2017 website (www.adass.cl)
“A modern observatory today is a true data factory, and the creation of systems and infrastructure capable of storing this data and analyzing and sharing it will contribute to the democratization of access to current, critical and unique information, necessary for the hundreds of groups of researchers of the Universe around the world,” says Jorge Ibsen, Head of the ALMA Computing Department and Co-Chair of ADASS.
The Chilean Virtual Observatory (ChiVO) and The International Virtual Observatory Alliance (IVOA), have worked together for years to define standards for sharing data between observatories around the world and to create public access protocols. Mauricio Solar, Director of ChiVO and Co-Chair of the ADASS conference, assures that Chile can contribute to astronomy, not just through astronomers, but also through the development of applications in astroinformatics that, for example, can help find evidence of extraterrestrial life.
Local Organizing Committee. Credit: ADASS 2017 website (http://www.adass.cl)
Astroinformatics combines advanced computing, statistics applied to mass complex data, and astronomy. Topics to be addressed at ADASS include: high-performance computing (HPC) for astronomical data, human-computer interaction and interfaces for large data collections, challenges in the operation of large-scale highly complex instrumentation, network infrastructure and data centers in the era of mass data transfer, machine learning applied to astronomical data, and software for the operation of Earth and space observatories, diversity and inclusion, and citizen education and science, among other subjects.
The ADASS Conference will bring together 350 experts from 33 countries at the Sheraton Hotel in Santiago, and will be followed by an Interoperability Meeting of the International Virtual Observatories Alliance (IVOA), organized by ChiVO, from October 27 to 29. More information at http://www.adass.cl.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726 nicolas.lira@alma.cl
Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324 cblue@nrao.edu
Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory , Tokyo – Japan
Phone: +81 422 34 3630 hiramatsu.masaaki@nao.ac.jp
Richard Hook
Public Information Officer, ESO
Garching bei München, Germany
Phone: +49 89 3200 6655
Cell phone: +49 151 1537 3591 rhook@eso.org
Composite image of the Fomalhaut star system. The ALMA data, shown in orange, reveal the distant and eccentric debris disk in never-before-seen detail. The central dot is the unresolved emission from the star, which is about twice the mass of the Sun. Optical data from the Hubble Space Telescope is in blue; the dark region is a coronagraphic mask, which filtered out the otherwise overwhelming light of the central star. Credit: ALMA (ESO/NAOJ/NRAO), M. MacGregor; NASA/ESA Hubble, P. Kalas; B. Saxton (NRAO/AUI/NSF)
Debris disks are common features around young stars and represent a very dynamic and chaotic period in the history of a solar system. Astronomers believe they are formed by the ongoing collisions of comets and other planetesimals in the outer reaches of a recently formed planetary system. The leftover debris from these collisions absorbs light from its central star and reradiates that energy as a faint millimeter-wavelength glow that can be studied with ALMA.
Using the new ALMA data and detailed computer modeling, the researchers could calculate the precise location, width, and geometry of the disk. These parameters confirm that such a narrow ring is likely produced through the gravitational influence of planets in the system, noted MacGregor.
The new ALMA observations are also the first to definitively show “apocenter glow,” a phenomenon predicted in a 2016 paper by lead author Margaret Pan, a scientist at the Massachusetts Institute of Technology in Cambridge and co-author on the new ALMA papers. Like all objects with elongated orbits, the dusty material in the Fomalhaut disk travels more slowly when it is farthest from the star. As the dust slows down, it piles up, forming denser concentrations in the more distant portions of the disk. These dense regions can be seen by ALMA as brighter millimeter-wavelength emission.
ALMA image of the debris disk in the Fomalhaut star system. The ring is approximately 20 billion kilometers from the central star and it is about 2 billion kilometers wide. The central dot is the unresolved emission from the star, which is about twice the mass of the Sun. Credit: ALMA (ESO/NAOJ/NRAO); M. MacGregor
Using the same ALMA dataset, but focusing on distinct millimeter-wavelength signals naturally emitted by molecules in space, the researchers also detected vast stores of carbon monoxide gas in precisely the same location as the debris disk.
“These data allowed us to determine that the relative abundance of carbon monoxide plus carbon dioxide around Fomalhaut is about the same as found in comets in our own solar system,” said Luca Matrà with the University of Cambridge, UK, and lead author on the team’s second paper. “This chemical kinship may indicate a similarity in comet formation conditions between the outer reaches of this planetary system and our own.” Matrà and his colleagues believe this gas is either released from continuous comet collisions or the result of a single, large impact between supercomets hundreds of times more massive than Hale-Bopp.
The presence of this well-defined debris disk around Fomalhaut, along with its curiously familiar chemistry, may indicate that this system is undergoing its own version of the Late Heavy Bombardment, a period approximately 4 billion years ago when the Earth and other planets were routinely struck by swarms of asteroids and comets left over from the formation of the Solar System.
“Twenty years ago, the best millimeter-wavelength telescopes gave the first fuzzy maps of sand grains orbiting Fomalhaut. Now with ALMA’s full capabilities the entire ring of material has been imaged,” concluded Paul Kalas, an astronomer at the University of California at Berkeley and principal investigator on these observations. “One day we hope to detect the planets that influence the orbits of these grains.”
This research is presented in a paper titled A complete ALMA map of the Fomalhaut debris disk, M. MacGregor, et al., appearing in The Astrophysical Journal, and Detection of exocometary CO within the 440MYR-old Fomalhaut belt: A similar CO+CO2 ice abundance in exocomets and solar system comets,” L. Matrà et al., appearing in The Astrophysical Journal.
This work benefited from: NASA’s Nexus for Exoplanet System Science (NExSS) research coordination network sponsored by NASA’s Science Mission Directorate, NASA grants NNX15AC89G, NNX15AD95G, NSF grant AST-1518332, NSF Graduate Research Fellowship DGE1144152, and from NRAO Student Observing Support. This work has also been possible thanks to an STFC postgraduate studentship and the European Union through ERC grant number 279973.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres ALMA
20 September 2017
Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell: +56 9 9445 7726 nicolas.lira@alma.cl
Richard Hook
Public Information Officer, ESO
Garching bei München, Germany
Phone: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Francisco Rodríguez I.
ESO Press Officer in Chile
Santiago, Chile
+56 2 24633019 frrodrig@eso.org
Charles E. Blue.
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324 cblue@nrao.edu
Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory , Tokyo – Japan
Phone: +81 422 34 3630 hiramatsu.masaaki@nao.ac.jp
Related Posts
Astronomers have used ALMA to capture a strikingly beautiful view of a delicate bubble of expelled material around the exotic red star U Antliae. These observations will help astronomers to better understand how stars evolve during the later stages of their life-cycles.
In the faint southern constellation of Antlia (The Air Pump) the careful observer with binoculars will spot a very red star, which varies slightly in brightness from week to week. This very unusual star is called U Antliae and new observations with the Atacama Large Millimeter/submillimeter Array (ALMA) are revealing a remarkably thin spherical shell around it.
This image was created from ALMA data on the unusual red carbon star U Antliae and its surrounding shell of material. The colours show the motion of the glowing material in the shell along the line of sight to the Earth. Blue material lies between us and the central star, and is moving towards us. Red material around the edge is moving away from the star, but not towards the Earth.
For clarity this view does not include the material on the far side of the star, which is receding from us in a symmetrical manner. Credit: ALMA (ESO/NAOJ/NRAO), F. Kerschbaum
Astronomers have used ALMA to capture a strikingly beautiful view of a delicate bubble of expelled material around the exotic red star U Antliae. These observations will help astronomers to better understand how stars evolve during the later stages of their life-cycles.
This short podcast takes a look at this important new result and what it means. Credit:ESO.
Directed by: Nico Bartmann.
Editing: Nico Bartmann.
Web and technical support: Mathias André and Raquel Yumi Shida.
Written by: Izumi Hansen and Richard Hook.
Music: Colin Rayment & Stan Dart.
Footage and photos: ESO, spaceengine.org, NASA, SDO, M.Kornmesser, ALMA (ESO/NAOJ/NRAO), F. Kerschbaum.
Executive producer: Lars Lindberg Christensen.
U Antliae [1] is a carbon star, an evolved, cool and luminous star of the asymptotic giant branch type. Around 2700 years ago, U Antliae went through a short period of rapid mass loss. During this period of only a few hundred years, the material making up the shell seen in the new ALMA data was ejected at high speed. Examination of this shell in further detail also shows some evidence of thin, wispy gas clouds known as filamentary substructures.
This spectacular view was only made possible by the unique ability to create sharp images at multiple wavelengths that is provided by the ALMA radio telescope, located on the Chajnantor Plateau in Chile’s Atacama Desert, at 5,000 metres. ALMA can see much finer structure in the U Antliae shell than has previously been possible.
The new ALMA data are not just a single image; ALMA produces a three-dimensional dataset (a data cube) with each slice being observed at a slightly different wavelength. Because of the Doppler Effect, this means that different slices of the data cube show images of gas moving at different speeds towards or away from the observer. This shell is also remarkable as it is very symmetrically round and also remarkably thin. By displaying the different velocities we can cut this cosmic bubble into virtual slices just as we do in computer tomography of a human body.
Understanding the chemical composition of the shells and atmospheres of these stars, and how these shells form by mass loss, is important to properly understand how stars evolve in the early Universe and also how galaxies evolved. Shells such as the one around U Antliae show a rich variety of chemical compounds based on carbon and other elements. They also help to recycle matter, and contribute up to 70% of the dust between stars.
Notes
[1] The name U Antliae reflects the fact that it is the fourth star that changes its brightness to be found in the constellation of Antlia (The Air Pump). The naming of such variable stars followed a complicated sequence as more and more were found and is explained here.
More information
The team is composed of F. Kerschbaum (University of Vienna, Austria), M. Maercker (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. Brunner (University of Vienna, Austria), M. Lindqvist (Chalmers University of Technology, Onsala Space Observatory, Sweden), H. Olofsson (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. Mecina (University of Vienna, Austria), E. De Beck (Chalmers University of Technology, Onsala Space Observatory, Sweden), M. A. T. Groenewegen (Koninklijke Sterrenwacht van België, Belgium), E. Lagadec (Observatoire de la Côte d’Azur, CNRS, France), S. Mohamed (University of Cape Town, South Africa), C. Paladini (Université Libre de Bruxelles, Belgium), S. Ramstedt (Uppsala University, Sweden), W. H. T. Vlemmings (Chalmers University of Technology, Onsala Space Observatory, Sweden), and M. Wittkowski (ESO)
The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of ESO, the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).
ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.
ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.
VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.
ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.
ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.
VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.
ALMA on the Chajnantor plateau at 5,000 metres.
ESO/E-ELT to be built at Cerro Armazones at 3,060 m.
APEX Atacama Pathfinder 5,100 meters above sea level, at the Llano de Chajnantor Observatory in the Atacama desert.
Leiden MASCARA instrument, La Silla, located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)
Leiden MASCARA cabinet at ESO Cerro la Silla located in the southern Atacama Desert 600 kilometres (370 mi) north of Santiago de Chile at an altitude of 2,400 metres (7,900 ft)
ESO Next Generation Transit Survey at Cerro Paranel, 2,635 metres (8,645 ft) above sea level
SPECULOOS four 1m-diameter robotic telescopes 2016 in the ESO Paranal Observatory, 2,635 metres (8,645 ft) above sea level
ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres ALMA
17 August, 2017
Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726 nicolas.lira@alma.cl
An international team of doctors and researchers conducted a study at the Atacama Large Millimeter/submillimeter Array (ALMA) to identify the consequences of working at high altitude where the body can experience oxygen deficiency, a medical condition known as hypoxia. The extreme altitude of the observatory — 2,900 meters at the Operations Support Facility (OSF) and the Array Operations Site (AOS) at 5,000 meters — makes it a natural laboratory for this type of research, which is extremely useful to both ALMA and other operations at high altitudes. The first results of these studies are being made available to the scientific community (see posters) and will soon be published.
Canadian, Swiss, and Chilean experts met at ALMA in April 2016 to examine workers who volunteered for the study, separating those who suffer from chronic illnesses such as hypertension or obesity from healthy workers in order to compare and understand the effects of hypoxia. Over the course of six weeks, doctors examined their cognitive skills, sleep quality, breathing patterns, blood flow to the brain, and hemodynamic changes between the heart and lungs.
For Dr. Marc Poulin from the University of Calgary, Canada, who forms part of this study, “The working conditions at ALMA are ideal for our research. It has high quality infrastructure and is a true natural laboratory due to its high altitude.”
An international team of doctors and researchers conducted a study at ALMA to identify the consequences of working at high altitude where the body can experience oxygen deficiency, a medical condition known as hypoxia. The extreme altitude of the observatory — 2,900 meters at the OSF and the AOS at 5,000 meters — makes it a natural laboratory for this type of research, which is extremely useful to both ALMA and other operations at high altitudes. Credit: Iván López – ALMA (NRAO/NAOJ/ESO)
Most of the workers at the observatory live in cities located at low altitudes, and work 8×6 shifts (8 days of work followed by 6 days off) at the ALMA OSF. The camp where the workers sleep is located here, as well as the laboratories, workshops, offices and antenna control room. Some workers have to ascend to the ALMA AOS at 5,000 meters, where they work with the antennas and correlator that synchronizes their signals. It is at this higher altitude that some staff experience intermittent hypoxia.
The purpose of this study is to understand the long-term effects on workers’ performance, health, and safety from ongoing or intermittent exposure to hypoxia. This study is meant to optimize treatments that would help workers operate at altitude. It also may lead to new treatments from the lessons learned through this study in development.
“We are very happy about this study, as it gives us an objective database of the effects of hypoxia in workers and helps adapt the risk prevention program to real conditions, in order to improve the quality of life of all staff,” says Iván López, ALMA Risk Prevention, Health, Environment and Safety Manager.
An international team of doctors and researchers conducted a study at ALMA to identify the consequences of working at high altitude where the body can experience oxygen deficiency, a medical condition known as hypoxia. The extreme altitude of the observatory — 2,900 meters at the OSF and the AOS at 5,000 meters — makes it a natural laboratory for this type of research, which is extremely useful to both ALMA and other operations at high altitudes. Credit: Iván López – ALMA (NRAO/NAOJ/ESO)
Early results from these studies suggest that intermittent and/or regular exposure to high altitudes may have a negative effect on psychomotor alertness, which is especially evident in those who work on tasks that require a high level of concentration, such as those found in mining and astronomical observatories. It also has bearing on athletes performing at high altitude.
These studies also indicate that there is an alteration in workers’ sleep quality, although acclimatization would reduce these effects after a few days of exposure. Cognitive abilities would also be affected at extreme altitude exposure (5,050 meters above sea level), especially cognitive abilities and, to a much lesser extent, executive capacity. These effects would also be partially reduced as workers are acclimatized after a few days.
Among the measures taken by ALMA to reduce the effects of hypoxia are the mandatory use of portable medical oxygen for all workers performing tasks over an altitude of 3000 meters, permanent oxygenation of the technical building located at an altitude of 5000 meters, and constant on-site monitoring by the observatory’s medical team. In addition, new strategies are being developed that include a special diet and exercise program.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
A far-infrared image of the long filament of star formation activity known as DR21, seen here in emission by the Herschel Space Telescope. A study of the magnetic field along the filament and around six star-forming cores within it finds that magnetic effects are primarily important during the early stages of star formation. ESA/Herschel
ESA/Herschel spacecraft
Studies of molecular clouds have revealed that star formation usually occurs in a two step process. First, supersonic flows compress the clouds into dense filaments light-years long, after which gravity collapses the densest material in the filament into cores. In this scenario, massive cores (each more than about twenty solar–masses) preferentially form at intersections where filaments cross, producing sites of clustered star formation. The process sounds reasonable and is expected to be efficient, but the observed rate of star formation in dense gas is only a few percent of the rate expected if the material really were freely collapsing. To solve the problem, astronomers have proposed that magnetic fields support the cores against the collapse induced by self-gravity.
Magnetic fields are difficult to measure and difficult to interpret. CfA astronomers Tao-Chung Ching, Qizhou Zhang, and Josep Girat led a team that used the Submillimeter Array to study six dense cores in a nearby star formation region in Cygnus.
CfA Submillimeter Array Mauna Kea, Hawaii, USA
They measured the field strengths from the polarization of the millimeter radiation; elongated dust grains are known to be aligned by magnetic fields and to scatter light with a preferred polarization direction. The scientists then correlated the field direction in these cores with the field direction along the filament out of which the cores developed.
The astronomers find that the magnetic field along the filament is well-ordered and parallel to the structure, but at the cores themselves the field direction is much more complex, sometimes parallel and sometimes perpendicular. They conclude that during the formation of the cores the magnetic fields, at least at small scales, become unimportant compared to turbulence and infall. Although the field may play an important role as the filament initially collapses, once the dense cores develop the local kinematics from infall and gravitational effects become more important.
The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy.
ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres ALMA
2 August, 2017
Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726 nicolas.lira@alma.cl
Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory , Tokyo – Japan
Phone: +81 422 34 3630 hiramatsu.masaaki@nao.ac.jp
Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Phone: +1 434 296 0314
Cell phone: +1 202 236 6324 cblue@nrao.edu
Richard Hook
Public Information Officer, ESO
Garching bei München, Germany
Phone: +49 89 3200 6655
Cell phone: +49 151 1537 3591 rhook@eso.org
No image caption or credit
Astronomers observed a galaxy cluster 9.4 billion light-years away using the ALMA radio telescope array and found evidence that hot gas strips away the cold gas in the member galaxies. Since cold gas is the material for forming new stars, removing the cold gas inhibits star formation. This result is key to understanding the declining birthrate of stars throughout the history of the Universe and the evolutionary process of galaxy clusters.
Understanding the history of star formation in the Universe is a central theme in modern astronomy. Various observations have shown that the star formation activity has varied through the 13.8 billion-year history of the Universe. The stellar birth rate peaked around 10 billion years ago and has declined steadily since then. However, the cause of the declining stellar birth rate is still not well understood.
“Aiming to investigate what suppresses the star formation activity, we focused on the environment around the galaxies,” said Masao Hayashi at the National Astronomical Observatory of Japan (NAOJ).
Hayashi and his colleagues observed the galaxy cluster XMMXCS J2215.9–1738 located 9.4 billion light-years away [1] with the Atacama Large Millimeter/submillimeter Array (ALMA). Because it takes time for the light from distant objects to reach us, observing far-away galaxies shows us what the Universe looked like when the light was emitted. In this case, the light from XMMXCS J2215.9-1738 was emitted 9.4 billion years ago, which is around the time that the stellar birth rate peaked. In fact, previous observations with NAOJ’s Subaru Telescope revealed that many of the galaxies in the cluster are actively forming stars.
NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA
ALMA detected radio signals emitted from carbon monoxide gas in 17 of the galaxies in the cluster. This is a record-high number for the detection of gas-rich galaxies at such a distance. Interestingly, the gas-rich galaxies detected with ALMA are located towards the outer part of the galaxy cluster, not in the center. This is the first time ever that such a location differentiation has been found in a galaxy cluster 10 billion light-years away.
Galaxy cluster XMMXCS J2215.9–1738 observed with ALMA and the Hubble Space Telescope. Gas rich galaxies detected with ALMA are shown in red and marked with circles. Most gas rich galaxies are located in the outer part, not the center, of the galaxy cluster (around the center of the image). Credit: ALMA (ESO/NAOJ/NRAO), Hayashi et al., the NASA/ESA Hubble Space Telescope
NASA/ESA Hubble Telescope
The team assumes that the gas-rich galaxies detected with ALMA are in an intermediate step in the process of becoming members of the cluster. As new member galaxies pass through the hot gas filling the cluster, cold gas in the galaxies is stripped away by the hot gas. Active star formation consumes what little gas survives in the galaxies. As the cold gas needed to make stars run out, star formation stops.
Actually, there are some galaxies with active star formation at the central part of the cluster. The team suggests that they are rather evolved, old members of the cluster consuming the last of their gas to form stars.
“Recent observational and theoretical studies show that the distribution of gas is key to understanding the evolution of galaxies,” explains Hayashi. “Our observations provide robust statistics showing that a number of gas-rich galaxies are located in the outer part of a galaxy cluster. With this result, we have opened a future path for revealing the evolutionary process of galaxies in galaxy clusters.”
Notes
[1] The measured redshift of the galaxy cluster is z=1.46. A calculation based on the latest cosmological parameters measured with Planck (H0=67.3 km/s/Mpc, Ωm=0.315, Λ=0.685: Planck 2013 Results) yields the distance of 9.4 billion light-years. Please refer to “Expressing the distance to remote objects” for the details.
The research team members are: Masao Hayashi (National Astronomical Observatory of Japan), Tadayuki Kodama (NAOJ/SOKENDAI/Tohoku University), Kotaro Kohno (The University of Tokyo), Yuki Yamaguchi (The University of Tokyo), Ken-ichi Tadaki (NAOJ/Max Planck Institute for Extraterrestrial Physics), Bunyo Hatsukade (The University of Tokyo), Yusei Koyama (NAOJ/SOKENDAI), Rhythm Shimakawa (NAOJ/University of California), Yoichi Tamura (The University of Tokyo/Nagoya University), and Tomoko L. Suzuki (NAOJ)
This research was supported by Grants-in-Aid from the Japan Society for the Promotion of Science and the Ministry of Education, Culture, Sports, Science and Technology, Japan (No. 26707006, 21340045, 24244015, 15H02073, 25247019).
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
The human eye can only see a tiny band of the electromagnetic spectrum. That tiny band is enough for most day-to-day things you might want to do on Earth, but stars and other celestial objects radiate energy at wavelengths from the shortest (high-energy, high-frequency gamma rays) to the longest (low-energy, low-frequency radio waves).
The electromagnetic spectrum is made up of radiation of all frequencies and wavelengths. Only a tiny range is visible to the human eye. NASA.
Beyond the visible spectrum
To see what’s happening in the distant reaches of the spectrum, astronomers use non-optical telescopes. There are several varieties, each specialised to catch radiation of particular wavelengths.
Non-optical telescopes utilise many of the techniques found in regular telescopes, but also employ a variety of techniques to convert invisible light into spectacular imagery. In all cases, a detector is used to capture the image rather than an eyepiece, with a computer then processing the data and constructing the final image.
There are also more exotic ways of looking at the universe that don’t use electromagnetic radiation at all, like neutrino telescopes and the cutting-edge gravitational wave telescopes, but they’re a separate subject of their own.
To start off, let’s go straight to the top with the highest-energy radiation, gamma rays.
Gamma ray telescopes
Gamma radiation is generally defined as radiation of wavelengths less than 10−11 m, or a hundredth of a nanometre.
Gamma-ray telescopes focus on the highest-energy phenomena in the universe, such as black holes and exploding stars. A high-energy gamma ray may contain a billion times as much energy as a photon of visible light, which can make them difficult to study.
Unlike photons of visible light, that can be redirected using mirrors and reflectors, gamma rays simply pass through most materials. This means that gamma-ray telescopes must use sophisticated techniques that track the movement of individual gamma rays to construct an image.
One technology that does this, in use in the Fermi Gamma-ray Space Telescope among other places, is called a pair production telescope.
NASA/Fermi Telescope
It uses a multi-layer sandwich of converter and detector materials. When a gamma ray enters the front of the detector it hits a converter layer, made of dense material such as lead, which causes the gamma-ray to produce an electron and a positron (known as a particle-antiparticle pair).
The electron and the positron then continue to traverse the telescope, passing through layers of detector material. These layers track the movement of each particle by recording slight bursts of electrical charge along the layer. This trail of bursts allows astronomers to reconstruct the energy and direction of the original gamma ray. Tracing back along that path points to the source of the ray out in space. This data can then be used to create an image.
The video below shows how this works in the space-based Fermi Large Area Telescope.
NASA/Fermi LAT
X-ray telescopes
X-rays are radiation with wavelengths between 10 nanometres and 0.01 nanometres. They are used every day to image broken bones and scan suitcases in airports and can also be used to image hot gases floating in space. Celestial gas clouds and remnants of the explosive deaths of large stars, known as supernovas, are the focus of X-ray telescopes.
Like gamma rays, X-rays are a high-energy form of radiation that can pass straight through most materials. To catch X-rays you need to use materials that are very dense.
X-ray telescopes often use highly reflective mirrors that are coated with dense metals such as gold, nickel or iridium. Unlike optical mirrors, which can bounce light in any direction, these mirrors can only slightly deflect the path of the X-ray. The mirror is orientated almost parallel to the direction of the incoming X-rays. The X-rays lightly graze the mirror before moving on, a little like a stone skipping on a pond. By using lots of mirrors, each changing the direction of the radiation by a small amount, enough X-rays can be collected at the detector to produce an image.
To maximise image quality the mirrors are loosely stacked, creating an internal structure resembling the layers of an onion.
Diagram showing how ‘grazing incidence’ mirrors are used in X-ray telescopes. NASA.
NASA/Chandra X-ray Telescope
ESA/XMM Newton X-ray telescope
NASA NuSTAR X-ray telescope
Ultraviolet telescopes
Ultraviolet light is radiation with wavelengths just too short to be visible to human eyes, between 400 nanometres and 0.01 nanometres. It has less energy than X-rays and gamma rays, and ultraviolet telescopes are more like optical ones.
Mirrors coated in materials that reflect UV radiation, such as silicon carbide, can be used to redirect and focus incoming light. The Hopkins Ultraviolet Telescope, which flew two short missions aboard the space shuttle in the 1990s, used a parabolic mirror coated with this material.
A schematic of the Hopkins Ultraviolet Telescope. NASA.
NASA Hopkins Ultraviolet Telescope which flew on the ISS
As redirected light reaches the focal point, a central point where all light beams converge, they are detected using a spectrogram. This specialised device can separate the UV light into individual wavelength bands in a way akin to splitting visible light into a rainbow.
Analysis of this spectrogram can indicate what the observation target is made of. This allows astronomers to analyse the composition of interstellar gas clouds, galactic centres and planets in our solar system. This can be particularly useful when looking for elements essential to carbon-based life such as oxygen and carbon.
Optical telescopes
Optical telescopes are used to view the visible spectrum: wavelengths roughly between 400 and 700 nanometres. See separate article here.
Keck Observatory, Maunakea, Hawaii, USA
ESO/VLT at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level
Gran Telescopio Canarias at the Roque de los Muchachos Observatory on the island of La Palma, in the Canaries, Spain, sited on a volcanic peak 2,267 metres (7,438 ft) above sea level
Gemini/North telescope at Maunakea, Hawaii, USA
Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile
Infrared telescopes
Sitting just below visible light on the electromagnetic spectrum is infrared light, with wavelengths between 700 nanometres and 1 millimetre.
It’s used in night vision goggles, heaters and tracking devices as found in heat-seeking missiles. Any object or material that is hotter than absolute zero will emit some amount of infrared radiation, so the infrared band is a useful window to look at the universe through.
Much infrared radiation is absorbed by water vapour in the atmosphere, so infrared telescopes are usually at high altitudes in dry places or even in space, like the Spitzer Space Telescope.
Infrared telescopes are often very similar to optical ones. Mirrors and reflectors are used to direct the infrared light to a detector at the focal point. The detector registers the incoming radiation, which a computer then converts into a digital image.
NASA/Spitzer Infrared Telescope
Radio telescopes
At the far end of the electromagnetic spectrum we find the radio waves, with frequencies less than 1000 megahertz and wavelengths of a metre and more. Radio waves penetrate the atmosphere easily, unlike higher-frequency radiation, so ground-based observatories can catch them.
Radio telescopes feature three main components that each play an important role in capturing and processing incoming radio signals.
The first is the massive antenna or ‘dish’ that faces the sky. The Parkes radio telescope in New South Wales, Australia, for instance, has a dish with a diameter of 64 metres, while the Aperture Spherical Telescope in southwest China is has a whopping 500-metre diameter.
The great size allows for the collection of long wavelengths and very quiet signals. The dish is parabolic, directing radio waves collected over a large area to be focused to a receiver sitting in front of the dish. The larger the antenna, the weaker the radio source that can be detected, allowing larger telescopes to see more distant and faint objects billions of light years away.
The receiver works with an amplifier to boost the very weak radio signal to make it strong enough for measurement. Receivers today are so sensitive that they use powerful coolers to minimise thermal noise generated by the movement of atoms in the metal of the structure.
Finally, a recorder stores the radio signal for later processing and analysis.
Radio telescopes are used to observe a wide array of subjects, including energetic pulsar and quasar systems, galaxies, nebulae, and of course to listen out for potential alien signals.
CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia
GBO radio telescope, Green Bank, West Virginia, USA
ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres ALMA
10 July, 2017
Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
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Charles E. Blue
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National Radio Astronomy Observatory Charlottesville, Virginia – USA
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Cell phone: +1 202 236 6324 cblue@nrao.edu
Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory , Tokyo – Japan
Phone: +81 422 34 3630 hiramatsu.masaaki@nao.ac.jp
Richard Hook
Public Information Officer, ESO
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This artist’s illustration of Supernova 1987A reveals the cold, inner regions of the exploded star’s remnants (red) where tremendous amounts of dust were detected and imaged by ALMA. This inner region is contrasted with the outer shell (blue), where the energy from the supernova is colliding (green) with the envelope of gas ejected from the star prior to its powerful detonation. Credit: A. Angelich; NRAO/AUI/NSF
Deep inside the remains of an exploded star lies a twisted knot of newly minted molecules and dust forged in the cooling aftermath of a supernova first detected in 1987. Using ALMA, astronomers mapped the location of these new molecules to create a high-resolution 3-D image of this “dust factory,” providing important insights into the relationship between a young supernova remnant and its home galaxy.
Supernovas — the violent ending of the brief but brilliant lives of massive stars — are among the universe’s most cataclysmic events. Though supernovas mark the death of stars, they also trigger the birth of new elements and the formation of molecules that fill the universe.
In February of 1987, astronomers witnessed one of these events unfold inside the Large Magellanic Cloud, a tiny dwarf galaxy in the suburbs of the Milky Way approximately 163,000 light-years from Earth.
Over the next 30 years, observations of the remnant of that explosion revealed never-before-seen details about the death of stars and how atoms created in those stars — like carbon, oxygen, and nitrogen — spill out into space and combine to form new molecules and dust. These microscopic particles may eventually find their way into future generations of stars and planets.
Remnant of Supernova 1987A as seen by ALMA. Purple area indicates emission from SiO molecules. Yellow area is emission from CO molecules. The blue ring is actual Hubble data (H-alpha) that has been artificially expanded into 3-D. Credit: ALMA (ESO/NAOJ/NRAO); R. Indebetouw
NASA/ESA Hubble Telescope
Recently, astronomers used the Atacama Large Millimeter/submillimeter Array (ALMA) to probe the heart of this supernova, named SN 1987A. ALMA’s ability to see remarkably fine details allowed the researchers to produce a detailed 3-D rendering of newly formed molecules inside the supernova remnant. These results are published in the Astrophysical Journal Letters.
“When this supernova exploded now more than 30 years ago, astronomers knew much less about the way these events reshape interstellar space and how the hot, glowing debris from an exploded star eventually cools and produces new molecules,” said Rémy Indebetouw, an astronomer at the University of Virginia and the National Radio Astronomy Observatory (NRAO) in Charlottesville. “Thanks to ALMA we can finally see cold ‘star dust’ as it forms, revealing important insights into the original star itself and the way supernovas create the basic building blocks of planets.”
Supernovas – Star Death to Dust Birth
Prior to ongoing investigations of SN 1987A, there was only so much astronomers could determine about these explosive cosmic events.
It was well understood that massive stars, those approximately 10 times the mass of our sun, ended their lives in spectacular fashion. When these stars run out of fuel, there is no longer enough heat and energy to fight back against the force of gravity. The outer reaches of the star, once held up by the power of fusion, then come crashing down on the core with tremendous force. The rebound of this collapse triggers an explosion that blasts material into space.
As the endpoint of massive stars, scientists have learned that supernovas have far-reaching effects on galaxies across the universe. To get a better understanding of these effects, Indebetouw helps break down the impact of these star-shattering events. “The reason some galaxies have the appearance that they do today is in large part because of the supernovas that have occurred in them,” he said. “Though less than 10 percent of stars in galaxies , the ones that explode as supernovas dominate the evolution of galaxies.”
Throughout the observable universe, supernovas are quite common, but since they appear – on average – about once every 50 years in a galaxy the size of the Milky Way, astronomers have precious few opportunities to study one from its first detonation to the point where it cools enough to form new molecules. Though SN 1987A is not technically in our home galaxy, it is still close enough for ALMA and other telescopes to study in fine detail.
Astronomers combined observations from three different observatories to produce this colorful, multiwavelength image of the intricate remains of Supernova 1987A.The red color shows newly formed dust in the center of the supernova remnant, taken at submillimeter wavelengths by the Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. The green and blue hues reveal where the expanding shock wave from the exploded star is colliding with a ring of material around the supernova. The green represents the glow of visible light, captured by NASA’s Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory.The ring was initially made to glow by the flash of light from the original explosion. Over subsequent years the ring material has brightened considerably as the explosion’s shock wave slams into it. Supernova 1987A resides 163,000 light-years away in the Large Magellanic Cloud, where a firestorm of star birth is taking place. Credit: NASA/ESA, ALMA (ESO/NAOJ/NRAO)
NASA/Chandra Telescope
Capturing 3-D Image of SN1987A with ALMA
For decades, radio, optical, and even X-ray observatories have studied of SN 1987 A, but obscuring dust in the outer regions of the remnant made it difficult to analyze the supernova’s innermost core. ALMA’s ability to observe at millimeter wavelengths – a region of the electromagnetic spectrum between infrared and radio light – made it possible to see through the intervening dust and gas and study the abundance and location of newly formed molecules – especially silicon monoxide (SiO) and carbon monoxide (CO), which shine brightly at the short submillimeter wavelengths that ALMA can perceive.
In the new ALMA image and animation, emission from SiO (colored purple) and CO (colored yellow) is located in discrete clumps within the core of SN 1987A. Indebetouw said that scientists previously predicted how and where these molecules would appear, but without ALMA they were unable to capture images with high enough resolution to confirm the structure inside the remnant and test those models.
Aside from obtaining the first 3-D image of SN 1987A, the ALMA data also reveal compelling details about how the physical conditions have changed and continues to change over time. These observations also provide insights into the physical instabilities in a supernova.
New Insights from SN 1987A
Earlier observations with ALMA verified that SN 1987A produced a massive amount of dust. The new observations provide more details on how the supernova made the dust as well as the type of molecules found in it.
“One of our goals was to observe SN 1987A in a blind search for other molecules,” said Indebetouw. “We expected to find carbon monoxide and silicon monoxide, since we had previously detected these molecules.” The astronomers, however, were excited to find the previously undetected molecules HCO+ and sulfur monoxide (SO).
“These molecules had never been detected in a young supernova remnant before,” noted Indebetouw. “HCO+ is especially interesting because its formation requires particularly vigorous mixing during the explosion.”
The current observations allow the astronomers to estimate that about 1 in 1000 silicon atoms from the exploded star are now found in SiO molecules; astronomers think that the majority of the silicon is currently in dust grains. Even the small amount of SiO that is present is 100 times greater than predicted by dust formation models. These new observations will aid astronomers in refining these models.
These observations also find that 10 percent or more of the carbon in the exploded star is currently in a CO molecule. Only a few out of every million carbon atoms are in a HCO+ molecule.
New Questions and Future Research
Even though the new ALMA observations shed important light on SN 1987A, there are still several questions that remain. Exactly how abundant are the molecules of HCO+ and SO? Are there other molecules that have yet to be detected? How will the 3-D structure of SN 1987A continue to change over time?
Future ALMA observations at different wavelengths may also shed light on what sort of compact object — a pulsar or neutron star — resides at the center of this object. Such an object has been predicted but so far not detected inside SN 1987A.
There are many animations in the article which are [foolishly] in Vimeo, which I cannot reproduce. See the full article for these animations.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory Tokyo, Japan
Tel: +81 422 34 3630
E-mail: hiramatsu.masaaki@nao.ac.jp
Charles E. Blue
Public Information Officer
National Radio Astronomy Observatory
Charlottesville, Virginia, USA
Tel: +1 434 296 0314
Cell: +1 202 236 6324
E-mail: cblue@nrao.edu
Richard Hook
Public Information Officer, ESO
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org
Artist’s impression of the baby twin system IRAS 04191+1523. Credit: ALMA (ESO/NAOJ/NRAO)
Using the Atacama Large Millimeter/submillimeter Array (ALMA), researchers obtained a critical clue to an underlying problem: how are widely separated twin stars formed? The team found very low mass newborn twin stars with misaligned rotation axes. This misalignment indicates that they were formed in a pair of fragmented gas clouds produced through turbulence, not via evolution of tightly-coupled twin. This finding strongly supports the turbulent fragmentation theory of binary star formation down to the substellar regime.
An international team of astronomers led by Jeong-Eun Lee in Kyung Hee University, Korea, observed the baby twin star system IRAS 04191+1523 with ALMA. Thanks to the high resolution of ALMA, the team successfully imaged the rotation of the gas disks around the very low mass twin stars and found that the rotation axes of the two stars are misaligned.
“This revelation is particularly interesting because both baby stars’ masses derived from our ALMA data are about 10% of the solar mass, which is very low. The formation of very low mass wide binary stars has been a mystery. But our result is strong evidence that wide binaries of these very low mass stars and even brown dwarfs can form in the same way as normal stars via turbulent fragmentation.” said Lee.
More than a half of the stars in the Universe are born as twins or multiple systems. Therefore, unveiling the formation mechanism of twin stars is crucial for a comprehensive understanding of stellar evolution.
There are two types of multiple stars: close systems and widely separated systems. Astronomers have witnessed a close system being formed via fragmentation of the gas disk around the firstborn stars [1]. On the other hand, there is no clear evidence on how widely separated systems are formed. Some researchers assume that a close system evolves into a wide system over millions of years due to dynamical interactions, but others guess that turbulence in a gas cloud fragments the cloud into smaller ones and stars are formed in each small cloud.
Aiming to find clues to the formation of wide binary systems, the researchers selected IRAS 04191+1523 as the target of their ALMA observations. The separation of the two stars is about 30 times the distance of Neptune from the Sun and classified as a wide binary. The age of the system is estimated to be far younger than half a million years old, therefore it is a good target to investigate the initial phase of wide binary formation.
Composite image of the very young baby twin star system IRAS 04191+1523. ALMA revealed the disks around two stars (white) and a common gas envelope (yellow). Red color shows the distribution of a dense cloud seen in far infrared light observed by the Herschel Space Observatory. Credit: ALMA (ESO/NAOJ/NRAO), Lee et al., ESA/Herschel/PACS
ESA/Herschel spacecraft
The team analyzed the signal from carbon monoxide molecules in the disks to derive their motion and found that the two disks around the baby stars are not aligned. The angle between the rotation axes of the disks is 77 degrees.
“The system is too young for the alignment of axes to have been modified by interactions,” said Lee [2], “so we conclude that this system was formed by the turbulent fragmentation of a cloud, not by disk fragmentation and migration.”
If a binary system is formed via disk fragmentation, the rotational moment of the gas aligns the axes of two stars. This alignment would be maintained even if the separation between the two is extended via tidal interactions. The misalignment of the axes in the infant system IRAS 04191+1523 clearly rejects this scenario.
Previous ALMA observations of a young binary system HK Tauri show that the two disks are misaligned. However, HK Tauri is much more evolved than IRAS 04191+1523 and it is difficult to reject the possibility of orbit evolution to become a widely-separated system.
Additional information
These observation results were published as Lee et al. Formation of Wide Binaries by Turbulent Fragmentation in Nature Astronomy on June 30, 2017.
The research team members are:
Jeong-Eun Lee (Kyung Hee University), Seokho Lee (Kyung Hee University), Michel Dunham (State University of New York at Fredonia), Ken’ichi Tatematsu (National Astronomical Observatory of Japan / SOKENDAI), Minho Choi (Korea Astronomy and Space Science Institute), Edwin A. Bergin (University of Michigan), Neal J. Evans II (Korea Astronomy and Space Science Institute / The University of Texas at Austin)
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (grant No. NRF-2015R1A2A2A01004769) and the Korea Astronomy and Space Science Institute under the R&D program (Project No. 2015-1-320-18) supervised by the Ministry of Science, ICT and Future Planning, Korea.
ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.
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