TRAPPIST-1: The ‘Habitable’ Star System That’s Probably a Hellhole

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Red dwarfs can be angry little stars (NASA/GSFC/S. Wiessinger)

There are few places that elicit such vivid thoughts of exotic habitable exoplanets than TRAPPIST-1 — a star system located less than 40 light-years from Earth. Alas, according to two recent studies, the planetary system surrounding the tiny red dwarf star may actually be horrible.

For anyone who knows a thing or two about red dwarfs, this may not come as a surprise. Although they are much smaller than our sun, red dwarfs can pack a powerful space weather punch for any world that orbits too close. And, by their nature, any habitable zone surrounding a red dwarf would have to be really compact, a small detail that would bury any “habitable” exoplanet in a terrible onslaught of ultraviolet radiation and a blowtorch of stellar winds. These factors would make the space weather environment around TRAPPIST-1 extreme to say the least.

“The concept of a habitable zone is based on planets being in orbits where liquid water could exist,” said Manasvi Lingam, a Harvard University researcher who led a Center for Astrophysics (CfA) study, published in the International Journal of Astrobiology. “This is only one factor, however, in determining whether a planet is hospitable for life.”

The habitable zone around any star is the distance at which a small rocky world can orbit and receive just the right amount of heating to maintain liquid water on its hypothetical surface. Orbit too close and the water vaporizes; too far and it freezes. As life needs liquid water to evolve, seeking out exoplanets in their star’s habitable zone is a good place to start.

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The peaceful surface of a TRAPPIST-1 habitable zone exoplanet as imagined in this artist’s rendering (NASA/JPL-Caltech)

For the sun-Earth system, we live in the middle of the habitable zone, at a distance of one astronomical unit (1 AU). For a world orbiting a red dwarf like TRAPPIST-1, its orbital distance would be a fraction of that — i.e. three worlds orbit TRAPPIST-1 in the star’s habitable zone at between 2.8% and 4.5% the distance the Earth orbits the sun. This is because red dwarfs are very dim and produce meager heating — for a world to receive the same degree of heating that our planet enjoys, a red dwarf world would need to snuggle up really close to its star.

But just because TRAPPIST-1 is dim, it doesn’t mean it holds back on ultraviolet radiation. And, according to this study, the three “habitable” exoplanets in the TRAPPIST-1 system are likely anything but — they would receive disproportionate quantities of damaging ultraviolet radiation.

“Because of the onslaught by the star’s radiation, our results suggest the atmosphere on planets in the TRAPPIST-1 system would largely be destroyed,” said co-author Avi Loeb, who also works at Harvard. “This would hurt the chances of life forming or persisting.”

Life as we know it needs an atmosphere, so the erosion by UV radiation seems like a significant downer for the possible evolution of complex life.

That’s not the only bad news for our extraterrestrial life dreams around TRAPPIST-1, however. Another study carried out by the CfA and the University of Massachusetts in Lowell (and published in The Astrophysical Journal Letters) found more problems. Like the sun, TRAPPIST-1 generates stellar winds that blast energetic particles into space. As these worlds orbit the star so close, they would be sitting right next to the proverbial nozzle of a stellar blowtorch — models suggest they experience 1,000 to 100,000 times stellar wind pressure than the solar wind exerts on Earth.

And, again, that’s not good news if a planet wants to hold onto its atmosphere.

“The Earth’s magnetic field acts like a shield against the potentially damaging effects of the solar wind,” said Cecilia Garraffo of the CfA and study lead. “If Earth were much closer to the sun and subjected to the onslaught of particles like the TRAPPIST-1 star delivers, our planetary shield would fail pretty quickly.”

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The TRAPPIST-1 exoplanet family. TRAPPIST-1 e, f and g are located in the system’s habitable zone (NASA/JPL-Caltech)

So it looks like TRAPPIST-1 e, f and g really take a pounding from their angry little star, but the researchers point out that it doesn’t mean we should forget red dwarfs as potential life-giving places. It’s just that life would have many more challenges to endure than we do on our comparatively peaceful place in the galaxy.

“We’re definitely not saying people should give up searching for life around red dwarf stars,” said co-author Jeremy Drake, also from CfA. “But our work and the work of our colleagues shows we should also target as many stars as possible that are more like the sun.”

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Pictures from the Red Dwarf Set

Robert Llewellyn (Kryton), Chris Barrie (Rimmer) and Danny John-Jules (The Cat) on the set of Coronation Street (Dave)
Robert Llewellyn (Kryton), Chris Barrie (Rimmer) and Danny John-Jules (The Cat) on the set of Coronation Street (Dave)

Behind the scene pictures of the forthcoming mini-series of the UK space comedy, Red Dwarf, have just been released by the Dave channel. TV comedies are out of the remit of Astroengine, but Red Dwarf will always have a special Astroengine.com VIP Pass. Why? Because it’s awesome.

The pictures above were taken on the Coronation Street set (a UK soap, that I also miss terribly) during the making of the upcoming Easter pair of episodes in April. For me, seeing the cast back together, after nearly a decade apart, is great. I loved each series (although the original four seasons were probably the best in my opinion) and I can’t wait to see how these new episodes turn out.

Smegging fantastic!

For more, check out “They’re (Not) Dead Dave…” – Red Dwarf Returns!

Source: Dave

“They’re (Not) Dead Dave…” – Red Dwarf Returns! (Update)

Chris Barrie (front), Craig Charles, Robert Llewellyn and Danny John-Jules (back), plus computerized Hattie Hayridge (series 3-5)
Chris Barrie (front), Craig Charles, Robert Llewellyn and Danny John-Jules (back), plus computerized Hattie Hayridge (series 3-5)

I don’t usually post stuff about TV shows, but this is HUGE news.

Besides, Red Dwarf was the best sci-fi sitcom, and it still is the BEST SCI-FI SITCOM to grace the TV in the UK ever since the mining spaceship Red Dwarf‘s crew was wiped out by a radiation leak, 3 million years ago. Lister (played by Craig Charles), the last remaining crew member (who was held in suspended animation for the duration), is joined by Rimmer (a hologram of Lister’s despised crew mate, played by Chris Barrie) and a descendent from Lister’s pregnant cat, called… Cat (Danny John-Jules). As the second series progressed, the trio meet the mechanoid Kryten, played by Robert Llewellyn (who, incidentally, I leant this news from via @bobbyllew).

The first show was aired back in 1988 and it continued (for eight seasons) until 1999, and I was addicted to each and every episode. Red Dwarf taught me many things, including:

1) There is no Silicon Heaven.
2) Toasters should not be allowed to talk.
3) There’s no such thing as “brown alert”.
4) The BSc in “Arnold Rimmer BSc” stands for “Bronze Swimming Certificate”.
5) Kryten has some amazing uses for his groin attachment.

So it looks like there will be a returning Easter special of two episodes, plus another two improvised episodes that will be done in front of a live audience! Alas, I’ll be in the US when it airs on the UKTV Channel Dave in April, but I will be sure to get it recorded!

For more info, check out The Guardian coverage of this superb news. Also, check out the Red Dwarf website, it’s just brought back some superb memories.

UPDATE: The Dave Channel Overlord just left a message informing me that Dave will be “revealing an exclusive piece of news from the production set every Wednesday at noon at http://www.joindave.co.uk. Enjoy!” Hopefully this will also be accessible to the continentally-challenged individuals like myself who’ll be missing out on the live airing in the UK… is there any news the new episodes will be online?

Please Dave, polymorph Red Dwarf into joyful smegtastic streaming video… pleeeaase?