Astronomers uncover one-in-ten-billion binary star system
Astronomers have identified the first example of an incredibly rare type of binary star system that has all the right conditions to eventually trigger a kilonova – an ultra-powerful explosion created by two colliding neutron stars.
“We know that the Milky Way contains at least 100 billion stars and likely hundreds of billions more. This remarkable binary system is essentially a one-in-ten-billion system,” explains Dr André-Nicolas Chené, astronomer at the National Science Foundation (NSF) NOIRLab in the US, and co-author of the study published in Nature.
“Prior to our study, the estimate was that only one or two such systems should exist in a spiral galaxy like the Milky Way.”
Using the SMARTS 1.5-meter Telescope at Cerro Tololo Inter-American Observatory in Chile, the researchers studied the unusual system known as CPD-29 2176. Located about 11,400 light-years from Earth, it includes a neutron star created by an ultra-stripped supernova and a closely orbiting massive star that is in the process of becoming an ultra-stripped supernova itself.
Ultra-stripping supernovas are the end-of-life explosion of a massive star that has had much of its outer atmosphere stripped away by a companion star it’s orbiting with. This type of supernova doesn’t have as much explosive force as a traditional supernova, which would kick a nearby companion star right out of the binary system.
“The current neutron star would have to form without ejecting its companion from the system. An ultra-stripped supernova is the best explanation for why these companion stars are in such a tight orbit,” says Noel D. Richardson, assistant professor at Embry-Riddle Aeronautical University in the US, and lead author of the paper.
“To create a kilonova, the other star would also need to explode as an ultra-stripped supernova so the two neutron stars could eventually collide and merge.”
New antimicrobial surgical stitches glow in medical imaging
Surgical infections occur in 2-4% of all patients. To help address this problem, a multidisciplinary team including experts in nano-engineering, biomedicine, textiles, and surgery, has designed a new antimicrobial suture material.
The material, which also glows in medical imaging, could be a promising alternative for mesh implants and internal stitches, according to the new study published in OpenNano.
“Our smart surgical sutures can play an important role in preventing infection and monitoring patient recovery, and the proof-of-concept material we’ve developed has several important properties that make it an exciting candidate for this,” says Dr Shadi Houshyar, lead author and senior research fellow at RMIT University’s School of Engineering, Australia.
The team designed the material using iodine attached to nanoparticles, called carbon dots, that were incorporated into a biodegradable polyester.
Carbon dots are inherently fluorescent and can be tuned to levels of luminosity that stand out from surrounding tissue in medical imaging. The material, threaded through chicken meat samples, was easily visible in CT scans even three weeks later.
The suture’s antimicrobial properties also killed 99% of highly drug-resistant bacteria after six hours at body temperature.
Next, the team plan to produce larger suture samples to use in pre-clinical trials.
Neanderthals hunted elephants 125,000 years ago
The first indisputable proof that early humans hunted elephants has been published in the journal Science Advances.
Archaeologists studying the world’s largest collection of the remains of European straight-tusked elephants (Palaeoloxodon antiquus) at the Neumark-Nord site near Halle in Germany, have found that Neanderthals deliberately hunted these animals 125,000 years ago.
The elephants, which had unusually long and essentially straight tusks, roamed Europe and Western Asia from 800,000 to 100,000 years ago. They were significantly larger than today’s African and Asian elephants and were even bigger than the woolly mammoth – reaching up to 4 metres high and weighing as much 13 tonnes.
Until now, it was unclear whether prehistoric hominins actively hunted these enormous animals, or whether they only scavenged from the carcases of individuals that had died a natural death.
Analysis of lesion distribution across the skeletal remains of the elephants suggests that Neanderthals continuously hunted them in the area over a period of 2,000 years. The findings suggest Neanderthals came together – at least temporarily – in much larger social groups than had been previously assumed.
Fungus can invade and infect ants by hiding from them
Disease-causing organisms like fungus develop mechanisms to outsmart and evade their hosts’ immune systems. Some social groups, like ants, fight back against these infections with “social immunity” – collective hygiene and health care measures to avoid spreading disease throughout the community.
Now, scientists have shown that fungal pathogens are adapting to overcome these social immunity measures through reducing their natural chemical signals, according to a new study in Nature Ecology & Evolution.
“Fungi infect the ants from the body surface and grow inside, but nestmates groom off many of the spores before they can cause internal infection,” explains Dr Barbara Milutinović, an evolutionary biologist at the Ruđer Bošković Institute in Croatia and co-lead author of the paper.
Argentine ants (Linepithema humile) were infected with pathogenic Metarhizium fungi, either in the absence or presence of caregiving colony members. The team found that, over ten infection cycles, fungi which experienced grooming nestmate ants, boosted their spore production compared to fungi surrounded by only individual ants.
But the researchers were surprised to see that the ants also showed less grooming against the spores, suggesting that they had become more difficult to detect.
“The fungi that adapted to social hosts were perceived less strongly due to a strong reduction of a fungi-specific compound called ergosterol,” explains co-author Professor Thomas Schmitt, a chemical ecologist from the University of Würzburg, Germany.
By exposing the ants to pure fungal ergosterol or a slightly different non-fungal vertebrate equivalent, the researchers showed that only the fungal compound induced intense grooming.
“This demonstrates that fungal pathogens react to the presence of caregiving ants by reducing their characteristic fungal signals. They are no longer recognised as a disease threat and can escape the social immunity of the colony,” says Milutinović.