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
NASA's James Webb Space Telescope completes final cryogenic testing
21.11.2017 | NASA/Goddard Space Flight Center
Previous evidence of water on mars now identified as grainflows
21.11.2017 | US Geological Survey
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.
During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....
The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.
Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
21.11.2017 | Physics and Astronomy
21.11.2017 | Physics and Astronomy
21.11.2017 | Life Sciences