Despite the extreme conditions astronomers were surprised to find the same proportions of low- and high-mass young stars in the cluster as are found in more tranquil locations in our Milky Way.
The massive Arches Cluster is a rather peculiar star cluster. It is located 25 000 light-years away towards the constellation of Sagittarius (the Archer), and contains about a thousand young, massive stars, less than 2.5 million years old . It is an ideal laboratory to study how massive stars are born in extreme conditions as it is close to the centre of our Milky Way, where it experiences huge opposing forces from the stars, gas and the supermassive black hole that reside there. The Arches Cluster is ten times heavier than typical young star clusters scattered throughout our Milky Way and is enriched with chemical elements heavier than helium.
Using the NACO adaptive optics instrument on ESO’s Very Large Telescope, located in Chile, astronomers scrutinised the cluster in detail. Thanks to adaptive optics, astronomers can remove most of the blurring effect of the atmosphere, and so the new NACO images of the Arches Cluster are even crisper than those obtained with telescopes in space. Observing the Arches Cluster is very challenging because of the huge quantities of absorbing dust between Earth and the Galactic Centre, which visible light cannot penetrate. This is why NACO was used to observe the region in near-infrared light.
The new study confirms the Arches Cluster to be the densest cluster of massive young stars known. It is about three light-years across with more than a thousand stars packed into each cubic light-year — an extreme density a million times greater than in the Sun’s neighbourhood.
Astronomers studying clusters of stars have found that higher mass stars are rarer than their less massive brethren, and their relative numbers are the same everywhere, following a universal law. For many years, the Arches Cluster seemed to be a striking exception.
“With the extreme conditions in the Arches Cluster, one might indeed imagine that stars won’t form in the same way as in our quiet solar neighbourhood,” says Pablo Espinoza, the lead author of the paper reporting the new results. “However, our new observations showed that the masses of stars in this cluster actually do follow the same universal law”.
In this image the astronomers could also study the brightest stars in the cluster. “The most massive star we found has a mass of about 120 times that of the Sun,” says co-author Fernando Selman. “We conclude from this that if stars more massive than 130 solar masses exist, they must live for less than 2.5 million years and end their lives without exploding as supernovae, as massive stars usually do.”
The total mass of the cluster seems to be about 30 000 times that of the Sun, much more than was previously thought. “That we can see so much more is due to the exquisite NACO images,” says co-author Jorge Melnick.Note
ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe. It is supported by 14 countries: Austria, Belgium, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in the Atacama Desert region of Chile: La Silla, Paranal and Chajnantor.Contacts
Dr. Henri Boffin | EurekAlert!
X-ray photoelectron spectroscopy under real ambient pressure conditions
28.06.2017 | National Institutes of Natural Sciences
New photoacoustic technique detects gases at parts-per-quadrillion level
28.06.2017 | Brown University
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
28.06.2017 | Physics and Astronomy
28.06.2017 | Physics and Astronomy
28.06.2017 | Health and Medicine