- Pallab Ghosh
- Science Correspondent, La Palma
Credit, BBC News/Stelios Thoukidides
Collision of neutron stars is an opportunity to see what’s inside them
Astronomers can for the first time detect the collision of dead suns, known as neutron stars, thanks to a powerful new telescope.
Collisions of neutron stars are fundamental to our understanding of the Universe.
They are believed to have created heavy metals that formed stars and planets, including our own, billions of years ago.
Light from collisions is only visible for a few nights, so the telescope needs to be agile to spot them.
Astronomers observed one such collision in 2017, but came across it pretty much by chance.
Built by the British, the Gravitational Wave Transient Optical Observer (GOTO), located above the clouds on the volcanic island of La Palma, Spain, will now systematically track them.
“When really good detection comes along, everyone gets their hands dirty to make the most of it,” says Professor Danny Steeghs of the University of Warwick in England, who is based in La Palma.
“Speed is of the essence. We’re looking for something very short-lived — not long before they disappear.”
Neutron stars are so heavy that a small teaspoon of their material weighs four billion tons.
The telescope allows astronomers, in practice, to see its “inner contents”.
Credit, BBC News/Kevin Church
New telescope looks like a battery of rocket launchers
So you can get a clear view of the sky, the telescope is located on a mountain peak, which houses a dozen instruments of all shapes and sizes, each studying a different phenomenon.
When its twin domes open, they reveal two black batteries of eight cylindrical telescopes bolted together — structures that look more like menacing rocket launchers. Each battery covers the patch of sky above it by rapidly rotating vertically and horizontally.
A neutron star is a dead sun that has collapsed under its immense weight, crushing the atoms that once made it shine. They have such a strong gravity that they are attracted to each other. Sooner or later, they collide and merge.
When this happens, they create a flash of light, and a powerful shock wave ripples through the Universe. It makes everything in the Universe oscillate, including, imperceptibly, the atoms within each of us.
The shock wave, called a gravitational wave, distorts space. And when it is detected on Earth, the new telescope springs into action to find the exact location of the flare.
Credit, BBC News/Stelios Thoukidides
Neutron stars are suns that have collapsed under the weight of their own gravity, crushing the atoms that once made them shine.
The operators’ goal is to locate it within hours, or even minutes, of detecting the gravitational wave.
They take pictures of the sky and then digitally remove the stars, planets and galaxies that were there the night before.
Any point of light that wasn’t there before could be the collision of neutron stars.
This normally takes days and weeks, but should now be done in real time. It’s a big task, performed by means of computer software.
“You would think these explosions are very energetic, very luminous, it should be easy,” says astrophysics professor Joe Lyman.
“But we have to look in a hundred million stars for the only object we are interested in.”
“And we have to do it really fast because the object will disappear in two days.”
Credit, BBC News/Kevin Church
The team works with other astronomers to study the collision in more detail.
Once they identify the collision, they turn to bigger and more powerful telescopes around the world to analyze the collision in much more detail, and at different wavelengths.
This process is “telling us about physics to the extreme,” explains Lyman.
Credit, BBC News/Kevin Church
Telescope is located above the clouds so you can get a clear view of the night sky
The mountain peak brings astronomers a little closer to the stars. With the telescope, they have a new way to explore the cosmos, says Kendall Ackley, instrumentation scientist at GOTO.
According to her, traditional astronomy was all about “getting lucky.” But that is changing.
“Now we are no longer waiting for new discoveries. Instead, we are being told where to find them and discovering, piece by piece, what exists in the Universe.”
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