Astronomi

Ville det at blive kastet ud af Mælkevejsgalaksen have nogen væsentlig indvirkning på livet på Jorden?

Ville det at blive kastet ud af Mælkevejsgalaksen have nogen væsentlig indvirkning på livet på Jorden?


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Jeg læste om den forestående kollision mellem vores galakse og Andromeda-galaksen og lærte, at der er en lille mulighed for, at vores solsystem kunne blive kastet ud under kollisionen.

Hvis vi antager, at kredsløb i vores solsystem forbliver uændrede (det skubbes ud som en helhed), ville flydende i det intergalaktiske rum medføre væsentlige ændringer i levevilkårene på jorden?


Jeg kan tænke på to måder, det er til gavn for livet.

  • Mindre chance for, at en stjerne, der går forbi, forstyrrer vores Oort Cloud og sender dødbringende kometer, der styrter ned på jorden.
  • Mindre chance for nærliggende supernova ødelægger vores ozonlag.

På den anden side, hvis vores solsystem passerer nær en relativistisk stråle, der stammer fra det centrale sorte hul i en galakse, vil Jorden blive ramt af partikler med høj hastighed, der vil forstyrre magnetosfæren og ozonlaget. Bestemt ikke godt for noget liv på Jorden på det tidspunkt.

At blive skubbet ud af galaksen betyder også, at der er mindre chance for, at fremtidige mennesker udforsker galaksen ved at hoppe til nærliggende stjerner. Vi ville kun have vores solsystem til at udforske og kolonisere. Der ville ikke være et andet stjernesystem inden for hundrede tusind lysår.


Solsystemet, der bevæger sig gennem det intergalaktiske rum, ville ikke have nogen indvirkning på livet. For at solen kan skubbes ud af galaksen, ville det imidlertid være nødvendigt med et meget tæt møde med et stjernemæssigt objekt. Det ville sandsynligvis have en enorm negativ indvirkning på livet på jorden, i det mindste forstyrre mange genstande i Oort Cloud i den indre solsystem. I den anden ende af spektret kunne jordens bane ændres væsentligt, eller jorden kunne endda kastes ud fra solsystemet afhængigt af geometrien på mødet.


10 fakta om Andromeda - Den nærmeste galakse til mælkevejen

Andromeda-galaksen er en spiralgalakse, der ligger ca. 2,5 millioner lysår fra jorden. Denne galakse er den nærmeste større g.

Andromeda-galaksen er en spiralgalakse, der ligger ca. 2,5 millioner lysår fra jorden. Denne galakse er den nærmeste større galakse til Mælkevejen. Dette navn stammer fra det område af himlen, hvor det vises, dvs. konstellationen af ​​Andromeda, som blev opkaldt efter den mytologiske prinsesse Andromeda.

Andromeda var ifølge den græske mytologi datter af Cepheus og Cassiopeia, kongen og dronningen af ​​det nordafrikanske rige Aethiopia. Hun har været meget populær inden for kunst siden klassisk tid.

Andromedagalaksen er også kendt som Messier 31, M31 og NGC 224. I ældre tekster er den også blevet omtalt som den store Andromedatåge.

1. Andromeda indeholder to gange antallet af stjerner end mælkevejen

Der er en billion billioner stjerner i Andromeda. Dette er dobbelt så mange stjerner, der er estimeret i Mælkevejen (200-400 milliarder). Disse observationer blev foretaget af Spitzer-rumteleskopet i 2006. Desuden anslås massen af ​​Andromeda-galaksen til at være 1,5 × 10 12 solmasser, mens Mælkevejen har 8,5 × 10 11 solmasser ifølge estimaterne. (Solmasse (M) er standard måleenhed i astronomi for massen af ​​stjerner, klynger og galakser. Det tager ikke hensyn til mørkt stof.)

2. Det blev engang kategoriseret som stjernetåge

Før de sande fakta om universet blev realiseret, blev det, der vides at være kanten af ​​Milky Galaxy i dag, anset for at være kanten af ​​rummet. Andromeda-galaksen blev betragtet som en simpel samling af stjerner og kosmiske støvskyer. Det blev oprindeligt kaldt den store Andromedatåge. I 1864 bemærkede William Huggins, at Andromeda-spektret adskiller sig fra gasformet tåge. Dens spektre viser et kontinuum af frekvenser, der er overlejret med mørke absorptionslinjer, som hjælper med at identificere den kemiske sammensætning af et objekt.

3. Dusinvis af sorte huller ligger her

I centrum af M31 er der 26 kendte sorte huller. Nogle flere er blevet udvalgt af Chandra X-ray Observatory. Der er også et massivt sort hul i midten ligesom Mælkevejen. Der er mulighed for, at to andre huller muligvis kredser som binære og har en tilnærmelsesvis masse på 140 millioner gange den for Solen.

4. På vej til at kollidere med mælkevejen

Når det meste af universet accelererer væk fra vores galakse, nærmer Andromeda-galaksen sig mod Mælkevejen med en hastighed på 100 kilometer i sekundet. Det betyder, at omkring 4,5 milliarder år kolliderer Andromeda-galaksen med Mælkevejen. Der vil være en galaktisk smash-up mellem de to galakser.

Årsagen til denne direkte kollision er den tangentielle hastighed i Andromeda-galaksen, som er relativt meget mindre end den nærmer hastighed. Det sandsynlige resultat af denne kollision vil være en fusion af begge galakser for at danne en kæmpe elliptisk galakse eller endda en stor diskgalakse. Virkningen af ​​denne kollision på jorden og solsystemet er endnu ikke kendt. Der er også et minuts chance for, at solsystemet udstødes fra Mælkevejen eller slutter sig til Andromeda-galaksen inden kollisionen.

5. Amatørobservation

Andromeda Galaxy kan ses med det blotte øje. Selv med en vis lysforurening er galaksen lys nok til at blive set uden nogen enhed. Efterår er den bedste sæson for at se galaksen. På den nordlige halvkugle om natten, når galaksen når zenit fra midten af ​​højderne, kan de være tydeligt synlige i næsten hele natten.

Fra den sydlige halvkugle er det forårssæsonen for den bedste synlighed. Ved hjælp af kikkert kan der også ses nogle større strukturer og de to lyseste satellitgalakser, M32 og M110. Amatørteleskop kan også afsløre Andromedas disk, NGC 206 (den store stjernesky), mørke støvbaner og nogle lyseste kuglehobe.

6. Største galakse i den lokale gruppe

Andromeda Galaxy er den største galakse i den lokale gruppe. Lokal gruppe er en galakse gruppe, der består af mere end 54 galakser. Mælkevejen er også en del af denne gruppe. Den lokale gruppe dækker en diameter på 10 megalight-år. Tyngdepunktet for Local Group ligger et sted mellem Mælkevejen og Andromedagalaksen. De tre største medlemmer af denne gruppe (i faldende rækkefølge) er Andromeda Galaxy, Mælkevejen og Triangulum Galaxy.

7. Satellitter

Andromeda-galaksen består af satellitgalakser ligesom Mælkevejen. Der er 14 kendte dværggalakser, og de bedst kendte og mest observerede satellitgalakser er M32 og M110. M32 gennemgik et tæt møde med M31 tidligere ifølge de nuværende beviser. Forskere vurderer også, at M32 muligvis har været en større galakse, når den fik sin stjerneskive fjernet af M31. Dette førte til en kraftig stigning i dannelsen af ​​stjerner i kerneområdet, som varede indtil relativt nylig.

M110 havde også interageret med Andromeda Galaxy. Astronomer fandt en strøm af metalrige stjerner i Andromedas halo, som syntes at være fjernet fra disse satellitgalakser. M110 indeholder også en støvet bane, der indikerer en nylig eller igangværende stjernedannelse.

2006 bragte endnu en opdagelse, at ni satellitgalakser, der ligger på et plan, der skærer kernen i Andromeda-galaksen, ikke er arrangeret tilfældigt som modsat forventningen. Dette kan antyde, at satellitterne har en fælles tidevandsoprindelse.

8. Første Supernova, der blev opdaget uden for Mælkevejen

Supernova er en stjerneksplosion, der udstråler lige så meget energi som solen eller enhver almindelig stjerne. Det får hele galaksen til at skinne. S Andromedae var den første supernova, der blev opdaget uden for Mælkevejen i 1885. Det er den eneste supernova, der nogensinde er registreret i den galakse.

Det blev observeret den 20. august 1885 ved Dorpat Observatory i Estland af Albrecht Hartwig. Mellem 17. og 20. august nåede supernovaen en styrke på seks, men den falmede til seksten i februar 1890. I den periode blev Andromeda kun betragtet som et nærliggende objekt, så det blev anset for at være en uafhængig begivenhed og meget mindre lysende. Det blev således navngivet som Nova 1885.

9. Bright Center In The Galaxy

Ved hjælp af Hubble-rumteleskopet i 2005 opdagede astronomer, at centrum for Andromeda Galaxy består af gamle røde stjerner i en elliptisk ring og mindre og lysere unge blå stjerner i en tættere disk. Dette var omkring 200 millioner år gammelt. De omgav det super-massive sorte hul placeret i centrum af galaksen, der målte 140 millioner solmasser.

10. Andromeda har dobbeltkerne

Andromeda eller M31 er kendt for sin tætte og kompakte stjerneklynge i midten. Når man ser det med et større teleskop, er der et visuelt indtryk af en stjerne indlejret i den mere diffuse omgivende udbulning. Den indre kerne af Andromeda Galaxy blev afbildet med Hubble-rumteleskopet i 1991. Den består af to koncentrationer adskilt af 1,5 parsec.

Den lysere, som er forskudt fra centrum af galaksen, betegnes som P1, mens den lysere, P2 er i det sande centrum af galaksen og består af et sort hul, der målte 3–5 × 10 7 M i 1993 og 1.1-2.3 × 10 8 M i 2005.


Galaxy-fusioner kan begrænse stjernedannelse

Denne kunstners indtryk af ID2299 viser galaksen, produktet af en galaktisk kollision, og noget af dens gas skubbes ud af en "tidevandshale" som et resultat af fusionen. Nye observationer foretaget med ALMA, hvor ESO er partner, har fanget de tidlige stadier af denne udstødning, før gassen nåede de meget store skalaer, der er afbildet i denne kunstners indtryk. Kredit: ESO / M. Kornmesser

Astronomer har set ni milliarder år i fortiden for at finde beviser for, at galakse-fusioner i det tidlige univers kunne lukke stjernedannelsen og påvirke galakse vækst.

Ny forskning ledet af Durham University, UK, den franske alternative energi- og atomenergikommission (CEA) -Saclay og University of Paris-Saclay, viser at en enorm mængde stjernedannende gas blev skubbet ud i det intergalaktiske medium ved at komme sammen af to galakser.

Forskerne siger, at denne begivenhed sammen med en stor mængde stjernedannelse i galaksens nukleare regioner til sidst ville fratage den fusionerede galakse - kaldet ID2299 - brændstof til nye stjerner. Dette ville stoppe stjernedannelsen i flere hundrede millioner år og effektivt standse galaksenes udvikling.

Astronomer observerer mange massive, døde galakser indeholdende meget gamle stjerner i det nærliggende univers og ved ikke nøjagtigt, hvordan disse galakser er dannet.

Simuleringer antyder, at vind, der genereres af aktive sorte huller, når de fodrer, eller dem, der er skabt af intens stjernedannelse, er ansvarlige for sådanne dødsfald ved at uddrive gassen fra galakser.

Nu tilbyder den Durham-ledede undersøgelse galakse-fusioner som en anden måde at lukke stjernedannelse på og ændre galaksvækst.

Observationsmæssige træk ved vind og "tidevandshal" forårsaget af gravitationsinteraktionen mellem galakser i sådanne fusioner kan være meget ens, så forskerne antyder, at nogle tidligere resultater, hvor galaktiske vinde er blevet set som årsagen til at stoppe stjernedannelse, muligvis skal genoprettes -evalueret.

En simuleret kollision mellem to gasrige galakser. En del af gassen skubbes ud i store haler, og når galakserne kommer tættere, smelter de sammen og danner et enkelt system. Kredit: Jeremy Fensch, et al

Resultaterne er offentliggjort i tidsskriftet Naturastronomi.

Hovedforfatter Dr. Annagrazia Puglisi, i Durham University's Center for Extragalactic Astronomy, sagde: "Vi ved endnu ikke, hvad de nøjagtige processer ligger bag frakoblingen af ​​stjernedannelse i massive galakser.

"Feedbackdrevne vinde fra stjernedannelse eller aktive sorte huller menes at være hovedansvarlige for at uddrive gassen og slukke væksten af ​​massive galakser.

"Vores forskning giver overbevisende dokumentation for, at gassen, der kastes fra ID2299, sandsynligvis er blevet kastet tidevandsud på grund af fusionen mellem to gasrige spiralgalakser. Gravitationsinteraktionen mellem to galakser kan således give tilstrækkelig vinkelmoment til at sparke en del af gassen ud ind i galakseomgivelserne.

"Dette antyder, at fusioner også er i stand til at ændre den fremtidige udvikling af en galakse ved at begrænse dens evne til at danne stjerner i millioner af år og fortjener mere efterforskning, når man tænker på de faktorer, der begrænser galaksvæksten."

På grund af den tid, det tager lyset fra ID2299 at nå jorden, var forskerne i stand til at se galaksen, som den ville have vist sig for ni milliarder år siden, da den var i de sene faser af sin fusion.

Dette er en tid, hvor universet kun var 4,5 milliarder år gammelt og var i sin mest aktive "unge voksne" fase sammenlignet med et menneskeliv.

Kort over den kolde molekylære gas fra galaksen ID2299 taget ved hjælp af European Southern Observatory's Atacama Large Millimeter Array (ALMA) teleskop. Kredit: A Puglisi et al

Ved hjælp af European Southern Observatory's Atacama Large Millimeter Array (ALMA) teleskop i det nordlige Chile så forskerne, at det udskød ca. halvdelen af ​​dets samlede gasreservoir i galaksen.

Forskere var i stand til at udelukke stjernedannelse og galaksens aktive sorte hul som årsag til denne udkastning ved at sammenligne deres målinger med tidligere undersøgelser og simuleringer og ved at måle de fysiske egenskaber af den undslippede gas.

Den hastighed, hvormed gassen udvises fra ID2299, er for høj til at være forårsaget af den energi, der er skabt af et sort hul eller stjernebryd som set i tidligere undersøgelser, mens simuleringer antyder, at ingen sorte huller kan sparke ud så meget kold gas fra en galakse.

Excitationen af ​​den undslippede gas er heller ikke kompatibel med en vind genereret af et sort hul eller fødslen af ​​nye stjerner.

Medforfatter Dr. Emanuele Daddi fra CEA-Saclay sagde: "Denne galakse er vidne til en virkelig ekstrem begivenhed.

"Det er sandsynligvis fanget i en vigtig fysisk fase for galakseudvikling, der finder sted inden for et relativt kort tidsvindue. Vi var nødt til at se på over 100 galakser med ALMA for at finde det."

Kollega medforfatter Dr. Jeremy Fensch fra Centre de Recherche Astrophysique de Lyon tilføjede: "At studere denne enkelt sag afslørede muligheden for, at denne type begivenhed overhovedet ikke var usædvanlig, og at mange galakser led af denne 'gravitationelle gasfjernelse ', herunder fejlagtede fortidens observationer.

"Dette kan have enorme konsekvenser for vores forståelse af, hvad der faktisk former galaksernes udvikling."


Skyttens dværggalakse kolliderer med Mælkevejen

Se ikke nu, men vores galakse bliver invaderet af Skytten Dværg. Endnu værre, vores Mælkevej er på kollisionskurs med Andromeda-galaksen, og vi kan ikke gøre noget ved det.

Der er ikke meget grund til panik - vores sammenbrud med Andromeda skyldes ikke i yderligere fire eller fem milliarder år. Og mens Skytten Dværg allerede er her, ser det ud til at have overraskende ringe indflydelse.

Delegater blev fortalt i går om kolliderende galakser. Disse lyder måske som katastrofale begivenheder, og store ting kan og smadrer ind i hinanden, men de fleste galakser har meget åbent rum, og individuelle stjerner har en tendens til at glide forbi hinanden.

"Du kunne sove igennem det hele," foreslog dr. Mark Dickinson fra Johns Hopkins University og Space Telescope Science Institute. "Beviset ser ud til at fusionsgraden var højere tidligt i universets historie end nu."

Faktisk er vi allerede i kollision med en lille galakse, Skytten Dværg. Med sine titusinder af millioner af stjerner er den 10.000 gange mindre end vores Mælkevej. Dr. Rosemary Wyse, også fra Johns Hopkins, forklarede, at dværgen kredser gennem vores galakse en gang hvert milliard år eller deromkring og i øjeblikket er indlejret nær "bulen" i midten af ​​Mælkevejen.

"Skyttens dværg interagerer allerede stærkt med Mælkevejen," sagde hun. Dens tilstedeværelse blev kun opdaget ved et uheld i 1994, så det kan ikke være så stort. Sammenstødende galakser har dog tydeligt vækket astronomer, og de bruger nye jordteleskoper og Hubble-rumteleskopet til at scanne himlen.

"Du er nødt til at forstå, hvad der sker, når galakser kolliderer, hvis du vil forstå, hvordan galakser fungerer," sagde dr. Bradley Whitmore fra Space Telescope Institute. Han søger efter den "fossile optegnelse" af tidligere smadre for at vurdere, hvad der vil ske, når Mælkevejen gør sit head-to-head med Andromeda.

"Vi behøver ikke bekymre os om, at stjerner rammer hinanden," foreslog dr. Chris Mihos hjælpsomt, men tilføjede alle de samme, "Vi kan blive udvist fra galaksen i en tidevandshale." Dette er de fortællende stråler af materiale, der er spyddet ud, der viser, når to galakser har hærdet det.

At blive skubbet ud i kosmos er måske ikke sådan en dårlig ting, mener han. Vi bor i udkanten af ​​Mælkevejen, langt væk fra byens centrum. Ting har tendens til at blive varme - og farlige - i midten under kollisioner med ny stjernedannelse og en nyindspilning af det gamle. Gudskelov for forstæderne.


Hotspots i en aktiv galaktisk kerne

Et billede taget ved radiobølgelængder af de dramatiske stråler af ladede partikler, der skubbes ud fra kernen i galaksen Cygnus-A. Nyligt opnåede radiobilleder var i stand til at løse hotspots i jetflyene på de steder, hvor de påvirker det omgivende medium. Den konventionelle tænkning er, at størstedelen af ​​strålingen i sådanne hotspots produceres af stød, men de nye resultater viste, at nogle andre processer, måske absorption, skal være involveret. Kredit: NRAO / AU

Kernen i en såkaldt "aktiv" galakse indeholder et massivt sort hul, der kraftigt akkreterer materiale. Som et resultat skubber kernen ofte ud bipolære stråler af hurtigt bevægelige ladede partikler, der stråler stærkt ved mange bølgelængder, især radiobølgelængder. Aktive galakser viser en række dramatisk forskellige egenskaber, og de, der er lyse i radioen, kan stråle så meget som en billion solstråler fra lysstråling ud i rummet ved disse bølgelængder.

Den intense emission opstår fra det sorte huls varme miljø, fordi elektroner, der bevæger sig tæt på lysets hastighed i et miljø med stærke magnetfelter, udstråler i radioen. De rettede partikelstråler kolliderer til sidst med det omgivende medium og omdanner meget af deres bulk-bevægelsesenergi til stød. Punktene for afslutning i jetstrømmen ses som meget hot spots, lyse og kompakte strukturer. Hotspots kan vende strømmen tilbage til det sorte hul og dermed generere yderligere turbulens og tilfældige bevægelser. Den karakteristiske temperatur på et hot spot (eller mere præcist, den spektrale afhængighed af lysstyrken versus bølgelængde) afslører arten af ​​de fysiske processer på arbejdspladsen. De fleste kendte aktive radiogalakser har hotspots, hvis spektrale afhængighed stemmer godt overens med ideen om afslutningschok og omvendte strømme, men nogle meget lysende radiogalakser stemmer ikke overens.

Radiogalaksen Cygnus A er det nærmeste og mest kraftfulde eksempel på en dobbeltradiogalakse og er som sådan en arketype af denne klasse. Det er også et af de første genstande, der blev opdaget, hvis hotspots ikke syntes at være i overensstemmelse med det konventionelle billede, og i årtier har astronomer diskuteret de mulige årsager. Den begrænsede evne for langbølgelængde (lavfrekvente) radioteleskoper til at løse de små størrelser af hotspots var en komplicerende faktor. CfA-astronomer Reinout van Weeren og Gianni Bernardi (nu hos SKA Sydafrika) var en del af et stort team, der brugte radiofrekvent teleskop med lav frekvens ("LOFAR") til at opnå billeder med høj rumlig opløsning af hotspots i Cygnus A. Deres resultater giver det første direkte bevis for, at den tidligere udledte spektrale formforskel er reel. Forskerne præsenterer en detaljeret analyse i et særskilt papir, men i dette papir indikerer de grundlæggende resultater, at en anden proces udover chokaktivitet skal være involveret.


Gamle sorte hul hastigheder gennem galaksen

Astronomer, der bruger National Science Foundation & VLBA-radioteleskopet (Very Long Baseline Array), har fundet et gammelt sort hul, der kører gennem solens galaktiske kvarter og fortærer en lille ledsagerstjerne, når parret bevæger sig i en excentrisk bane, der løber til de ydre strækninger af vores Mælkevejsgalakse. Forskerne mener, at det sorte hul er en rest af en massiv stjerne, der levede sit korte liv for milliarder af år siden og senere blev gravitationelt sparket fra sin hjemmestjerneklynge for at vandre Galaxy med sin ledsager.

& # 8220Denne opdagelse er det første skridt mod at udfylde et manglende kapitel i historien om vores galakse, & # 8221 sagde Felix Mirabel, en astrofysiker ved Institute for Astronomy and Space Physics of Argentina og French Atomic Energy Commission. & # 8220Vi tror, ​​at hundreder af tusinder af meget massive stjerner dannedes tidligt i historien om vores Galaxy, men dette er det første sorte hulsrester af en af ​​de enorme urstjerner, som vi ikke har fundet. & # 8221

& # 8220Dette er også første gang, at et sort hul og dens bevægelse gennem rummet måles, tilføjede Mirabel. Et sort hul er en tæt massekoncentration med en tyngdekraft så stærk, at ikke engang lys kan undslippe den. Forskningen rapporteres i 13. september-udgaven af ​​det videnskabelige tidsskrift Natur.

Objektet hedder XTE J1118 + 480 og blev opdaget af Rossi X-Ray-satellitten den 29. marts 2000. Senere observationer med optiske og radioteleskoper viste, at det er omkring 6.000 lysår fra Jorden, og at det er en & # 8220microquasar & # 8221, hvor materiale, der suges af det sorte hul fra sin ledsagerstjerne, danner en varm, roterende disk, der spytter ud & # 8220jets & # 8221 af subatomære partikler, der udsender radiobølger.

De fleste af stjernerne i vores Mælkevejsgalakse er inden for en tynd disk, kaldet Galaxy-planet. Men der er også kuglehobe, hver indeholder hundreder af tusinder af de ældste stjerner i Galaxy, der kredser om Galaxy 's centrum i stier, der fører dem langt fra Galaxy' s plan. XTE J1118 + 480 kredser om Galaxy 's centrum på en sti svarende til de kuglehobers klynger og bevæger sig med 145 kilometer i sekundet (90 miles i sekundet) i forhold til Jorden.

Hvordan kom det ind i en sådan bane? & # 8220Der er to muligheder: enten dannede det sig i galaksenes plan og blev på en eller anden måde sparket ud af flyet, eller det dannedes i en kugleformet klynge og blev sparket ud af klyngen, & # 8221 sagde Vivek Dhawan, en astronom ved National Radio Astronomy Observatory (NRAO) i Socorro, New Mexico.

En massiv stjerne slutter sit liv ved at eksplodere som en supernova og efterlader enten en neutronstjerne eller et sort hul som en rest. Nogle neutronstjerner viser hurtig bevægelse, menes at være resultatet af et sidelæns & # 8220kick & # 8221 under supernovaeksplosionen. & # 8220Dette sorte hul har meget mere masse & # 8212 omkring syv gange massen af ​​vores sol & # 8212 end nogen neutronstjer, & # 8221 sagde Dhawan. & # 8220For at accelerere den til sin nuværende hastighed ville det kræve et spark fra supernovaen, som vi anser for usandsynlig, tilføjede Dhawan.

& # 8220Vi mener, at det er mere sandsynligt, at det blev skubbet ud fra den kuglehob, "sagde Dhawan. Simuleringer af tyngdekraftens interaktioner i kuglehobe har vist, at de sorte huller som følge af sammenbruddet af de mest massive stjerner i sidste ende skal kastes ud af klyngen.

& # 8220Stjernen, der gik forud for dette sorte hul, dannedes sandsynligvis i en kugleformet klynge, selv før vores Galaxy-disk blev dannet, sagde Mirabel. & # 8220Hvad vi laver her er det astronomiske ækvivalent med arkæologi, idet vi ser spor af den intense udbrud af stjernedannelse, der fandt sted i et tidligt stadium af vores Galaxy's udvikling. & # 8221

Det sorte hul har fortæret så meget af sin ledsagerstjerne, at de indre lag af den mindre stjerne & # 8212 kun ca. en tredjedel af solens masse & # 8212 nu er eksponeret. Forskerne mener, at det sorte hul fangede ledsageren, før de blev skubbet ud af den kugleformede klynge, som om det tog en snack til vejen.

& # 8220Fordi denne mikroquasar tilfældigvis var relativt tæt på Jorden, var vi i stand til at spore dens bevægelse med VLBA, selvom det normalt svimler, & # 8221 sagde Mirabel. & # 8220Nu vil vi finde flere af disse gamle sorte huller. Der må være hundreder af tusinder, der hvirvler rundt i vores Galaxy. & # 8221

Astronomerne brugte VLBA til at observere XTE J1118 + 480 i maj og juli 2000 ved hjælp af VLBAs store opløsningskraft eller evne til at se fine detaljer for nøjagtigt at måle objektets bevægelse på baggrund af fjernere himmelsk kroppe. VLBA-observationer blev foretaget ved radiofrekvenser på 8,4 og 15,4 GHz.

Derudover fandt de, at objektet vises i optiske billeder lavet til Palomar Observatory Sky Survey (POSS) med 43 års mellemrum. POSS-billederne blev digitaliseret for at muliggøre hurtig søgning og analyse af Space Telescope Science Institute. Dataene fra både radio og optiske billeder tillod astronomerne at beregne objektets orbitale sti rundt om det galaktiske centrum.

& # 8220Med VLBA kunne vi begynde at observere kort efter, at dette objekt blev opdaget og få ekstremt præcise oplysninger om dets position. Derefter var vi i stand til at bruge de digitaliserede data fra Palomar-undersøgelserne til at forlænge vores informations tidsrum. Dette er et godt eksempel på at anvende flere værktøjer til moderne astronomi & # 8212 teleskoper, der dækker forskellige bølgelængder og digitale databaser & # 8212 på et enkelt problem, & # 8221 sagde Dhawan.

Ud over Mirabel og Dhawan blev forskningen udført af Roberto Mignani fra European Southern Observatory Irapuan Rodrigues, der er stipendiat fra det brasilianske nationale forskningsråd ved den franske atomenergikommission og Fabrizia Guglielmetti fra Space Telescope Science Institute i Baltimore, MD.


Den evige fælde

& quotGo. Vi sætter gang i lanceringen. 3. 2. 1. Løft af, vi har løftet af & quot Jorden kommando sagde, den uslebne statisk fyldte stemme næppe gennemtrængende gennem det høje brøl fra de traditionelle raketmotorer. Efter adskillige minutter med høj G, befandt vi os vægtløse og langsomt glider længere og længere væk fra det, vi plejede at kalde hjem. En rejsedag bragte os langt nok fra Jorden til at starte vores virkelige rejse.

& quotEarth-kommando, dette er kaptajn Davis. Vi er ved at engagere fase 2-motorer. Vi giver dig denne sidste besked, når vi begiver os ud i det store ud over. Ret godt for dem af jer, vi kender, og hej til alle fremtidige generationer, vi vil se på den anden side. & Quot Jeg talte ind i den lille kommunikationsmikrofon.

Med det blev der givet ordrer, det store besætningsmedlem blev fastspændt, og vi begyndte at starte vores sekundære thrustere. Et højt klynk informerede os om, at motorerne kom op i fart, og en gradvis acceleration kunne ses gennem kommandocentrets vinduer. Udvidelse af rummet var et underligt fænomen at se fjerne hvide stjerner, der skiftede til blå, derefter violet, derefter sort, lejlighedsvis flimrende gennem regnbuens farver.

Flere timers høj acceleration blev efterfulgt af nogle få med lav acceleration for at give besætningen mulighed for at udføre forskellige undersøgelser, vedligeholdelseskontrol og personlig forretning. En cyklus, der blev gentaget i flere uger, indtil lav acceleration var acceptabel for at holde missionsplanen.

Det var over et år efter vores rejse ud over kanten af ​​Mælkevejsgalaksen, da skibet ryste, og skibets alarmer begyndte at blare. Diagnostikken var klar, navigeringskort har savnet noget, noget vi ikke kunne have vidst var der. Nu sidder vi uden for hjælp, en evig fælde i uendelighed.

Når en mand & # x27s sidste øjeblik tikker forbi, kan du ikke lade være med at undre dig over, hvad der går gennem deres sind. Blinker deres liv foran deres øjne? Oversvømmer deres børn hver eneste tanke? Er handlinger og fejltagelser en bevidsthed om en døende mand? På godt og ondt vil jeg aldrig vide det.

Udødelighed er ikke en evne, der gives mig, snarere en fejl, der blev snublet over. Dette er ingen gave eller forbandelse, men en anamolen videnskabelig artefakt, et ondt smuthul i en umulig virkelighed. Dette er ikke noget nogen af ​​os tilmeldte sig.

Som en del af den første forskningsexpedition til Andromeda-galaksen skulle vi køre i et stykke eksperimentel hardware en motor, der teoretisk kunne nå relativistiske hastigheder fastgjort til et skib, der teoretisk har ekstreme energipåvirkninger. Mine besætningsmedlemmer og jeg selv får førstehåndsoplevelse af dette håndværks sande evner.

Jeg husker, at jeg først havde lagt øje på dette massive fartøj. Det havde mærkelige asymmetrier som et stykke abstrakt kunst lavet af et stof, som jeg antager at være klassificeret i naturen. Det omgivende lys, der ramte skroget, reflekterede en rød, der næsten gjorde ondt at se på. De skyggefulde dele af skibet var mærkelige, den sorteste sorte jeg nogensinde har set, og jeg er ikke fremmed for tomrummet. Ser man nu ud af portvinduet, afgiver materialet en flammende lilla og ser ud til at skifte langsomt mod sort. Besætningen har haft mange diskussioner, der spekulerer i materialets oprindelse og struktur, en samtale synes ingen at bryde sig om nu.

Et skib & # x27s år ind i denne rejse, hundrede tusind lysår fra resten af ​​mennesket, udførte besætningen fremragende, fokuseret, forberedt, pligtopfyldende. Nu skrubber vi mens vi venter på at evigheden skal gå. Designerne af dette skib lægger sandsynligvis hundreder af tusinder af timer i det, men hver bølgende metalliske knirk sætter os længere på kanten. Vi ved, at skibet skulle være i stand til at få indflydelse på næsten alt, selvom vi er helt skeptiske, var det designet til en kollision med et sorthul.

Da denne begivenhed aldrig har været oplevet af mennesker, håber jeg simpelthen nogen finder denne besked og bruger den. For os er det for sent.

Vi tror, ​​at oprørelsen af ​​vores knibe stammer fra et sort sort hul, der skubbes ud fra dets himmelske kvarter og sætter det på et næsten kollisionskurs med os. Når vi blev låst fast i en faldende bane, fandt vi, at vores motor ikke var i stand til at accelerere os til at undslippe hastighed, og vores fysiker bekræftede disse mistanker. Vi indstiller vores skib til maksimal acceleration for chancen for, at en gravitationskrybning giver os mulighed for at nå effektiv flugthastighed, håbet er ikke højt blandt besætningen. I løbet af den sidste dag er vi vant til skibet, der lejlighedsvis ryster, sandsynligvis fra skibets resonansfrekvens, der matcher de tyngdekraftsbølger, vi utvivlsomt passerer igennem. Jeg kan kun gætte, hvor mange gange vi ramte de samme bølger, som vi cirklede rundt om det sorte hul. Vi ser vores eget skib fremad, når lyset bøjer og forvrænger omkring sorten.

Har du nogensinde set et hjul spinde hurtigt? Husk hvordan det drejer så hurtigt, at det ser ud til at være stoppet eller endda rotere baglæns? At se ud over det modsatte sidevindue ind i den store tomhed i rummet ser ud som det, som om vi langsomt kredser om det sorte hul. I look out and see the blue shifted Andromeda Galaxy, a faint dot far in the distance. Suspiciously, it seems to be getting larger. It could just be my imagination, hard to tell.

"Computer, analyze Andromeda proximity" I command

"1.3469. 1.3468. . cannot resolve distance. Resolve using predictive methods?" The computer responds

Ship's computer whirs before answering. "Resolving. approaching Andromeda at 3e 10 * c."

"Recalculate using fixed position and predictive time dilation effects" I state, now slightly annoyed with the quantity of commands required to get the answer I need.

"One moment" The computer states before that same whirring sound. "Error. Unable to calculate. Exceeding input parameters."

An unpleasant answer I had hoped wouldn't be the case. I hesitate before asking the next query, not sure if I want an answer. "Approximate earth time"

"Approximately. 244 million CE."

Several in the command center gasp, as this news could only mean one thing: It appears time dilation is more severe here that we previously approximated, and accelerating as we fall inward has further exacerbated this effect. The announcement sent several of the crew into deep sobs. No one can fathom what this implies for our future. The plan to get to Andromeda, spend several years acquiring information, and return. We anticipated a total mission of 25 years, and approximately 6 million earth years. We can prepare for things to be different, humanity to have evolved, and massive progress to be made or lost. We cannot prepare for massive changes on a scale that is beyond comprehensible if they are encountered. We cannot prepare for the remnants of creatures we know as human to vanish, replaced with ancestors that could take any form, creatures that would call us gods or aliens, or ants. We most certainly cannot prepare for a civilization that has likely advanced beyond the boundaries of this universe. This assumes life even still exists on our blue and green marble.

I don't cry, as I had joined this mission for the adventure of a life time. I hold hopes that we may still escape, the quaking of the ship becomes more frequent with each passing minute, a sign gravity is not constant and escape closer than before.

The flight psychologist has been making rounds, informing everyone they can speak with him if they need to. After he's finished, I pull him aside and tell him that he may speak to me if he needs. He seems less disturbed by our situation that I am, putting up the same facade he wears during his sessions. Pulling him into a tight embrace, I feel him relax followed by a few deep heaves. We've know eachother for several years now and I consider us close friends. Friendship may be the only thing that gets us through this situation.

"Thank you" he says, pulling away and wiping his eyes, now slightly glimmering and reddened. We both turn and walk down the corridors, away from the command center.

The ship shudders, buckling one of my knees. "Jesus" I explain, before straits ing up and continuing on. I follow the flight psychologist for a minute before turning into the lab.

One of our engineers was frantically scambling through papers, writing gibberish on a note book. She doesn't notice me until I make my presence aware. Talking complex mathematics, she speaks about how little time we have, noting that we might be able to escape our predicament. Lost in her ramblings, I nod at what ever approval she requested this should help her cope with the reality we found ourselves in. Conveniently, another engineer entered the room at that moment, and they both rush out together without wasting another moment another harsh shuddering of the ship wishing them luck on their quest.

I make my way to the last place on the ship people congrate, a long walk down a mostly silent corridor. but the ever more frequent shuddering almost knocked me off my feet. Grasping the wall to prevent myself from falling, I hear a rough, wet slapping from just beyond carnal cries and lewd grunting identifying the location of our doctor and mechanic. Even upon death, some of us find ourselves but simple creatures, though this coupling had been building since shortly after launch. Checking in on them now would likely be problematic I strip myself from the wall and carry onward.

The mess hall was packed, yet silent.

One by one, I spoke with each person present, the soft speak being the only noise resonating across the metalic hull. Finishing the short speech with the last person in the mess, i leave it once again silent, quieter than before. Heading back toward the command center was even more discomforting than entering the mess, deafening hollow steps ringing loud in a dying ship.

Approaching command was daunting, the sounds of the mechanic and doctor no longer present, nothing but thoughts of time with every step. A step takes less than a second ship time and thousands of years Earth time. Each and every stride, hundreds of generations of human ancestors live and die.

Stripping me from my thoughts, I hear a soft commotion stretching halfway down the brightly lit hall. Quickening my pace, I reach command to discover the source of the chaos. The navigation and enforcement officer barrage Dr. Phang with questions. The confusion in her responses clearly indicating the officers proding was unhelpful.

My arrival brings a sudden hush to the command center.

"What's going on here?" I strain my voice to overcome another harsh shuddering.

The navigation officer began to explain engineering arrived a few moments ago and took the mechanic to the engine room. Engineering simply stated I gave approval for engine modification, of which I now recall.

". and by increasing our velocity we may have a way out. We will loose lots of time, but it can be done. We need to flood the engine with SQZ, then replace the rods. Captain, do I have your approval?"

Sirens now sound across the ship once more.

"Engine compromised, take immediate action" An emergency response voice demanded of its crew.

Engineering spoke out over the intercom "Alright everyone, you've got 30 second, we're getting out of this pit. Hold on, buckle up. This is going to be a bumpy ride." Hanging up with a sharp click

Those words stun the command center to unmoving silence, the alarm deafening all of us. Without many options, I start issuing orders.

"You heard the lass, get a seat and secure yourself!" I shout. Picking up the intercom I repeat the same phrase and pray the others on the ship batten themselves down.

The siren wails continuously as we wait for extreme acceleration. I hear navigation officer whispered under her breath "3. 2. 1."

A loud bang rang through the ship, followed by a short jolt of acceleration, and the whining sound of of engines winding down.

I grab the intercom. "Engineering, What the f. & quot

Cutting me off, the engine wind up to a screaming pitch, smothering the sirens. After several minutes, on the verge of fainting, the engines wind down to their original gentle humm.

After a moment, not wanting any additional surprises pulled on me, I grab the intercom mic again. "Did it work?" Followed by a silent pause. "Engineering, did it work?" My voice strained.

Dealing another major blow to the moral of the ship, we wander to the port to see a shifting sky. Andromeda now fast approaching, what ever they did worsened our position, and we can do nothing except watch as all of existence rushes toward its death.

Once a far off small dot, our destination ironically came rushing toward us. Bright lights I assume to be stars zip past, and as if to torment us our lightless captor was ejected from the chaos to give us a brilliant view of the ongoing collision.

Dust in a whirl pool, the galaxies danced, twisting and morphing into a new shape. It twinkled with the birth and death of stars, growing dimmer and redder with each second. The engineer who derived this insane plot arrived in the command center with the mechanic to watch as what seemed to be the last of the stars winked out of existence.

"Computer, identify stars" I command.

"One local star located. Displaying"

Flickering weakly, a dull white light emanates from the star as it seems to grasp for life, fight against the oppressive void. Hours pass, or so it feels like they do as we watch the last light die. And with its vanishing, I feel something inside me change.

"Computer, identify stars" I command again

"Extensive search" I command, needing there to be something. Anything.

A familiar whirring followed by several seemingly unused lights flashing ledding us to the unsettlingly response.

"Check again!" I demand, pleading with fate to give us an impossibility.

There is a new whirring and beeping, leading to the same response.

The last glimmer of the universe is gone. Along with its death so went that spark I hold inside. I sit down on the hard floor, holding my knees close to my chest and weep, the tears carrying the last bit of humanity I have left.

I now take the days as they come, trying to discuss with the crew a path forward. Everyone has resigned to either solitude to process the gravity of our situation or hedonism to give our remaining pointless years some level of meaning. I have taken to the former, staring out the port to see something, anything.

Occasionally my mind plays tricks on me and I see splotches, or tendrils, or eyes staring back into my own. With no orientational reference and the ship quakes having ended shortly after the last star vanished, we don't know if we're still orbiting the black hole, if we've been ejected from its grasp, or have passed its event horizon. All fates no one aboard anticipated on launch.

When we boarded this ship, we knew it would be the last time we saw our family. We knew humanity may evolve into strange humanoids, and the humanity we returned to would not be what we knew. Accepting the facts of a changing universe was difficult. Watching all existence come to an end, where we are the last living beings, no words can describe this hollow sensation. Staring out into the void, true endless nothingness, I cannot help but wonder what is more empty. The expanse outside of this strange contraption, or the vacancy now residing inside myself.


Starburst to star bust: Light shed on mystery of missing massive galaxies

New observations from the ALMA telescope in Chile have given astronomers the best view yet of how vigorous star formation can blast gas out of a galaxy and starve future generations of stars of the fuel they need to form and grow. The dramatic images show enormous outflows of molecular gas ejected by star-forming regions in the nearby Sculptor Galaxy. These new results help to explain the strange paucity of very massive galaxies in the Universe.

The study is published in the journal Natur on July 25, 2013.

Galaxies -- systems like our own Milky Way that contain up to hundreds of billions of stars -- are the basic building blocks of the cosmos. One ambitious goal of contemporary astronomy is to understand the ways in which galaxies grow and evolve, a key question being star formation: what determines the number of new stars that will form in a galaxy?

The Sculptor Galaxy, also known as NGC 253, is a spiral galaxy located in the southern constellation of Sculptor. At a distance of around 11.5 million light-years from our Solar System it is one of our closer intergalactic neighbours, and one of the closest starburst galaxies [1] visible from the southern hemisphere. Using the Atacama Large Millimeter/submillimeter Array (ALMA) astronomers have discovered billowing columns of cold, dense gas fleeing from the centre of the galactic disc.

"With ALMA's superb resolution and sensitivity, we can clearly see for the first time massive concentrations of cold gas being jettisoned by expanding shells of intense pressure created by young stars," said Alberto Bolatto of the University of Maryland, USA lead author of the paper. "The amount of gas we measure gives us very good evidence that some growing galaxies spew out more gas than they take in. We may be seeing a present-day example of a very common occurrence in the early Universe."

These results may help to explain why astronomers have found surprisingly few high-mass galaxies throughout the cosmos. Computer models show that older, redder galaxies should have considerably more mass and a larger number of stars than we currently observe. It seems that the galactic winds or outflow of gas are so strong that they deprive the galaxy of the fuel for the formation of the next generation of stars [2].

"These features trace an arc that is almost perfectly aligned with the edges of the previously observed hot, ionised gas outflow," noted Fabian Walter, a lead investigator at the Max Planck Institute for Astronomy in Heidelberg, Germany, and a co-author of the paper. "We can now see the step-by-step progression of starburst to outflow."

The researchers determined that vast quantities of molecular gas -- nearly ten times the mass of our Sun each year and possibly much more -- were being ejected from the galaxy at velocities between 150 000 and almost 1 000 000 kilometres per hour [3]. The total amount of gas ejected would add up to more gas than actually went into forming the galaxy's stars in the same time. At this rate, the galaxy could run out of gas in as few as 60 million years.

"For me, this is a prime example of how new instruments shape the future of astronomy. We have been studying the starburst region of NGC 253 and other nearby starburst galaxies for almost ten years. But before ALMA, we had no chance to see such details," says Walter. The study used an early configuration of ALMA with only 16 antennas. "It's exciting to think what the complete ALMA with 66 antennas will show for this kind of outflow!" Walter adds.

More studies with the full ALMA array will help determine the ultimate fate of the gas carried away by the wind, which will reveal whether the starburst-driven winds are recycling or truly removing star forming material.

[1] Starburst galaxies are producing stars at an exceptionally high rate. As NGC 253 is one of the closest such extreme objects it is an ideal target to study the effect of such growth frenzy on the galaxy hosting it.

[2] Previous observations had shown hotter, but much less dense, gas streaming away from NGC 253's star-forming regions, but alone this would have little, if any, impact on the fate of the galaxy and its ability to form future generations of stars. This new ALMA data show the much more dense molecular gas getting its initial "kick" from the formation of new stars and then being swept along with the thin, hot gas on its way to the galactic halo.

[3] Although the velocities are high, they may not be high enough for the gas to be ejected from the galaxy. It would get trapped in the galactic halo for many millions of years, and could eventually rain back on the disk, causing new episodes of star formation.


Earth Impact Plumes Seed Life Through the Galaxy

Since it formed about 4.5 billion years ago, our planet has suffered catastrophic collisions with other space bodies, which sometimes led to extinction events here. However, it could be that the same instances led to the spreading of basic lifeforms to other celestial bodies in our solar system.

In a new study published online in the journal arXiv, investigators analyze the probabilities of Earth's ejecta plumes reaching other planets and moons. They say that the debris may have even reached points beyond the orbits of Jupiter, the fifth planet form the Sun.

What makes this discovery interesting is the fact that basic microorganisms such as microbes and bacteria can travel inside such ejecta objects, able to withstand the harsh conditions of outer space.

Investigations conducted over the past decade or so have demonstrated that lifeforms can survive being ejected to space in a violent cosmic collision, traveling for millions of years inside their lifeboats, and then surviving atmospheric reentry on another body.

Once there, life uses its built-in ability to adapt, which functions extremely well regardless of the environment it comes across. On Earth, microorganisms live anywhere from 3 kilometers below the ices of Antarctica and miles beneath the Earth's crust to volcanic crater and near hydrothermal vents.

Given this resiliency, it may not be such a stretch to assume that life was carried by ejecta plumes generated when Earth was impacted by massive asteroids. According to experts, the most probable scenario is where the microbes reached Venus or the Moon.

The reason why this is the most likely scenario is because the Sun's gravity would have pulled on the ejecta plumes towards the inner solar system. However, it is not entirely impossible for some material to have made its way towards Mars, Jupiter, or even beyond.

The recent investigation, led by Universidad Nacional Autonoma de Mexico astronomer Mauricio Reyes-Ruiz, represents that largest, most comprehensive simulation of Earth eject plume behaviors.

Their computer model shows that two orders of magnitude more particles reach Mars than what was originally calculated. Interestingly, at high and very high ejection speeds, test particles are more likely to make their way to Jupiter rather than Mars, Technology Review reports.

Another remarkable finding was that many particles make their way out of the solar system entirely. What this implies is that lifeforms originating on our planet may now be on their way to colonize other worlds as we speak.


Observing galactic 'blow out': Stellar growth spurts stunt future growth

This image shows a 3D volume rendering of the IRAM observation of SDSSJ0905+57, revealing the detection of carbon monoxide. The bright ‘head’ shows gas associated with the dense, compact star-forming nucleus. The ‘tail’ (colour coded in velocity red=high velocity) shows gas in a high velocity outflow, up to 1000 km/s, highlighting molecular gas being ejected from the galaxy by stellar feedback. Credit: J. Geach & R. Crain

(Phys.org)—For the first time, an international team of astronomers, led by Dr James Geach from the University of Hertfordshire, has revealed the dramatic 'blow out' phase of galactic evolution.

The astronomers have discovered dense gas being blasted out of a compact galaxy (called SDSS J0905+57) at speeds of up to two million miles per hour. The gas is being driven to distances of tens of thousands of light years by the intense pressure exerted on it by the radiation of stars that are forming rapidly at the galaxy's centre. This is having a major impact on the evolution of the galaxy.

The team used the Institut de Radioastronomie Millimétrique (IRAM) Plateau de Bure Interferometer, a radio telescope based in the French Alps. By detecting the molecule carbon monoxide, they were able to infer the amount of hydrogen gas present. Stars are born from clouds of hydrogen, so by removing this gas the galaxy can rapidly shut down its star formation. There is enough gas in the outflowing material to form the equivalent of over a billion Suns.

Dr Geach, who is funded by the Royal Society, explained: "This discovery highlights the serendipity of scientific research. Originally we were simply trying to measure the amount of dense gas in SDSS J0905+57. What we found was something surprising – a large fraction of the gas is being blasted out of the galaxy by the concentration of stars forming at the galaxy's centre.

"We are witnessing the aggressive termination of star formation, and the mechanism by which this is happening is an important new clue in our understanding of the evolution of galaxies."

Outflows of warm, ionized gas from galaxies are well known, but the team's observation of large amounts of cold, dense gas being violently removed from the central regions of the galaxy and far into space is a new discovery. Previously it was not known whether the stars alone could drive out gas in this way. Instead, it was thought that energy associated with a growing central black hole would be required, but this is known not to be happening in SDSS J0905+57. This result provides important new insights into how the growth of stars is regulated in galaxies.


Meanwhile, in a galaxy not so far, far away.

The fantasy creations of the "Star Wars" universe are strikingly similar to real planets in our own Milky Way galaxy.

The fantasy creations of the "Star Wars" universe are strikingly similar to real planets in our own Milky Way galaxy. A super Earth in deep freeze? Think ice-planet "Hoth." And that distant world with double sunsets can't help but summon thoughts of sandy "Tatooine."

No indications of life have yet been detected on any of the nearly 2,000 scientifically confirmed exoplanets, so we don't know if any of them are inhabited by Wookiees or mynocks, or play host to exotic alien bar scenes (or even bacteria, for that matter).

Still, a quick spin around the real exoplanet universe offers tantalizing similarities to several Star Wars counterparts.

The most recently revealed exoplanet possessing Earth-like properties, Kepler-452b, might make a good stand-in for Coruscant -- the high-tech world seen in several Star Wars films whose surface is encased in a single, globe-spanning city. Kepler-452b belongs to a star system 1.5 billion years older than Earth's. That would give any technologically adept species more than a billion-year jump ahead of us. The denizens of Coruscant not only have an entirely engineered planetary surface, but an engineered climate as well. On Kepler-452b, conditions are growing markedly warmer as its star's energy output increases, a symptom of advanced age. If this planet (which is 1.6 times the size of Earth) were truly Earth-like, and if technological life forms were present, some climate engineering might be needed there as well.

Mining the atmospheres of giant gas planets is a staple of science fiction. NASA, too, has examined the question, and found that gases such as helium-3 and hydrogen could be extracted from the atmospheres of Uranus and Neptune. Gas giants of all stripes populate the real exoplanet universe in "The Empire Strikes Back," a gas giant called Bespin is home to a "Cloud City" actively involved in atmospheric mining. The toadstool-shaped city provides apparent refuge for a fleeing Princess Leia and company -- at least until Darth Vader wreaks his usual havoc.

Many of the gas giants found so far by instruments such as NASA's Kepler Space Telescope are so-called "hot Jupiters" -- star-hugging behemoths far too thoroughly barbecued to be proper sites for floating cities. One recent discovery, however, shows that gas "exogiants" can orbit their stars at distances remarkably similar to those in our solar system. An international astronomical team discovered a twin of our own Jupiter, orbiting its star at about the same distance as Jupiter is from the sun. The star, HIP 11915, is about the same age and composition as our sun, raising the possibility that its entire planetary system might be similar to ours. This not-so-hot Jupiter, about 186 light-years away from Earth, was detected using the 11.8-foot (3.6-meter) telescope at La Silla Observatory in Chile.

Bespin's atmospheric layers include a band of breathable air, ideal for floating cities. In our galaxy, emerging technology allows us to read out the components of real exoplanet atmospheres -- including gas giants (though so far none show signs of habitable layers). And tasting the atmospheres of smaller, rocky, potentially habitable exoplanets soon could be within reach. Astronomers using K2, the second planet-finding mission of the Kepler space telescope, recently detected three such planets orbiting a nearby dwarf star. The starlight shining through the atmospheres of these planets could reveal their composition in future observations.

The planet Mustafar, scene of an epic duel between Obi-Wan Kenobi and Anakin Skywalker in "Revenge of the Sith," has a number of exoplanet counterparts. These molten, lava-covered worlds, such as Kepler-10b and Kepler-78b, are rocky planets in Earth's size range whose surfaces could well be perpetual infernos. Kepler-78b, roughly 20 percent larger than Earth, weighs in at twice Earth's mass a comparable density means it could be composed of rock and iron. That might make it, like Mustafar, suitable for mining, although its extremely tight orbit around its sun-like star, along with scorching temperatures, provides an unlikely arena for industrial operations -- or for fencing with lightsabers.

Kepler-10b isn't much more pleasant. The first rocky world discovered using the Kepler telescope, it also hugs its sun, some 20 times closer than Mercury orbits ours. A balmy day on Kepler-10b means daytime highs of more than 2,500 Fahrenheit (1,371 Celsius), even hotter than lava flowing on Earth. The surface, free of any kind of atmosphere, might be boiling with iron and silicates.

At 3,600 degrees Fahrenheit (1,982 Celsius), however, CoRoT-7b has Kepler-10b beat. This well-grilled planet, discovered in 2010 with France's CoRoT satellite, lies some 480 light-years away, and has a diameter 70 percent larger than Earth's, with nearly five times the mass. Possibly the boiled-down remnant of a Saturn-sized planet, its orbit is so tight that its star looms much larger in its sky than our sun appears to us, keeping its sun-facing surface molten.

The planet OGLE-2005-BLG-390, nicknamed "Hoth," is a cold super-Earth that might be a failed Jupiter. Unable to grow large enough, it had to settle for a mass five times that of Earth and a surface locked in the deepest of deep freezes, with a surface temperature estimated at minus 364 degrees Fahrenheit (minus 220 Celsius). That most likely means no "Hoth"-style tauntauns to ride, or even formidably fanged abominable snowmen (aka "wampas"). Astronomers used an extraordinary planet-finding technique known as microlensing to find this world in 2005, one of the early demonstrations of this technique's ability to reveal exoplanets. In microlensing, backlight from a distant star is used to reveal planets around a star closer to us.

The planet lies toward the heart of the Milky Way, where a greater density of stars makes microlensing events more likely. The one-time event revealing the distant Hoth was captured by the Optical Gravitational Lensing Experiment, or OGLE, and confirmed by other instruments.

We won't have to travel 20,000 light years, however, to visit icy worlds. Saturn's smoggy moon, Titan, where the Cassini spacecraft's Huygens probe landed in 2005, is pocked with methane lakes and socked in permanently with thick, hydrocarbon haze. The freeze is so deep that water ice is no different from rock. Another Saturn moon, Enceladus, looks like a snowball but harbors a subsurface ocean much like Jupiter's moon Europa, another ice ball with a likely ocean underneath. That ocean would be warmed by tidal flexing as the little moon orbits Jupiter.

Sunset? Make it a double

Luke Skywalker's home planet, Tatooine, is said to possess a harsh, desert environment, swept by sandstorms as it roasts under the glare of twin suns. Real exoplanets in the thrall of two or more suns are even harsher. Kepler-16b was the Kepler telescope's first discovery of a planet in a "circumbinary" orbit -- circling both stars, as opposed to just one, in a double-star system. This planet, however, is likely cold, about the size of Saturn, and gaseous, though partly composed of rock. It lies outside its two stars' "habitable zone," where liquid water could exist. And its stars are cooler than our sun, and probably render the planet lifeless. Of course, we could look on the bright side (so to speak). When the discovery was announced in 2011, Bill Borucki, the now-retired NASA principal investigator for Kepler at Ames Research Center, Moffett Field, California, said finding the new planet might actually broaden the prospects for life in our galaxy. About half of all stars belong to binary systems, so the fact that planets form around these, as well as around single stars, can only increase the odds.

A more recently announced exoplanet, Kepler-453b, is also a circumbinary and a gas giant, though its orbit within its star's habitable zone means any moons it might have could be hospitable to life. It was the tenth circumbinary planet discovered using the Kepler telescope.

Kepler-22b, analog to the Star Wars planet Kamino (birthplace of the army of clone soldiers)), is a super-Earth that could be covered in a super ocean. Watery, storm-drenched Kamino makes its appearance in "Attack of the Clones."

The jury is still out on Kepler-22b's true nature at 2.4 times Earth's radius, it might even be gaseous. But if the ocean world idea turns out to be right, we can envision a physically plausible Kamino-like planet, with the help of scientists at the Massachusetts Institute of Technology in Cambridge. An ocean world tipped on its side -- a bit like our solar system's ice giant, Uranus -- turns out to be comfortably habitable based on recent computer modeling. Researchers found that an exoplanet in Earth's size range, at a comparable distance from its sun and covered in water, could have an average surface temperature of about 60 degrees Fahrenheit (15.5 degrees Celsius). Because of its radical tilt, its north and south poles would be alternately bathed in sunlight and darkness, for half a year each, as the planet circled its star.

Scientists previously thought such a planet would seesaw between boiling and freezing, rendering it uninhabitable. But the MIT scientists' three-dimensional model showed that the planet, even with a relatively shallow ocean of about 160 feet (50 meters), would absorb heat during its odd polar summer and release it in winter. That would keep the overall climate mild and spring-like year round.

The shallow depth, by the way, would be ideal for Kamino-style ocean platforms, allowing construction of covered cities at the ocean surface, where armies of clones could march and drill in peace.

Fly me to the exomoon

Endor, the forested realm of the Ewoks, orbits a gas giant and was introduced in "Return of the Jedi." Detection of exomoons -- that is, moons circling distant planets -- is still in its infancy for scientists here on Earth. A possible exomoon was observed in 2014 via microlensing. It will remain forever unconfirmed, however, since each microlensing event can be seen only once. If the exomoon is real, it orbits a rogue planet, unattached to a star and wandering freely through space. The planet might have hung on to its moon after somehow being ejected during the early history of a forgotten planetary system. A team of Japanese, New Zealand, and American astronomers analyzed data gathered in 2011 with telescopes in New Zealand and Tasmania, and suggested the possible exomoon. They said a small star accompanied by a large planet also could have caused the same lensing effect.

More exomoons might soon be popping out from the depths of space. The Harvard-based Hunt for Exomoons with Kepler, or HEK, has begun to scour data from Kepler for signs of them. In early 2015, the researchers examined about 60 Kepler planets and determined that existing technology is sufficient to capture evidence of exomoons.

The hunt could have powerful implications in the search for life beyond Earth. If exomoons are shown to be potentially habitable, it would open another avenue for biology habitable moons might even outnumber habitable planets. Could they have bustling ecosystems, with life forms even more exotic than Endor's living teddy bears, swinging between trees Tarzan-style? Stay tuned.

Breaking up is hard to do

In "A New Hope," Princess Leia's home planet, Alderaan, is blown to smithereens by the Empire's Death Star as she watches in horror. Real exoplanets also can experience extreme destruction. A white dwarf star was caught in the act of devouring the last bits of a small planet in 2015, observed with the help of NASA's Chandra X-ray Observatory. White dwarfs are super-dense stellar remnants about the size of Earth, but with gravity more than 10,000 times that of our sun's surface. Tidal forces could rip a planet caught in its pull to shreds.

Observers thought at first they were seeing a black hole in the act of feeding inside a star cluster on the Milky Way's rim. X-ray observations, however, matched theoretical models of a planet being torn apart by a white dwarf.

A similar observation of a closer white dwarf was made by K2 in 2014. In this case, a tiny rocky object, probably an asteroid, was being vaporized into little more than a dusty ring as it whipped around the star every 4.5 hours.

NASA's Spitzer Space Telescope also picked up signs of debris from a likely asteroid collision in 2014. But rather than a sign of planetary destruction, the colliding asteroids could be part of a construction site. This young star -- about 1,200 light years away and only 35 million years old -- is surrounded by a ring of dust where such collisions are frequent. The smashed and broken bits fuse into larger and larger agglomerations, eventually forming full-sized planets.

Our own solar system might once have looked very similar, if anyone was watching.

NASA's Ames Research Center in Moffett Field, California, manages the Kepler and K2 missions for NASA's Science Mission Directorate. NASA's Jet Propulsion Laboratory in Pasadena, California, managed Kepler mission development. Ball Aerospace & Technologies Corp. operates the flight system with support from the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

JPL, a division of the California Institute of Technology in Pasadena, manages the Spitzer Space Telescope for NASA.


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