From Leiden University [Universiteit Leiden] (NL) : “High-mass stars are formed not from dust disk but from debris”

From Leiden University [Universiteit Leiden] (NL)

03 May 2021

Credit: CC0 Public Domain

A Dutch-led team of astronomers has discovered that high-mass stars are formed differently from their smaller siblings. Whereas small stars are often surrounded by an orderly disk of dust and matter, the supply of matter to large stars is a chaotic mess. The researchers used the Atacama Large Millimeter/submillimeter Array (ALMA) telescope for their observations, and recently published their findings in The Astrophysical Journal.

European Southern Observatory [Observatoire européen austral][Europäische Südsternwarte] (EU)/National Radio Astronomy Observatory(US)/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

It is well known how small, young stars are created. They accrete matter from a disk of gas and dust in a relatively orderly fashion. Astronomers have already seen many of these disks of dust around young, low-mass stars but never around young, high-mass stars. This raised the question of whether large stars come into existence in the same way as small ones.

Large stars are formed in a different way

“Our findings now provide convincing evidence to show that the answer is ‘No'”, according to Ciriaco Goddi, affiliated with the ALMA expertise centre Allegro at Leiden University and with Radboud University [Radboud Universiteit](NL) in Nijmegen.

Goddi led a team that studied three young, high-mass stars in star-forming region W51, roughly 17,000 light years from Earth. The researchers were looking in particular for large, stable disks expelling jets of matter perpendicular to the surface of the disk. Such disks should be visible with the high resolution ALMA telescopes.

Not stable disks but chaos

Goddi: “But instead of stable disks, we discovered that the accretion zone of young, high-mass stars looks like a chaotic mess.”

The observation showed strands of gas coming at the young, high-mass stars from all directions. In addition, the researchers saw jets which indicate that there may be small disks, invisible to the telescope. Also, it would appear that some hundred years ago the disk around one of three stars studied rotated. In short: chaos.

Matter from multiple directions

The researchers concluded that these young, high-mass stars, in their early years at least, are formed by matter coming from multiple directions and at an irregular speed. This is different for small stars, where there is a stable influx of matter. The astronomers suspect that that multiple supply of matter is probably the reason that no large, stable disks can be created.

“Such an unstructured influx model had previously been proposed, on the basis of computer simulations. We now have the first observational evidence to support the model”, says Goddi.

See the full article here.

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Universiteit Leiden Heijmans onderhoudt

Leiden University [Universiteit Leiden] (NL) is a public research university in Leiden, Netherlands. Founded in 1575 by William, Prince of Orange as a reward to the town of Leiden for its defense against Spanish attacks during the Eighty Years’ War, it is the oldest institution of higher education in the Netherlands.

Known for its historic foundations and emphasis on the social sciences, the university came into particular prominence during the Dutch Golden Age, when scholars from around Europe were attracted to the Dutch Republic due to its climate of intellectual tolerance and Leiden’s international reputation. During this time, Leiden became the home to individuals such as René Descartes, Rembrandt, Christiaan Huygens, Hugo Grotius, Baruch Spinoza and Baron d’Holbach.

The university has seven academic faculties and over fifty subject departments while housing more than 40 national and international research institutes. Its historical primary campus consists of buildings scattered across the college town of Leiden, while a second campus located in The Hague houses a liberal arts college and several of its faculties. It is a member of the Coimbra Group, the Europaeum, and a founding member of the League of European Research Universities.

Leiden University consistently ranks among the top 100 universities in the world by major ranking tables. It was placed top 50 worldwide in thirteen fields of study in the 2020 QS World University Rankings: classics & ancient history, politics, archaeology, anthropology, history, pharmacology, law, public policy, public administration, religious studies, arts & humanities, linguistics, modern languages and sociology.

The school has produced twenty-one Spinoza Prize Laureates and sixteen Nobel Laureates, including Enrico Fermi and Albert Einstein. It is closely associated with the Dutch Royal Family, with Queen Juliana, Queen Beatrix and King Willem-Alexander being alumni. Ten prime ministers of the Netherlands were also Leiden University alumni. Internationally, it is associated with nine foreign leaders, among them John Quincy Adams (the 6th President of the United States), two NATO Secretaries General, a President of the International Court of Justice, and a Prime Minister of the United Kingdom.

In 1575, the emerging Dutch Republic did not have any universities in its northern heartland. The only other university in the Habsburg Netherlands was the University of Leuven [Universiteit Leuven](BE) in southern Leuven, firmly under Spanish control. The scientific renaissance had begun to highlight the importance of academic study, so Prince William founded the first Dutch university in Leiden, to give the Northern Netherlands an institution that could educate its citizens for religious purposes, but also to give the country and its government educated men in other fields. It is said the choice fell on Leiden as a reward for the heroic defence of Leiden against Spanish attacks in the previous year. Ironically, the name of Philip II of Spain, William’s adversary, appears on the official foundation certificate, as he was still the de jure count of Holland. Philip II replied by forbidding any subject to study in Leiden. Originally located in the convent of St Barbara, the university moved to the Faliede Bagijn Church in 1577 (now the location of the University museum) and in 1581 to the convent of the White Nuns, a site which it still occupies, though the original building was destroyed by fire in 1616.

The presence within half a century of the date of its foundation of such scholars as Justus Lipsius; Joseph Scaliger; Franciscus Gomarus; Hugo Grotius; Jacobus Arminius; Daniel Heinsius; and Gerhard Johann Vossius rapidly made Leiden university into a highly regarded institution that attracted students from across Europe in the 17th century. Renowned philosopher Baruch Spinoza was based close to Leiden during this period and interacted with numerous scholars at the university. The learning and reputation of Jacobus Gronovius; Herman Boerhaave; Tiberius Hemsterhuis; and David Ruhnken, among others, enabled Leiden to maintain its reputation for excellence down to the end of the 18th century.

At the end of the nineteenth century, Leiden University again became one of Europe’s leading universities. In 1896 the Zeeman effect was discovered there by Pieter Zeeman and shortly afterwards given a classical explanation by Hendrik Antoon Lorentz. At the world’s first university low-temperature laboratory, professor Heike Kamerlingh Onnes achieved temperatures of only one degree above absolute zero of −273 degrees Celsius. In 1908 he was also the first to succeed in liquifying helium and can be credited with the discovery of the superconductivity in metals.

The University Library, which has more than 5.2 million books and fifty thousand journals, also has a number of internationally renowned special collections of western and oriental manuscripts, printed books, archives, prints, drawings, photographs, maps, and atlases. It houses the largest collections worldwide on Indonesia and the Caribbean. The research activities of the Scaliger Institute focus on these special collections and concentrate particularly on the various aspects of the transmission of knowledge and ideas through texts and images from antiquity to the present day.

In 2005 the manuscript of Einstein on the quantum theory of the monatomic ideal gas (the Einstein-Bose condensation) was discovered in one of Leiden’s libraries.

The portraits of many famous professors since the earliest days hang in the university aula, one of the most memorable places, as Niebuhr called it, in the history of science.

In 2012 Leiden entered into a strategic alliance with Delft University of Technology [Technische Universiteit Delft](NL) and Erasmus University Rotterdam [Erasmus Universiteit Rotterdam](NL)in order for the universities to increase the quality of their research and teaching. The university is also the unofficial home of the Bilderberg Group, a meeting of high-level political and economic figures from North America and Europe.

The university has no central campus; its buildings are spread over the city. Some buildings, like the Gravensteen, are very old, while buildings like Lipsius and Gorlaeus are much more modern.

Among the institutions affiliated with the university are The KITLV or Royal Netherlands Institute of Southeast Asian and Caribbean Studies [Koninklijk Instituut voor Taal-, Land- en Volkenkunde] (NL) (founded in 1851); the observatory 1633; the natural history museum; with a very complete anatomical cabinet; the Rijksmuseum van Oudheden (National Museum of Antiquities) with specially valuable Egyptian and Indian departments; a museum of Dutch antiquities from the earliest times; and three ethnographical museums, of which the nucleus was Philipp Franz von Siebold’s Japanese collections. The anatomical and pathological laboratories of the university are modern, and the museums of geology and mineralogy have been restored.

The Hortus Botanicus (botanical garden) is the oldest botanical garden in the Netherlands, and one of the oldest in the world. Plants from all over the world have been carefully cultivated here by experts for more than four centuries. The Clusius garden (a reconstruction), the 18th century Orangery with its monumental tub plants, the rare collection of historical trees hundreds of years old, the Japanese Siebold Memorial Museum symbolising the historical link between East and West, the tropical greenhouses with their world class plant collections, and the central square and Conservatory exhibiting exotic plants from South Africa and southern Europe.

From ALMA [The Atacama Large Millimeter/submillimeter Array] (CL): “ALMA Shows Massive Young Stars Forming in ‘Chaotic Mess'”

European Southern Observatory/National Radio Astronomy Observatory(US)/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

From ALMA [The Atacama Large Millimeter/submillimeter Array] (CL)

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Amy C. Oliver
Public Information & News Manager
National Radio Astronomical Observatory (NRAO), USA
Phone: +1 434 242 9584
Email: aoliver@nrao.edu

A team of astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) has taken a big step toward answering a longstanding question — do stars much more massive than the Sun form in the same way as their smaller siblings?

Young, still-forming stars similar in mass to the Sun are observed gaining material from their surrounding clouds of gas and dust in a relatively orderly manner. The incoming material forms a disk orbiting the young star and that disk feeds the star at a pace it can digest. Condensations of material within the disk form planets that will remain after the star’s growth process is complete.

The disks are commonly seen around young low-mass stars, but have not been found around much more massive stars in their forming stages. Astronomers questioned whether the process for the larger stars is simply a scaled-up version of that for the smaller ones.

Artist’s conception illustrates process seen in forming stars much more massive than the Sun. At top left, material is being drawn into the young star through an orbiting disk which generates a fast-moving jet of material outward. At top right, material begins coming in from another direction, and at bottom left, begins deforming the original disk until, at bottom right, the disk orientation — and the jet orientation — have changed. Credit: Bill Saxton, National Radio Astronomy Observatory (US)/Associated Universities Inc (US)/National Science Foundation (US).

ALMA image of the chaotic scene around a massive young protostar, in this case one called W51e2e. Grey shows dust close to the star, while the red and blue indicate material in the jets moving rapidly outward from the star. Red shows material moving away from Earth and blue material moving toward Earth. Credit: Goddi, Ginsburg, et al., Sophia Dagnello, NRAO/AUI/NSF.

ALMA image of the chaotic scene around a massive young protostar, in this case one called W51north . Grey shows dust close to the star, while the red and blue indicate material in the jets moving rapidly outward from the star. Red shows material moving away from Earth and blue material moving toward Earth. Credit: Goddi, Ginsburg, et al., Sophia Dagnello, NRAO/AUI/NSF.

ALMA image of the chaotic scene around a massive young protostar, in this case one called W51e8 . Grey shows dust close to the star, while the red and blue indicate material in the jets moving rapidly outward from the star. Red shows material moving away from Earth and blue material moving toward Earth. Credit: Goddi, Ginsburg, et al., Sophia Dagnello, NRAO/AUI/NSF.

Credit: Goddi, Ginsburg, et al., S. Dagnello, B. Saxton, NRAO/AUI/NSF.

“Our ALMA observations now provide compelling evidence that the answer is no,” said Ciriaco Goddi, of Radboud University [Radboud Universiteit](NL).

Goddi led a team that used ALMA to study three high-mass, very young stars in a star-forming region called W51, about 17,000 light-years from Earth. They used ALMA when its antennas were spread apart to their farthest extent, providing resolving power capable of making images 10 times sharper than previous studies of such objects.

They were looking for evidence of the large, stable disks seen orbiting smaller young stars. Such disks propel fast-moving jets of material outward perpendicular to the plane of the disk.

“With ALMA’s great resolving power, we expected to finally see a disk. Instead, we found that the feeding zone of these objects looks like a chaotic mess,” said Adam Ginsburg of the University of Florida (US).

The observations showed streamers of gas falling toward the young stars from many different directions. Jets indicated that there must be small disks that are yet unseen. In one case, it appears that some event actually flipped a disk about 100 years ago.

The researchers concluded that these massive young stars form, at least in their very early stages, by drawing in material from multiple directions and at unsteady rates, in sharp contrast to the stable inflows seen in smaller stars. The multiple channels of incoming material, the astronomers said, probably prevent the formation of the large, steady disks seen around smaller stars.

“Such a ‘disordered infall’ model was first proposed based on computer simulations, and we now have the first observational evidence supporting that model,” Goddi said.

Additional Information

Goddi, Ginsburg and their colleagues from the U.S., Mexico, and Europe reported their findings in The Astrophysical Journal.

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

The Atacama Large Millimeter/submillimeter Array (ALMA) (CL) , an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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.

ALMA is a time machine!

ALMA-In Search of our Cosmic Origins

From ALMA [The Atacama Large Millimeter/submillimeter Array] (CL): “Record-breaking Stellar Flare from Nearby Star Recorded in Multiple Wavelengths for the First Time”

European Southern Observatory/National Radio Astronomy Observatory(US)/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

From European Southern Observatory (EU)/National Astronomy Observatory of Japan (JP)/National Radio Astronomy Observatory (US) ALMA [The Atacama Large Millimeter/submillimeter Array] (CL)

21 April, 2021

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Amy C. Oliver
Public Information & News Manager
National Radio Astronomical Observatory (NRAO), USA
Phone: +1 434 242 9584
Email: aoliver@nrao.edu

Artist’s conception of the violent stellar flare from Proxima Centauri discovered by scientists in 2019 using nine telescopes across the electromagnetic spectrum, including the Atacama Large Millimeter/submillimeter Array (ALMA). Powerful flares eject from Proxima Centauri with regularity, impacting the star’s planets almost daily. Credit: NRAO/S. Dagnello.

Artist’s conception of a violent stellar flare erupting on neighboring star, Proxima Centauri. The flare is the most powerful ever recorded from the star, and is giving scientists insight into the hunt for life on planets in M dwarf star systems, many of which have unusually lively stars. Credit: NRAO/S. Dagnello.

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have spotted a flare from Earth’s nearest neighboring star, Proxima Centauri, that is 100 times more powerful than any similar flare seen from the Sun. The flare, which is the largest ever recorded from the star, has revealed the inner workings of such events to astronomers, and could help to shape the hunt for life beyond the Solar System.

Stellar flares occur when the release of magnetic energy in stellar spots explodes in an intense burst of electromagnetic radiation that can be observed across the entire electromagnetic spectrum, from radio waves to gamma rays. This is the first time that a single stellar flare, other than those that occur on the Sun, has been observed with such complete wavelength coverage. The study was precipitated by the serendipitous discovery of a flare from Proxima Centauri in 2018 ALMA archival data.

“We had never seen an M dwarf flare at millimeter wavelengths before 2018, so it was not known whether there was corresponding emission at other wavelengths,” said Meredith MacGregor, an assistant professor at the Center for Astrophysics and Space Astronomy (CASA) and Department of Astrophysical and Planetary Sciences (APS) at University of Colorado (US), and the lead author on the study.

To better understand the flares on Proxima Centauri— a red dwarf star located roughly four light-years or 20 trillion miles from Earth— a team of astronomers observed the star for 40 hours over the course of several months in 2019 using nine telescopes on the ground and in space.

In May 2019, Proxima Centauri ejected a violent flare that lasted just seven seconds, but generated a surge in both ultraviolet and millimeter wavelengths. The flare was characterized by a strong, impulsive spike never before seen at these wavelengths. The event was recorded by five of the nine telescopes involved in the study, including the Hubble Space Telescope (HST) in ultraviolet, and ALMA in millimeter wavelengths.

National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation] (EU) Hubble Space Telescope.

“The star went from normal to 14,000 times brighter when seen in ultraviolet wavelengths over the span of a few seconds,” said MacGregor, adding that similar behavior was captured in millimeter wavelengths by ALMA at the same time.

“In the past, we didn’t know that stars could flare in the millimeter range, so this is the first time we have gone looking for millimeter flares,” said MacGregor, adding that the new observations could help researchers gather more information about how stars generate flares, which can have an impact on nearby life.

Powerful flares from our Sun are uncommon, occurring only a few times in a solar cycle. According to MacGregor, that’s not the case on Proxima Centauri. “Proxima Centauri’s planets are getting hit by something like this not once in a century, but at least once a day, if not several times a day,” said MacGregor.

The star is prominent in discussions surrounding the prospect for life around red dwarf stars because of its proximity to Earth, and because it is host to Proxima Centauri b, a planet that resides in the star’s habitable zone.

“If there was life on the planet nearest to Proxima Centauri, it would have to look very different than anything on Earth,” MacGregor said. “A human being on this planet would have a bad time.”

Future observations will focus on unveiling the many secrets behind Proxima Centauri’s flares in the hopes of uncovering the internal mechanisms that cause such powerful outbursts.

“We want to see what surprises this star has in store for us to help us understand the physics of stellar flaring,” said MacGregor.

Additional Information

The results of the study are reported today in The Astrophysical Journal Letters.

Author lists and affiliation:

Meredith A. MacGregor1, Alycia J. Weinberger2, R. O. Parke Loyd3, Evgenya Shkolnik3, Thomas Barclay4,5, Ward S. Howard6, Andrew Zic7,8, Rachel A. Osten9,10, Steven R. Cranmer1,12, Adam F. Kowalski1,11, Emil Lenc8, Allison Youngblood12, Anna Estes1, David J. Wilner13, Jan Forbrich13,14, Anna Hughes15, Nicholas M. Law6, Tara Murphy7, Aaron Boley15, and Jaymie Matthews15

1 Department of Astrophysical and Planetary Sciences, University of Colorado, 2000 Colorado Avenue, Boulder, CO 80309, USA
2 Earth & Planets Laboratory, Carnegie Institution for Science, Washington, DC 20015, USA
3 School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287, USA
4 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
5 University of Maryland, Baltimore County, Baltimore, MD 21250, USA
6 Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
7 Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW 2006, Australia
8 CSIRO Astronomy and Space Science, Epping, NSW 1710, Australia
9 Space Telescope Science Institute, Baltimore, MD 21218 USA
10 Center for Astrophysical Sciences, Johns Hopkins University, Baltimore, MD 21218, USA
11 National Solar Observatory, University of Colorado Boulder, Boulder, CO 80303, USA
12 Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
13 Center for Astrophysics Harvard & Smithsonian, Cambridge, MA 02138, USA
14 Centre for Astrophysics Research, University of Hertfordshire, AL10 9AB, UK
15 Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T 1Z1, Canada

Regarding the telescopes involved:

“We executed a multi-wavelength campaign to monitor Proxima Cen for ∼ 40 hours between April–July 2019 simultaneously at radio through X-ray wavelengths. This paper presents the first results from this observing campaign, highlighting an extremely short duration flaring event observed on 2019 May 1 UTC by the Australian Square Kilometre Array Pathfinder (ASKAP), ALMA, the TESS – Transiting Exoplanet Survey Satellite, the Las Campanas Observatory Irénée du Pont Telescope — Las Campanas Observatory, and the National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation] (EU) Hubble Space Telescope(HST). Details on the data reduction and analysis are provided in the Appendix. Several other telescopes including Evryscope-South, The Las Cumbres Observatory Global Telescope (LCOGT) 1m, the Neil Gehrels Swift Observatory, and NASA Chandra X-ray Observatory (US) were involved in the full campaign but were not observing at the time of this event. This observing campaign aligned with TESS observations in Sectors 11 and 12. Several other analyses incorporating the available TESS data from this time period have been previously published by Vida et al. (2019) and Zic et al. (2020). However, the campaign presented here is unique in the multi-wavelength observations obtained simultaneously. Indeed, this is the first time that a stellar flare has been observed with such complete wavelength coverage (spanning millimeter to FUV wavelengths) and high time resolution (1 sec integrations with ALMA and HST) enabling unique insights into the process of flaring on M dwarfs. “

SKA Pathfinder Radio Telescope

European Southern Observatory/National Radio Astronomy Observatory(US)/National Astronomical Observatory of Japan(JP) ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

National Aeronautics Space Agency (US)/Massachusetts Institute of Technology(US) TESS – Transiting Exoplanet Survey Satellite replaced NASA Kepler Space Telescope (US) in search for exoplanets .

National Science Foundation (US) NOIRLab Carnegie Institution for Science (US) Las Campanas Observatory(CL) 2.5 meter Irénée Dupont telescope, Atacama Desert, over 2,500 m (8,200 ft) high approximately 100 kilometres (62 mi) northeast of the city of La Serena, Chile.

National Aeronautics and Space Administration(US)/European Space Agency [Agence spatiale européenne] [Europäische Weltraumorganisation] (EU) Hubble Space Telescope.

The Evryscope

LCOGT Las Cumbres Observatory 1M Global Telescope Network, Haleakala Hawaii, USA, Elevation 10,023 ft (3,055 m).

National Aeronautics and Space Administration(US) Neil Gehrels Swift Observatory.

National Aeronautics and Space Administration(US) Chandra X-ray telescope(US).

See the full article here .

five-ways-keep-your-child-safe-school-shootings

Please help promote STEM in your local schools.

Stem Education Coalition

The Atacama Large Millimeter/submillimeter Array (ALMA) (CL) , an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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.

ALMA is a time machine!

ALMA-In Search of our Cosmic Origins

From ALMA (CL): “Discovery of Interaction between Jet and Disk Wind from a Star-Forming Accretion Disk”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

From ALMA (CL)

2.9.21

Nicolás Lira
Education and Public Outreach Coordinator
Joint ALMA Observatory, Santiago – Chile
Phone: +56 2 2467 6519
Cell phone: +56 9 9445 7726
Email: nicolas.lira@alma.cl

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago – Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Cell phone: +1 (434) 249 3423
Email: alma-pr@nrao.edu

An international research team, led by Chin-Fei Lee at Academia Sinica Institute of Astronomy & Astrophysics [中央研究院天文及天文物理研究所](TW), has spatially resolved a magnetic wind launched from a star-forming accretion disk and discovered the first jet and disk wind interaction in star formation, using the Atacama Large Millimeter/submillimeter Array (ALMA). The finding supports that disk wind and jet can both be present, extracting angular momentum from different parts of the disk, allowing material to transport within the disk from the outer to the inner part and then fall onto the central protostar (baby star), providing a combined solution to the long-standing angular momentum problem in the accretion process for star formation.

(Left) ALMA composite image of dust emission (gray image), SO emission (orange), and SiO emission (green) towards the center of the HH 212 star-forming system. Accretion disk is seen in dust emission, jet is seen in SiO and SO emission along the symmetric axis, bow shocks are seen in SiO emission at large distances from the protostar. Faint wind is seen in SO emission, fanning out from the disk. The shells produced by the jet-wind interaction is also seen in SO emission, connecting to the bow shocks at large distances. Credit: ALMA (ESO/NAOJ/NRAO)/Lee et al. (Right) An artistic conception showing the disk, jet, wind (greenish), and shells in the system.
Credit: Ya-Ling Huang/ASIAA.

“Thanks to the powerful ALMA, we spatially resolve a previously detected disk wind in the HH 212 star-forming system and confirm it to be a magnetic wind launched from an accretion disk”, says Chin-Fei Lee at ASIAA with excitement. “In addition, we also detect its interaction with the jet, providing the first evidence of jet and disk wind interaction in star formation. A thin shell produced by the interaction can be clearly seen, forming an inner boundary of the disk wind and connecting to the large bow shocks driven by the jet at large distance.”

Benoit Tabone at Leiden Observatory [Sterrewacht Leiden](NL), who provided the theoretical model to this study, said “It is amazing to see how well our magnetic disk wind models can match the observed morphology and kinematics of the HH 212 wind. Our model initially reproduced low spatial resolution ALMA observations, but with these new high angular resolution observations we are able to robustly test the magnetic disk wind models and infer the angular momentum carried away by the wind.”

“The observations and modeling of the jet-wind interaction open an entirely new and promising avenue to constrain the large-scale magnetic field in accretion disks, which can have fundamental impact on the early process of planet formation”, commented also Sylvie Cabrit at The Paris Observatory [Observatoire de Paris](FR).

Schematic diagram showing the launching of the jet and disk wind from an accretion disk, driving the accretion process for star formation. Credit: Ya-Ling Huang/ASIAA.

HH 212 is a nearby star-forming system in Orion at a distance of about 1300 ly. The central protostar (baby star) is very young with an age of only ~ 40,000 yrs (which is about 10 millionth of the age of Our Sun) and a mass of ~ 0.25 Msun. It accretes material actively through an accretion disk. A powerful bipolar jet is ejected from the center of the disk, allowing disk material there to be accreted to the central protostar.

Previous search in SO molecular emission at a resolution of 60 au detected a disk wind around the jet. Now with a resolution of 13 au (i.e. about 5 times higher resolution) and an unprecedented high sensitivity, ALMA resolved the disk wind and detected its interaction with the jet (see Figure 1). Quantitative modeling indicates (see Figure 2): (1) the wind is consistent with an extended magnetic disk wind launched from ≃ 4 to 40 au, extracting angular momentum to drive disk accretion; (2) the jet is launched from the dust-free zone of the disk, allowing material there to fall onto the baby star; and (3) the jet drives large bow shocks interacting with the disk wind and producing a cavity, with a thin SO shell forming its boundary. This interaction provides unique first clues to the unknown magnetic field strength and distribution in young accretion disks.

Science paper:
First Detection of Interaction between a Magnetic Disk Wind and an Episodic Jet in a Protostellar System
The Astrophysical Journal Letters

See the full article here.

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Please help promote STEM in your local schools.

Stem Education Coalition

The Atacama Large Millimeter/submillimeter Array (ALMA) (CL) , an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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.

ALMA is a time machine!

ALMA-In Search of our Cosmic Origins

From National Autonomous University of Mexico [Universidad Nacional Autónoma de México](MX) via Science Alert(AU): “Astronomers Mapped The Spectacular Accelerating Outflows of a Stellar Explosion”

From National Autonomous University of Mexico [Universidad Nacional Autónoma de México](MX)

via

Science Alert(AU)

19 FEBRUARY 2021
MICHELLE STARR

ALMA’s map of the Orion streamers. (ALMA (ESO/NAOJ/NRAO), J. Bally/H. Drass et al.)

Material accelerating away from the site of a stellar explosion has been discovered in a star-forming cloud.

It’s only the second time molecular outflows of this kind have ever been clearly seen, but it could help astronomers understand how the most massive stars get their start in life.

In the 1980s, astronomers discovered something peculiar in the star-forming Orion nebula: streamers of dense molecular gas, travelling at speed through space. When these streamers were mapped, they seemed to originate from a single point.

Orion Nebula ESO/VLT

Since then, molecular outflows have been discovered in many star-forming regions. They are thought to play an important role in the formation of low-mass stars, transporting away the excess angular momentum that would otherwise cause baby stars to spin themselves into oblivion.

The Orion outflow, however, was one of a kind. Molecular outflows in low-mass stars are bipolar; that is, there are only two of them, shooting out in opposite directions. The outflows in Orion were much more numerous… and they were also found in a region where much more massive stars – over 10 times the mass of the Sun – are forming.

Combined X-ray, radio and optical image of W28, the region’s parent complex. (NASA/ROSAT; NOIRLab NOAO/CTIO/P.F. Winkler et al; NSF/NRAO/VLA/G. Dubner et al.)

ROSAT X-ray satellite built by DLR (DE) , with instruments built by West Germany, the United Kingdom and the United States.

NOIRLab CTIO Cerro Tololo Inter-American Observatory,approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

NRAO Karl G Jansky Very Large Array, located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

Now, we don’t know as much about the formation of massive stars as we do about the smaller ones. Massive stellar nurseries are rarer and tend to be more distant, making them harder to see. So astronomers thought that maybe the Orion outflows could yield some clues.

Yet there was nothing at the source of the outflows – no baby massive star. This could imply several explosive scenarios, such as a merger between two massive baby stars, or gravitational energy liberated by the formation of a nearby massive binary. But with only one observation of its kind, it’s difficult to make a firm ruling.

To try and learn more about this phenomenon, a team of astronomers led by Luis Zapata of the National Autonomous University of Mexico [Universidad Nacional Autónoma de México](MX) decided to turn one of our most powerful radio telescopes, the Atacama Large Millimeter/submillimeter Array (ALMA), at a known massive stellar nursery.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

False-colour image of W28. Credit:NRAO/AUI/NSF and Brogan et al.

G5.89−0.39 [JHEA], also known as W28 A2, is around 9,752 light-years away. It contains a bright, expanding shell-like ultra-compact hydrogen cloud and powerful molecular outflows. Zapata and his team had previously noted that six of these filaments seemed to point directly at the centre of the hydrogen cloud, but their results were inconclusive.

ALMA cleared that ambiguity right up. It detected dense streamers based on the millimetre-wavelength emission from carbon dioxide and silicon monoxide.

Credit:The Astrophysical Journal

The astronomers were able to identify 34 molecular streamers zooming radially away from the heart of the cloud, accelerating outwards. Based on their velocities of up to 130 kilometres (80 miles) per second, the outflows are about 1,000 years old; whatever explosion produced them occurred about a millennium ago.

They are not as powerful as the outflows you’d expect from a supernova explosion, which occurs when a massive star dies. In addition, as was also seen in the case of Orion, there was no star in the centre – just a region of ionised gas, possibly the result of heating during an explosive event.

If there was a star (or multiple stars) associated with the event that produced the outflows, it could have been ejected from the region.

Because massive stars always form in clusters, such interactions are possibly quite common, which in turn could shed some light on massive star formation. If two protostars merged, they would likely have ended up as one much larger star.

Based on the Orion outflows, the G5.89 outflows, and the marginal detection of what could be similar outflows in a star-forming region known as DR-21, the team estimates that these events occur every 130 years or so. That’s very close to an estimated rate of supernova explosions.

The unpredictability of these events, and the short duration of the outflow phase, may make them pretty hard to find; but, now that we know what to look for and how, astronomers may be able to build a catalogue of these kinds of events. In turn, that will help us understand why they occur.

“If enough of these outflows can be detected in the future, the merging of clusters of stars may be an important formation mechanism of massive stars,” Zapata said.

The research has been published in The Astrophysical Journal Letters.

See the full article here.

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Please help promote STEM in your local schools.

Stem Education Coalition

The National Autonomous University of Mexico [Universidad Nacional Autónoma de México](MX) is a public research university in Mexico. It ranks highly in world rankings based on the university’s extensive research and innovation. It is the largest university in Latin America and has one of the biggest campuses in the world. UNAM’s main campus in Mexico City, known as Ciudad Universitaria (University City), is a UNESCO World Heritage site that was designed by some of Mexico’s best-known architects of the 20th century. Murals in the main campus were painted by some of the most recognized artists in Mexican history, such as Diego Rivera and David Alfaro Siqueiros. In 2016, it had an acceptance rate of only 8%. UNAM generates a number of strong research publications and patents in diverse areas, such as robotics, computer science, mathematics, physics, human-computer interaction, history, philosophy, among others. All Mexican Nobel laureates are either alumni or faculty of UNAM.

UNAM was founded, in its modern form, on 22 September 1910 by Justo Sierra as a liberal alternative to its predecessor, the Royal and Pontifical University of Mexico, the first to be founded in North America. UNAM obtained its autonomy from the government in 1929. This has given the university the freedom to define its own curriculum and manage its own budget without government interference. This has had a profound effect on academic life at the university, which some claim boosts academic freedom and independence.

UNAM was the birthplace of the student movement of 1968, which turned into a nationwide rebellion against autocratic rule and began Mexico’s three-decade journey toward democracy.

From Instituto de Astrofísica de Canarias – IAC (ES): “A challenge to models of star-formation truncation in massive galaxies”

From Instituto de Astrofísica de Canarias – IAC (ES)

11/01/2021
Annagrazia Puglisi

HST imaging and narrow and broad components ALMA maps of ID2299. The top-left panel shows the HST-F814W imaging of the source, sampling the UV rest-frame emission from young stars. The top (bottom) rows show the CO(2-1), CO(5-4), [CI](2-1) and CO(7-6) ALMA maps of the narrow (broad) emission. The luminosity of the broad line emission indicates that half of the total molecular gas mass is decoupled from the galaxy. Credit: Instituto de Astrofísica de Canarias – IAC (ES)

The physical processes which suppress the growth of the stellar population in massive galaxies are not clear, although there is considerable agreement about the idea that the feedback winds from galaxies with active nuclei slow down their star formation. Now an international study published in Nature Astronomy, in which the Instituto de Astrofísica de Canarias (IAC) is a participant, suggests that the feedback winds do not have a direct impact on braking the formation of stars in massive galaxies, and attributes the process to other events such as ejection by huge tides caused when galaxies merge.

The rapid accumulation of matter by a supermassive black hole causes the emission of strong jets, winds, and radiation, which are expelled from the centre of the galaxy towards the exterior. This phenomenon of feedback by Active Galactic Nuclei (AGN) has been thought of as a probable way for rapid braking of star formation, because the radiation emitted could eliminate the cold molecular gas clouds aroiund the nucleus which give birth to stars.

In addition, according to accepted theory, different models of galaxy evolution need the injection of energy from the AGN into the interstellar medium to explain the observed properties of massive galaxies, such as the phenomenology of star-formation truncation.

However, the study, in which over 15 scientific institutions have participated, warns about the scarce scientific evidence of cases of massive galaxies whose star formation was truncated abruptly due to feedback winds. In fact, using observations and simulations, the results show that the mechanism which brakes the formation of stars in those galaxies is not due to feedback winds, but to other extreme mass ejections driven by mergers of galaxies.

The article also suggests that the activity of accretion by the central black holes occurs together with the formation of stars, and that these two phenomena self-regulate during thousands of millions of years. That means that the accretion onto the black holes, and the mechanisms driven by the feeback winds are slow processes, so that it is not likely that they cause the events which truncate star formation rapidly.

The observations are centred on ID2299, a typical galaxy whose star formation is about to switch off (and will remain like that for a long period of time) due to a violent event which has eliminated a major part of its interstellar medium.

“Our observations are tracing an extreme episode, which is unlikely to be consistent with the classical interpretation of a nuclear wind causing feedback” say those responsible for the study.

We don’t question that the feedback outflows play an important role. They are needed, for example, to explain the highest components of velocity in the spectra of galaxies with AGN” notes Shuowen Jin, a researcher at the IAC who has participated in the work. “However their importance may have been overestimated and it would be worth while reconsidering at least part of the literature about these outflows and their general impact on the evolution of the galaxies” adds this astrophysicist, and points out that “in this study we have shown a new mechanism for the rapid cooling of galaxies: massive tidal ejections”

The difficulty of the work is due to the connection between phenomena on very different timescales and spatial scales, and this is where the IAC contribution comes in, by supplying photometry at multiple wavelengths, and also a catalogue of galaxies produced in 2018 and led by Jin, in which the authors estimated the numerical density of the disruptive events in the early universe.

For this an exhaustive analysis of data has been performed, most of them obtained directly from satellites, and from the Large Atacama Millimetre Array (ALMA) in Chile.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

“We have also provided a very useful method for identifying weak residual emission lines, which is very important for a firm confirmation of the broader line of work in this study, and which is the key evidence for massive ejections” adds Shuowen Jin.

References:

Jin et al. 2018 https://ui.adsabs.harvard.edu/abs/2018ApJ…864…56J/

JIn et al. 2019 https://ui.adsabs.harvard.edu/abs/2019ApJ…887..144J/

See the full article here.

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Please help promote STEM in your local schools.

Stem Education Coalition

The Instituto de Astrofísica de Canarias(IAC) (ES) is an international research centre in Spain which comprises:

The Instituto de Astrofísica (ES), the headquarters, which is in La Laguna (Tenerife).
The Centro de Astrofísica en La Palma (CALP) (ES)
The Observatorio del Teide (OT) ES, in Izaña (Tenerife).

These centres, with all the facilities they bring together, make up the European Northern Observatory(ENO).

The IAC is constituted administratively as a Public Consortium, created by statute in 1982, with involvement from the Spanish Government, the Government of the Canary Islands, the University of La Laguna and Spain’s Science Research Council (CSIC).

The International Scientific Committee (CCI) manages participation in the observatories by institutions from other countries. A Time Allocation Committee (CAT) allocates the observing time reserved for Spain at the telescopes in the IAC’s observatories.

The exceptional quality of the sky over the Canaries for astronomical observations is protected by law. The IAC’s Sky Quality Protection Office (OTPC) regulates the application of the law and its Sky Quality Group continuously monitors the parameters that define observing quality at the IAC Observatories.

The IAC’s research programme includes astrophysical research and technological development projects.

The IAC is also involved in researcher training, university teaching and outreachactivities.

The IAC has devoted much energy to developing technology for the design and construction of a large 10.4 metre diameter telescope, the ( Gran Telescopio CANARIAS, GTC), which is sited at the Observatorio del Roque de los Muchachos ES.

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

From ALMA (CL): “ALMA captures distant colliding galaxy dying out as it loses the ability to form stars”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

From ALMA (CL)

11 January 2021

Valeria Foncea
Education and Public Outreach Manager
Joint ALMA Observatory Santiago – Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
valeria.foncea@alma.cl

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
pio@eso.org

Iris Nijman
News and Public Information Manager
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Cell phone: +1 (434) 249 3423
inijman@nrao.edu

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory, Tokyo – Japan
Phone: +81 422 34 3630
hiramatsu.masaaki@nao.ac.jp

This artist’s impression of ID2299 shows the galaxy, the product of a galactic collision, and some of its gas being ejected by a “tidal tail” as a result of the merger. New observations made with ALMA have captured the earliest stages of this ejection, before the gas reached the very large scales depicted in this artist’s impression.
Credit: ESO/M. Kornmesser.

Galaxies begin to “die” when they stop forming stars, but until now astronomers had never clearly glimpsed the start of this process in a far-away galaxy. Using the Atacama Large Millimeter/submillimeter Array (ALMA), astronomers have seen a galaxy ejecting nearly half of its star-forming gas. This ejection is happening at a startling rate, equivalent to 10 000 Suns-worth of gas a year — the galaxy is rapidly losing its fuel to make new stars. The team believes that this spectacular event was triggered by a collision with another galaxy, which could lead astronomers to rethink how galaxies stop bringing new stars to life.

“This is the first time we have observed a typical massive star-forming galaxy in the distant Universe about to ‘die’ because of a massive cold gas ejection,” says Annagrazia Puglisi, lead researcher on the new study, from the Durham University (UK), and the Saclay Nuclear Research Centre (CEA-Saclay)(FR). The galaxy, ID2299, is distant enough that its light takes some 9 billion years to reach us; we see it when the Universe was just 4.5 billion years old.

The gas ejection is happening at a rate equivalent to 10 000 Suns per year, and is removing an astonishing 46% of the total cold gas from ID2299. Because the galaxy is also forming stars very rapidly, hundreds of times faster than our Milky Way, the remaining gas will be quickly consumed, shutting down ID2299 in just a few tens of million years.

The event responsible for the spectacular gas loss, the team believes, is a collision between two galaxies, which eventually merged to form ID2299. The elusive clue that pointed the scientists towards this scenario was the association of the ejected gas with a “tidal tail”. Tidal tails are elongated streams of stars and gas extending into interstellar space that result when two galaxies merge, and they are usually too faint to see in distant galaxies. However, the team managed to observe the relatively bright feature just as it was launching into space, and were able to identify it as a tidal tail.

Most astronomers believe that winds caused by star formation and the activity of black holes at the centres of massive galaxies are responsible for launching star-forming material into space, thus ending galaxies’ ability to make new stars. However, the new study published today in Nature Astronomy [.pdf below] suggests that galactic mergers can also be responsible for ejecting star-forming fuel into space.

“Our study suggests that gas ejections can be produced by mergers and that winds and tidal tails can appear very similar,” says study co-author Emanuele Daddi of CEA-Saclay (FR). Because of this, some of the teams that previously identified winds from distant galaxies could in fact have been observing tidal tails ejecting gas from them. “This might lead us to revise our understanding of how galaxies ‘die’,” Daddi adds.

Puglisi agrees about the significance of the team’s finding, saying: “I was thrilled to discover such an exceptional galaxy! I was eager to learn more about this weird object because I was convinced that there was some important lesson to be learned about how distant galaxies evolve.“

This surprising discovery was made by chance, while the team were inspecting a survey of galaxies made with ALMA, designed to study the properties of cold gas in more than 100 far-away galaxies. ID2299 had been observed by ALMA for only a few minutes, but the powerful observatory, located in northern Chile, allowed the team to collect enough data to detect the galaxy and its ejection tail.

“ALMA has shed new light on the mechanisms that can halt the formation of stars in distant galaxies. Witnessing such a massive disruption event adds an important piece to the complex puzzle of galaxy evolution,” says Chiara Circosta, a researcher at the University College London (UK), who also contributed to the research.

In the future, the team could use ALMA to make higher-resolution and deeper observations of this galaxy, enabling them to better understand the dynamics of the ejected gas. Observations with the future ESO’s Extremely Large Telescope could allow the team to explore the connections between the stars and gas in ID2299, shedding new light on how galaxies evolve.

More Information

This research was presented in the paper “A titanic interstellar medium ejection from a massive starburst galaxy at z=1.4” to appear in Nature Astronomy. [.pdf only at this point]

The team is composed of A. Puglisi (Centre for Extragalactic Astronomy, Durham University (UK) and CEA, IRFU, DAp, AIM, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, CNRS, (FR) [CEA]), E. Daddi (CEA), M. Brusa (Dipartimento di Fisica e Astronomia, Università di Bologna (IT) and INAF-Osservatorio Astronomico di Bologna (IT)), F. Bournaud (CEA), J. Fensch (Univ. Lyon, ENS de Lyon, Univ. Lyon 1, CNRS, Centre de Recherche Astrophysique de Lyon, France), D. Liu (Max Planck Institute for Astronomy(DE)), I. Delvecchio (CEA), A. Calabrò (INAF-Osservatorio Astronomico di Roma, (IT)), C. Circosta (Department of Physics & Astronomy, University College London (UK), F. Valentino (Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen and DTU-Space, Technical University of Denmark (DK)), M. Perna (Centro de Astrobiología (CAB, CSIC–INTA), Departamento de Astrofísica (ES) and INAF-Osservatorio Astrofisico di Arcetri(IT)), S. Jin (Instituto de Astrofísica de Canarias and Universidad de La Laguna, Dpto. Astrofísica (ES)), A. Enia (Dipartimento di Fisica e Astronomia, Università di Padova (IT)]), C. Mancini (Padova) and G. Rodighiero (Padova and INAF-Osservatorio Astronomico di Padova, (IT)).

See the full article here.

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Please help promote STEM in your local schools.

ALMA is a time machine!
Stem Education Coalition

The Atacama Large Millimeter/submillimeter Array (ALMA) (CL) , an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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.

ALMA is a time machine!

ALMA-In Search of our Cosmic Origins

From Sky & Telescope: “Astronomers Chart Star Formation History- Glimpse Fate of the Universe”

From Sky & Telescope

October 26, 2020
Monica Young

Astronomers have tallied how star-making material evolved over cosmic time — and predicted how long stars will keep forming before the universe goes dark.

ALMA has captured a gold mine of galaxies in the Hubble Ultra Deep Field: Those rich in carbon monoxide gas (which traces molecular hydrogen) have lots of star-forming potential (colored orange). Those galaxies imaged solely by Hubble appear in blue. This image from the ALMA Spectroscopic Survey (ASPECS) covers one-sixth of the full Hubble Ultra Deep Field.
Credit: B. Saxton (NRAO / AUI / NSF) / ALMA (ESO / NAOJ / NRAO) / NASA / ESA Hubble.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

Astronomers have always been historians, looking back through time to piece together the story of the universe.

Now, they have a new primary source in hand, a historical record of molecular hydrogen gas — the stuff that makes stars. The new observations enable not only a sweeping survey of the past, but a glimpse into our cosmic future.

A History of Star Stuff

Astronomers have spent decades charting the rise and fall of galaxies’ star formation over time. The stellar baby boom occurred about 10 billion years ago, at so-called “cosmic noon” [Annual Review of Astronomy & Astrophysics 2020]. During these early years of the universe, galaxies were bursting with newborn stars, sometimes birthing thousands per year. But rates have been falling ever since.

To explore this rise and fall, astronomers went a step earlier in the process, charting not just the stars born but the material used to make them. Molecular hydrogen gas is cool enough that hydrogen atoms pair up — and it’s also cool enough to collapse into stars. Fabian Walter (Max Planck Institute for Astronomy, Germany) and colleagues used the Atacama Large Millimeter/submillimeter Array (ALMA) to survey the Hubble Ultra Deep Field (HUDF), one of the best-studied regions of the sky. The results of that survey appear in The Astrophysical Journal.

ASPECS Project: ALMA and Hubble UDF

ALMA is a 66-dish array in Chile capable of spying cool gas and dust in galaxies whose light has been traveling for up to 12 billion years. “This is one of the largest programs executed at ALMA,” Walter says, adding that the program used almost 200 hours of ALMA observing time. Along with other studies of the HUDF, ALMA provided the data Walter and colleagues needed to trace the flow of gas into galaxies and into stars.

The gas that falls into galaxies is generally ionized, which means that the hydrogen atom is missing its electron. That gas has to cool, first recombining with electrons and then combining again into molecules, before it can form stars. Walter and colleagues are able to track both atomic and molecular gas to follow the flow of gas from the outermost reaches of a galaxy into its star-forming heart.

“I think we already knew that’s how it has to work, but this paper nicely quantifies, perhaps for the first time, the global rate at which that happened, averaged over all galaxies, and over most of cosmic history,” says Mark Dickinson (NOAO), who was not involved in the study.

This diagram shows the flow of gas from the outermost reaches of a galaxy into its star-forming core. Feedback also occurs, tossing some gas back out again.Credit: Tumlinson et al. / Annual Reviews of Astronomy & Astrophysics 2018.

The observations clearly show that galaxies never, at any one point in time, hold all the gas they need to make all their stars. The gas has to come from outside — the inflow of gas necessary for star formation has continued for all observed cosmic history.

“Those are very challenging millimeter and radio measurements that were impossible not long ago,” Dickinson notes. “I think the Walter et al. paper sets an important benchmark for future analyses as new data are collected.”

The Fate of the Universe

As ever, examining the past also hints at the future. Star formation rates have declined ever since cosmic noon 10 billion years ago. The inflow of gas will only continue to decline, the researchers write: “The cosmic star formation rate density will continue its steady descent to the infinitesimal.”

It’s a one-way street, Walter says: “I cannot think of a simple way to ‘reverse’ or ‘restart’ this trend.”

The good news is that we have billions of years before the universe goes dark. And even as the influx of star-making material continues to decrease over the next 5 billion years, galaxies will continue making new stars with what they still receive. We’re hardly at the end of times just yet.

See the full article here .

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Please help promote STEM in your local schools.

Stem Education Coalition

Sky & Telescope magazine, founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer, has the largest, most experienced staff of any astronomy magazine in the world. Its editors are virtually all amateur or professional astronomers, and every one has built a telescope, written a book, done original research, developed a new product, or otherwise distinguished him or herself.

Sky & Telescope magazine, now in its eighth decade, came about because of some happy accidents. Its earliest known ancestor was a four-page bulletin called The Amateur Astronomer, which was begun in 1929 by the Amateur Astronomers Association in New York City. Then, in 1935, the American Museum of Natural History opened its Hayden Planetarium and began to issue a monthly bulletin that became a full-size magazine called The Sky within a year. Under the editorship of Hans Christian Adamson, The Sky featured large illustrations and articles from astronomers all over the globe. It immediately absorbed The Amateur Astronomer.

Despite initial success, by 1939 the planetarium found itself unable to continue financial support of The Sky. Charles A. Federer, who would become the dominant force behind Sky & Telescope, was then working as a lecturer at the planetarium. He was asked to take over publishing The Sky. Federer agreed and started an independent publishing corporation in New York.

“Our first issue came out in January 1940,” he noted. “We dropped from 32 to 24 pages, used cheaper quality paper…but editorially we further defined the departments and tried to squeeze as much information as possible between the covers.” Federer was The Sky’s editor, and his wife, Helen, served as managing editor. In that January 1940 issue, they stated their goal: “We shall try to make the magazine meet the needs of amateur astronomy, so that amateur astronomers will come to regard it as essential to their pursuit, and professionals to consider it a worthwhile medium in which to bring their work before the public.”

From UC Berkeley: “Active volcanoes feed Io’s sulfurous atmosphere”

From UC Berkeley

October 21, 2020
Robert Sanders
rlsanders@berkeley.edu

A composite image of Io in front of a Hubble Space Telescope photo of Jupiter. The observations for the first time show plumes of sulfur dioxide (yellow) rising up from Io’s volcanoes. Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA/ESA.

The atmosphere on Jupiter’s moon Io is a witches’ brew, composed primarily of the sulfurous exhalations of more than 400 volcanoes that dot the surface.

Until now, however, it has been unclear whether volcanoes spewing hot sulfur dioxide (SO2) are the main contributors to the atmosphere, or whether the main component is the accumulated cold SO2, much of which is frozen on the surface, but in sunlight evaporates or sublimates into the atmosphere.

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, led by astronomer Imke de Pater of the University of California, Berkeley, partially resolve that question.

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres.

“It was not known which process drives the dynamics in Io’s atmosphere,” said de Pater, who is a Professor of the Graduate School in the departments of astronomy and of earth and planetary science at UC Berkeley. “Is it volcanic activity, or gas that sublimates from the icy surface when Io is in sunlight? What we show is that, actually, volcanoes do have a large impact on the atmosphere.“

As the most volcanically active moon in our solar system, Io (“EYE oh”) provides a laboratory for exotic environments unlike anything on Earth. And since we’re unable to probe inside Io, the atmosphere — about a billion times thinner than Earth’s atmosphere — provides a window into the moon’s roiling interior and the internal magma reservoirs feeding the volcanoes.

With no nearby satellite currently observing the moon — NASA’s Juno mission focuses primarily on Jupiter and will end next July — astronomers like de Pater must rely on Earth-based telescopes to probe the atmosphere.

NASA/Juno.

She has been observing Io’s atmosphere for 30 years with radio telescopes like ALMA and optical and infrared telescopes, primarily the Keck telescopes in Hawaii.

Keck Observatory, operated by Caltech and the University of California, Maunakea Hawaii USA, altitude 4,207 m (13,802 ft).

One surprise from the new observations is that the atmosphere becomes dramatically unstable when Io passes through Jupiter’s shadow every 42 hours as it orbits the planet. In a paper accepted for publication in the Planetary Science Journal, de Pater and her colleagues report that the radio emissions from sulfur dioxide (SO2) gas dropped exponentially as Io was eclipsed by Jupiter on March 20, 2018, indicating that the lower atmosphere — below 10 to 20 kilometers in altitude — essentially collapsed, quickly freezing out onto the surface.

This video shows images of Jupiter’s moon Io in radio (obtained by ALMA) and optical light (from the Voyager 1 and Galileo missions) as Io is eclipsed by Jupiter and comes out of eclipse. These radio images for the first time show plumes of sulfur dioxide (in yellow) rise up from the volcanoes on Io. [Video courtesy of ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA]

NASA/Voyager 1.

NASA/Galileo 1989-2003

Although Io’s surface is always cold — about 150 degrees Celsius below freezing, or -230 F — a further drop in temperature by a few tens of degrees, down to -270 F, brings the temperature below the freezing point of SO2.

As the moon reemerged from Jupiter’s shadow during observations on Sept. 2 and 11 in 2018, the cold sulfur dioxide emissions returned within about 10 minutes.

“As soon as Io gets into sunlight, the temperature increases, and you get all this SO2 ice subliming into gas, and you reform the atmosphere in about 10 minutes’ time, faster than what models had predicted,” said de Pater.

She noted that not all the cold SO2 froze out as the temperature dropped in Jupiter’s shadow. During the eclipse, in addition to abundant SO2 gas over some volcanoes, ALMA also detected low levels of SO2 globally in Io’s atmosphere, suggesting that many unseen volcanoes — so-called stealth volcanoes, because they emit no smoke or other particulates that can be easily seen — are constantly spewing SO2 into the atmosphere that remains too warm to condense.

There were also hints of stealth volcanism in observations reported by de Pater and her colleagues in July, based on Keck observations. They saw widespread sulfur monoxide (SO) gas in the atmosphere — not, as expected, only over active volcanoes. As de Pater shows in her new paper, SO is likely produced when sunlight breaks the sulfur-oxygen bond in SO2 that has been ejected hundreds of kilometers above the surface.

“The SO2 that we see with ALMA when Io is in eclipse is at a very low level, and we can’t say if that is stealth volcanism or caused by SO2 not completely condensing out,” she said. “But then, when we looked at the SO with Keck, we can only explain the SO emissions, which are widespread on the surface, through this stealth volcanism, because excitation of the SO requires a very high temperature.”

Io in eclipse

With such a thin atmosphere, Io is exposed to the cold of space, as well as to the hot plasma around Jupiter. The tidal tug that Jupiter and two of its largest moons, Ganymede and Europa, exert on Io heats the moon’s interior, creating the volcanoes that bathe the surface in hot sulfur dioxide fumes. Io’s largest volcano, Loki Patera, spans more than 200 kilometers (124 miles).

The volcanic SO2 eventually condenses on the surface to form a thick frozen layer of sulfur dioxide ice, recently mapped globally by de Pater and her colleagues. This frozen SO2, often overlain by a layer of volcanic dust, is what gives Io its characteristic yellow, white, orange and red colors.

Though the dominance of SO2 in Io’s atmosphere was well known — de Pater was a member of the first team to observe global SO2 in 1990 — it was still unclear whether recently emitted hot SO2 or sublimation from the accumulated SO2 ice (referred to as cold SO2) dominated the atmosphere.

To disentangle the contributions of hot and cold SO2, de Pater and her colleagues, including Statia Luszcz-Cook from Columbia University in New York and Katherine de Kleer of the California Institute of Technology, chose to observe Io during its transition from sunlight into darkness during an eclipse and again when it reemerged into the light from eclipse. Because of the alignment of Io and Earth relative to Jupiter, it’s impossible to observe both entry and exit of Jupiter’s moon from the same eclipse, so the two observations took place six months apart.

“When Io passes into Jupiter’s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io’s surface. During that time, we can only see volcanically-sourced sulfur dioxide. We can, therefore, see exactly how much of the atmosphere is impacted by volcanic activity,” Luszcz-Cook said.

Thanks to ALMA’s exquisite resolution and sensitivity, the astronomers could, for the first time, clearly see the plumes of SO2 and SO rise up from the volcanoes, two of which — Karei Patera and Daedalus Patera — were erupting in March, while a third volcano was active in September. Based on the snapshots, they calculated that active volcanoes directly produce 30% to 50% of Io’s atmosphere.

The ALMA images also showed a third gas coming out of volcanoes: potassium chloride (KCl). Both KCl and sodium chloride — NaCl, or common table salt — are common components of magma.

“We see KCl in volcanic regions where we do not see SO2 or SO,” said Luszcz-Cook. “This is strong evidence that the magma reservoirs are different under different volcanoes.”

“By studying Io’s atmosphere and volcanic activity, we can understand more about the volcanoes, the tidal heating process and Io’s interior,” added de Kleer.

De Pater and her colleagues also hope to observe Io at other radio wavelengths that can probe several inches below the surface, potentially revealing the content and temperature of the magma underlying the volcanoes.

A big unknown remains the temperature in Io’s lower atmosphere. In future research, the astronomers hope to measure this with ALMA.

“To measure the temperature of Io’s atmosphere, we need to obtain a higher resolution in our observations, which requires that we observe the moon for a longer period of time. We can only do this when Io is in sunlight, since it does not spend much time in eclipse,” said de Pater. “During such an observation, Io will rotate by tens of degrees. We will need to apply software that helps us make unsmeared images. We have done this previously with radio images of Jupiter made with ALMA and the Very Large Array.”

Other co-authors of the paper reporting ALMA observations are Patricio Rojo of the Universidad de Chile in Santiago, Erin Redwing of UC Berkeley and Arielle Moullet of the NASA Ames Research Center in Moffett Field, California.

The research was funded by the National Science Foundation (AST-1313485). The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities Inc.

RELATED INFORMATION

ALMA Observations of Io Going into and Coming out of Eclipse
The Planetary Science Journal

High Spatial and Spectral Resolution Observations of the Forbidden 1.707 μm Rovibronic SO Emissions on Io: Evidence for Widespread Stealth Volcanism
The Planetary Science Journal

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From ALMA: “ALMA Shows Volcanic Impact on Io’s Atmosphere”

ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

From ALMA

Valeria Foncea
Education and Public Outreach Officer
Joint ALMA Observatory Santiago – Chile
Phone: +56 2 2467 6258
Cell phone: +56 9 7587 1963
Email: valeria.foncea@alma.cl

Masaaki Hiramatsu
Education and Public Outreach Officer, NAOJ Chile
Observatory
, Tokyo – Japan
Phone: +81 422 34 3630
Email: hiramatsu.masaaki@nao.ac.jp

Bárbara Ferreira
ESO Public Information Officer
Garching bei München, Germany
Phone: +49 89 3200 6670
Email: pio@eso.org

Iris Nijman
Public Information Officer
National Radio Astronomy Observatory Charlottesville, Virginia – USA
Cell phone: +1 (434) 249 3423
Email: alma-pr@nrao.edu

Composite image showing Jupiter’s moon Io in radio (ALMA), and optical light (Voyager 1 and Galileo). The ALMA images of Io show for the first time plumes of sulfur dioxide (in yellow) rise up from its volcanoes. Jupiter is visible in the background (Hubble). Credit: ALMA (ESO/NAOJ/NRAO), I. de Pater et al.; NRAO/AUI NSF, S. Dagnello; NASA/ESA.

New radio images from the Atacama Large Millimeter/submillimeter Array (ALMA) show for the first time the direct effect of volcanic activity on the atmosphere of Jupiter’s moon Io.

Io is the most volcanically active moon in our solar system. It hosts more than 400 active volcanoes, spewing out sulfur gases that give Io its yellow-white-orange-red colors when they freeze out on its surface.

Although it is extremely thin – about a billion times thinner than Earth’s atmosphere – Io has an atmosphere that can teach us about Io’s volcanic activity and provide us a window into the exotic moon’s interior and what is happening below its colorful crust.

Previous research has shown that Io’s atmosphere is dominated by sulfur dioxide gas, ultimately sourced from volcanic activity. “However, it is not known which process drives the dynamics in Io’s atmosphere,” said Imke de Pater of the University of California, Berkeley. “Is it volcanic activity, or gas that has sublimated (transitioned from solid to gaseous state) from the icy surface when Io is in sunlight?“

To distinguish between the different processes that give rise to Io’s atmosphere, a team of astronomers used ALMA to make snapshots of the moon when it passed in and out of Jupiter’s shadow (they call this an “eclipse”).

“When Io passes into Jupiter’s shadow, and is out of direct sunlight, it is too cold for sulfur dioxide gas, and it condenses onto Io’s surface. During that time we can only see volcanically-sourced sulfur dioxide. We can therefore see exactly how much of the atmosphere is impacted by volcanic activity,” explained Statia Luszcz-Cook from Columbia University, New York.

Thanks to ALMA’s exquisite resolution and sensitivity, the astronomers could, for the first time, clearly see the plumes of sulfur dioxide (SO2) and sulfur monoxide (SO) rise up from the volcanoes. Based on the snapshots, they calculated that active volcanoes directly produce 30-50 percent of Io’s atmosphere.

The ALMA images also showed a third gas coming out of volcanoes: potassium chloride (KCl). “We see KCl in volcanic regions where we do not see SO2 or SO,” said Luszcz-Cook. “This is strong evidence that the magma reservoirs are different under different volcanoes.”

Io is volcanically active due to a process called tidal heating. Io orbits Jupiter in an orbit that is not quite circular and, like our Moon always faces the same side of Earth, so does the same side of Io always face Jupiter. The gravitational pull of Jupiter’s other moons Europa and Ganymede causes tremendous amounts of internal friction and heat, giving rise to volcanoes such as Loki Patera, which spans more than 200 kilometers (124 miles) across. “By studying Io’s atmosphere and volcanic activity we learn more about not only the volcanoes themselves, but also the tidal heating process and Io’s interior,” added Luszcz-Cook.

A big unknown remains the temperature in Io’s lower atmosphere. In future research, the astronomers hope to measure this with ALMA. “To measure the temperature of Io’s atmosphere, we need to obtain a higher resolution in our observations, which requires that we observe the moon for a longer period of time. We can only do this when Io is in sunlight since it does not spend much time in eclipse,” said de Pater. “During such an observation, Io will rotate by tens of degrees. We will need to apply software that helps us make un-smeared images. We have done this previously with radio images of Jupiter made with ALMA and the Very Large Array (VLA).”

NRAO Karl G Jansky Very Large Array, located in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, ~50 miles (80 km) west of Socorro. The VLA comprises twenty-eight 25-meter radio telescopes.

Additional Information

Imke de Pater and Statia Luszcz-Cook worked with Patricio Rojo of the Universidad de Chile, Erin Redwing of the University of California, Berkeley, Katherine de Kleer of the California Institute of Technology (Caltech), and Arielle Moullet of SOFIA/USRA in California.

This research titled ALMA Observations of Io Going into and Coming out of Eclipse is in The Planetary Science Journal.

See the full article here .

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Please help promote STEM in your local schools.

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

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.