Australian_Science_Illustrated_Issue_52_2017

scienceillustrated.com.au | 57

By Rolf Haugaard Nielsen

I

s the explanation a construction

boom in an alien civilization? Did a star

consume a planet? Or is the confusion

caused by huge groups of comets?

Astronomers are at a loss, when it

comes to the KIC 8462852 star.

Originally discovered in 1890, the star

never really attracted much interest, before

a team of American amateur astronomers

took a closer look at data from NASA’s Kepler

space telescope, which observed the star for

four years. During that period of time, two

major and one series of minor dimmings of

the starlight have occurred at irregular

intervals. This is very unusual and unlike

anything astronomers ever observed.

So, the mysterious star will now be

monitored closely. For 12 months, a global

network of telescopes will keep a constant

eye on the star, measuring the spectrum of

light during the next major dimming. Nobody

knows when it will come, but hopefully, new

measurements can reveal what is blocking out

the light of the star, answering the question

once and for all. Although scientists have

introduced one explanation after the other,

none of them seem to tell the whole truth.

TELESCOPE MISSED DIMMING

The KIC 8462852 star is located in a dwarf

galaxy 1,276 light years from Earth, and for

Astronomers do
not know why the
star's brightness
varies so much, but it
might be due to huge
groups of comets.

many years, its life was an anonymous one.

Not until the Planet Hunters amateur

astronomers took a closer look at the large

quantity of Kepler telescope data, scientists

took an interest in it.

In 2009-2013, the space telescope

studied 150,000 stars to find any orbiting

planets by measuring their brightness. The

subsequent analyses were made by

computers programmed to look for changes

in brightness of a few %, and so, they did not

find the major dimmings. But when the Planet

Hunters scrutinised the Kepler data, the

team discovered that during the four year

observation period, the star's brightness had

been reduced twice, by 16 and 21 %

respectively, and by 0.2-8 % 10 times for

periods of up to several months.

The KIC 8462852 is an ordinary, Sun-like

star, which normally shines stably with the

same brightness for billions of years.

Something large was bound to block out the

light of the star, but the team did not know

STAR

Data from Kepler revealed several

mysterious dimmings.

The Kepler space telescope has kept an

eye on KIC 8462852 for four years,

during which the star's brightness has

fallen twice, by 16 and 21 %, plus

several minor dimmings. This

type of star should be stable.

Something unknown must block

out the light of the star at irregular

intervals. It cannot be other planets, as

they would reduce the starlight no more

than a few % at regular intervals.

Chaotic dimmings

puzzle astronomers

75

80

85

90

95

0 1,000 500 1,500

100

STAR

BRIGHTNESS(%)

NUMBER

OF DAYS

The Kepler telescope has

observed the star for four

years (2009-2013).

NASA

HENNING DALHOFF

STAR'S

BRIGHTNESSNORMAL

BRIGHTNESS

REDUCTION