CLOSE
NASA/JPL-Caltech
NASA/JPL-Caltech

Space Dust, Not an Alien Megastructure, Is to Blame for Star's Bizarre Behavior

NASA/JPL-Caltech
NASA/JPL-Caltech

Space is filled with unsolved mysteries, but rarely do they rivet astronomers and sci-fi fans the way KIC 8462852 has. In 2015, researchers announced that the distant star's light had periodically waned over the course of several years (once by as much as 22 percent), prompting some to theorize that a type of power-harnessing "alien megastructure" could be the culprit. This explanation was largely dismissed, but scientists still didn't know what caused the star's bizarre behavior. Now, Space.com reports that space dust is likely responsible for the mysterious phenomenon.

Published in the journal The Astrophysical Journal Letters [PDF], a new study of KIC 8462852's behavior "shows that different colors of light are being blocked at different intensities," said Tabetha Boyajian, an astronomer at Louisiana State University and the study's lead author, in a statement. "Therefore, whatever is passing between us and the star is not opaque, as would be expected from a planet or alien megastructure."

KIC 8462852 sits 1500 light-years away from Earth, and is about 50 percent larger and 1000 degrees hotter than the Sun, according to scientists. It's nicknamed "Tabby's star" after Boyajian, who first observed its unusual flickering pattern in 2011 while perusing data from NASA's Kepler Space Telescope with a team of citizen scientists from the online Planet Hunters group. Boyajian and several of the group's members published a paper in 2015 that detailed KIC 8462852's waning and waxing brightness over the course of four years. The data puzzled scientists around the world.

KIC 8462852's otherwise consistent flux was interrupted by sporadic—and substantial—dips in light. Planets can cross in front of distant stars and occlude their light, but even transiting Jupiter-sized planets typically cause a dip of less than 1 percent. In KIC 8462852's case, the difference was up to 22 percent. Further adding to scientists' confusion, KIC 8462852 is an older star that isn't surrounded by the dust and debris from its formation, which can obscure a star's shine.

Theories for the star's behavior ranged from telescope malfunctions to comet fragments moving in an elliptical orbit around the star. Another hypothesis was that a dusty debris disk could be enveloping a black hole located between KIC 8462852 and Earth, National Geographic reports.

Meanwhile, Penn State astronomer Jason Wright hypothesized that alien megastructures, otherwise known as Dyson Spheres, could be harvesting energy from KIC 8462852. (This idea was swiftly debunked.)

To find some answers, Boyajian and colleagues performed follow-up research from March 2016 to December 2017 that was funded through a Kickstarter campaign that raised more than $100,000. Using ground telescopes provided by Las Cumbres Observatory in Goleta, California (and numerous volunteer telescopes around the world), they noted four additional instances in which KIC 8462852 dimmed for stretches of time ranging from days to weeks, according to Gizmodo. (Kickstarter supporters even got to name these instances.)

So far, real-time data from this new study suggests that space dust (perhaps the fragments of a recently destroyed planet or moon) is the likely answer for KIC 8462852's unusual flickering. But no conclusive results have been reached quite yet. For now, the star will continue to stymie scientists. At least they can finally eliminate the phrase "alien megastructure" from their vocabularies.

[h/t Space.com]

nextArticle.image_alt|e
iStock
arrow
Space
Mysterious 'Hypatia Stone' Is Like Nothing Else in Our Solar System
iStock
iStock

In 1996, Egyptian geologist Aly Barakat discovered a tiny, one-ounce stone in the eastern Sahara. Ever since, scientists have been trying to figure out where exactly the mysterious pebble originated. As Popular Mechanics reports, it probably wasn't anywhere near Earth. A new study in Geochimica et Cosmochimica Acta finds that the micro-compounds in the rock don't match anything we've ever found in our solar system.

Scientists have known for several years that the fragment, known as the Hypatia stone, was extraterrestrial in origin. But this new study finds that it's even weirder than we thought. Led by University of Johannesburg geologists, the research team performed mineral analyses on the microdiamond-studded rock that showed that it is made of matter that predates the existence of our Sun or any of the planets in the solar system. And, its chemical composition doesn't resemble anything we've found on Earth or in comets or meteorites we have studied.

Lead researcher Jan Kramers told Popular Mechanics that the rock was likely created in the early solar nebula, a giant cloud of homogenous interstellar dust from which the Sun and its planets formed. While some of the basic materials in the pebble are found on Earth—carbon, aluminum, iron, silicon—they exist in wildly different ratios than materials we've seen before. Researchers believe the rock's microscopic diamonds were created by the shock of the impact with Earth's atmosphere or crust.

"When Hypatia was first found to be extraterrestrial, it was a sensation, but these latest results are opening up even bigger questions about its origins," as study co-author Marco Andreoli said in a press release.

The study suggests the early solar nebula may not have been as homogenous as we thought. "If Hypatia itself is not presolar, [some of its chemical] features indicate that the solar nebula wasn't the same kind of dust everywhere—which starts tugging at the generally accepted view of the formation of our solar system," Kramer said.

The researchers plan to further probe the rock's origins, hopefully solving some of the puzzles this study has presented.

[h/t Popular Mechanics]

nextArticle.image_alt|e
NASA
arrow
science
The Ozone Layer Is Healing, Thanks to an International Ban on Harmful Man-Made Chemicals
NASA
NASA

The ozone layer is on the mend, thanks to a decrease in human-produced chemicals called chlorofluorocarbons, or CFCs, in the atmosphere. Using data from NASA's Aura satellite, scientists were able to measure the chemical composition of the thinned gas layer above the Antarctic and found about 20 percent less ozone depletion than there was in 2005. They published their findings on January 4 in the journal Geophysical Research Letters.

In 1985, UK scientists published a landmark study in the journal Nature announcing their discovery of an annually recurring hole in the ozone layer above Antarctica. (Each September, as the Southern Hemisphere's winter arrives, the Sun's UV rays trigger a reaction between the ozone and chemical elements from CFCs, chlorine and bromine, which destroys the ozone molecules.) The finding led to the Montreal Protocol in 1987, an international treaty that gradually banned the production and use of CFCs in refrigerants, aerosol sprays, solvents, and air conditioners.

In July 2016, Antarctic researchers published a study in the journal Science reporting that the ozone layer appeared to be healing (although it wasn't projected to completely patch up for decades). They tracked this progress by monitoring the Antarctic ozone hole's area, height, and chemical profile. Still, they didn't know whether this progress could be attributed to the Montreal Protocol's mandate.

NASA itself has used Aura to monitor the hole since the mid-2000s. After analyzing data produced by the Microwave Limb Sounder, a satellite instrument aboard Aura that measures trace gases, the space agency has confirmed that the CFC ban has led to the big decrease in ozone depletion during the Antarctic winter.

By winter, ozone-busting chlorine compounds have converted into hydrochloric acid, a process that occurs after it's destroyed ozone particles and reacts with methane. "By around mid-October, all the chlorine compounds are conveniently converted into one gas, so by measuring hydrochloric acid, we have a good measurement of the total chlorine," researcher Susan Strahan said in a NASA statement. Scientists compared these hydrochloric acid levels with nitrous oxide, which is similar in nature to CFCs but isn't diminishing in the atmosphere.

Their study is billed as "the first to use measurements of the chemical composition inside the ozone hole to confirm that not only is ozone depletion decreasing, but that the decrease is caused by the decline in CFCs," according to NASA. But while these initial results are promising, scientists say that the ozone layer's full recovery is still a long way off.

"As far as the ozone hole being gone, we're looking at 2060 or 2080,” study co-author Anne Douglass said. “And even then there might still be a small hole."

SECTIONS

arrow
LIVE SMARTER