How do planets die? They’re murdered, by stars. And one day, billions of years in the future, Earth may suffer the same fate. And right now, astronomers observing a dwarf star eating its planet are getting to see what that would look like.
NASA’s Kepler telescope recently picked up evidence of this crime, and then astronomers on the ground pieced together the rest of the picture. What they’re witnessing is a first for humankind and will help them understand how a white dwarf evolves, what elements are inside a planetary body, and what its atmosphere looks like.
“It’s the first object known to have been born, survived and [be] dying around the host star — which is very cool,” astronomer Francesca Faedi, told Space.com.
This particular planet-eating dwarf is located in the Virgo constellation, about 570 light-years from Earth. The planetary body orbits the star from a distance of about 520,000 miles, which is about twice our distance from the moon.
It all began with a few clues. Via the Kepler telescope, Andrew Vanderburg and his team at the Harvard-Smithsonian Center for Astrophysics observed some planetary pieces in the star’s orbit, Discovery reported. Together, these pieces equaled the mass of the giant asteroid Ceres, which is about the size of Texas. These pieces trailed dust clouds in their orbits, and when they looked closer, they figured out what elements were inside them.
This dust contained magnesium, aluminium, and silicon — the ingredients of a small rocky planet. Since these pieces and their dusty trails surrounded the dwarf, they concluded that it was in the process of eating the planet — ripping it apart and scattering the pieces.
Vanderburg was stunned.
“This is something no human has seen before. We’re watching a solar system get destroyed.”
They also got a clue by looking at its light, which kept dimming and then brightening at intervals. These stars are so small that any passing body can block its light. This time, a planet wasn’t responsible, but several planetary pieces and their dusty trails, which were blocking and changing the starlight.
Stars eating planets isn’t unheard of, of course. The process begins when a main star — our Sun for instance — runs out of fuel. It then transforms into a red giant, sloughing off its outer layers as stellar winds. The core contracts into the small white dwarf, the final form of a star like the Sun (larger stars end via supernova explosions).
The dwarf is pretty rough on nearby planets that manage to survive this violent transformation. It will suck in heavy elements like hydrogen or helium into its center, and if a planet or asteroid comes too close for comfort, the dwarf begins eating it, ripping the body to a million piece, and leaving a cloud in its wake. In the end, the inner solar system will be reduced to a field of dust.
In five billion years, our Sun will turn into a dwarf star and begin eating Earth — probably. It will also engulf Mercury and Venus. By then, however, our fragile home will likely be a shadow of its former self and humankind part of its forgotten history.
Dwarf stars like this one have been studied before but never have scientists been able to actually witness one eating a planet. And they are seeing this eating process unfold as it happens.
Because the planet’s elements are still in orbit, this tells scientists that it was ripped to shreds not too long ago, about the past million years. This suggests that the star is eating right now; the dwarf star will take about another million years to completely devour the planet.
[Image via sciencepics / Shutterstock]