Astronomers have found the biggest star in space hidden inside the Tarantula Nebula.
A team of researchers lead by Paul Crowther at the University of Sheffield announced this week that they had discovered the most massive star known to science. Dubbed R136a1, the star weighs about 265 times more than our own sun, which clocks in at 2x1030 kilograms (about 334 million Earths).
And it was probably even bigger in the past, Crowther said in a press release. “Unlike humans, these stars are born heavy and lose weight as they age.” The intense energies at its core cause the star to spray matter in all directions, creating a stellar wind. Crowther’s team guesses that this star has shed about 50 suns-worth of mass in the last million years, and was about 320-suns heavy at birth.
This particular star is about 165,000 light-years away inside the Tarantula Nebula in the Large Magellanic Cloud, which is another galaxy. It’s also about 10 million times brighter than our sun.
Its discovery challenges current theories on star formation, says Doug Hube, a retired astronomer at the University of Alberta. Gravity pulls stars inward, causing fusion, which releases energy that pushes them out. Once you hit 150 suns of mass, the theory says the radiation should overpower gravity, causing the star to blow apart. “Something peculiar is going on with this one,” he says — we’ve either messed up our theory or our measurements.
This is a star to watch, Hube says. “Something of this size can’t have a potential lifetime of more than a couple of million years,” he says, and it’s destined to explode in a supernova, creating a black hole or neutron star.
Crowther’s findings can be found in this week’s Monthly Notices of the Royal Astronomical Society.
If you’ve ever had your liver jump into your throat, you might know how a caterpillar feels when it moves.
Michael Simon and his team at Tufts University discovered an entirely new form of locomotion when they X-rayed a caterpillar: the insect’s guts move forward before its body does.
In most creatures, Simon says in an email, the insides move in sync with the outsides — your gut might bounce a bit due to inertia at high speed, but that’s it. His team was studying hawkmoth caterpillars with X-rays to figure out how they moved.
From the outside, the eight-centimetre, turquoise, striped and spotted caterpillars seemed normal: they’d pull their butts forward, causing a segment-by-segment motion wave to travel up their bodies. But the X-rays showed that the larva’s guts would contract and move forward up to a full segment ahead of the middle of their body as this happened.
“It’s like, if you were trying to climb a ladder, raising your leg resulted in your liver moving up into your throat,” he says, or your stomach moving between your throat and belly as you crawled. The result was a piston-like motion where the caterpillar’s gut and skin moved independently of each other.
Simon’s team isn’t sure why the caterpillar evolved this way, but guesses that this might help it move food back along its digestive track as it crawls forward. They hope this discovery could help engineers design squishy robots that can move through debris or intestines.
This is what science is all about, Simon says: finding the extraordinary in the ordinary. “It’s satisfying in a way to know that there are still amazing discoveries to be made in the most humble of creatures.
His research can be found in this week’s Current Biology.
