Blue stragglers (ringed) are irresistable to others.
Succession of relationships keeps heavenly bodies young
Astronomers have uncovered a scandalous degree of promiscuity in the cosmos. Clusters where stars gather more densely than usual are veritable hotbeds of partner-swapping. Some stars engage in half a dozen or so relationships during their lifetime1.
Star clusters range from loose groups of ten thousand or so stars to dense globular clusters of a million or more. They exist throughout galaxies like ours - from near the Galactic Centre to far outside the main galaxy body. In the centre of a globular cluster, star density can be more than 10 million times that around our own Sun.
Previous generations of GRAPE made many simple and unrealistic assumptions about the interactions between stars in clusters. GRAPE-6 follows the lives of individual stars in a population of 50,000 or so in great detail.
Clusters are so dense that two stars often become bound into binary systems. These pirouette around their common centre of mass. Some stars can even get trapped in groups of three or more. Hurley and Shara were surprised to find that these partnerships can form and break many times in a star’s life; so a star could have several different partners in close succession.
This promiscuity takes its toll. When they get together, stars can undergo profound character changes. In particular, they can coalesce or pull material from their partner to form larger, more massive stars.
Ménages and mergers
The researchers followed one particular star that began life as an object much like the Sun, but bound in a binary system with another star of about half its mass. First, this pair had a short-lived ménage-à-trois with a smaller star. They then got together with a triple system in a group of five.
After some dramatic exits from the group, the initial star, now aged about 3.5 billion, merged with another, doubling its mass. It then hooked up with another star of similar mass; they eventually coalesced to form a star with about four times the Sun’s mass. This found itself in another foursome, before merging again to make a still more massive star, which blew off much of its outer material and ended up, 4.3 billion years after the initial star formed, as a white dwarf.
This lurid case history "is not at all rare", say Hurley and Shara. Cluster stars are constantly reinventing themselves.
A star such as the Sun gets gradually hotter, bluer and brighter as it ages. But astronomical observations have revealed that many stars in clusters show a different relationship between colour, brightness and age.
For example, globular clusters contain so-called blue straggler stars. These are much older than the Sun but look, judging from their colour and brightness, almost as young. Merging with or cannibalizing other stars may rejuvenate blue stragglers. Indeed, Hurley and Shara say that, once a star has become a blue straggler, it is irresistible to others: subsequent relationships "are almost inevitable".
PHILIP BALL | © Nature News Service
A cavity leads to a strong interaction between light and matter
21.10.2019 | Universität Basel
A new stable form of plutonium discovered at the ESRF
21.10.2019 | European Synchrotron Radiation Facility
A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)
It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.
The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...
Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.
Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...
A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.
The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...
Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).
Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...
02.10.2019 | Event News
02.10.2019 | Event News
19.09.2019 | Event News
21.10.2019 | Materials Sciences
21.10.2019 | Materials Sciences
21.10.2019 | Medical Engineering