White dwarf and red giant
When a white dwarf star gets too big after absorbing material from another nearby star, it explodes, sending a burst of light out into the universe in what is called a Type 1a supernova.
What scientists have not fully understood is the identity of the white dwarf's partner. Some have suggested that mergers between white dwarfs can lead to these explosions. But according to a new paper in the journal Science, the aged, puffy stars called red giants can also feed white dwarfs and cause supernovas.
Astrophysicists first caught sight of an unusual-looking supernova in January, 2011. It was around 675 million light-years away in the constellation Lynx. Until its telltale flashy burst, a future supernova is indistinguishable from other stars.
"It's really not possible to look at them before they explode," said the paper's lead author, Benjamin Dilday, an astrophysicist at Las Cumbres Observatory Global Telescope Network in Goleta, Calif.
From the behaviour of gas in the area after the explosion, Dilday and colleagues were able to deduce that their supernova had originally been a white dwarf orbiting a red giant. Gas from the red giant had blown onto the white dwarf, repeatedly igniting its surface and causing explosions called novas.
Eventually the star ignited at its center, leading to the supernova. Astrophysicists use Type 1a supernovas, which are highly consistent in their brightness, as standard measures of distance in the universe. They help underpin the study of dark energy and how the universe expands. Dilday hopes his work will help classify supernovas with greater precision.
Chimps and human strains of bacterium
Chimpanzees in African sanctuaries harbour human strains of the bacterium Staphylococcus aureus, according to a new paper in The American Journal of Primatology. Chimpanzees carry their own strains of staph, but scientists worry that some human strains are particularly pathogenic and could be harmful if spread to wild chimpanzees.
Nose and mouth swabs from 62 chimpanzees were taken in two sanctuaries in Uganda and Zambia. Scientists isolated staph from 36 animals; many of the strains showed drug resistance and had sequences usually found only in humans.
Ten chimpanzees tested positive for staph carrying a gene for the toxin Panton-Valentine leukocidin, which is associated with severe infections of the skin, soft tissues and lungs in humans.
The chimps themselves did not become ill, the scientists said; they were merely carriers. Staph spread through close contact. Sanctuary workers often hold baby chimps to warm them, so this is a likely route of transmission.
The sanctuaries that took part in the study do not release chimps, but other African sanctuaries do; releases are considered necessary in the face of overcrowding. Chimps are quarantined and tested for diseases before release, but they are not commonly tested for staph.
When a white dwarf star gets too big after absorbing material from another nearby star, it explodes, sending a burst of light out into the universe in what is called a Type 1a supernova.
What scientists have not fully understood is the identity of the white dwarf's partner. Some have suggested that mergers between white dwarfs can lead to these explosions. But according to a new paper in the journal Science, the aged, puffy stars called red giants can also feed white dwarfs and cause supernovas.
Astrophysicists first caught sight of an unusual-looking supernova in January, 2011. It was around 675 million light-years away in the constellation Lynx. Until its telltale flashy burst, a future supernova is indistinguishable from other stars.
"It's really not possible to look at them before they explode," said the paper's lead author, Benjamin Dilday, an astrophysicist at Las Cumbres Observatory Global Telescope Network in Goleta, Calif.
From the behaviour of gas in the area after the explosion, Dilday and colleagues were able to deduce that their supernova had originally been a white dwarf orbiting a red giant. Gas from the red giant had blown onto the white dwarf, repeatedly igniting its surface and causing explosions called novas.
Eventually the star ignited at its center, leading to the supernova. Astrophysicists use Type 1a supernovas, which are highly consistent in their brightness, as standard measures of distance in the universe. They help underpin the study of dark energy and how the universe expands. Dilday hopes his work will help classify supernovas with greater precision.
Chimps and human strains of bacterium
Chimpanzees in African sanctuaries harbour human strains of the bacterium Staphylococcus aureus, according to a new paper in The American Journal of Primatology. Chimpanzees carry their own strains of staph, but scientists worry that some human strains are particularly pathogenic and could be harmful if spread to wild chimpanzees.
Nose and mouth swabs from 62 chimpanzees were taken in two sanctuaries in Uganda and Zambia. Scientists isolated staph from 36 animals; many of the strains showed drug resistance and had sequences usually found only in humans.
Ten chimpanzees tested positive for staph carrying a gene for the toxin Panton-Valentine leukocidin, which is associated with severe infections of the skin, soft tissues and lungs in humans.
The chimps themselves did not become ill, the scientists said; they were merely carriers. Staph spread through close contact. Sanctuary workers often hold baby chimps to warm them, so this is a likely route of transmission.
The sanctuaries that took part in the study do not release chimps, but other African sanctuaries do; releases are considered necessary in the face of overcrowding. Chimps are quarantined and tested for diseases before release, but they are not commonly tested for staph.