There’s not one but four celestial zombies near Earth

It’s a bit of a cosmic graveyard near us (Picture: Getty/Metro)

When our sun is on death’s door in five billion years, it will incinerate Earth and collapse, leaving behind a tiny smoldering speck.

And it turns out that not one but four of these dead embers, called a white dwarf, are on our cosmic doorstep, astronomers have told Metro.

Researchers at the University of Warwick and University of Colorado Boulder found these wisps hidden behind small, dim stars called red dwarves.

The results, published in the scientific journal MNRAS, took lead author Mairi O’Brien by surprise, to say the least.

‘There are lots of things in space that are hard to find even when they’re really nearby,’ the research fellow at the University of Warwick says.

Stars – including the sun – are giant balls of gas that burn hydrogen and helium as fuel.

The zombie stars were hiding behind red dwarf stars (Picture: University of Warwick)

Once the star’s fuel tank runs empty, its atmosphere puffs up as it throws other chemicals on the fire instead to stay alight, becoming a red giant.

‘During the red giant phase, the sun will get so big that it might swallow the Earth,’ O’Brien says.

‘If we manage to avoid that though, the Earth could exist as a planet orbiting a tiny white dwarf.

‘The Earth would be freezing cold and the light from the white dwarf would be very faint compared to the sun, so we wouldn’t have bright sunny days like we do now.’

This is why white dwarves are notoriously hard to find. But O’Brien and her colleagues looked at the four systems closely because they noticed the red dwarves wobbled slightly, as if something was dancing around them.

Spotting red dwarves

A white dwarf star is very dim, making it hard to see from Earth (Picture: PA)

Compared to zombie stars, red dwarves are giants, easily shining too bright to see the other smaller stellar body if nearby.

But researchers managed to spot them flickering from afar using ultraviolet telescopes, a type of light we can’t see that stars emit.

Earth’s atmosphere mostly absorbs ultraviolet light – yes, that one used to make invisible ink – so O’Brien used the Hubble Telescope in space.

One system they found 25 light years away, G 203-47, has a red dwarf that rotates every 100 days or so.

Yet it orbits its white dwarf every 14.9 days, as if it’s dragging behind its celestial dance partner.

G 203-47 is now officially the ninth closest white dwarf to the sun, making our local area a bit of a celestial graveyard.

O’Brien estimates that there could be another 10 binary star systems – those with two suns – near us that we haven’t found yet.

This wisp is what our sun will look like one day – though you probably won’t be around to see it (Picture: Shutterstock/Sciencepics)

This could include brown dwarves, failed stars that never ignited with nuclear fusion, which power these celestial engines.

‘These stars are very faint unless you look for them in infrared light, and many of them have gone unnoticed until recently, even though they’re right in front of us,’ O’Brien says.

All these dead and dim stars lurking around the corner could have planets orbiting them, called exoplanets.

While white dwarves are dying, life could actually exist on the planets orbiting them, scientists think, if they’re close enough to the stellar remnants to be kept warm enough for liquid water to form.

‘Hopefully with upcoming missions like PLATO from the European Space Agency,’ O’Brien adds, ‘we will find a planet like the Earth orbiting a star like the sun.’

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