International researcher team with Heidelberg involvement discovers ancient stars from when the universe was young
An international team, including researchers from the Centre for Astronomy of Heidelberg University (ZAH), has discovered three “cosmic Methusalems” from the earliest years of the universe. These unusual stars are about 13 billion years old and experts assign them to the first generations of stars after the “dark ages”.
The chemical qualities of these extremely rare stellar bodies enable new insights into the events that must have led to the origins of the stars. The first stars have been assumed to be high-mass and to shine especially brightly.
However, the latest observations point to hitherto unknown phenomena in the young universe, allowing for the emergence of much smaller stars. This conclusion is suggested by analyses in part conducted at the State Observatory Königstuhl and at the Institute of Theoretical Astrophysics, both of which belong to the ZAH.
The universe emerged approximately 13.8 billion years ago through the big bang. The initially extremely hot gas of the “explosion cloud” expanded and grew colder and colder. As the cosmic expanses were completely empty of stars at the time, scientists talk of the “dark ages” of the universe.
About 400 million years after the big bang, the first stars formed out of the gases created by the explosion. Due to the chemical composition of the initial gases – mainly hydrogen, helium and traces of lithium – the stars’ mass must have been 10 to 100 times greater than that of the sun, and therefore they must have emitted an extremely brilliant light. They rapidly exhausted their nuclear fuel and so these stars only shone for a few million years.
They disintegrated in gigantic explosions, during which heavy chemical elements were released and “recovered” by subsequent stellar generations. An exact chemical investigation of this second generation of stars can enable conclusions to be drawn regarding the properties of the very first stars.
The three original stars were discovered thanks to observations at the Paris observatory by a team of astronomers led by Dr. Piercarlo Bonifacio. Apart from hydrogen and helium they contain only extremely small quantities of other chemical elements, these include a striking amount of carbon. Astronomer Dr. Paolo Molaro from the Trieste observatory therefore suspects that they belong to a special – completely new – class of original stars.
The programme at the European Southern Observatory (ESO) in Chile to observe such objects was initiated by Dr. Elisabetta Caffau during her time as Gliese Fellow of Heidelberg University at the Königstuhl Observatory. In order to be able to determine the extremely slight element frequencies with great accuracy, scientists use computer simulations of star atmospheres. These models are developed by Dr. Hans-Günter Ludwig, a researcher at the Königstuhl Observatory.
Events contributing to the formation of the first stars in the universe are being explored at the Institute of Theoretical Astrophysics by the Star Formation Group led by Prof. Dr. Ralf Klessen. He reports that carbon played a major role in the young universe as a “coolant” contributing to the contraction of interstellar gas into a star. The better the cooling, the smaller the stars that can form.
Yet even with carbon the first stars should still have had at least ten times more mass than the newly discovered candidates. “Probably interstellar dust was the coolant contributing to the formation of these low-mass stars. We are now going to examine that in detail,” says Prof. Klessen.
The current discoveries allow a fascinating new insight into the events surrounding the emergence of the first stars. Accordingly, these stars must not have arisen in isolation but in groups, Prof. Klessen underlines. The high-mass stars exploded after only a few million years, but far less violently than had been assumed.
The Heidelberg scientist explains: “Only then could the lighter elements such as carbon or oxygen be projected far enough into the cosmos to be of use to the new stars, which have a lower mass but a longer life.” However, there is another puzzling question. The three newly discovered stars display no trace of lithium, although this chemical element is also contained in the original gas. For Dr. Marco Limongi from the Rome observatory, which is also part of the international research team, this is another mystery waiting to be elucidated.
P. Bonifacio, E. Caffau, M. Spite, M. Limongi, A. Chieffi, R.S. Klessen., P. François, P. Molaro, H.-G. Ludwig, S. Zaggia, F. Spite et al.: TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Astronomy & Astrophysics (in advance), http://dx.doi.org/10.1051/0004-6361/201425266
Dr. Guido Thimm
Centre for Astronomy of Heidelberg University
Phone: +49 6221 54-1805
Communications and Marketing
Press Office, phone: +49 6221 54-2311
Marietta Fuhrmann-Koch | idw - Informationsdienst Wissenschaft
The taming of the light screw
22.03.2019 | Max-Planck-Institut für Struktur und Dynamik der Materie
21.03.2019 | Max-Planck-Institut für Polymerforschung
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
25.03.2019 | Trade Fair News
25.03.2019 | Life Sciences
25.03.2019 | Information Technology