Amongst the far reaches of space, there resides a mysterious alien star whose odd variations in brightness and tendency to dim inexplicably have left scientists baffled for several months.
Astronomers have now come across another
star sporting those same odd light variations, and scientists are
beginning to formulate an explanation. Dubbed EPIC 204278916, this second star is about the size of our Sun in diameter, but with only half its mass.
Discovered by NASA’s Kepler spacecraft
in 2014, a team of astronomers has been keeping a close eye on its dips
in light, finding them even more perplexing than those of KIC 8462852.
The team of astronomers, led by Simone
Scaringi from the Max Planck Institute for Extraterrestrial Physics in
Germany, reported that, over 78.8 days of observations, EPIC 204278916
showed irregular dimming that was up to 65 percent for an estimated 25 consecutive days.
The scientists were baffled. Something
as large as a huge planet orbiting a star can cause it to dim a mere 1
percent. This made them wonder what could possibly be large enough to
cause a dimming of a whopping 65 percent. They came up with three explanations:
1. The first explanation seemed
plausible — the large and irregular light curves are the result of a
massive swarm of comets orbiting the star.
2. The second also seemed plausible —
it’s simply a distorted star that spins so fast, it becomes oblate,
which means it has a larger radius at the equator than it does at the
poles.
3.
The third explanation was a not-so-plausible one — the dimming is
caused by a Dyson Sphere, which is a gigantic sphere made of solar
panels that encircles a star in its entirety. This type of answer is
only found in science fiction stories.
Researchers have pretty much rejected
the distorted star hypothesis, and a study back in January discovered
that, for a star to dim about 20 percent over the course of an entire
century, it would need some 648,000 comets, each roughly 200 kilometers wide, to have transited it.
As for the dust disk, the German team
behind the new EPIC 204278916 observations thinks its massive dips in
the light curve may be the result of a rotating disk of dense gas and
dust that we see edge-on from Earth, as opposed to at an angle like we
usually do. This means it’s both blocking the light from the star at
specific times and doing so at an angle that blocks its own infrared
radiation.
A protoplanetary disk tends
to surround a newly formed star, making this explanation plausible
since EPIC 204278916 appears to be no older than 11 million years —
still relatively young, especially in comparison to our Sun, which is
estimated to be around 4.5 billion years old.
“Many disks are very thin, and we’re
used to seeing them at an angle. However, every once in a while, we’re
bound to be aligned with a star that has its disk oriented edge-on to
us, which means that any infrared radiation would be invisible,”
explained Ethan Siegel. “Young
Stellar Objects (YSOs) are known to have the large flux dips that this
weird star has, and they’ve recently been shown to come in a variety of
inclination angles.”
Siegel believes the hypothesis could
also be applied to KIC 8462852, since many astronomers have argued that
it is also relatively young.
“If this star turns out to be younger
than is generally accepted (which many professional observers think it
is), if it has a disk that happens to be edge-on (so we don’t see the
infrared flux), and if there’s either a warped inner disk or
cometary-like debris, then what we’ve discovered is a new stage in the
early evolution of a class of stars!” said Siegel.
Much more research is needed to figure out if this hypothesis can explain the mystery surrounding KIC 8462852, however.