Tabby’s Star Dust-Up: There’s No Alien Megastructure

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Sadly, not aliens (NASA/Getty/Ian O’Neill)

If you were hoping that the bizarre transit signals coming from Tabby’s Star were signs of a massive alien construction site, you’d better sit down.

A new study published in Astrophysical Journal Letters today documents a highly-detailed astronomical study of the star, concluding that this stellar oddity is driven by natural phenomena and most likely not caused by an extraterrestrial intelligence.

Since citizen scientists of the exoplanet project Planet Hunters identified the odd transit signal of KIC 8462852 from publicly-available data collected by NASA’s Kepler Space Telescope in 2015, the world has been captivated by what it means. Though KIC 8462852 is a fairly average star as stars go, it exhibited inexplicable dimming events that have never been seen before.

Finding something extraordinary in deep space is often followed by extraordinary explanations, including the possibility that some super-advanced alien civilization is building a “megastructure” around its star. Over time, more rational hypotheses have been ruled out, but how do you rule out aliens fiddling with their star’s brightness? Well, that’s taken a little more time.

Now, thanks to a study headed by astronomer Tabetha Boyajian of Louisiana State University in Baton Rouge, it seems the alien megastructure hypothesis has bitten the dust, literally.

“Dust is most likely the reason why the star’s light appears to dim and brighten,” Boyajian said in a statement. “The new data shows that different colors of light are being blocked at different intensities. Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure.”

As you’d expect, if something solid (like a massive Alien Made™ solar energy collector) were to pass in front of a star, all wavelengths of light would be stopped at the same time. The fact that the dimming events are wavelength (brightness) dependent suggests that whatever is blocking the starlight isn’t a solid mass.

Boyajian, Tabby’s Star’s namesake who led the team that discovered the stellar dimming phenomenon, and her team of over 100 astronomers carried out an unprecedented observation campaign on the star from March 2016 to December 2017 using the Las Cumbres Observatory network. The project was supported by a Kickstarter campaign that raised $100,000 from 1,700 backers.

During the campaign, four distinct dimming events were detected at Tabby’s Star and each were given names by the project’s crowdfunding community. Starting in May 2017, the first two dips were named “Elsie” and “Celeste,” and the second two were named after the lost cities of Scotland’s “Scara Brae” and Cambodia’s “Angkor.”

“They’re ancient; we are watching things that happened more than 1,000 years ago. They’re almost certainly caused by something ordinary, at least on a cosmic scale. And yet that makes them more interesting, not less. But most of all, they’re mysterious.” — from “The First Post-Kepler Brightness Dips of KIC 8462852,” ApJL, 2018

Although the story of the alien megastructure may be coming to an end, this astronomical saga has been an incredible success for science outreach and public engagement with citizen science projects, like Planet Hunters. In this incredible age of astronomy where there’s simply too much data to analyse, scientists are increasingly turning to the public for help in making groundbreaking discoveries.

“If it wasn’t for people with an unbiased look on our universe, this unusual star would have been overlooked,” added Boyajian. “Again, without the public support for this dedicated observing run, we would not have this large amount of data.”

So, the search continues and I, for one, am excited for the next “alien megastructure” mystery …

Read more: The ‘Alien Megastructure’ Star Is Doing Weird Things Again

It’s a Trap: Extraterrestrial Ozone May be Hidden at Exoplanets’ Equators

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ESO/M. KORNMESSER

Fortunately for life on Earth, our planet has an ozone layer. This high-altitude gas performs an invaluable service to biology, acting as a kind of global “sunscreen” that blocks the most damaging forms of ultraviolet radiation. Early in the evolution of terrestrial life, if there were no ozone layer, life would have found it difficult to gain a foothold.

So, in our effort to seek out exoplanets that are suitable for life, future telescopes will seek out so-called “biosignatures” in the atmospheres of alien worlds. Astrobiologists would be excited to find ozone in particular — not only for its biology-friendly, UV-blocking abilities, but also because the molecule’s building blocks (three oxygen atoms) can originate from biological activity on the planet’s surface.

But in a new study published Wednesday (Nov. 29) in the journal Monthly Notices of the Royal Astronomical Society, researchers modeling atmospheric dynamics on tidally-locked “habitable zone” exoplanets have concluded that finding ozone in these exo-atmospheres may be a lot more challenging than we thought.

Red Dwarf Hellholes

Recently, two exoplanets have taken the science news cycle by storm. The first, Proxima b, is touted as the closest temperate exoplanet beyond our solar system. Located a mere 4.22 light-years from Earth, this (presumably) rocky world orbits its star, Proxima Centauri, at just the right distance within the habitable zone. Should this world possess an atmosphere, it would receive just the right amount of energy for any water on its surface to exist in a liquid state. As liquid water is essential for life on Earth, logic dictates that life may be possible there too.

Whether or not Proxima b has the right orbit about its star is academic; there are many other factors to consider before calling it “Earth-like.” For starters, habitable zone exoplanets around red dwarfs will be “tidally locked.” Tidal locking occurs because red dwarf habitable zones are very close to the cool star; so to receive the same amount of heating as our (obviously) habitable Earth, habitable exoplanets around red dwarfs need to cuddle up close. And because they are so close, the same hemisphere will always face the star, while the other hemisphere will always face away. These strange worlds are anything but “Earth-like.”

Also, Proxima Centauri is an angry little star, blasting its locale with regular flares, irradiating its interplanetary space with X-rays, UV and high-energy particles — things that will strip atmospheres from planets and drench planetary surfaces with biology-wrecking radiation. As I’ve previously written, Proxima b is likely a hellhole. And things don’t bode well for that other “habitable” exoplanet TRAPPIST-1d, either.

It’s a Trap

But let’s just say, for astrobiology-sake, that a tidally-locked world orbiting a red dwarf does host an atmosphere and an alien biosphere has managed to evolve despite these stellar challenges. This biosphere is also pretty Earth-like in that oxygen-producing lifeforms are there and the planetary atmosphere has its own ozone layer. As previously mentioned, ozone would be a pretty awesome molecule to find (in conjunction with other biosignatures). But what if no ozone is detected? Well, according to Ludmila Carone, of the Max Planck Institute for Astronomy in Germany, and her team, not finding detecting ozone doesn’t necessarily mean it’s not there, it’s just that the atmospheric dynamics of tidally-locked worlds are very different to Earth’s.

“Absence of traces of ozone in future observations does not have to mean there is no oxygen at all,” said Carone in a statement. “It might be found in different places than on Earth, or it might be very well hidden.”

Earth’s ozone is predominantly produced at the equator where sun-driven chemical reactions occur high in the atmosphere. Atmospheric flows then transport chemicals like ozone toward the poles, giving our planet a global distribution. When carrying out simulations of tidally-locked worlds, however, Carone’s team found that atmospheric flows may operate in reverse, where atmospheric flows travel from the poles to the equator. Therefore, any ozone produced at the equator will become trapped there, greatly reducing our ability to detect it.

“In principle, an exoplanet with an ozone layer that covers only the equatorial region may still be habitable,” added Carone. “Proxima b and TRAPPIST-1d orbit red dwarfs, reddish stars that emit very little harmful UV light to begin with. On the other hand, these stars can be very temperamental, and prone to violent outbursts of harmful radiation including UV.”

So the upshot is, until we have observatories powerful enough to study these hypothetical exoplanetary atmospheres — such as NASA’s James Webb Space Telescope (JWST) or the ESO’s Extremely Large Telescope (ELT) — we won’t know. But modelling the hypothetical atmospheres of these very alien worlds will help us understand what we will, or won’t, see in the not-so-distant future.

“We all knew from the beginning that the hunt for alien life will be a challenge,” said Carone. “As it turns out, we are only just scratching the surface of how difficult it really will be.”

Alien vs. Comet: Is the SETI “Wow!” Signal Dead? (Astroengine Video)

There’s a new hypothesis about what happened on August 15, 1977, and, sadly, it doesn’t involve aliens — just a photobombing comet. I was surprised about the controversy surrounding Antonio Paris’ research into the possibility of comets generating radio signals at 1420MHz and mimicking the famous “Wow!” signal nearly 40 years ago, so I decided to record Astroengine’s second YouTube video on the topic. Enjoy! And remember to subscribe and like, there’s a lot more to come!

Could Alien Spacecraft Propulsion Explain the Cosmic Mystery of Fast Radio Bursts?

It’s an “out there” hypothesis, but radiation from alien spacecraft zooming around space could account for the strange bursts of radio waves coming randomly from the deep cosmos.

M. Weiss/CfA

Powerful bursts of radio waves have been observed at random all over the sky and astronomers are having a hard time figuring out what the heck could be causing them. Many natural phenomena have been put forward as candidates — from massive stellar explosions to neutron star collisions — but none seem to fit the bill. It’s a mystery in its purest sense.

Pulling the alien card will likely raise some eyebrows in some academic circles, but if these so-called fast radio bursts (FRBs for short) end up lacking a satisfactory explanation, according to Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA), an artificial source (e.g. advanced extraterrestrial intelligence) could become the prime suspect.

“Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven’t identified a possible natural source with any confidence,” said Loeb in a statement. “An artificial origin is worth contemplating and checking.”

FRBs are super weird. First detected in 2007, several radio observatories on Earth — including the famous Arecibo Observatory in Puerto Rico and the Parkes Observatory in Australia — have serendipitously detected only a couple of dozen events. And they are powerful; in a fraction of a second, they erupt with as much energy as our sun pumps out in 10,000 years. These are lucky detections as they only occur when the radio dishes just happen to be pointing at the right place at the right time. Astronomers predict there could be thousands of FRB events across the entire sky every single day. There seems to be no pattern, they appear to originate from distant galaxies billions of light-years away and they have no known progenitor.

So far, FRBs have been mainly identified from looking back through historic radio data, but now, the Parkes Observatory has a real-time FRB detection system that will alert astronomers of their detection, allowing rapid follow-up investigations of source regions. This system resulted in a breakthrough last year when astronomers were able to work out that one FRB originated in an old elliptical galaxy some six billion light-years away. This single event helped researchers narrow down FRB sources — as the galaxy is old and exhibits little star formation processes, some production mechanisms could be ruled out (or at least determined to be less likely).

“This is not what we expected,” said Simon Johnston, Head of Astrophysics at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) which manages Parkes, at the time. “It might mean that the FRB resulted from, say, two neutron stars colliding rather than anything to do with recent star birth.”

But say if the source is a little more, well, alien; why would extraterrestrial intelligence(s) be blasting this incredibly powerful radiation into space in the first place?

In their research to be published in Astrophysical Journal Letters, Loeb and co-investigator Manasvi Lingam of Harvard University looked at a form of beamed energy that could be used to propel interstellar probes to the stars. Vast planet-sized solar receivers could collect the required energy and the power collected could be transferred into a laser-like device that is bigger than we can currently imagine. Although the technology required to create such a device is in the realms of science-fiction, according to the researchers’ work, it’s not beyond the realms of physics.

This hypothetical mega-laser could then be used to blast a huge solarsail-like spacecraft across interstellar — perhaps even intergalactic — distances. The photon pressure exerted by this kind of propulsion technique could accelerate spacecraft of a million tons to relativistic speeds. The engineering details of such a device are only known to these advanced hypothetical aliens, however.

Like this… kinda. (Credit: Walt Disney Studios Motion Pictures)

This form of beamed energy would need to be continuously aimed at the departing spacecraft, like a dandelion seed being constantly blown through the air by a steady breeze, to help it accelerate sufficiently to its desired destination — so why would such a technology manifest itself on Earth as a mere radio flash in the sky? Well, to keep the beamed energy on target (i.e. centered on the spacecraft’s sail), it will remain fixed on the spacecraft. But the spacecraft, planet and star will all be moving relative to us, sweeping the beam across the sky, so the beam will only briefly appear in our skies and then disappear as a random FRB. Even if there’s a permanent “beamed energy station” continuously firing spacecraft into deep space, we may only ever see one flash from that location — space is a big place, we’d need to lie directly in the firing line (over millions to billions of light-years away) for us to even glimpse it.

And if these FRBs are originating all over the sky, from many different stars in many different galaxies, it could mean that this beamed propulsion technology is a natural progression for sufficiently advanced civilizations. We could be in the middle of a vast intergalactic transportation network that we can only join when we are sufficiently advanced ourselves to build our own beamed energy station — like an intergalactic bus stop. Mind-bending stuff, right?

Alternatively, FRBs could just be a natural phenomena that our current understanding of the universe cannot explain, but it’s good to investigate all avenues, scientifically.

“Science isn’t a matter of belief, it’s a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge,” concludes Loeb.

And you know what? I couldn’t agree more.

The Day Aliens Invaded… [UPDATE]

UPDATE (Mon. 9:50 a.m. PT): Shocker. NASA refutes Hoover’s claims. Apparently his paper failed peer review for publication in the International Journal of Astrobiology… in 2007! More here: “NASA Refutes Alien Discovery Claim — Discovery News

Original post: On Saturday, a NASA astrobiologist announced his “irrefutable proof” that aliens — the size of bacteria — exist. Using a sophisticated electron microscope, Richard Hoover looked deep into meteorite samples to see complex fossilized microscopic structures that looked suspiciously like bacteria found here on Earth.

Some of the suspect alien microorganisms even resemble cyanobacteria, a basic microorganism that helped make early-Earth hospitable to life by producing oxygen. Cyanobacteria can live in space for extended periods of time; tests on the International Space Station have shown the single-celled specks are hardy little buggers, surviving in a kind of “suspended animation,” sleeping for months (even years) in vacuous, frozen, high-radiation conditions. When brought back to Earth, the critters come back to life.

Needless to say, when Hoover announced this discovery of “alien” microbes, I wasn’t the only one who was thinking panspermia, the hypothetical mechanism where life — in the form of a microbe like cyanobacteria — hops from one planet to the next encased inside meteoroids.

Is this really proof of aliens? Is it evidence for panspermia? Does this mean life on Earth may have been seeded by alien microbes stowing away inside chunks of space rock? Does mankind need to invent an anti(alien)bacterial handwash?! (I’ve watched The Andromeda Strain.)

As mentioned in my Discovery News article on the subject, I’m skeptical about Hoover’s claims. This isn’t because I think Hoover’s work is rubbish (I have yet to finish digesting his lengthy paper), it’s just the way he decided to publish his work. The online Journal of Cosmology isn’t exactly the best place to submit your paper if you want your research to be taken seriously. And why the hell he gave FOX News the “exclusive,” I have no idea.

Sure, Hoover has discovered some odd-looking, alien-looking, bacteria-sized shapes in meteorite samples (he’s even done some interesting chemical analysis on the micro-“fossils”), but he’s going to have to do a far better job at convincing the scientific community that they are extraterrestrials.

Personally, I think these dinky “fossils” are a little too well preserved. Perhaps a far simpler explanation can be found? *cough* Contamination. *cough*

I’d love to know what NASA’s official line is, they seem to be staying remarkably quiet considering one of their employees has just announced the discovery of ET…

Read more: “Has Evidence for Alien Life Been Found?

The Search For Life, What’s the Point?

Another mission, another brave “search for life”…

Is it me, or does virtually every robotic foray into space have some ET-searching component attached? In the case of Mars exploration, every lander and rover’s prime directive is find life, evidence of past life, potential for life or the building blocks of life. Even the very first man-made artefact to land (crash) on the planet, the 1971 Soviet Mars 2 mission, was designed to find organic compounds and… any sign of life.

On writing an article yesterday (“Wasteful” Sample Storage Box Removed from Mars Science Laboratory), I started to think that we might just be trying a little too hard and spending too much money on this endeavour. Perhaps there’s another way for us to work out if we are, indeed, an interplanetary (possibly intergalactic?) oasis, or a component of a biological cosmic zoo…
Continue reading “The Search For Life, What’s the Point?”