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

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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.

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.