Alien Megastructure Debunked - Astronomers Finally Explain the Weirdest Star in the Universe
Scientists come up with an explanation for the strange dimming of Tabby's star and it doesn't involve aliens.
Among the most recent promises of extraterrestrial contact, the so-called “alien megastructure” has been one of the most exciting. It’s a star that inexplicably dims and brightens, prompting the Penn State astronomer Jason Wright to famously theorize that the explanation might be that it’s not a star at all but a swarm of alien energy-collecting spacecrafts in a Dyson sphere-like formation. But a new study puts a damper on the conspiracy, with scientists now thinking the fluctuations in light are causes by cosmic dust that passes in front of the star.
In 2014, citizen scientists participating in the Planet Hunters project were sifting through data gathered by the Kepler space telescope and discovered the unusual properties of the star KIC 8462852, which is about 50% bigger than our Sun and is located more than 1,000 light years away. The star later became known as "Tabby’s Star" in honor of the person who did a first proper study of it in 2015 - Louisiana State University astronomer Tabetha Boyajian. What was strange about the star? It dimmed up to 20% at times, raising speculation that something big was passing in front of it at irregular intervals.
The weirdness of the star’s behavior was a catalyst for a crowdfunding campaign on Kickstarter that resulted in $100,000 in donations from 1,700 people who wanted to fund further research. As a result of this public support, Boyajian was able to buy more ground-based telescope time to observe and collect a trove of new data, which point to dust being behind the star’s light effects.
LSU Astronomer Tabetha Boyajian (center) and her students and research staff. (Left to right) Robert Parks, undergraduate student Rory Bentley, Assistant Professor Tabetha Boyajian, PhD candidate Tyler Ellis, undergrad Katie Nugent, Professor Geoff Clayton and graduate student Emily Safron.
The reason scientists think that dust may be the culprit is because the dimming is not completely opaque, as if something is filtering the light. An opaque object would block out both red and blue light in the same way, but it appears the blue light is blocked much more than red when the star dims.
“Dust is most likely the reason why the star’s light appears to dim and brighten,” Boyajian said. “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.”
By observing the star during the period from March 2016 to December 2017, the scientists saw four episodes of dipping starlight. All the updates and findings were constantly shared with the backers via the project’s website “Where’s the Flux?”
Boyajian reiterated the importance of enthusiastic amateur scientists in discovering the star in the first place and then helping fund additional findings.
“If it wasn’t for people with an unbiased look on our universe, this unusual star would have been overlooked,” Boyajian said, adding “I am so appreciative of all of the people who have contributed to this in the past year – the citizen scientists and professional astronomers. It’s quite humbling to have all of these people contributing in various ways to help figure it out.”
Check out Tabetha Boyajian’s TED Talk about the Star:
Dominique Crenn, the only female chef in America with three Michelin stars, joins Big Think Live this Thursday at 1pm ET.
Scientists discover the inner workings of an effect that will lead to a new generation of devices.
- Researchers discover a method of extracting previously unavailable information from superconductors.
- The study builds on a 19th-century discovery by physicist Edward Hall.
- The research promises to lead to a new generation of semiconductor materials and devices.
Credit: Gunawan/Nature magazine
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The images and our best computer models don't agree.
A trio of intriguing galaxy clusters<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yNDQzNDA0OS9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxNTkzNzUyOH0.0IRzkzvKsmPEHV-v1dqM1JIPhgE2W-UHx0COuB0qQnA/img.jpg?width=980" id="d69be" class="rm-shortcode" data-rm-shortcode-id="2d2664d9174369e0a06540cb3a3a9079" data-rm-shortcode-name="rebelmouse-image" />
The three galaxy clusters imaged for the study
Mapping dark matter<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="d904b585c806752f261e1215014691a6"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/fO0jO_a9uLA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>The assumption has been that the greater the lensing effect, the higher the concentration of dark matter.</p><p>As scientists analyzed the clusters' large-scale lensing — the massive arc and elongation visual effects produced by dark matter — they noticed areas of smaller-scale lensing within that larger distortion. The scientists interpret these as concentrations of dark matter within individual galaxies inside the clusters.</p><p>The researchers used spectrographic data from the VLT to determine the mass of these smaller lenses. <a href="https://www.oas.inaf.it/en/user/pietro.bergamini/" target="_blank" rel="noopener noreferrer">Pietro Bergamini</a> of the INAF-Observatory of Astrophysics and Space Science in Bologna, Italy explains, "The speed of the stars gave us an estimate of each individual galaxy's mass, including the amount of dark matter." The leader of the spectrographic aspect of the study was <a href="http://docente.unife.it/docenti-en/piero.rosati1/curriculum?set_language=en" target="_blank">Piero Rosati</a> of the Università degli Studi di Ferrara, Italy who recalls, "the data from Hubble and the VLT provided excellent synergy. We were able to associate the galaxies with each cluster and estimate their distances." </p><p>This work allowed the team to develop a thoroughly calibrated, high-resolution map of dark matter concentrations throughout the three clusters.</p>
But the models say...<p>However, when the researchers compared their map to the concentrations of dark matter computer models predicted for galaxies bearing the same general characteristics, something was <em>way</em> off. Some small-scale areas of the map had 10 times the amount of lensing — and presumably 10 times the amount of dark matter — than the model predicted.</p><p>"The results of these analyses further demonstrate how observations and numerical simulations go hand in hand," notes one team member, <a href="https://nena12276.wixsite.com/elenarasia" target="_blank">Elena Rasia</a> of the INAF-Astronomical Observatory of Trieste, Italy. Another, <a href="http://adlibitum.oats.inaf.it/borgani/" target="_blank" rel="noopener noreferrer">Stefano Borgani</a> of the Università degli Studi di Trieste, Italy, adds that "with advanced cosmological simulations, we can match the quality of observations analyzed in our paper, permitting detailed comparisons like never before."</p><p>"We have done a lot of testing of the data in this study," Meneghetti says, "and we are sure that this mismatch indicates that some physical ingredient is missing either from the simulations or from our understanding of the nature of dark matter." <a href="https://physics.yale.edu/people/priyamvada-natarajan" target="_blank">Priyamvada Natarajan</a> of Yale University in Connecticut agrees: "There's a feature of the real Universe that we are simply not capturing in our current theoretical models."</p><p>Given that any theory in science lasts only until a better one comes along, Natarajan views the discrepancy as an opportunity, saying, "this could signal a gap in our current understanding of the nature of dark matter and its properties, as these exquisite data have permitted us to probe the detailed distribution of dark matter on the smallest scales."</p><p>At this point, it's unclear exactly what the conflict signifies. Do these smaller areas have unexpectedly high concentrations of dark matter? Or can dark matter, under certain currently unknown conditions, produce a tenfold increase in lensing beyond what we've been expecting, breaking the assumption that more lensing means more dark matter?</p><p>Obviously, the scientific community has barely begun to understand this mystery.</p>
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