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Het ek 'n ontploffing in 'n supernova gesien?

Het ek 'n ontploffing in 'n supernova gesien?


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Ek dink ek het net 'n supernova met my eie oë sien ontplof deur my GSO 12 duim Dobsonian. Vertel my asseblief wat dit was! Ek is nog steeds besig om uit te vind wat dit gedagtes was!

Ek het omstreeks 18:20 (Nieu-Delhi, Indië) op my dak uitgegaan en opgekyk en gedink dat ons vanaand 'n helder lug gaan hê.

Skielik sien ek die helder ster sonder die teleskoop, en ek was verbaas om so 'n helder voorwerp naby die hoogtepunt te sien, en ek hardloop toe in en haal my teleskoop uit. Toe ek deur die omvang kyk, lyk dit soos 'n helder borrel wat baie blink en die buitenste oppervlak lyk helderder. Ek het gedink my kollimasie was buite, so ek het die omvang gekollimeer en dit was nie te af nie. Na kollimasie kon ek 'n klein voorwerp in 'n wentelbaan om die ster / voorwerp sien. Toe ek dit bly waarneem, het dit skielik soos vuurwerke ontplof en klein deeltjies wat baie helder skyn, het in golwe begin draai en vinnig verdof. Dit was omstreeks 18:38. Ek het foto's met my foon deur die okularis geneem en die lug was nog steeds verlig en blou van kleur. Die onderstaande foto's word in 'n kitsblad op my foon geredigeer.


Supernovas neem helderheid toe oor etlike dae en neem oor maande af. Wat u ook al gesien het, was dus nie 'n supernova nie, jammer.


Ek weet nie van u land nie, maar in die Verenigde State loods die grootste weerdienste twee keer per dag instrumentêre ballonne. Hulle is ongeveer 1 of 2 meter in deursnee. Ons sien hulle gereeld saans in die sterrewag, en u beskrywing stem ooreen. 'N Helder ster wat sigbaar is vir die blote oog in die skemer. Die ballon en instrumente wat onder die ballon hang, is maklik op te los in 'n teleskoop. Die ballon bars wanneer dit te hoog word en het 'n wolk van sprankelende fragmente tot gevolg.


Ek was betrokke by 'n vrywilligersprojek wat nuwe supernovas gesoek het en was een persoon uit verskeie wat SN 2016 dln as 'n nuwe supernova geïdentifiseer het.

Die identifisering van die moontlike supernovas was redelik delikaat en het baie ure en oefening geverg, en daarom vermoed ek (ook as u u beskrywing in ag neem) dat dit wat u gesien het waarskynlik nie 'n supernova was nie en waarskynlik 'n mensgemaakte voorwerp was.


Die Hubble-teleskoop het 'n resolusie van ongeveer 1/20 van 'n boogsekonde, of 1/25920000 van 'n sirkel. 'N Juliaanse jaar het 31557600 sekondes. Dit beteken vir iets wat 'n ligjaar ver is, sal dit 1,2175 sekondes neem voordat 'n voorwerp ver genoeg beweeg voordat die beweging deur die Hubble-teleskoop opgelos kan word, selfs al beweeg dit met die ligspoed. (En daarmee bedoel ek dit sal 1,2175 sekondes neem voordat dit beweeg een pixel.)

'N Supernova naby die aarde is 'n ontploffing as gevolg van die dood van 'n ster wat naby genoeg aan die aarde voorkom (ongeveer 10 tot 300 parsek (30 tot 1000 ligjare) weg [2]) om 'n merkbare uitwerking op die Aarde se biosfeer te hê. .

Aangesien tipe Ia-supernovas voortspruit uit dowwe, algemene wit dwergsterre, is dit waarskynlik dat 'n supernova wat die aarde kan beïnvloed onvoorspelbaar sal voorkom en plaasvind in 'n sterstelsel wat nie goed bestudeer is nie. IK Pegasi is die naaste bekende kandidaat.

https://en.wikipedia.org/wiki/Near-Earth_supernova

IK Pegasi is 150 LY weg. Dus, selfs al gaan IK Pegasi supernova toe (wat onwaarskynlik is), sal ons meer as 3 minute benodig om enige beweging met Hubble op te los. Met 'n amateurteleskoop sou baie meer tyd nodig wees. Die feit dat u die voorwerp in reële tyd kon sien verander, wys dat dit astronomies baie naby was.


Het u die moontlikheid oorweeg om na te kyk? Jupiter en sy helderste maan (s)?

Om 18:20 plaaslike tyd sou Jupiter amper direk bokant wees, en beslis helder genoeg om te sien nie lank nadat die son ondergegaan het nie; in vervaagende skemering sou enige nie-verduisterde Galilese mane ook maklik in 'n teleskoop sigbaar wees. [Ek het onlangs die vier in my gewone veldverkyker waargeneem, en ek is in 'n groot stad van 4 miljoen met aansienlike ligbesoedeling, alhoewel dit nou baie minder besoedel is omdat ek COVID opgesluit het.]

Dit verklaar nie u beskrywing nie "dit het skielik ontplof soos vuurwerke en klein deeltjies wat baie helder skyn, het in golwe begin draai en vinnig verdof", maar daar is geen manier wat enige voorwerp buite die aarde kan beskryf nie, gegewe die vinnige veranderinge wat u beskryf. Dit is heel waarskynlik dat u iets in die aarde se atmosfeer gesien het. U was miskien ongelooflik gelukkig dat u deur u teleskoop gekyk het op die punt waar 'n klein meteoriet die atmosfeer amper 'front-up' na u toe binnegegaan het en in 'n stort 'vonke' geduur het wat hoogstens 'n paar sekondes geduur het.


Baie het. Ongelukkig het jy waarskynlik nie. Ek moet my datums nagaan, maar ek glo die laaste keer was in '80 -is. 'N Oënskynlike supernova sou die bekendste gesig in die lug wees. Antieke Chinese het daaroor (Crab nebula) gepraat en hul bevindings opgeteken. As daar een was, kon NASA dit nie verberg nie. U sou weet.


Het 'n Supernova-ontploffing 359 miljoen jaar gelede 'n uitwissing veroorsaak?

Die oorsaak van die uitwissing van die Devoon-periode 359 miljoen jaar gelede, gereken as een van die vyf groot uitwissings van die lewe op aarde, bly 'n raaisel. Nou onthul 'n nuwe studie dat die ontploffing van 'n ster in die omgewing moontlik een van die grootste uitsterwingsgebeurtenisse in die geskiedenis van ons planeet veroorsaak het.

Die Devoon-periode het begin met byna al die landmassa in die wêreld wat in twee groot superkontinente, Gondwana en Euramerica, gekonsentreer is. Hierdie twee liggame sou later die enkele wêreldkontinent Pangea vorm.

Klein, wortellose plante het oor die droë land gewaai. In die loop van 60 miljoen jaar het die eerste plante met sade opgekom, plante het vir die eerste keer ware hout in hul strukture gebruik, en klein vleuelose insekte, soortgelyk aan myte, het eers hul verskyning gemaak. Teen die laat Devoon het bome met ware wortels gedy, en het plante ontwikkel om voort te plant deur die verspreiding van sade.

Jesse Miller, links, Zhenghai Liu, sittende, Adrienne Ertel en professor Brian Fields. Beeldkrediet: Foto deur L. Brian Stauffer

Dit sou Sunblock met SPF-Two Million vereis het

'N Supernova-ontploffing, veroorsaak deur die dood van 'n massiewe ster op 65 ligjare van die aarde, het blykbaar die lewe op aarde gedurende hierdie era vernietig. Die seelewe in warm water is die meeste geraak deur die uitwissing van die Devoon-tydperk.

Dodelike kosmiese strale wat tydens die sterre-uitbarsting geproduseer is, sou die aarde beïnvloed het en baie van die lewe verskeur het.

'Reefbousponse wat stromatoporoïede genoem word, en korale het verliese gely en stromatoporoïede het uiteindelik verdwyn in die derde uitwissing naby die einde van die Devoon. Brachiopode wat met riwwe verband hou, het ook uitgesterf. Groepe trilobiete het by elk van die drie uitwissings verdwyn en baie min het in die volgende koolstofagtige periode oorleef, ”berig die Sam Noble Museum.

Onlangse studies lewer bewys van 'n verlies aan biodiversiteit en 'n uiterste daling in die hoeveelheid osoon in die atmosfeer van die aarde aan die einde van die Devoon-periode. Die lewe van hierdie era het gedurende hierdie tyd drie uitwissings beleef, elk geskei deur 10 miljoen jaar. Die laaste hiervan word gewoonlik beskou as een van die vyf groot uitwissingsgebeurtenisse.

Ondersoek van gesteentes wat in die geologiese lae neergelê is wat die grens van die Devoniese en Koolstofagtige tydperke aandui, toon bewyse van uiterste gevalle van sonbrand wat gesien word in die fossiele van plante van daardie era, wat dui op 'n langdurige periode waarin die osoonlaag van die aarde, wat beskerm ons van ultravioletlig, is uitgeput.

'N Kykie na hoe die landskap aan die einde van die Devoniese tydperk kon lyk. Beeldkrediet: Eduard Riou (1838–1900) van The World Before the Deluge (1872).

“Aardgebaseerde rampe soos grootskaalse vulkanisme en aardverwarming kan ook die osoonlaag vernietig, maar bewyse hiervoor is onoortuigend vir die betrokke tydperk. In plaas daarvan stel ons voor dat een of meer supernova-ontploffings, ongeveer 65 ligjare weg van die aarde, verantwoordelik sou kon wees vir die langdurige verlies aan osoon, "het dr. Brian Fields van die Universiteit van Illinois, Urbana-Champaign, gesê.

Daar sou 'n aardbrekende Kaboom wees!

Daar is verskillende vorms van supernova-ontploffings, en hierdie gebeurtenis was die gevolg van 'n supermassiewe rooi reuse-ster wat aan die einde van sy lewe inmekaargeval het. Die bekendste rooi reuse-ster, Betelgeuse, het onlangs 'n verduisteringsperiode deurgemaak. Daar word nou geglo dat hierdie gebeurtenis die gevolg is van die feit dat die ster 'n wolk materiaal vrystel wat die tyd tydelik belemmer om die aarde te bereik. Die lewe op aarde sal heeltemal uitgewis word deur die ontploffing van 'n rooi reuse-ster binne 25 ligjare van ons tuisplaneet. Gelukkig vir ons sit die naaste rooi reus, Gacrux, op 'n gemaklike afstand van 88 ligjare van ons tuiswêreld.

“... [Een van die naaste supernova-bedreigings van vandag is van die ster Betelgeuse, wat meer as 600 ligjaar weg is en ver buite die doodafstand van 25 ligjare," studeer student aan die Universiteit van Illinois (U van I). Adrienne Ertel verklaar.

Uitputting van osoon kan die gevolg wees van verskillende triggers in die omgewing, maar ander oorsake stem nie ooreen met die besonderhede wat in die geologiese rekord van destyds voorkom nie. Die navorsingspan het die impak van meteoriete, sonuitbarstings en gammastralings (GRB's) op die omgewing van die antieke aarde ondersoek. Virtuele modelle het verliese aan osoon regoor die wêreld getoon.

"Maar hierdie gebeure eindig vinnig en sal waarskynlik nie die langdurige ozonuitputting veroorsaak wat aan die einde van die Devoniese periode plaasgevind het nie," het Jesse Miller, 'n student aan die U of I, gesê.

Anders as hierdie ander gebeurtenisse, lewer supernovas 'n kragtige een-twee slag wat die omgewing kan verwoes. Die aanvanklike ontploffing bad ons planeet in ultravioletstraling, X-strale en gammastrale. Dan val 'n kragtige ontploffing van supernova-afval in die sonnestelsel, wat 'n aanhoudende vertoning van kosmiese strale vrystel wat die aarde met straling kan oorstroom en die osoonlaag van die aarde vir 100 000 jaar vernietig.

Op die foto is 'n simulasie van 'n nabygeleë supernova wat met die sonwind bots en saamdruk. Die baan van die aarde, die blou streep en die son, rooi kolletjie, word vir skaal getoon. Beeldkrediet: Jesse Miller

'Hier bestudeer ons 'n alternatiewe moontlike oorsaak vir die gepostuleerde osoonval: 'n nabygeleë supernova-ontploffing wat skade kan aanrig deur kosmiese strale te versnel wat tot [100.000 jaar] ioniserende straling kan lewer. Ons stel dus voor dat die einde van die Devoon-uitwissing veroorsaak is deur supernova-ontploffings op [65 ligjaarafstand], iets verder as die 'doodafstand' wat 'n volle massa-uitwissing sou veroorsaak, 'skryf navorsers in die Proceedings of the National Academy of Sciences. van die Verenigde State van Amerika (PNAS).

Ja, ons het vandag geen supernovas nie ...

“Uitwissing is die reël. Oorlewing is die uitsondering. ”
- Carl Sagan

Selfs hierdie uitgerekte apokalips word verdwerg deur die daling van 300 000 jaar in biodiversiteit wat net voor die uitsterwing gesien is. Dit kan daarop dui dat 'n reeks supernovas die aarde beïnvloed het en die lewe vir ewig sou vorm. Onlangse studies dui daarop dat supernovas geneig is om in trosse voor te kom, wat bewys lewer vir hierdie idee.

Sulke uitbarstings sal die radioaktiewe isotope plutonium-244 en samarium-146, wat nie natuurlik op die aarde voorkom nie, in rotse wat in die geologiese grens van die Devoniese periode uitsterf, voorkom.

'As u groen piesangs in Illinois sien, weet u dat dit vars is en dat u nie hier gegroei het nie. Soos piesangs, verval Pu-244 en Sm-146 met verloop van tyd. As ons dus vandag hierdie radio-isotope op aarde vind, weet ons dat dit vars is en nie van hier af nie - die groen piesangs van die isotoopwêreld - en dus die rookgewere van 'n nabygeleë supernova, ”verduidelik Fields.

As hierdie nuwe studie dit ondersteun deur verdere navorsing, kan dit navorsers help om die gebeure beter te begryp wat gelei het tot een van die grootste uitwissings in die geskiedenis van ons planeet.

James Maynard

James Maynard is die stigter en uitgewer van The Cosmic Companion. Hy is 'n gebore New England-woestynrot in Tucson, waar hy saam met sy pragtige vrou, Nicole, en Max the Cat woon.

Die atmosfeer van Saturnus kan die tuiste van heliumreën wees

Marsverkenning hede en toekoms & # 8211 Kirsten Siebach en Fatima Ebrahimi

Wolf-Rayet Stars vermom as 'n eksotiese sterre pou en die wolf

Komende gaste

29 Junie (s4 / e26): Alyssa Mills, gegradueerde intern by JPL, praat oor die grootste maan in die sonnestelsel, Ganymedes.

6 Julie (s5 / e1): SEISOEN VYF VORIGE! New York Times topverkoper skrywer Earl Swift, skrywer van Oor die Airless Wilds, die eerste belangrike geskiedenis van NASA se maan-buggy.

13 Julie (s5 / e2):

Stella Kafka, uitvoerende hoof van The American Association of Variable Star Observers, praat oor Betelgeuse.

20 Julie (s5 / e3):

Geoff Notkin, gasheer van Meteoriet Mans op die Science Channel en president van die National Space Society, praat meteoriete.

27 Julie (s5 / e4):

CHIME-lid Kaitlyn Shin, student in die MIT-graad, verduidelik vinnige radio-sarsies (FRB's)

3 Augustus (s5 / e5):

Onderrig in wetenskap aan kinders met Stephanie Ryan, skrywer van & # 8220Let & # 8217s Learn Chemistry. & # 8221

Teken in op ons nuusbrief!

Ja! Teken my in vir die Cosmic Companion nuusbrief!

Waardering

& # 8220Nemand hou van sterrekunde daar buite nie, en jy is in die middel daarvan, so hou so aan. & # 8221 & # 8211 Neil deGrasse Tyson

& # 8220Die skou is 'n uitstekende manier om tred te hou met nuwe ontdekkings in die ruimtewetenskap. 'N Mens kan direk van wetenskaplikes hoor in 'n maklik verstaanbare taal. & # 8221- Dr. Dimitra Atri, NYU Abu Dhabi

& # 8220Jou webwerf is wonderlik, en ek dink jou video's is wonderlik. & # 8221 & # 8211 Dr. Jack Hughes, Rutgers Universiteit


Het 'n Supernova 'n 17de-eeuse koning se geboorte?

Die koninklike troue in Engeland sal vandeesmaand beslis vol prag wees, maar 'n 17de-eeuse koning van Groot-Brittanje kan die geleentheid troef met 'n supernova wat sy geboorte aangekondig het, sê navorsers. Die teorie plaas die ontdekking van die sterontploffing 50 jaar vroeër as wat voorheen gedink is.

Die gloeiende warm wolk bekend as Cassiopeia A is die oorblyfsel van 'n massiewe sterontploffing - 'n supernova - wat ongeveer 11 000 ligjare van die aarde af plaasgevind het. Die lig van die kosmiese ontploffing was die eerste keer sigbaar op die aarde toe dit iewers in die 17de eeu aankom.

Maar die presiese datum waarop Cas A se ontploffing vanaf die aarde kon gesien word, was 'n jarelange raaisel in die sterrekunde. Volgens rekords kan die eerste "sterrekundige koninkryk" van Engeland, John Flamsteed, die supernova in 1680 opgeneem het.

Tog moes die lig van die supernova maklik sigbaar gewees het vir almal in die lug.

Nou voer navorsers aan dat dit wyd gesien is - as 'n 'nuwe' ster wat moontlik die geboorte van die toekomstige koning Karel II van Groot-Brittanje op 29 Mei 1630 gekenmerk het. [Top 10 Star Mysteries]

Vrolike monarg word gebore

Karel II, dikwels bekend as die 'Merry Monarch' vir sy lewendige, hedonistiese hof, het na bewering 'n 'middag-ster' by sy geboorte laat verskyn. Dit het 'n belangrike (en miskien twyfelagtige) kenmerk geword in die latere propaganda van die herstel van die monargie wat hom aan bewind gebring het - sy vader, Charles I, is in 1649 tereggestel tydens die hoogtepunt van die Engelse burgeroorlog.

"Ek het 'n weergawe van Charles 'se' middagster 'in 'n boek gesien en het 'n eureka-oomblik gehad," het die navorser Martin Lunn, voormalige kurator vir sterrekunde in die Yorkshire Museum in Engeland, gesê. "Dit pas by die klassieke beskrywing van 'n supernova, en ek het my afgevra of dit dalk 'n waarneming van Cas A. is."

Lunn probeer daarna om te sien hoe lugdig die saak is om Cas A tot die laaste helfte van die 17de eeu te dateer. [Video: Supernovas: vernietigers en skeppers]

"Die getuienis vir die lig wat iewers in die laaste helfte van die 17de eeu aankom, is gebaseer op veronderstelde afstande tot Cassiopeia A, sowel as 'n veronderstelde konstante snelheid van die gas van die uitgestote gas - albei hierdie aannames is egter problematies , "Het Lunn aan SPACE.com gesê. "Ons kan nie seker wees oor die presiese afstand van Cas A nie, en die spoed van die knope van gas sou kon wissel as gevolg van interstellêre materiaal. Hierdie veranderlikes beteken dat ons op sy beste net 'n gemiddelde reeks In ag genome hierdie dubbelsinnigheid, is 'n datum vir Cas A van 1630 buite die moontlikheid. "

Die roete gaan voort

Terselfdertyd het die historikus Lila Rakoczy ondersoek ingestel na die historiese bewyse vir hierdie ster van die middaguur. Daar is baie bronne uit die vroeë 1660's wat hierdie lig in die lug oor Charles II se geboorte noem, waaronder die digter John Dryden.

"As ons 'n bietjie verder gaan, verwys William Lilly, die beroemde parlementêre astroloog, na die ster, maar maak dit af as Venus, in sy 1651-boek 'Monarchy or No Monarchy'," het Rakoczy gesê. "Ek ken geen verwysings na die ster in die 1640's nie, maar dit is nie verbasend nie, aangesien die land besig was met die Engelse burgeroorlog."

"Alhoewel dit volop is, is al hierdie bronne problematies omdat dit 20 tot 30 jaar na die beweerde gebeurtenis verskyn, en die stergebeurtenis is in die 1660's gebruik as 'n belangrike instrument vir die herstel van propaganda, wat dit moeiliker maak om die akkuraatheid van die gebeurtenis te vertrou. , "Het Rakoczy verduidelik.

"Die sterkte van ons saak is dat ons 'n boek 'Britanniae Natalis' van 1630, die jaar van Charles II se geboorte, gevind het, wat help om albei probleme aan te spreek - dit is nie te ver verwyderd van die gebeurtenis nie, en die Engelse burgeroorlog en herstel het nog nie plaasgevind nie, wat beteken dat die politieke onderstrominge baie minder problematies is, 'het sy aan SPACE.com gesê. "Boonop het die boek meer as honderd outeurs, wat almal verbonde was aan die Universiteit van Oxford en dit bestaan ​​uit die room van die Britse intelligensie van die dag. Gesamentlik verteenwoordig hulle 'n menigte akademiese vakgebiede, politieke oortuigings en sosiale agtergronde. Een daarvan is selfs John Bainbridge, die eerste Saviliaanse professor in sterrekunde, so dit is 'n redelik indrukwekkende versameling karakters. '

"Die aantal en verskeidenheid bronne wat na die nuwe ster verwys, dui sterk daarop dat 'n astronomiese gebeurtenis regtig plaasgevind het," het Lunn gesê. "Ons werk laat vrae ontstaan ​​oor die huidige metode vir die datering van supernovas, maar dit lei tot die opwindende moontlikheid om 'n dekades oue astronomiese raaisel op te los."

"Ons idees het die potensiaal om die manier waarop sterrekundiges die afstand tot Cassiopeia A bereken, die snelheid wat die materiaal wegbeweeg vanaf die middelpunt van die ontploffing, radikaal te verander, en hoe die materiaal kan reageer met die interstellêre medium daaromheen," het hy bygevoeg. "Dit kan moontlik ook deure oopmaak vir die volgende generasie sterrekundiges wat Cassiopeia A bestudeer deur hulle toe te laat om die probleem vanuit 'n ander dimensie te beskou."

Lunn en Rakoczy sal hul bevindinge op 18 April tydens die Nasionale Sterrekundevergadering van die Royal Astronomical Society in Llandudno, Wallis, uiteensit.

'N Omstrede eis?

Die navorsers verwag wel dat hul werk omstredenheid sal lok.

"Die datum van 1670 word byna universeel deur sterrekundiges gebruik - dit het 'n bietjie vasgeval in baie mense se gedagtes," het Lunn gesê. "Deur hierdie vroeëre datum voor te stel, daag ons resultate sterrekundiges uit om hul ondersoeke volledig te hersien. Dit is iets wat baie van hulle onwillig sal wees om te doen. Die feit dat dit 'n gesamentlike astronomie-geskiedenisondersoek is eerder as 'n suiwer sterrekunde, sal ook maak ons ​​versigtig met ons gevolgtrekkings. Dit is waarskynlik dat ons buite die gemaksones van baie hoofstroomsterrekundiges opereer. '

"My hoop is dat diegene wat aan Cas A werk, ons saak bloot 'n regverdige verhoor sal gee voordat hulle besluit," het Rakoczy gesê.

Wat toekomstige werk betref, "sou dit interessant wees om te sien of ander waarnemings rondom 1630 in die dokumentêre rekord gevind kan word - nie net in Brittanje nie, maar ook in ander lande," het Rakoczy gesê. "Niemand het, na ons wete, aktief na hulle gaan soek nie."

'Of ons 'n middagster op 29 April sal sien verskyn, kan ek onvoorspelbaar voorspel, alhoewel ek dit op die een of ander manier betwyfel,' het Rakoczy gesê.


Het ek 'n ontploffing in 'n supernova gesien? - Sterrekunde

Week van 28 Februarie 2000

". selfs die helderste ster sal nie vir ewig hou nie. ”
Die Alan Parsons-projek, Spitstyd

Verlede week het ons gesien hoe SN87A ontdek is. 'N Interessanter vraag kan weesHoekom het ons dit gesien? ' Met ander woorde, wat laat 'n ster ontplof? Regverdige waarskuwing: dit is nie 'n maklike onderwerp nie, en selfs met die groot vereenvoudigings wat ek gemaak het, is hierdie snack 'n bietjie lank. Ek dink tog jy sal dit geniet.

Sterre, soos mense, tree op soos hulle optree weens interne stryd. Sterre speel 'n toutrekkery tussen swaartekrag, wat hulle in duie laat stort en hitte en druk, wat hulle wil laat uitbrei. Sterre is baie massief, wat baie swaartekrag gee. Hierdie krag is aansienlik en druk die binnekant van die ster saam. Sterre is basies groot bolle gas, en die gas reageer op hierdie druk deur warmer te word en hul interne druk te verhoog. As dinge net reg uitwerk (en dit gewoonlik doen), word die innerlike swaartekrag gebalanseer deur die uiterlike krag van druk en hitte. 'N Stabiele ster is die resultaat.

Hierdie balans word die grootste deel van 'n ster se lewe gehandhaaf. Die druk en die hitte is so groot in die kern van die ster dat waterstof in helium versmelt word. Hierdie samesmelting gee baie hitte af, wat weer gebruik word om die ster teen sy eie swaartekrag te hou. Let wel, hierdie samesmelting vind diep in die kern van die ster plaas. U kan aan 'n ster dink dat dit twee lae het: 'n baie klein kern waar al die samesmeltingsaksie is, en die buitenste lae van die ster, wat eintlik die grootste deel van die ster se massa bevat. Dit is later belangrik!

Maar daar is 'n probleem: 'n ster het nie 'n oneindige hoeveelheid waterstof nie. Op 'n dag sal dit brandstof raak. Hoe lank dit neem, hang af van die massa van die ster: hoe massiewer hy is, hoe vinniger verbrand hy sy brandstof. 'N Ster soos die Son het genoeg waterstof om sy fusiebrande vir miljarde jare aan die gang te hou, maar 'n ster soos Rigel, 'n massiewe ster in Orion, verbrand sy waterstof so vinnig dat dit binne 'n paar miljoen jaar kan opraak. Sterre met lae massa hou baie waterstof in, en kan honderde miljarde jare skyn.

As die waterstof in 'n ster opraak, raak dinge ingewikkeld. Afhangend van die massa van die ster, kan dit helium in koolstof begin smelt, of dit kan eenvoudig nie die massa hê om dit te doen nie en samesmeltingsreaksies stop. Dit sal 'n rooi reus word, sy buitenste lae afskud en 'n pragtige (indien tydelike) planetêre newel word - maar ons praat daaroor in die volgende week se Snack, belowe ek.


Vir nou is die interessanter geval wanneer 'n massiewe ster nie meer brandstof het nie. Dit het genoeg swaartekrag om die kern verder saam te pers en 'n ketting van reaksies te begin: helium versmelt tot koolstof, en wanneer helium op is, word koolstof in suurstof versmelt, dan suurstof tot magnesium en magnesium in silikon. Hierdie lys is oorvereenvoudig, maar dit gee u 'n idee van wat aangaan. Elke element word op sy beurt weer saamgesmelt tot 'n swaarder element. 'N Alchemis se droom! Die sterre lyk soos 'n ui, met laag vir laag verskillende samesmeltingsprodukte.

Elke opeenvolgende stap gebeur in 'n vinniger tempo, en 'n ster kan miljoene of tienmiljoene jare spandeer om waterstof in helium in te smelt, maar die laaste paar stappe kan letterlik oor tien of honderde jare gebeur. Die probleem is dat daar op hierdie stadium iets sleg gebeur: silikon smelt om te stryk.

Waarom is dit sleg? Want tot nou toe het al hierdie reaksies plaasgevind geproduseer energie in die vorm van hitte. Daardie hitte hou die ster op. Yster is egter 'n spesiale geval. Dit neem energie om yster in swaarder elemente te smelt, energie wat van die ster self kom. As daar genoeg yster in die kern opbou, word die druk groot genoeg om te begin smelt. Dit beroof energie van die ster. Erger nog, die samesmelting van yster vreet groot hoeveelhede elektrone op, en elektrone help ook om die ster te hou.

As yster begin versmelt, gaan dit sleg vinnig. Die ysterkern stort in, aangesien die hitte en elektrone wat dit ophou gewoond raak om die yster te smelt. Die geweldige swaartekrag van die kern stort dit van duisende kilometers oor na 'n bal saamgeperste materie, net 'n paar kilometer in deursnee. in 'n duisendste van 'n sekonde. Dit is soos om die bene onder 'n tafel uit te skop. Soos toe Wile E. Coyote skielik besef dat hy nie meer oor vaste grond is nie en begin val, kom die buitenste lae van die ster afgejaag. Hulle slaan teen 'n goeie fraksie van die ligspoed in die saamgeperste kern in. Dit doen twee dinge: dit stel a op groot rebound, stuur die buitenste lae van die ster weer uit, en stel ook 'n groot aantal neutrino's, subatomiese deeltjies vry wat die energie van die ineenstorting wegdra. Die gas van die buitenste lae absorbeer hierdie neutrino's, soos om 'n vuurhoutjie in 'n vuurwerkfabriek aan te steek. Die buitenste lae ontplof opwaarts, en verskeie sonmassas van gedoemde ster skeur na buite met snelhede van etlike duisende kilometer per sekonde.

Die groot hoeveelheid energie wat vrygestel word, word beskou as 'n supernova. Dit kan ure of dae duur voordat die lig tot 'n maksimum vermeerder, maar gedurende die tyd kan dit binne een sekonde soveel energie produseer as wat ons son gedurende sy hele leeftyd doen, en word dit regoor die heelal gesien. Toe SN87A byna 180 000 ligjare weg is, kan dit maklik met die blote oog gesien word, en dit word as 'n onderlê gebeurtenis beskou! Nogtans was 87A helder genoeg om honderde ligjare alles daaraan toe te lig, en daarop rig ek ons ​​Snack vir volgende week.

'N Interessante uiteinde: in 1987 was daar verskeie neutrino-verklikkers hier op aarde. Hulle is gebruik om die deeltjies van die son te monitor. Op daardie aand van 23 Februarie het een detector in Japan egter 'n geringe uitbarsting van 11 neutrino's opgespoor, wat eintlik baie meer is as wat hy op enige gegewe oomblik gewoonlik van die son ontvang. Neutrino's is, soos dit gebeur, baie moeilik om tydens hul vlug te stop, en die meeste neutrino's wat in die kern van 'n ster ineenstort, vlieg reguit die ruimte in. Dit beteken dat die neutrino's wat deur die Japannese detector opgespoor is, direk van die dood van die ster gekom het. Alhoewel dit 'n paar dae neem om die maksimum te bereik, stel die neutrino's die werklike voor oomblik van ineenstorting. Daaruit weet ons dat Supernova 1987A om 23:36 Greenwich-tyd, 23 Februarie 1987, gebore is. [opmerking: Voordat ek tonne e-posse ontvang en sê dat dit eintlik 180 000 jaar voor die datum gebore is, laat ek dit sê ja, ek weet dit, maar ek wil nie in netelige besprekings van relatiwiteit, gelyktydigheid en dies meer beland nie. Die meeste sterrekundiges gee sulke datums aan, wat beteken dat dit is toe ons die lig opgespoor het, en daarom sal ek ook die snelskrif gebruik.]

    Kyk na Nick Strobel se Astronomy Notes-webwerf vir 'n goeie bespreking van hoe swaartekrag druk in 'n ster balanseer. Hy het 'n prettige geanimeerde afbeelding daarvan. Hy het ook 'n baie meer gedetailleerde beskrywing van hoe sterre ook ontwikkel. Dit sal u help om 'n paar leë spasies in te vul wat ek hier oor het.


Dit is wat ons sal sien as Betelgeuse regtig Supernova word

Die indruk van hierdie kunstenaar toon die reusagtige ster Betelgeuse soos dit aan die lig gebring is danksy verskillende. [+] moderne tegnieke op die Very Large Telescope (VLT) van ESO, wat twee onafhanklike sterrekundespanne in staat gestel het om die skerpste uitsig ooit op die reusagtige ster Betelgeuse te kry. Hulle wys dat die ster 'n groot gaspluim het wat byna net so groot is as ons sonnestelsel en 'n reusagtige borrel wat op sy oppervlak kook.

Die sterre aan die naghemel, gewoonlik staties en onveranderlik, het tans 'n uitsondering. Betelgeuse, die rooi superreus wat een van die "skouers" van die konstellasie Orion vorm, het nie net in helderheid gewissel nie, maar verdof op 'n manier wat lewende mense nog nooit gesien het nie. Dit was een van die tien helderste sterre aan die hemel, en dit is nou net vergelykbaar met die helderheid van die sterre op Orion se gordel, en dit verdof steeds.

Sowat 100 000 jaar, maar baie van ons - waaronder baie professionele en amateur-sterrekundiges - hoop om die eerste supernova met blote oë in ons sterrestelsel sedert 1604 te aanskou. Alhoewel dit geen gevaar vir ons sal inhou nie, sal dit skouspelagtig wees. . Hier is wat ons hier op aarde sal kan waarneem.

Hierdie simulasie van die oppervlak van 'n rooi superreus, het 'n hele jaar van evolusie getoon. [+] net 'n paar sekondes, wys hoe 'n "normale" rooi superreus gedurende 'n relatiewe stil periode ontwikkel, sonder dat dit waarneembaar is aan sy binneprosesse. Die enorme oppervlak en die wisselvalligheid van die tingerige buitenste lae lei tot geweldige wisselvalligheid op kort, maar onreëlmatige tydskale.

Bernd Freytag met Susanne Höfner & amp Sofie Liljegren

Op die oomblik is Betelgeuse absoluut enorm, onreëlmatig gevorm en met 'n oneweredige oppervlaktemperatuur. Dit is ongeveer 640 ligjaar verder geleë, dit is meer as 2000 ° C koeler as ons son, maar ook baie groter, teen ongeveer 900 keer ons sonradius en beslaan ongeveer 700.000.000 keer ons sonvolume. As u ons son sou vervang deur Betelgeuse, sou dit Mercurius, Venus, Aarde, Mars, die asteroïdegordel en selfs Jupiter verswelg!

Maar daar is ook enorme, uitgebreide emissies rondom Betelgeuse van materiaal wat die afgelope paar tientalle millennia afgewaai is: materie en gas wat verder strek as die baan van Neptunus om ons son. Met verloop van tyd, namate die onvermydelike supernova naderkom, sal Betelgeuse meer massa vergiet, voortgaan om uit te brei, chaoties te verdof en te verhelder en geleidelik swaarder elemente in die kern te verbrand.

Die newel van verdrywe materiaal wat rondom Betelgeuse geskep word, word vir skaal in die binneland vertoon. [+] rooi sirkel. Hierdie struktuur, wat lyk soos vlamme wat uit die ster voortspruit, vorm omdat die bek sy materiaal in die ruimte werp. Die uitgebreide uitstoot strek verder as die ekwivalent van Neptunus se baan om die son.

Selfs wanneer dit van koolstof na neon na suurstof na silikonfusie oorgaan, sal ons geen direkte waarneembare handtekeninge van die gebeure hê nie. Die tempo van die kern se samesmelting en energie-uitset sal verander, maar ons begrip van hoe dit die ster se fotosfeer en chromosfeer beïnvloed - die dele wat ons kan waarneem - is te swak vir ons om konkrete voorspellings oor te haal. Die energiespektrum van die neutrino's wat in die kern geproduseer word, die waarneembare waarvan ons weet dat dit sal verander, is irrelevant, aangesien die neutrino-vloed heeltemal te laag is om op te spoor vanaf honderde ligjare.

Maar op 'n kritieke oomblik in die evolusieproses van die ster sal die silikonverbranding van die innerlike kern voltooi wees en die stralingsdruk diep binne Betelgeuse sal daal. Aangesien hierdie druk die enigste ding was wat die ster teen swaartekrag ineenstort, hou die binnekern, wat bestaan ​​uit elemente soos yster, kobalt en nikkel, nou in.

Kunstenaar se illustrasie (links) van die binnekant van 'n massiewe ster in die finale stadiums, pre-supernova,. [+] silikonverbranding. (Silicon-burning is where iron, nickel, and cobalt form in the core.) A Chandra image (right) of the Cassiopeia A supernova remnant today shows elements like Iron (in blue), sulphur (green), and magnesium (red). Betelgeuse is expected to follow a very similar pathway to previously observed core-collapse supernovae.

NASA/CXC/M.Weiss X-ray: NASA/CXC/GSFC/U.Hwang & J.Laming

It's difficult to imagine the scale of this: an object totaling about 20 solar masses, spread out over the volume of Jupiter's orbit, whose inner core is comparable to (and more massive than) the size of the Sun, suddenly begins to rapidly collapse. As large as the gravitational force was pulling everything in on itself, it was counterbalanced by the radiation pressure coming from nuclear fusion in the interior. Now, that fusion (and that outward pressure) is suddenly gone, and collapse proceeds uninhibited.

The innermost atomic nuclei — a dense collection of iron, nickel, cobalt and other similar elements — get forcefully scrunched together, where they fuse into an enormous ball of neutrons. The layers atop them also collapse, but rebound against the dense proto-neutron star in the core, which triggers an incredible burst of nuclear fusion. As the layers pile up, they rebound, creating waves of fusion, radiation, and pressure that cascade through the star.

In the inner regions of a star that undergoes a core-collapse supernova, a neutron star begins to . [+] form in the core, while the outer layers crash against it and undergo their own runaway fusion reactions. Neutrons, neutrinos, radiation, and extraordinary amounts of energy are produced.

TeraScale Supernova Initiative

These fusion reactions take place over a timescale of approximately 10 seconds, and the overwhelming majority of the energy is carried away in the form of neutrinos, which hardly ever interact with matter. The remaining energy-carrying particles, including neutrons, nuclei, electrons, and photons, even with the intense amounts of energy imparted to them, have to have their energy cascade and propagate through the entire outer layers of the star.

As a result of this, the neutrinos become the first signals to escape, and the first signal to arrive on Earth. With the energies that supernovae impart to these particles — on the order of around

10-50 MeV per quantum of energy — the neutrinos will move at speeds indistinguishable from the speed of light. Whenever the supernova actually occurs (or occurred, which could have been anytime from the 14th century onward), it will be the neutrinos that arrive here on Earth first, some 640 years later.

A neutrino event, identifiable by the rings of Cerenkov radiation that show up along the . [+] photomultiplier tubes lining the detector walls, showcase the successful methodology of neutrino astronomy and leveraging the use of Cherenkov radiation. This image shows multiple events, and is part of the suite of experiments paving our way to a greater understanding of neutrinos. The neutrinos detected in 1987 marked the dawn of both neutrino astronomy and the rebranding of nucleon decay experiments as neutrino detector experiments.

Super Kamiokande collaboration

In 1987, a supernova from 168,000 light-years away wound up creating a signal of a little over 20 neutrinos across three small neutrino detectors that were operating at the time. There are many different neutrino observatories in operation today, much larger and more sensitive than the ones we had at our disposal 33 years ago, and Betelgeuse, just 640 light-years away only, would send a signal some 70,000 times stronger on Earth due to its close proximity.

In 2020, if Betelgeuse were to go supernova, our first surefire signature would come in the form of high-energy neutrinos flooding our neutrino detectors all over the world in a burst spanning some 10-15 seconds. There would literally be millions, perhaps even tens of millions, of neutrinos picked up all at once by these observatories. A few hours later, when the first energetic ripples created by this cataclysm reached the star's outer layers, a "breakout" of photons would reach us: a swift spike that increased Betelgeuse's optical brightness tremendously.

In 2011, one of the stars in a distant galaxy that happened to be in the field of view of NASA's . [+] Kepler mission spontaneously and serendipitously went supernova. This marked the first time that a supernova was caught occurring in the act of transitioning from a normal star to a supernova event, with a surprising 'breakout' temporarily increasing the star's brightness by a factor of about 7,000 over its previous value.

All of a sudden, the luminosity of Betelgeuse would spike by about a factor of 7,000 from its previously steady value. It would go from one of the brightest stars in the night sky to the brightness of a thin crescent Moon: about 40 times brighter than the planet Venus. That peak brightness would only last for a few minutes before falling again back to being just about 5 times brighter than it previously was, but then the traditional supernova rise begins.

Over a time period of approximately 10 days, the brightness of Betelgeuse will gradually rise, eventually becoming about as bright as the full Moon. Its brightness will surpass all the stars and planets after about an hour, will reach that of a half Moon in three days, and will reach its maximum brightness after approximately 10 days. To skywatchers across the globe, Betelgeuse will appear to be even brighter than the full Moon, as instead of being spread out over half a degree (like the full Moon), all of its brightness will be concentrated into a single, solitary, saturated point.

The constellation Orion as it would appear if Betelgeuse went supernova in the very near future. Die . [+] star would shine approximately as brightly as the full Moon.

Wikimedia Commons user HeNRyKus / Celestia

As a type II supernova, Betelgeuse will remain bright for a very long time, although there are large variations within these classes of supernovae for exactly how bright they become and how bright they remain over long periods of time. The supernova, after reaching maximum brightness, will slowly begin to fade over the timespan of about a month, becoming about as dim as a half Moon after 30 days time.

Over the next two months, however, its brightness will plateau, becoming dimmer only to instruments and astrophotographers the typical human eye will not be able to discern a change in brightness over this time. All of a sudden, though, the brightness will drop precipitously over the next (fourth) month since detonation: it will go back to barely being brighter than Venus by the end of that time. And finally, over the next year or two, it will gradually fade out of existence, with the supernova remnant visible only through telescopes.

Type II supernovae vary between different sub-types and individual events, but obey the same general . [+] curve, with a rise lasting approximately 10 days, a short fall-off lasting a month, a plateau lasting another two months, a steep drop lasting a month, and then a gradual fade-out lasting a year or longer.

A. Singh et al. (2019), ApJ, 882, 1

At peak brightness, Betelgeuse will shine approximately as brightly as 10 billion Suns all packed together by the time a couple of years have gone by, it will be too faint to be seen with the naked human eye. The reason the supernova remains so bright for the first three months or so isn't even from the explosion itself, but rather from a combination of radioactive decays (from cobalt, for example) and the expanding gases in the supernova remnant.

During those first three months or so, Betelgeuse will be so bright that it will be clearly visible during the day as well as the night only after the fourth month or so will it become a nighttime-only object. And as it begins to fade from its brightness to look like a normal star once again, the extended structures should remain illuminated through a telescope for decades, centuries, and even millennia to come. It will become the closest supernova remnant in recorded history, and will remain a spectacular sight (and astronomical object of study) for generations to come.

The outward-moving shockwave of material from the 1987 explosion that occurred 168,000 light years . [+] away continues to collide with previous ejecta from the formerly massive star, heating and illuminating the material when collisions occur. A wide variety of observatories continue to image the supernova remnant today, but Betelgeuse's supernova will be even closer, easier to study, and will provide us with a far more spectacular visual and scientific feast.

NASA, ESA, and R. Kirshner (Harvard-Smithsonian Center for Astrophysics and Gordon and Betty Moore Foundation) and P. Challis (Harvard-Smithsonian Center for Astrophysics)

Whenever Betelgeuse finally does go supernova — and it could be tonight, next decade, or 100,000 years from now — it will become the most-witnessed astronomical event in human history, visible to nearly all of Earth's inhabitants. The first signal to arrive won't be visual at all, but will come in the form of neutrinos, a typically elusive particle that will flood our terrestrial detectors by the millions.

After that, a few hours later, the light will first arrive in a spike, followed by a gradual brightening over a little more than a week, which will fall off in stages over the coming months before gradually declining for years. The remnant, which consists of gaseous outer layers illuminated for thousands of years, will continue to delight our descendants for generations to come. We have no idea when the show will begin, but at least we know what to look for and expect when it actually occurs!


How to Dissect a Supernova

Top (click to enlarge): An artist's impression of the single white dwarf Type Ia supernova scenario. (Credit: NASA/CXC/M.Weiss)
Bottom: An artist's impression of the double white dwarf Type Ia supernova scenario. (Credit: NASA/CXC/M.Weiss)

One white dwarf star or two: Which scenario leads to a Type Ia supernova, one of the biggest, brightest explosions in the universe? In the single white dwarf scenario (top two images at left), the dwarf star gravitationally draws matter off of a normal, nearby companion star. That matter piles up on the white dwarf, eventually triggering a runaway thermonuclear explosion. An alternative scenario does not require a normal companion star instead, two merging white dwarfs sparks a Type Ia supernova (bottom three images at left).

A new theory, developed by the physicist Daniel Kasen, has offered a fresh way of finding out which scenario, or both, is correct. The theory predicts that the material hurled out from the supernova explosion of a single white dwarf should create an observable ultraviolet flash when it slams into a normal companion star. The absence of that flash, on the other hand, would lend support to the double white dwarf scenario. Recently, astronomers have found examples of Type Ia supernovae with and without Kasen’s ultraviolet flash, suggesting that there is more than one way to unleash this cosmic outburst.

  • LARS BILDSTEN – is the Director of the Kavli Institute for Theoretical Physics (KITP) and a Professor in the Physics Department at the University of California, Santa Barbara (UCSB).
  • ANDREW HOWELL – is a Staff Scientist at Las Cumbres Observatory Global Telescope Network (LCOGT) and an adjunct faculty member in the Physics Department at UCSB. Howell coauthored several recent papers on Type Ia supernovae suggesting single and double white dwarf scenarios are responsible.
  • DANIEL KASEN – is an Associate Professor of Astronomy and Physics at the University of California, Berkeley, and a faculty scientist at the Lawrence Berkeley National Laboratory. Kasen developed the intriguing “shock-wave theory” (see sidebar), used in the two recent papers, one of which he coauthored, that helped astronomers determine what triggers Type Ia supernovae.
  • LAURA CHOMIUK – is an Assistant Professor in Michigan State University's Department of Physics and Astronomy.

The following is an edited transcript of their roundtable discussion. The participants have been provided the opportunity to amend or edit their remarks.

THE KAVLI FOUNDATION: Why is it so important to understand how Type Ia supernovae are triggered?

LAURA CHOMIUK: It's about understanding one of the ultimate mysteries about stars. When our Sun dies, it's going to be a carbon-oxygen white dwarf, basically a big diamond that's going to cool and sort of fade into oblivion. But something in the universe makes one percent of white dwarfs commit suicide and explode as supernovae. We are only now starting to have an idea of what causes this.

ANDREW HOWELL: As Laura just said, we know a lot about how stars live, but we often don't know as much about how stars die. Another reason this interests us is the opportunity to understand the super-compressed gas known as degenerate matter that makes up white dwarfs. We could go to great lengths with hundreds-of-millions-of-dollar experiments to investigate just a little corner of the physics involved in degenerate matter. But with Type Ia supernovae, we get it for free from the universe. So we might as well study these explosions because they allow us to probe areas of science we've never been able to before.

TKF: How will figuring out what makes these supernovae go bang help with a broader understanding of the evolution of the cosmos and its galaxies?

HOWELL: Supernovae tie together so many areas of astrophysics. For example, if you’re interested in how galaxies evolve, the energy from a supernova can locally change the star formation in a galaxy by dissipating the gas and dust needed to form stars. And when supernovae explode, their intense nuclear fusion creates the heavy elements that chemically enrich a galaxy. It's like the alchemy we were trying to do in the Middle Ages, but real and occurring naturally.

In cosmology, we also use Type Ia supernovae to better understand dark energy, which is one of the central mysteries in astronomy right now, or all of physics, really. Nearly seventy percent of the universe is dark energy. So that's the normal stuff in the universe. We're the weird stuff, and we still don’t know what dark energy is. We want to make sure we get the workings of these Type Ia supernovae right so we're able to measure the effects of dark energy well. We rely on these supernovae as "standard candles" and use a portion of their light to calculate cosmic distances. Those distance calculations let us track how the expansion of the universe has changed over its history due to dark energy, so it's important we know just how "standard" our standard candles are.

KITP Director Lars Bildsten has conducted extensive theoretical research on the physics of white dwarf stars and Type Ia supernovae. (Credit: Erika Bildsten)

LARS BILDSTEN: Another mystery we need to solve about this type of supernova is how frequently they occur in the various possible scenarios. What fraction of the time are they the result of mergers of white dwarfs? What fraction of the time are they due to single white dwarfs and companion stars? And then which results in the brightest and most powerful supernova? Figuring out those kinds of things will then help us measure dark energy more efficiently.

We've seen that supernovae in high-mass galaxies behave differently than supernovae in low-mass galaxies. We don't know why that is, and that will be one of the challenges of the next ten years of supernovae research. The answer will be integral for dark energy research.

TKF: What have been the big breakthroughs in understanding this type of supernova?

BILDSTEN: Over the last ten years, we’ve gotten much stronger observational evidence that there are multiple scenarios that cause Type Ia supernovae rather than one. Recognizing that multiple paths lead to these events, I think, has really opened up the theoretical ideas about how these explosions unfold and been extremely healthy and exciting for the field.

HOWELL: Previously, we all thought there was just going to be one scenario for Type Ia supernovae. We would find it, then we'd all go home and that would be the end of it. But now we're starting to see that there are many different ways to make a Type Ia supernova.

TKF: What has enabled these breakthroughs?

Laura Chomiuk's radio wave astronomy research uses the Expanded Very Large Array to study the stellar conditions that lead to Type Ia supernovae. (Credit: Laura Chomiuk)

CHOMIUK: We live in a very lucky time from an observational perspective. That is due to both Mother Nature’s cooperation and several wonderful new facilities and instruments. For example, in 2011 and 2014 we had a couple of Type Ia supernovae explode in nearby galaxies. Because these explosions were so close and bright, we were able to perform detailed tests on them. We've also gotten really good astronomical surveys up and running that are scanning the whole sky, so we've been able to discover Type Ia supernovae earlier, basically right after they explode.

BILDSTEN: We can find a lot of supernovae now thanks to robotic telescopes all around the globe, such as the intermediate Palomar Transient Factory and the Las Cumbres Observatory Global Telescope that Andy works on, which allows for rapid monitoring of these supernovae discoveries. Then we have satellites that can go and get ultraviolet and x-ray observations right away. For radio observations, we have the Expanded Very Large Array in New Mexico that Laura uses, and which was modernized in 2012. So we can probe all wavelengths of light at once now. Lastly, there have been advances in computing that allow us to create three-dimensional simulations of supernovae to test out theoretical models. So it's not just new capabilities but all these new capabilities working together that are allowing us to make such progress.

HOWELL: I think that summary is true for astronomy as a whole. We're developing new capabilities that are leading to big, big jumps in our understanding of whatever it is we're studying, including supernovae.

TKF: Lars and Dan, as theorists, could you describe the feeling you get when your models are borne out by observations?

Daniel Kasen's research in theoretical and computational astrophysics focuses on supernovae, neutron star mergers and other energetic, short-lived cosmic events. (Credit: Daniel Kasen)

DANIEL KASEN: It's a little eerie. As a theorist, you're constantly developing ideas that seem a bit distant and abstract, almost like science-fiction. Then, suddenly, observers actually go out and bring home hard data. That’s when you’re reminded that what you're doing is connected to the real world.

BILDSTEN: It's a pretty rare time for theory because we are making predictions that are then tested on such short timescales. Historically, most theoretical work has not been strongly tested until long afterwards. Astronomy theorists are quite often, therefore, behind the observers in having a coherent picture of what is in fact out there in space. When we get ahead of the observer is when it's the most fun to be a theorist!

TKF: A perfect example of theory preceding observation is Dan's theoretical work. He proposed that material ejected by a Type Ia hits a companion star and produces an ultraviolet pulse. Andy, as well as some other astronomers, has now observed those pulses. Dan, how did you come up with this theory? And then Andy, how did you and your colleagues run with Dan's ideas?

KASEN: It was basically a question of simple curiosity. People have discussed over the years whether companion stars could survive the blast from a nearby supernova explosion. But nobody had asked, "What would it look like to actually see that happen?" It must be pretty incredible to witness the debris from the supernova—which moves at over a million miles an hour—slam head-on into another star. So I did a back-of-the-envelope calculation to estimate how hot that collision would be, how bright it might be, and so on. Surprisingly, the collision turned out to be bright enough to be seen on Earth. That gave the observers an idea of what to look for.

BILDSTEN: I remember seeing Dan give a talk at a conference here at KITP back in 2009 on his theory and saying to myself, "This is obviously the right calculation," and "This must happen." It was clear that his theory was going to provide a new avenue for testing the different hypotheses about the scenarios that generate Type Ia supernovae. And that’s what is now playing out. Dan's work is not just some made-up model. It's something you can really sink your teeth into.

Andrew Howell leads a group of scientists specializing in supernovae and dark energy research at LCOGT and UCSB. (Credit: Andrew Howell)

HOWELL: That's exactly what I was going to say, Lars. The first time I heard Dan describe his theory, it just blew me away. I remember thinking, "Whoa, this is incredible—we can totally test this out."

We quickly figured out, though, that the observations of supernovae we had on record weren't good enough. To test out Dan’s theory, we needed to do new studies to catch supernovae really early on. That realization has driven a lot of our subsequent telescope and observation proposals, like the robotic telescopes that Lars mentioned, which capture supernovae right after they occur rather than days or weeks later. As new surveys have captured hundreds of supernovae, it's been great to finally see Dan's theory play out.

TKF: What’s still missing in our picture about Type Ia supernovae? Dan, what’s still keeping you up at night?

KASEN: For a long time the question about Type Ia supernovae has been, "Is it a single white dwarf exploding, or is it a merging of two white dwarfs?" Today, a lot of people feel like both things happen. But within each of those ideas, we are still not sure how the supernova goes off how does the star gets ignited? Does it always explode or might it instead collapse into a superdense neutron star? Is the first spark of the explosion lit at the center as an accreting white dwarf is compactified, or is the star lit from the outside in, by igniting a fuse of accreted gas at the surface?

To try to connect your theory to observations, you have to use some pretty sophisticated, multi-dimensional computer simulations. We are still trying to draw those lines between the various theories and data.

BILDSTEN: It would be nice if there were a scenario we theorists could walk through with a fair amount of confidence that produces a Type Ia supernovae. I would say we're still not there, but we're getting closer.

TKF: What observations could plug these remaining gaps in our knowledge?

CHOMIUK: We've seen supernovae go off very close by in other galaxies, but we would really love it if one went off right in our galactic backyard, here in the Milky Way galaxy.

KASEN: With so many surveys happening, we're getting a very rich set of the "normal" Type Ias. But we're also really starting to probe the outliers, the unusual ones, and it could well be that some of those one-in-a-hundred weirdos will give us clues that will help unravel what’s happening in the dominant scenarios.

HOWELL: We also need theoretical breakthroughs. There's a crisis in supernova rates. No mechanism really accounts for how many supernovae we see. Figuring that out will require a lot of theoretical work, and observations will help get us there.

TKF: Does anyone have a sinking feeling that there could be three or more scenarios that explain Type Ia supernova?

KASEN: People feel confident that it is either one white dwarf or two white dwarfs exploding. But within each of those scenarios there are many different pathways, so to speak. Take the two white dwarfs scenario. There are several different ways to initiate the supernovae. You might imagine the stars wound up on a head-on collision course and blew up right away. Or maybe the two stars orbited each other and gradually spiraled in and merged, forming a single super-massive star that then later exploded. It is almost certainly white dwarfs exploding, but there might be almost a dozen different ways to make that happen.

BILDSTEN: We have categorized these major different pathways consisting of one white dwarf or two, but each of these is kind of hard and has steps that we don't understand. That could be the biggest clue that we don't actually have the right pathway. But if we don't, I think we're much better prepared now for the surprise.

CHOMIUK: To reiterate what Lars just said, we're all prepared to be surprised. We're at this really cool cultural moment right now where people are very humble and open-minded. If you ask almost anyone if they feel like they really understand what's going on in a Type Ia supernovae, they'll say no. They’ll say that the assumptions they’ve held for decades have been dashed by the wonderful observations and theoretical progress we've had in the last 10 years. Everybody's really open-minded and willing to go back to the drawing board.

KASEN: At once, we know more than we've ever known about Type Ia supernovae, and we also know less than we've ever known about Type Ia supernovae.


Putting the “Super” in Supernova

Image of most powerful supernova explosion ever recorded (SOURCE)

Within the past year, astronomers have made an incredible discovery about 4.5 million light years away from us. A supernova, but not just any supernova, the most powerful supernova recorded in history ever spotted by astronomers. This explosion is so powerful that astronomers did not even know that it was possible to have such a powerful supernova in our galaxy. The energy that was released from this supernova equated to about, “10 times more energy than the sun will emit during its entire lifetime,” truly putting into context the nature of such an explosion. According to astronomers researching this supernova, in order to create such a massive explosion the star must have shed a shell of material that made up about half of its mass before actually blowing up. This would mean that the explosion smashed through the shell, “like a wrecking ball,” at a speed of almost 4600 km/s which in turn would create a massive blast of radiation. Not only is this interesting that this supernova was the most massive one we have ever observed, but questions surrounding this explosion point to the fact that when modeling supernovas in the past we have never seen a star lose half of its mass about a decade before the actual explosion. This leads many astronomers to wonder what would have caused something like this to happen, and can potentially lead to us learning more about supermassive stars that may have existed in the early beginnings of our universe. Did you know that this discovery was made? Comment your reactions down below!


Scientists enthralled by biggest star explosion ever observed

WASHINGTON (Reuters) - Scientists have observed the biggest supernova - stellar explosion - ever detected, the violent death of a huge star up to 100 times more massive than our sun in a faraway galaxy.

The supernova, releasing twice as much energy as any other stellar explosion observed to date, occurred about 4.6 billion light years from Earth in a relatively small galaxy, scientists said. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

It might represent, they added, a type of supernova that until now has only been theorized.

Astrophysicist Matt Nicholl of the University of Birmingham in England said two very massive stars - each about 50 times the sun’s mass - may have merged to make one extremely massive star roughly 1,000 years before the explosion. They had been part of what is called a binary system with two stars gravitationally bound to each other.

The merged star exploded in a supernova, formally named SN2016aps, inside a very dense and hydrogen-rich envelope.

“We found that the supernova was able to become so bright because of a powerful collision between the debris ejected by the explosion and a shell of gas shaken off by the star a few years earlier,” said Nicholl, lead author of the study published this week in the journal Nature Astronomy.

Stars die in various different ways depending on their size and other properties. When a massive star - more than eight times the mass of our sun - uses up its fuel, it cools off and its core collapses, triggering shock waves that cause its outer layer to explode so violently that it can outshine entire galaxies.

The researchers, who observed the explosion for two years until it diminished to 1 percent of its maximum brightness, said it may have been an example of an extremely rare “pulsational pair-instability” supernova.

“Pulsational pair-instability is when very massive stars undergo pulsations which eject material away from the star,” said study co-author Peter Blanchard, a postdoctoral fellow in astrophysics at Northwestern University in Illinois.

“This discovery shows that there are many exciting and new phenomena left to be uncovered in the universe,” Blanchard added.

Very massive stars like this one were probably more common early in the universe’s history, Nicholl said.

“The nature of those first stars is one of the big questions in astronomy,” Nicholl added. “In astronomy, seeing things further away means looking back further and further in time. So we might actually be able to see the very first stars if they explode in a similar manner to this one. Now we know what to look for.”


Betelgeuse is dimming, again!

Betelgeuse is one of the stars that make up the constellation Orion, the bright red star that is its shoulder to be precise. It is a red supergiant, a star that is about 700 times the size of our Sun, and as you might have heard in recent news, it is dimming.

Now this dimming is not necessarily anything new, as this star has had a variable brightness for thousands of years to the extent where ancient Greeks and Aboriginal Australians have noticed this. What is special about this dimming is that it the star became about 6.5x dimmer than usual, which is much more than anything that has been recorded in the last century of measurements. Does this mean that it will blow up any time soon? Astronomers don’t think so, they postulate that it is caused by several cycles overlapping for the first time in many centuries.


NASA's NuSTAR Untangles Mystery of How Stars Explode

One of the biggest mysteries in astronomy, how stars blow up in supernova explosions, is being unraveled with the help of NASA's Nuclear Spectroscopic Telescope Array.

The high-energy X-ray observatory has created the first map of radioactive material in a supernova remnant. The results, from a remnant named Cassiopeia A (Cas A), reveal how shock waves likely rip apart massive dying stars.

"Stars are spherical balls of gas, and so you might think that when they end their lives and explode, that explosion would look like a uniform ball expanding out with great power," said Fiona Harrison, the principal investigator of NuSTAR at the California Institute of Technology (Caltech) in Pasadena. "Our new results show how the explosion's heart, or engine, is distorted, possibly because the inner regions literally slosh around before detonating."

Harrison is a co-author of a paper about the results appearing in the Feb. 20 issue of Nature.

Cas A was created when a massive star blew up as a supernova, leaving a dense stellar corpse and its ejected remains. The light from the explosion reached Earth a few hundred years ago, so we are seeing the stellar remnant when it was fresh and young.

Supernovas seed the universe with many elements, including the gold in jewelry, the calcium in bones and the iron in blood. While small stars like our sun die less violent deaths, stars at least eight times as massive as our sun blow up in supernova explosions. The high temperatures and particles created in the blast fuse light elements together to create heavier elements.

NuSTAR is the first telescope capable of producing maps of radioactive elements in supernova remnants. In this case, the element is titanium-44, which has an unstable nucleus produced at the heart of the exploding star.

The NuSTAR map of Cas A shows the titanium concentrated in clumps at the remnant's center and points to a possible solution to the mystery of how the star met its demise. When researchers simulate supernova blasts with computers, as a massive star dies and collapses, the main shock wave often stalls out and the star fails to shatter. The latest findings strongly suggest the exploding star literally sloshed around, re-energizing the stalled shock wave and allowing the star to finally blast off its outer layers.

"With NuSTAR we have a new forensic tool to investigate the explosion," said the paper's lead author, Brian Grefenstette of Caltech. "Previously, it was hard to interpret what was going on in Cas A because the material that we could see only glows in X-rays when it's heated up. Now that we can see the radioactive material, which glows in X-rays no matter what, we are getting a more complete picture of what was going on at the core of the explosion."

The NuSTAR map also casts doubt on other models of supernova explosions, in which the star is rapidly rotating just before it dies and launches narrow streams of gas that drive the stellar blast. Though imprints of jets have been seen before around Cas A, it was not known if they were triggering the explosion. NuSTAR did not see the titanium, essentially the radioactive ash from the explosion, in narrow regions matching the jets, so the jets were not the explosive trigger.

"This is why we built NuSTAR," said Paul Hertz, director of NASA's astrophysics division in Washington. "To discover things we never knew - and did not expect - about the high-energy universe."

The researchers will continue to investigate the case of Cas A's dramatic explosion. Centuries after its death marked our skies, this supernova remnant continues to perplex.