All_About_Space_-_Issue_94_2020

Investigating Tabby’s Star

With the tantalising suggestion of a

megastructure, astronomers have searched the

stellar object for other technosignatures

itsrepeateddigits– ismore

memorablethanmost.It’s

around 350 lightyearsawayinthe

constellationLibra,andratherthanbeinga single

starit’sa binarysystem,madeupofa Sun-like

G-typestaraccompaniedbya muchsmallerred

dwarfstar.Itslightcurvewasmeasuredbya team

ledbyAndrewVanderburgfromtheUniversityof

TexasatAustin,whosaidofit:“We’veneverseen

anythinglikethisinKepler,andKepler’slookedat

500,000stars.”

Theteamfoundnofewerthan 28 transits

overa three-monthperiodfrom 23 Augustto 20

November2017.Thesearen’tdeepdipslikethose

ofTabby’sStar– they’rethekindthatmightbe

producedbyanordinaryplanetjustslightlylarger

thantheEarth.Thedipsareremarkablyconsistent

insizeandshape,too,suggestingthattheycould

allhavebeenproducedbythesameobject.There’s

a catch,though– thedipsdon’thavetheclockwork

periodicityyou’dexpectfroma planet.Asthe

researchersputit:“Theunusualaspectofthesedips

isthattheyexhibitnoperiodicity,andtheirarrival

Below:
Alessexotic,
butmorelikely
explanationfor
thedimmingis
a swarm
ofcomets

©NASA

©Getty

AutomatedPlanetFinder

Thisisa largeopticaltelescopeattheLickObservatoryinCalifornia

whichisused,amongotherthings,bythe‘BreakthroughListen’

projecttosearchforlasersignalsthatmightemanatefroman

advancedextraterrestrialcivilisation.

Whatthemissiondiscovered

Thetelescopewasusedtolookforpossiblelaseremissionsfromthe

vicinityofTabby’sStarin2018.However,nothingwasfoundthat

appearedtobeofartificialorigin.

Allen Telescope Array

This is an array of 42 radio

telescope dishes in California,

operated by the SETI Institute,

withtheaimofdetectingsignals

fromextraterrestrialcivilisations.

SoonaftertheKeplerresultswere

publishedin2015,itwaspointedat

Ta b b y ’ sS t a r.

Whatthemissiondiscovered

Overa three-weekperiodthe

telescopearraywasfocused

exclusivelyonTabby’sStar.

Itscoureda widerangeof

frequencies,butfailedtodiscover

anyartificialsignals.

The Kepler Space Telescope

Launched by NASA in 2009, Kepler spent almost

ten years measuring light curves of hundreds of

thousands of stars in search of planetary systems. It

discovered some genuinely peculiar light curves, too –

none more so than Tabby’s Star.

What the mission discovered

Kepler found deep dips in the light curve, apparently

caused by periodic obscuration – but close analysis

suggests this is caused by a dust cloud rather than a

large solid object.

The weirdest star