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Wat sou gebeur as iemand 'n teleskoop sou hê en Betelgeuse sou aanskou as dit supernova word?

Wat sou gebeur as iemand 'n teleskoop sou hê en Betelgeuse sou aanskou as dit supernova word?


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Sou daardie persoon blind word?

Neutrino-detektore en die oorvloed Neutrinos sal die komende sigbare vertoning ongeveer 3 uur voor enige sigbare tekens opspoor, dus sal daar tyd wees om sekere teleskope te wys wat die helderheid daarheen kan hanteer.

Ek is nuuskierig of iemand met 'n teleskoop in die rigting wys 'n onaangename verrassing sal hê. Sou die wetenskaplike gemeenskap verstandig wees om die massiewe sterreontploffing eers aan te kondig nadat dit sigbaar is om potensiële negatiewe gevolge van oorgretige amateursterrekundiges te vermy.

Ek besef dit is 'n soort dom vraag en dit hang dalk te veel van die teleskoop af, maar ek is nuuskierig.


Nee, dit sou nie 'n probleem wees nie. Supernovas lyk glad nie soos gloeilampe nie - hulle word helder oor baie dae en verdof weer stadiger. Hier is 'n aantal verskillende ligkrommes wat uit Wikipedia geneem is:

Die styging is vinnig op 'n astronomiese skaal - verskeie orde van grootte gedurende ongeveer tien dae - maar baie stadig op menslike skaal. 'N Amateur wat daarna kyk, sien geen noemenswaardige verandering in die helderheid nie, maar as dieselfde persoon 'n paar uur later of die volgende nag terugkom, sal die verandering baie duidelik wees.

Sover ons kan agterkom, is die rede dat die lig met die hoogste helderheid veroorsaak word deur emissies van materiaal wat deur die ontploffing afgewaai word. Byvoorbeeld, in tipe 1a SNe is die grootste deel van die lig afkomstig van die radioaktiewe verval van die groot massa uitgestote nikkel-56 (halfleeftyd 6 dae).

Die Wikipedia-artikel oor supernovas is redelik goed en bespreek dit alles in meer besonderhede.


Helderheid wissel omgekeerd met die vierkant van die afstand. Betelgeuse is ongeveer 642,5 ligjare weg en het 'n skynbare grootte van 0,42. My begrip van skynbare groottebegrippe is 'n bietjie wankelrig, maar ek glo dat as dit 'n miljoen keer so helder geword het, dit miskien 'n skynbare grootte van -14,5 of so het, wat baie meer soos die helderheid van die maan lyk as die son.

Gegewe die groot afstand, die afname in helderheid as gevolg van die afstand, en die ontelbare hoeveelhede stof en gas tussen aarde en Betelgeuse, dink ek u sal waarskynlik goed wees. U kan u verstom deur die helderheid daarvan - 'n bietjie soos om na 'n gloeilamp te kyk, dink ek - maar ek twyfel of dit fisiese skade sou berokken.

REDIGERING: Ek hoop hier klink 'n regte sterrekundige. Ek is nie seker watter soort supernova ons van Betelgeuse kan verwag nie, maar blykbaar kan supernovas (supernovas?) 'N teoretiese helderheid bereik wat gelyk is aan 5 triljoen sons!


As u daarop aandring om die ontploffende Betelgeuse waar te neem, kan dit u oog beskadig. Die volledige antwoord betree die gebied van fisiologie. Hier bespreek ek die astronomiese dele:

Betelgeuse sal ontplof as 'n tipe II-supernova waarvan die helderheid tipies is $ M sim -17 $. Met 'n afstand van $ d simeq200 , mathrm {pc} $, is sy afstandsmodus $$ mu = 5 log (d / mathrm {pc}) - 5 simeq 6.5, $$ dus sal die skynbare grootte daarvan wees $$ m = M + mu simeq -10.5. $$

Vir hierdie berekeninge neem ek aan dat die son die drempel is om u oog te beskadig ('n kort blik op die son is goed, 'n langer kyk sal permanente skade veroorsaak. Maar ... fisiologie ...). Die son het 'n skynbare grootte van $ m_ odot = -26,7 $, dit wil sê dit is $ Delta m = 16,2 $ groottes helderder. Met ander woorde, Betelgeuse sal wees $$ f = 10 ^ { Delta m / 2.5} simeq 3 keer10 ^ 6 $$ dowwer as die son.

Die son is egter 'n uitgebreide bron wat ongeveer 'n hoek strek $ theta_ mathrm {Sun} = 32 $ boogminute oor. Daarenteen is Betelgeuse 'n puntbron wat versprei word deur die atmosfeer en die teleskoop $ theta_ mathrm {Bet} sim $ 'n paar vierkantige boogsekondes. Dus sal die lig daarvan meer gekonsentreerd wees; dit wil sê dit sal baie helderder wees, maar dit sal 'n baie kleiner area van u retina tref. Jou oog sal egter ook rondbeweeg en die lig uitsmeer. Omdat ek nie 'n fisioloog is nie, neem ek ter wille van hierdie berekening aan dat die lig uitgesmeer word oor 'n skyf 1 boogminuut (ongeveer die grootte van 'n planeet gesien vanaf die aarde).

Dus, die faktor $ f $ sal self 'n faktor wees $ ( theta_ mathrm {Sun} / theta_ mathrm {Bet}) ^ 2 simeq 1000 $ keer groter - dit is net Betelgeuse $ sim 3 , 000 $ dowwer as die son.

Dus, volgens ons aannames, sal u oog beskadig word as u waarneem hoe Betelgeuse deur 'n teleskoop met 'n gebied ontplof. $ sim 3 , 000 $ groter - of ongeveer 55 keer breër - as jou pupil. In helder lig trek die pupil tot 'n deursnee van ongeveer 3 mm saam, dus as u deur 'n teleskoop van 16 cm of groter waarneem, kan u u oog beskadig.

Gebaseer op evolusionêre modelle van Betelgeuse, Dolan et al. (2016) skat 'n skynbare grootte van $ m = -12,4 $, dit wil sê ongeveer 6 keer helderder as ons skatting. Dit sou beteken dat u slegs 'n 7 cm-teleskoop benodig om u oog te beskadig.

Soos Mark in sy antwoord skryf, verhoog supernovas egter nie tot hul piek helderheid in sekondes nie, maar eerder in sake (ongeveer 'n halwe mag per dag), dus het u genoeg tyd om weg te kyk.


Van Wikipedia: Die visuele ligkrommes van die verskillende supernovatipes hang almal op laat tye af van radioaktiewe verhitting, maar dit wissel in vorm en amplitude vanweë die onderliggende meganismes, die manier waarop sigbare bestraling geproduseer word, die periode van waarneming en die deursigtigheid van die uitgestote materiaal. Die ligkrommes kan by ander golflengtes aansienlik verskil. Byvoorbeeld, by ultraviolette golflengtes is daar 'n vroeë uiters helder piek wat slegs 'n paar uur duur, wat ooreenstem met die uitbreek van die skok wat deur die aanvanklike gebeurtenis geloods is, maar die uitbreek is amper nie opties waarneembaar nie.

Ek is nie seker of ek deur 'n groot teleskoop na Betelgeuse wil kyk as dit gebeur nie. Sigbare lig is nie wat jou oog beskadig nie. UV is.


Apa yang akan terjadi jika seseorang memiliki teleskop dan menyaksikan Betelgeuse ketika menggunakan supernova?

Detektor Neutrino dan kelimpahan Neutrino akan mendeteksi pertunjukan yang akan datang sekitar 3 jam sebelum tanda-tanda yang terlihat, sehingga akan ada waktu untuk mengarahkan teleskop tertentu yang dapat menangani kecerahan ke arah itu.

Saya ingin tahu apakah seseorang dengan teleskop yang menunjuk ke arah itu akan memiliki kejutan yang tidak menyenangkan. Apakah komunitas ilmiah bijaksana untuk tidak mengumumkan ledakan bintang besar sampai setelah itu terlihat untuk menghindari efek negatif potensial dari para astronom amatir yang terlalu bersemangat.

Saya menyadari ini adalah pertanyaan konyol dan mungkin terlalu bergantung pada teleskop, tapi saya penasaran.

Tidak, itu tidak akan menjadi masalah. Supernova sama sekali tidak seperti bola lampu - mereka mencerahkan selama beberapa hari dan redup lagi bahkan lebih lambat. Berikut sejumlah kurva cahaya berbeda yang diambil van Wikipedia:

Peningkatannya cepat pada skala astronomi - beberapa urutan besarnya selama sekitar sepuluh hari - tetapi sangat lambat pada skala manusia. Seorang amatir yang melihatnya tidak akan melihat perubahan signifikan dalam kecerahan, tetapi jika orang yang sama kembali beberapa jam kemudian atau malam berikutnya, perubahan itu akan sangat jelas.

Sejauh yang bisa kita katakan, alasannya adalah bahwa cahaya pada kecerahan puncak disebabkan oleh emisi dari material yang meledak oleh ledakan. Sebagai contoh, dalam Tipe 1a SNe, sebagian besar cahaya berasal dari peluruhan radioaktif dari massa besar nikel-56 yang dikeluarkan (waktu paruh 6 hari).

Die artikel Wikipedia pada supernova cukup baik dan mencakup semua ini secara lebih rinci.

Jika Anda bersikeras mengamati Betelgeuse yang meledak pada kecerahan puncak, Anda berpotensi merusak mata Anda. Jawaban lengkap memasuki ranah fisiologi. Di sini saya akan membahas bagian astronomi:

Betelgeuse akan meledak sebagai supernova tipe II, kecerahan tipikal adalah sekitar. Dengan jarak, modulus jaraknya adalah jadi besarnya yang terlihat adalah M ∼ - 17 d ≃ 200 p c

Untuk perhitungan ini saya berasumsi bahwa Matahari adalah ambang untuk merusak mata Anda (pandangan singkat pada Matahari tidak apa-apa, pandangan yang lebih lama akan menyebabkan kerusakan permanent. Tapi. Fisiologi.). Matahari memiliki magnitudo, yaitu magnitudo lebih terang. Dengan kata lain, Betelgeuse akan menjadi kali lebih redup daripada Matahari. m ⊙ = - 26,7 Δ m = 16,2

Namun, Matahari adalah somber yang diperluas, mencakup sudut kira-kira arcminutes. Sebaliknya, Betelgeuse adalah sumber titik, yang ketika ditransfer melalui atmosfer dan teleskop, tersebar di beberapa archesecond persegi. Dengan demikian cahayanya akan lebih terkonsentrasi yaitu akan jauh lebih terang, tetapi akan mengenai area retina yang jauh lebih kecil. Namun, mata Anda juga akan bergerak, mengoleskan cahaya. Bukan menjadi ahli fisiologi, demi perhitungan ini saya berasumsi bahwa cahaya dioleskan di atas cakram 1 melintas 1 (sekitar ukuran planeet dilihat dari Bumi). θ S u n = 32 θ B e t ∼

Dengan demikian, faktor itu sendiri akan menjadi faktor kali lebih besar - yaitu, Betelgeuse hanya kali lebih redup daripada matahari. f (θ S u n / θ B e t) 2 ≃ 1000 ∼ 3 000

Oleh karena itu, untuk asumsi kami mata Anda akan rusak jika Anda mengamati Betelgeuse yang meledak melalui teleskop dengan area lebih besar - atau kira-kira 55 kali lebih luas - dari murid Anda. Dalam cahaya terang, pupil berkontraksi dengan diameter sekitar 3 mm, jadi jika mengamati melalui teleskop 16 cm atau lebih besar, Anda dapat merusak mata Anda. 000 3 000

Berdasarkan model evolusi Betelgeuse, Dolan et al. (2016) memperkirakan besarnya, yaitu sekitar 6 kali lebih terang dari perkiraan kami. Ini berarti Anda hanya perlu teleskop 7 cm for merusak mata Anda. m = - 12.4

Namun, seperti yang ditulis Mark dalam jawabannya, supernova tidak meningkatkan kecerahan puncaknya dalam hitungan detik, tetapi dalam hitungan hari (kira-kira setengah mag per hari), jadi Anda punya banyak waktu untuk berpaling.


Hoe lank het die eens verduisterende ster Betelgeuse oor?

Dit word een van die beroemdste sterre van alle tye genoem: Betelgeuse (uitgespreek & quotBeetlejuice, & quot, soos die film) is deel van die bekende Orion-konstellasie en is gewoonlik die 10de helderste ster in die hemel, sigbaar selfs met die blote oog. .

& quotBetelgeuse was mettertyd meer bekend as Mickey Mouse, of enige mens wat vandag leef, & quot, sê Andy Howell, personeelsterrekundige by die Las Cumbres-sterrewag en 'n fisikus aan die Universiteit van Kalifornië, Santa Barbara, in 'n e-posonderhoud. & quotDit is omdat ons menslike nagtelike vermaak gedurende honderdduisende jare na die naghemel gekyk het. & quot

Maar in Oktober 2019 het Betelgeuse se ster geheimsinnig begin verdof. Sy gemak het selfs by toevallige waarnemers gesien. Sterrekundiges was verbouereerd oor die skielike verandering van die bui. Sommige het vermoed dat Betelgeuse nie meer brandstof gehad het nie, miskien supernova geword het. Sterre wat supernova word, skep die kragtigste ontploffings wat in die ruimte voorkom.

Meer onlangse navorsing dui egter daarop dat Betelgeuse nie noodwendig op die punt van dood is nie. Dit kan bloot 'n soort vuilveld geproduseer het wat die ongelooflike helderheid tydelik geblokkeer het.

& quot Betelgeuse is 'n rooi superreus-ster, ongeveer 12 keer die massa van die son, maar 'n allemintige 900 keer die deursnee, & quot; sê Howell. & quot Dit beteken dat as Betelgeuse was waar die son is, dit die aarde maklik sou insluk en uitstrek tot verder as die baan van Jupiter. & quot

Hy voeg by dat rooi superreuse aan die einde van hul lewens sterre is, nadat hulle al die waterstof tot helium in hul kern versmelt het. Aangesien hulle swaarder en swaarder elemente verbrand, trek hul kerne saam en hul buitenste lae trek op tot buitengewone afmetings.

Betelgeuse was nog altyd bekend vir sy veranderlike helderheid. Oor die algemeen kom hierdie skommelinge semi-gereeld voor en in slegs beskeie hoeveelhede. Howell sê dit gebeur omdat dit pols terwyl die ster-atmosfeer soos 'n pot kokende water woel en groot vlekke materiaal opgooi.

& quot Maar verlede jaar het dit vir die blote oog merkbaar begin verdof en het dit lankal taamlik verdof op 'n manier wat in meer as 'n eeu nie gesien is nie, & quot; sê hy. & quot Dit was 'n raaisel totdat waarnemings aan die lig gebring het dat daar 'n groot stofwolk was wat 'n groot fraksie van die ster bedek. & quot

& quotDie oorsaak van die verduistering word bespreek en beredeneer, & quot e-pos Edward Guinan, 'n professor in astrofisika en planetêre wetenskap aan Villanova. & quot Die verduistering kan wees as gevolg van die uitstoot van gas wat tot stof afgekoel het en die ster se lig versper het. Aan die ander kant het die onlangse verduistering (die 'groot verduistering' of 'groot floute' genoem) plaasgevind op die tydstip wat verwag is gedurende die 430-dae periode, dus in hierdie geval sou dit verband hou met verkoeling wat veroorsaak word deur polsing of die teenwoordigheid van 'n -grote konveksiesel. & quot

Guinan voeg by dat hy en sy kollegas dink dat die verduistering veroorsaak is deur 'n ekstra energieke pols of die opwelling van reuse-konveksiesel en nie nuwe stof nie. & quot Voortgesette waarnemings behoort hierdie vraag binnekort te beantwoord, & quot sê hy.


Betelgeuse: Sterwende vonke hoop op & # 8216maan & # 8217 -grootte supernova oor die aarde

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Betelgeuse, die gewoonlik helderrooi ster in die sterrebeeld Orion, kan sterf - en sy supernova sal eendag teen die maan in die lug bokant die aarde meeding. Eendag.

Betelgeuse is tans in sy rooi reusagtige fase, wat die geriatriese stadium van 'n ster se lewe is wanneer dit helder en opgeblase word voordat dit sterf. Die volgende fase is 'n volwaardige supernova, wanneer die ster op homself sal neerval in 'n massiewe ontploffing.

Na verwagting sal die ontploffing in die volgende 100 000 jaar plaasvind, volgens NASA. As dit wel gebeur, word daar van die aarde verwag om 'n skouspelagtige vertoning op te steek wat weke lank sal duur.

Baie skywatchers hoop dat & # 8220sometime & # 8221 binnekort & # 8220sometime & # 8221 sal wees nadat hulle die afgelope paar maande 'n duidelike afname in die lig van Betelgeuse gesien het. Betelgeuse & # 8217; s helderheid vervaag deur meer as die helfte in die laaste deel van 2019, maak dit dowwer as dit & # 8217; s ooit in die opgeneemde geskiedenis. Dit is nog steeds sigbaar in die & # 8220armpit & # 8221 van Orion, maar dit is nie naastenby so helder soos vroeër nie.

NASA sê Betelgeuse loop & # 8220waarskynlik & # 8221 net deur sy veranderlike siklusse, wat dit van tyd tot tyd helderder of dowwer laat lyk. Dit is 'n hoesende, kranige ou ster, en daar sal waarskynlik hik soos dit die einde nader.

3:09 NASA ontdek die eerste potensieel bewoonbare aarde-grootte planeet

'N Onlangse uitbarsting van swaartekraggolwe het die bespiegeling aangewakker dat die einde vir Betelgeuse naby kan wees, hoewel die sterrekundige Andy Howell sê dat die twee situasies waarskynlik nie verband hou nie.

Howell het toegegee dat hy na buite gestap het om te sien of Betelgeuse Dinsdag opgeblaas het, hoewel hy dit vergelyk het met & # 8220; koop 'n lotto & # 8221 in terme van die geringe kans dat dit kan voorkom.

& # 8220Betelgeuse-opblaas sou baie opwindender wees as om die lotto te wen, & # 8221 Howell getwiet. & # 8220Lotiewenners vind elke dag plaas. Dit is 400 jaar gelede dat mense 'n supernova in ons sterrestelsel gesien het, en ek is een van die beste voorbereide mense op die planeet daarvoor. & # 8221

Supernova-kenner J. Craig Wheeler sê dit is hoogs onwaarskynlik dat Betelgeuse op die punt staan ​​om te ontplof.

"My geld was deurentyd dat Betelgeuse 'n ietwat ekstreme, maar andersins normale, kwasi-periodieke verandering in helderheid ondergaan," het hy aan The New York Times van die Universiteit van Texas in Austin gesê.

Nietemin sê sommige hemelwagters dat hulle gereed is om die Betelgeuse-sterwenswag te begin. Net vir ingeval.

Net 'n ou, met 'n teleskoop, en hoop dat Betelgeuse gaan groei.

& mdash Mark Benson (@WaysideWriter) 14 Januarie 2020

Betelgeuse is ongeveer 640 ligjaar van die aarde af. Dit beteken dat dit naby genoeg is dat ons kan sien hoe dit sterf sonder 'n teleskoop, terwyl ons ver genoeg is dat dit ons nie seermaak as dit gaan nie, sê NASA. En dit sal absoluut iewers in die volgende 100 000 jaar verloop, wat volgens sterrekundiges 'n werklik skouspelagtige vertoning sal wees.

Wanneer Betelgeuse opblaas, sal die supernova omtrent so helder wees soos 'n kwartmaan in die aarde se lug, volgens 'n artikel in 2015 oor die onderwerp deur Jillian Scudder, 'n astrofisikus wat in die Verenigde Koninkryk gebaseer is. Die supernova verskyn duidelik in die naghemel en sal selfs bedags sigbaar wees as jy weet waar om te soek.

1:59 Prag van & # 8216Super Wolf Blood Moon & # 8217 vasgelê in time lapse video

Scudder het gesê dat 'n sterwende Betelgeuse ongeveer 16 keer helderder sou wees as die mees gedokumenteerde supernova, wat in 1006 'n opskudding onder baie antieke beskawings veroorsaak het.

& # 8220 Daar is gesê dat die supernova in 1006 helder genoeg was om snags 'n skaduwee te gooi, & # 8221 Scudder. & # 8220Betelgeuse, wat aansienlik helderder is, sal waarskynlik ook skaduwees gee. & # 8221

Een simulasie dui daarop dat dit vir 'n paar weke sal lyk soos 'n helder straatlig wat aan die lug hang voordat dit verdwyn en een minder ster in die Orion-konstellasie laat.

Die gewilde sterrekundige Neil deGrasse Tyson het die woorde van Scudder weergalm in 'n lang Twitter-draad oor die dood van Betegeuse vroeër hierdie maand.

& # 8220Het hoef nie paniekerig te raak nie, maar as dit sou ontplof, sou die flits bedags sigbaar wees en die helderheid van die maan vir 'n paar weke meeding, 'het Tyson geskryf.

Tyson het ook daarop gewys dat Betelgeuse & # 8220may reeds ontplof het, & # 8221 aangesien dit ongeveer 640 jaar sal neem voordat die lig die aarde bereik. Dit sal dit 'n spook maak of 'n & # 8220doodster wat loop, & # 8221 soos Tyson dit gestel het.

Trouens, daar is dalk nou baie & # 8220doodsterre & # 8221 in die naghemel, alhoewel ons dit millennia lank nie sou weet nie vanweë hoe lank dit neem vir lig om deur die ruimte te reis.

Soos die skrywer Alan Moore dit eens gestel het: & # 8220Al wat ons ooit van sterre sien, is hul ou foto's. & # 8221

En die volgende foto van Betelgeuse kan 'n mal foto wees - alhoewel dit 'n paar millennia kan neem voordat dit by ons uitkom.


Betelgeuse is kleiner, nader en sal binnekort nie ontplof nie

Betelgeuse soos gesien in golflengtes van sub-millimeter deur die ALMA-teleskoop in Chili. Die & # 8220bump & # 8221 aan die linkerkant is warm gas wat effens uit die rooi superreusster se uitgebreide atmosfeer uitsteek. Beeld via ALMA (ESO / NAOJ / NRAO) / E. O'Gorman / P. Kervella / ASU.

Betelgeuse is 'n rooi superreusster in die beroemde konstellasie Orion die jagter en een van die helderste sterre in ons naghemel. Verlede jaar het hierdie geliefde helder ster dramaties begin verdof, wat aanleiding gegee het tot bespiegeling of dit uiteindelik sy einde kan nader in 'n vurige ontploffing en 'n supernova & # 8211 soos verwag word in die toekoms. Baie het gevra, kan dit wees? Dit was baie opwindend. Maar nou dui 'n nuwe studie van navorsers aan die Australiese Nasionale Universiteit & # 8211 op 16 Oktober 2020 & # 8211 aan dat ons dalk nog 100.000 jaar sal moet wag voordat Betelgeuse se plofbare finale is. Die bevindings toon ook dat Betelgeuse kleiner en nader is as wat wetenskaplikes gedink het.

Die navorsers het hul gevolgtrekkings in 'n nuwe portuurbeoordeelde artikel in Die Astrofisiese Tydskrif op 13 Oktober 2020.

Hierdie vergelykingsbeeld toon die ster Betelgeuse voor en na sy ongekende verduistering, wat einde 2019 begin het. Die waarnemings - geneem met die SPHERE-instrument van die Very Large Telescope (VLT) in Januarie en Desember 2019 - toon aan hoeveel die ster vervaag het en hoe sy oënskynlike vorm het verander. Beeld via ESO / M. Montargès et al.

Meridith Joyce aan ANU, wat die studie gelei het, het gesê:

Dit is normaalweg een van die helderste sterre aan die lug, maar ons het twee druppels in die helderheid van Betelgeuse waargeneem sedert laat 2019. Dit het die bespiegeling aangespoor om te ontplof. Maar ons studie bied 'n ander verduideliking. Ons weet dat die eerste verduisteringsgeleentheid 'n stofwolk behels het. Ons het gevind dat die tweede kleiner gebeurtenis waarskynlik as gevolg van die pulsasies van die ster was.

As die tweede verduistering van die ster inderdaad te wyte was aan natuurlike pulsasies, sou dit belangrik wees in terme van wat met Betelgeuse in die nabye en langtermyn toekoms sal gebeur. Met behulp van hidrodinamiese en seismiese modellering kon die navorsers vasstel dat drukgolwe die oorsaak van die pulsasies was. Dit beteken dat die ster nog helium brand, en daarom moet dit nie binnekort ontplof nie. Mede-outeur Shing-Chi Leung van die Universiteit van Tokio het die studie gesê:

& # 8230 het bevestig dat drukgolwe & # 8211 in wese, klankgolwe & # 8211 die oorsaak was van die polsing van Betelgeuse.

Hierdie beeld, verkry met die VISIR-instrument op ESO se Very Large Telescope, toon die infrarooi lig wat in Desember 2019 deur die stof rondom Betelgeuse uitgestraal word. Die stofwolke, wat in hierdie dramatiese beeld lyk soos vlamme, word gevorm wanneer die ster sy materiaal werp terug in die ruimte. Die swart skyf verduister die middelpunt van die ster en baie van sy omgewing, wat baie helder is en gemasker moet word om die flouer stofpluime te laat sien. Die oranje kolletjie in die middel is die SPHERE-beeld van Betelgeuse se oppervlak, wat 'n grootte het naby aan die van Jupiter se baan. Beeld via ESO / P. Kervella / M. Montargès et al.

Dit brand tans helium in sy kern, wat beteken dat dit nie naastenby ontplof nie. Ons kan ongeveer 100 000 jaar kyk voordat 'n ontploffing plaasvind.

Die studie het ook ander verrassende besonderhede oor Betelgeuse verskaf: dit is kleiner en nader aan ons sonnestelsel as wat voorheen gedink is. Dit is nog steeds 'n rooi superreus-ster, honderde keer groter as ons son, maar met 'n effens kleiner radius. Volgens medeskrywer László Molnár van die Konkoly-sterrewag in Boedapest:

Die werklike fisiese grootte van Betelgeuse was 'n bietjie raaisel vroeër studies het voorgestel dat dit groter as die baan van Jupiter kan wees. Volgens ons resultate strek Betelgeuse slegs tot 2/3 daarvan, met 'n radius van 750 keer die sonstraal.

Sodra ons die fisiese grootte van die ster gehad het, kon ons die afstand vanaf die aarde bepaal. Ons resultate toon dat dit net 530 ligjare van ons af is, 25% nader as wat ons gedink het.

Meridith Joyce aan ANU, hoofskrywer van die nuwe studie. Beeld via ANU.

Dit is aansienlik nader as die voorheen geskatte afstand van 724 ligjare, maar nog steeds baie veilig. Telkens wanneer Betelgeuse uiteindelik ontplof, is dit steeds ver genoeg dat die ontploffing nie veel, indien enige, effek op die aarde sal hê nie. Dit is 'n vertroostende gedagte, maar as die wetenskaplikes reg is, sal niemand van ons wat op die oomblik lewe, daar wees om dit te sien nie. Maar vir enige ander destydse wetenskaplikes sal dit 'n unieke kans wees om 'n supernova te sien wat betreklik naby is. Joyce het gesê:

Dit is nog steeds 'n baie groot probleem as 'n supernova afgaan. En dit is ons naaste kandidaat. Dit gee ons 'n seldsame geleentheid om te ondersoek wat met sterre soos hierdie gebeur voordat hulle ontplof.

Verlede jaar in Augustus het wetenskaplikes wat die Hubble-ruimteteleskoop (HST) gebruik het, gerapporteer dat 'n groot stofwolk waarskynlik die eerste verduistering van die ster veroorsaak het, begin laat 2019. Die stofwolk is vermoedelik gevorm deur digte warm gas wat deur Betelgeuse beweeg het. # 8217s uitgebreide atmosfeer.

Die konsep van hierdie kunstenaar met drie panele illustreer nuwe navorsing en verduidelik waarom die helderrooi superreusster Betelgeuse skielik vir 'n paar maande flouer geword het gedurende die einde van 2019 en vroeg in 2020. In paneel 1 word 'n helder, warm vlek plasma van die ster uitgegooi. In paneel 2 brei die uitvloeiende gas vinnig na buite uit en word dit koel tot 'n enorme wolk van verduisterende stof. In paneel 3 keer die groot stofwolk Betelgeuse se lig gedeeltelik. Beeld via NASA / ESA / E. Wheatley (STScI) / CfA.

Die ster het later weer na normale helderheid begin terugkeer tot tussen einde Junie en vroeg in Augustus 2020, toe dit weer verdof. Soos in hierdie nuwe studie verduidelik, is die tweede, vlakker verduistering waarskynlik veroorsaak deur normale polsings in die ster self. Dit is nie te verrassend nie, aangesien Betelgeuse 'n veranderlike ster is en deur helderheidsiklusse gaan wat ongeveer 420 dae duur.

Die nuwe resultate ondersteun ander bewerings van wetenskaplikes dat Betelgeuse waarskynlik nie binnekort supernova sal wen nie. Boonop sal die navorsers die gedrag en die akkurate metings van die ster se grootte en afstand beter verstaan ​​en hoe en waarom hierdie reuse-sterre uiteindelik sulke vurige sterftes in die gesig staar.

Kortom: die rooi superreusster Betelgeuse kan dalk nog nie 100 000 jaar ontplof nie, en is volgens 'n nuwe studie ook kleiner en nader as wat eers gedink is.


SN1987A oorblyfsel

Al hierdie praatjies oor die minimum van honderd jaar van Betelgeuse het mense opgewonde gemaak oor die moontlikheid dat die groot rooi ster in 'n skouspelagtige supernova gaan groei. Terwyl 'n Betelgeuse-supernova weke of nie maande lank met die blote oog sigbaar is nie, sal dit uiteindelik verdwyn.

Hoe lank voordat ons kan verwag om die oorblyfsel visueel op te tel met 'n amateur-teleskoop?

Onthou SN1054 is nou M1, die eerste keer waargeneem

SN 1572 (Tycho's Supernova) is die eerste keer in die 60's waargeneem deur een van die Mt Palomar-teleskope te gebruik - dit klink asof dit onsigbaar is vir amateurteleskope.

SN 1604 (Kepler's Supernova) - status nie duidelik nie.

Is dit moontlik om die oorspronklike ster en die oorblyfsel binne 'n leeftyd te sien?

# 2 Ruimte Mier

Al hierdie praatjies oor die minimum van honderd jaar van Betelgeuse het mense opgewonde gemaak oor die moontlikheid dat die groot rooi ster in 'n skouspelagtige supernova gaan groei. Terwyl 'n Betelgeuse-supernova weke of nie maande lank met die blote oog sigbaar is nie, sal dit uiteindelik verdwyn.

Hoe lank voordat ons kan verwag om die oorblyfsel visueel op te tel met 'n amateurklas-teleskoop?

Onthou SN1054 is nou M1, die eerste keer waargeneem

700-800 jaar later.

SN 1572 (Tycho's Supernova) is die eerste keer in die 60's waargeneem deur een van die Mt Palomar-teleskope te gebruik - dit klink asof dit onsigbaar is vir amateurteleskope.

SN 1604 (Kepler's Supernova) - status nie duidelik nie.

Is dit moontlik om die oorspronklike ster en die oorblyfsel binne 'n leeftyd te sien?

Die oorblyfsel van 1987a is reeds deur Hubble en / of enkele groter sterrewagte, iirc, afgebeeld. Ek twyfel egter of die meeste amateur-toerusting dit kan waarneem / beeld.

# 3 Slaapgebrek

Onthou SN1054 is nou M1, die eerste keer waargeneem

700-800 jaar later.

SN 1572 (Tycho's Supernova) is die eerste keer in die 60's waargeneem deur een van die Mt Palomar-teleskope te gebruik - dit klink asof dit onsigbaar is vir amateurteleskope.

SN 1604 (Kepler's Supernova) - status nie duidelik nie.

Elk van die supernova's hierbo genoem, is relatief ver in vergelyking met Betelgeuse. Alhoewel daar baie onsekerheid is, is die geskatte afstande 6 000/8 000/20 000 ligjare, maar Betelgeuse is 700 IS LY ver.

As dit gaan, sal Betelgeuse se supernova skouspelagtig wees. As dit môre sou gebeur, sou ek verwag dat die uitbreidende oorblyfsel redelik vinnig sigbaar sou wees nadat die glans van die supernova afgeneem het, selfs in amateurbestek. 1987A is sigbaar in groot omvang, maar is baie (baie !!) kere verder as Betelgeuse, ek vermoed dat 'iets' altyd sigbaar sou wees - die glans van die SN eers, dan die verdofte wit dwerg, dan die uitbreidende oorblyfsel die wit dwerg verdof.

Daar was vandag 'n artikel op CNN oor presies dit, en dit het gesê dat sterre soos Betelgeuse (hulle het spesifiek oor Betelgeuse gepraat) verwag kan word om te lewe

9MY. Vervolgens word gesê dat 'n supernova waarskynlik 100 000 jaar af is, hoewel die presiese tydsberekening onvoorspelbaar is. Ek het geen idee van hierdie tydsbestek nie - ek gaan net deur wat ek gelees het. Hoe sal amateursterrekunde oor 100 000 jaar wees. Amateursterrekunde 100.000 jaar van nou af is moontlik presies wat dit 100.000 jaar gelede was, sodat wanneer die 'besoekersster' onder die drumpel van die menslike visie verdwyn, dit nooit weer gesien kan word nie.

Ape, aan die ander kant, kan dalk die vordering hierbo met hul amateur-omvang volg! Ten minste as die romp van die Statue of Liberty nie hul siening blokkeer nie. LOL.

# 4 B l a k S t a r

Ha. Donker lug in die verbode gebied.

# 5 Allan Wade

In 1987 het ek oor professionele sterrekunde gedink en sou ek elke aand buite deurbring. Ek het rondom die LMC gespan en 'n baie helder ster aan die rand van die Tarantula gesien wat die vorige aand nie daar was nie. Ek het dadelik my fisika-onderwyser gebel en hy het terloops gesê, dit is waarskynlik 'n supernova. Wat ek sou gee, het toe internet gehad.

Met die verband in gedagte, was dit 'n opwinding in April vanjaar toe ek vir die eerste keer die oorblyfsels van SN1987A in die 32 ”kon sien. Ek het dit nog nooit vantevore oorweeg nie, maar ek dink dit sou nie te algemeen wees dat iemand die supernova sowel as die oorblyfsel sien nie. In my geval is die waarnemings net meer as 32 jaar van mekaar geskei.

# 6 Araguaia

Hier is 'n vraag: wat gebeur as u 'n ster in die omgewing waarneem met 'n ordentlike opening wanneer dit ontplof? Raak jy blind?

# 7 AstroVPK

Elk van die supernovas wat hierbo genoem word, is relatief ver in vergelyking met Betelgeuse. Alhoewel daar baie onsekerheid is, is die geskatte afstande 6 000/8 000/20 000 ligjare, maar Betelgeuse is 700 IS LY ver.

As dit gaan, sal Betelgeuse se supernova skouspelagtig wees. As dit môre sou gebeur, sou ek verwag dat die uitbreidende oorblyfsel redelik vinnig sigbaar sou wees nadat die glans van die supernova afgeneem het, selfs in amateurbestek. 1987A is sigbaar in groot omvang, maar is baie (baie !!) kere verder as Betelgeuse, ek vermoed dat 'iets' altyd sigbaar sou wees - die glans van die SN eers, dan die verdofte wit dwerg, dan die uitbreidende oorblyfsel die wit dwerg verdof.

Daar was vandag 'n artikel op CNN oor presies dit, en dit het gesê dat sterre soos Betelgeuse (hulle het spesifiek oor Betelgeuse gepraat) verwag kan word om te lewe

9MY. Vervolgens word gesê dat 'n supernova waarskynlik 100 000 jaar af is, hoewel die presiese tydsberekening onvoorspelbaar is. Ek het geen idee van hierdie tydsbestek nie - ek gaan net deur wat ek gelees het. Hoe sal amateursterrekunde oor 100 000 jaar wees. Amateursterrekunde 100.000 jaar van nou af is moontlik presies wat dit 100.000 jaar gelede was, sodat wanneer die 'besoekersster' onder die drumpel van die menslike visie verdwyn, dit nooit weer gesien kan word nie.

Ape, aan die ander kant, kan dalk die vordering hierbo uiteengesit volg met hul amateur-omvang !! Ten minste as die romp van die Statue of Liberty nie hul siening blokkeer nie. LOL.

Die afstand maak enige oorblyfsel tien keer groter in hoekgrootte op 'n gegewe ware fisiese grootte - dit is 'n wonderlike punt. Allan Wade commented in the post above that he's seen the SN1987A remnant in a 32" scope. It's been 32 years since 1987, so it sounds like if Betelgeuse does go supernova, it'll be possible to have seen it as a star, supernova, and remnant within a lifespan. That's pretty cool.


What happens if Betelgeuse explodes?

As a star nears the end of its life, it runs out of fuel and essentially collapses under its own gravity. The death of a giant star results in a massive explosion witnessed across galaxies, a supernova.

Astronomers have only been able to observe supernovae faint stars in distant galaxies. Because of the distance, these supernovae are only detected long after the star has exploded. But Betelgeuse is right here in our neck of cosmic woods — being this close to the star means that scientists could observe the entire process from start to finish in unprecedented detail.

“We’ll have a front-row seat observation to what happens when a star becomes a supernova,” Guinan says.

The problem is knowing wanneer that might happen. Astronomers aren’t exactly sure what happens before a star goes supernova, so it’s hard to predict whether Betelgeuse will explode tomorrow -- or 100,000 years from now. When Betelgeuse explodes remain a cosmic mystery.

“No one has ever really seen a star before it became supernova, or measured it for weeks or months before it happened,” Guinan says. “There’s no precedence, there are no clues.”

Scientists still aren't sure whether this is part of the star’s irregular behavior or if Betelgeuse is about to give us the show of a lifetime.

“There’s a very, very, very low chance that it would blow up, but if it does -- then it would completely change my life,” Andy Howell, staff scientist at Las Cumbres Observatory Global Telescope Network, tells Inverse. “It’s like a lottery ticket . very low probability but life-changing.”

If Betelgeuse were to explode, the star will appear super bright once more— in fact, it's going to appear brighter than it's ever been.

The exploding star would reach peak brightness after a week or so, becoming as bright as the full Moon in the night sky and casting a shadow on Earth.

The detonation would also be visible during the daytime, similar to how Venus looks in twilight. Its light would last for a few months, before it plateauing and eventually completely fading from our vision over the course of a year or two.

Aside from the awe-inspiring sight of a star visible during the day, it would be an incredible learning opportunity for scientists around the world. An astronomical event of this size would make everyone hyper-aware of astronomy and the intricate science behind our stars, Howell says.

Observing a supernova in real time would also provide insight into some of the still-unexplored physics behind the stellar explosions, he says.

“People have been trying to simulate supernova for decades,” Howell says. “But in the simulators, they haven’t been blowing up.”

Because our knowledge of these events is incomplete, astronomers think they are likely still missing a piece of the puzzle behind what causes a star to explode.


Betelgeuse went dark, but didn’t go supernova. Wat het gebeur?

What look like dramatic flames are actually clouds of dust surrounding the red supergiant star Betelgeuse, as photographed in infrared light by the Very Large Telescope in Chile. The black disk blocks the star’s bright light to allow the dust plumes to show. Betelgeuse itself, photographed by the SPHERE instrument in Chile, is superimposed in the center of the black disk.

ESO, Pierre Kervella, M. Montargès et al

Deel dit:

November 29, 2020 at 6:00 am

Astrophysicist Miguel Montargès has a clear memory of the moment the stars became real places to him. He was 7 or 8 years old, looking up from the garden of his parents’ apartment in the south of France. A huge, red star winked in the night. The young space fan connected the star to a map he had studied in an astronomy magazine and realized he knew its name: Betelgeuse.

Something shifted for him. That star was no longer an anonymous speck floating in a vast uncharted sea. It was a destination, with a name.

“I thought, wow, for the first time … I can name a star,” he says. The realization was life-changing.

Since then, Montargès, now at the Paris Observatory, has written his Ph.D. thesis and about a dozen papers about Betelgeuse. He considers the star an old friend, observing it many times a year, for work and for fun. He says good-bye every May when the star slips behind the sun from the perspective of Earth, and says hello again in August when the star comes back.

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So in late 2019, when the bright star suddenly dimmed for no apparent reason, Montargès was a little alarmed. Some people speculated that Betelgeuse was about to explode in a brilliant supernova that would outshine the full moon. Astronomers know the star is old and its days are numbered, but Montargès wasn’t ready to see it go.

“It’s my favorite star,” he says. “I don’t want it to die.”

Other researchers, though, were eager to watch Betelgeuse explode in real time. Supernovas mark the violent deaths of stars that are at least eight times as massive as the sun (SN: 11/7/20, p. 20). But astronomers still don’t know what would signal that one is about to blow. The outbursts sprinkle interstellar space with elements that ultimately form the bulk of planets and people — carbon, oxygen, iron (SN: 2/18/17, p. 24). So the question of how supernovas occur is a question of our own origins.

A bit dim

The SPHERE instrument in Chile took images of Betelgeuse in January (top) and December (bottom) 2019. The December image shows a dark splotch, a dimming, over Betelgeuse’s southern hemisphere.

January 2019

ESO, M. Montargès et al
December 2019

ESO, M. Montargès et al

But the explosions are rare — astronomers estimate that one occurs in our galaxy just a few times a century. The last one spotted nearby, SN 1987A, was more than 33 years ago in a neighboring galaxy (SN: 2/18/17, p. 20). Betelgeuse is just one of the many aging, massive stars — called red supergiants — that could go supernova at any moment. But as one of the closest and brightest, Betelgeuse is the one that space enthusiasts know best.

So when the star started acting strangely at the end of last year, Montargès and a small band of Betelgeuse diehards aimed every telescope they could at the dimming giant. Over the following months, the star returned to its usual brightness, and the excitement over an imminent supernova faded. But the flurry of data collected in the rush to figure out what was happening might help answer a different long-standing question: How do massive, old stars send their planet-building star stuff into the cosmos even before they explode?

Orion’s shoulder

If you’ve looked up at the stars during winter in the Northern Hemisphere, you’ve probably seen Betelgeuse, whether you realized it or not. The star is the second brightest in the constellation Orion, marking the hunter’s left shoulder from our perspective.

And it’s huge. Estimates for Betelgeuse’s vital statistics vary, but if it sat at the center of our solar system, the star would fill much of the space between the sun and Jupiter. At about 15 to 20 times as massive as the sun, somewhere between 750 and 1,000 times its diameter and just about 550 light-years from Earth, Betelgeuse is typically between the sixth- and seventh-brightest star in the sky.

Betelgeuse’s brightness varies, even under normal circumstances. Its outer layers are a bubbling cauldron of hot gas and plasma. As hot material rises to the surface, the star brightens as material falls toward the core, the star dims. That convection cycle puts Betelgeuse on a semiregular dimmer switch that fluctuates roughly every 400 days or so. The star’s brightness also varies about every six years, though astronomers don’t know why.

Big deal

Betelgeuse is the left shoulder of the Orion constellation (left). The star’s first portrait, made with the Hubble Space Telescope in 1996, took some doing. Hubble’s operators worried that the bright star would fry the telescope’s detectors. So astrophysicist Andrea Dupree had to use every filter Hubble had — “like wearing four sets of sunglasses,” she says. “There was nothing. Black. No light got through.” Only by taking off the sunglasses could she finally see the massive star, with a diameter that rivals the width of Jupiter’s orbit.

What they do know is that Betelgeuse is running out of time. It’s less than 10 million years old, a youngster compared with the roughly 4.6-billion–year-old sun. But because Betelgeuse is so massive and burns through its fuel so quickly, it’s already in the final life stage of a red supergiant. Someday in the not too distant future, the star won’t be able to support its own weight — it will collapse in on itself and rebound in a supernova.

“We know one day it’s going to die and explode,” says Emily Levesque, an astrophysicist at the University of Washington in Seattle. But no one knows when. “In astronomical terms, ‘one day’ means sometime in the next 200,000 years.”

In October 2019, Betelgeuse started dimming, which wasn’t too strange in and of itself. The change fit within the normal 400ish-day cycle, says astronomer Edward Guinan of Villanova University in Pennsylvania, who has been tracking Betelgeuse’s cycles of brightness since the 1980s.

But by Christmas, Betelgeuse was the dimmest it had been in the 100-plus years that astronomers have measured it. And the dimming continued all the way through February.

Guinan was one of the first to sound the alarm. On December 7, and again on December 23, he and colleagues posted a bulletin on The Astronomer’s Telegram website announcing the star’s “fainting” and encouraging fellow astronomers to take a look.

There was no reason to think that the dimming was a harbinger of a supernova. “I never said it was going to be one,” Guinan says. But because these explosions are so rare, astronomers don’t know what the signals of an imminent supernova are. Dimming could be one of them.

That report of odd behavior was all astronomers and amateur space enthusiasts needed to hear. Online, the story caught fire.

“On Twitter, it was hysterical,” says Andrea Dupree, an astrophysicist at the Harvard & Smithsonian’s Center for Astrophysics in Cambridge, Mass. She recalls seeing one tweet suggesting that the explosion was going to happen that night, with the hashtag #HIDE. “Where am I going to hide? Under my desk?” (When Betelgeuse finally explodes, it probably won’t hurt life on Earth — it’s a safe distance away.)

Living large

After millions of years, stars that are between eight and 30 times the sun’s mass evolve into yellow supergiants, spend a few thousand years as such, then become red supergiants like Betelgeuse. Ultimately these stars explode violently as supernovas. The images above are not to scale.

C. ChangSources: Kathryn Neugent/Univ. of Washington S. Ekstrӧm et al/Astronomy & Astrophysics 2012

C. ChangSources: Kathryn Neugent/Univ. of Washington S. Ekstrӧm et al/Astronomy & Astrophysics 2012

Most astronomers didn’t really believe that Betelgeuse’s end was nigh, even as they rushed to schedule telescope time. But some got caught up in the excitement.

“I don’t expect it to blow,” Guinan recalls thinking. “But I don’t want to blink.” He signed up for phone alerts from telescopes that detect invisible particles called neutrinos and ripples in spacetime called gravitational waves. A detection of either one might be an early sign of a supernova. He found himself outside at 1 a.m. in January after a report of gravitational waves from the direction of Orion. “It was cloudy, but I thought I might see a brightening,” he says. “I’ve gotten crazy about it.”

Others were believers too, until their data cast doubt on the notion.

“I thought it might,” says astrophysicist Thavisha Dharmawardena of the Max Planck Institute for Astronomy in Heidelberg, Germany. “We knew there were other explanations, and we might have to look into it. But we know Betelgeuse is an old star, close to the end of its life. It was exciting.”

Two camps

Once the star started returning to its usual brightness in mid-February, talk of an imminent supernova faded. A paper published in the Oct. 10 Astrophysical Journal boosted confidence in Betelgeuse’s longevity, suggesting that the star is just at the beginning of its old age and has at least 100,000 years to go before it explodes. But what was it up to, if it was not on the verge of exploding?

As results from telescopes all over the world and in space flooded in, most astronomers have fallen into two camps. One says Betelgeuse’s dimming was caused by a cloud of dust coughed out by the star itself, blocking its glow. The other camp isn’t sure what the explanation is, but says “no” to the dust speculation.

One explanation for why Betelgeuse went dark in 2019 is that the star sneezed out a burst of gas and dust (illustrated, left), which condensed into a dark cloud. That cloud blocked the star’s face from the perspective of Earth (right). NASA, ESA, E. Wheatley/STScI

If the dust theory proves true, it could have profound implications for the origins of complex chemistry, planets and even life in the universe. Red supergiants are surrounded by diffuse clouds of gas and dust that are full of elements that are forged only in stars — and those clouds form before the star explodes. Even before they die, supergiants seem to bequeath material to the next generation of stars.

“The carbon, oxygen in our body, it’s coming from there — from the supernova and from the clouds around dying stars,” Montargès says. But it’s not clear how those elements escape the stars in the first place. “We have no idea,” he says.

Montargès hoped studying Betelgeuse’s dimming would let scientists see that process in action.

In December 2019, he and colleagues took an image of Betelgeuse in visible light with the SPHERE instrument on the Very Large Telescope in Chile. That image showed that, yes, Betelgeuse was much dimmer than it had been 11 months earlier — but only the star’s bottom half. Perhaps an asymmetrical dust cloud was to blame.

Observations from February 15, 2020, seem to support that idea (SN: 4/11/20, p. 6). Levesque and Philip Massey of the Lowell Observatory in Flagstaff, Ariz., compared the February observations with similar ones from 2004. The star’s temperature hadn’t dropped as much as would be expected if the dimming was from something intrinsic to the star, like its convection cycles, the pair reported in the March 10 Astrofisiese joernaalbriewe.

That left dust as a reasonable explanation. “We know Betelgeuse sheds mass and produces dust around itself,” Levesque says. “Dust could have come toward us, cooled and temporarily blocked the light.”

Dark cloud

A strong vote for dust came from Dupree, who was watching Betelgeuse with the Hubble Space Telescope. Like Guinan, she has a decades-long relationship with Betelgeuse. In 1996, she and colleague Ronald Gilliland looked at Betelgeuse with Hubble to make the first real image of any star other than the sun. Most stars are too far and too faint to show up as anything but a point. Betelgeuse is one of the few stars whose surface can be seen as a two-dimensional disk — a real place.

By the end of 2019, Dupree was observing Betelgeuse with Hubble several times a year. She had assembled an international team of researchers she calls the MOB, for Months of Betelgeuse, to observe the star frequently in a variety of wavelengths of light.

In late 2019, Betelgeuse started dimming (V curve, right) more than its normal up and down (V curve, left). The blue and green dots are brightness measurements from ground-based observatories.

Betelgeuse brightness measurements, 2019-2020

A.K. Dupree et al/Astrophysical Journal 2020

A.K. Dupree et al/Astrophysical Journal 2020

The goal was the same as Montargès’: to answer fundamental questions about how Betelgeuse, and perhaps other red supergiants, lose material. The MOB had baseline observations from before the dimming and already had Hubble time scheduled to track the star’s brightness cycles.

Those observations showed that in January and March 2019, Betelgeuse looked “perfectly normal,” Dupree says. But from September through November, just before the dimming event, the star gave out more ultraviolet light — up to four or five times its usual UV brightness — over its southern hemisphere.

The temperature and electron density in that region went up, too. And material seemed to be moving outward, away from the star and toward Earth.

Dupree and colleagues’ theory of what happened, reported in the Aug. 10 Astrophysical Journal, is that one of the giant bubbles of hot plasma always churning in the star’s outer layers rose to the edge of the star’s atmosphere and escaped, sending huge amounts of material flowing into interstellar space. That could be one way that red supergiants shed material before exploding.

Once it had fled the star, that hot stuff cooled, condensed into dust and floated in front of Betelgeuse for several months. As the dust cleared, Betelgeuse appeared brighter again.

“It seems to us that what we saw with the ultraviolet is kind of the smoking gun,” Dupree says. “This material moved on out, condensed and formed this dark, dark dust cloud.”

Paul Hertz, director of NASA’s astrophysics division, shared the Hubble results in a NASA online town hall meeting on September 10 as if it were the final answer. “Mystery solved,” he said. “Not gonna supernova anytime soon.”

Cycles and spots

Maybe not — but that doesn’t mean dust explains the dimming.

In the July 1 Astrofisiese joernaalbriewe, Dharmawardena and colleagues published observations of Betelgeuse that ran counter to the dust explanation. Her team used the James Clerk Maxwell Telescope in Hawaii in January, February and March to look at Betelgeuse in submillimeter wavelengths of light. “If we think it’s a dust cloud, the submillimeter is the perfect wavelength to look at,” she says.

Dust should have made Betelgeuse look brighter in those wavelengths, as floating grains absorbed and reemitted starlight. But it didn’t. If anything, the star dimmed slightly. “Our first thought was that we’d done something wrong — everyone in the community expected it to be dust,” she says. But “the fact that it didn’t increase or stay constant in the submillimeter was pretty much a dead giveaway that it’s not dust.”

Infrared observations with the airborne SOFIA telescope should have found the glowing signature of dust too, if it existed. “It never showed up,” Guinan says. “I don’t think it’s dust.”

Instead, Guinan thinks the dimming may have been part of Betelgeuse’s natural convection cycle. The star’s outer atmosphere constantly pulsates and “breathes” in and out as enormous bubbles of hot plasma rise to the surface and sink down again. “It’s driven by the internal core of the star,” he says. “You have hot blobs rising up, they cool, they get more dense, they fall back.”

Multiple cycles syncing up could explain why the 2019 dimming was so extreme. Guinan and colleagues analyzed about 180 years of observations of Betelgeuse, dating back to astronomer John Herschel’s 1839 discovery that the star’s brightness varies. Guinan’s group found that, in addition to the roughly six-year and 400-day cycles, Betelgeuse might have a third, smaller cycle of about 187 days. It looks like all three cycles might have hit their brightness nadirs at the same time in late 2019, Guinan says.

Or maybe the darkness in the southern hemisphere that Montargès’ team saw with SPHERE was an enormous star spot, Dharmawardena offers. In the sun’s case, those dark splotches, called sunspots, mark the sites of magnetic activity on the surface. Betelgeuse is one of a handful of stars on which star spots have been directly seen.

But to cause Betelgeuse’s dimming, a star spot would have to be enormous. Typical star spots cover about 20 to 30 percent of a star’s surface, Dharmawardena says. This one would need to cover at least half, maybe up to 70 percent.

“That’s rare,” Dharmawardena admits. “But so is this kind of dimming.”

Pandemic disruptions

Analyses are still coming in. But just as Betelgeuse was returning to its normal brightness, the COVID-19 pandemic hit.

“We were hoping to have a lot more data,” Dharmawardena says.

A few observations came in right under the wire. The SOFIA observations were made on one of the last flights before the pandemic grounded the plane that carries the telescope. And Montargès took another look with SPHERE just days before its observatory shut down in mid-March.

In mid-July 2020, astronomers announced that STEREO, a sun-watching spacecraft, had seen signs that the star Betelgeuse was beginning to dim yet again. HI/Stereo/NASA

In mid-July 2020, astronomers announced that STEREO, a sun-watching spacecraft, had seen signs that the star Betelgeuse was beginning to dim yet again. HI/Stereo/NASA

But one of Montargès’ most hoped-for results may never come. Eager to solve the dust versus not-dust mystery, his plan was to combine two kinds of observations: making a 2-D picture of the whole star’s disk, like Dupree did with Hubble in the ’90s, but in longer wavelengths such as infrared or submillimeter, like Dharmawardena’s images from early 2020. That way, you could differentiate the dust from the star, he reasoned.

Only one observatory can do both at once: the Atacama Large Millimeter/submillimeter Array, or ALMA, in Chile. Montargès had planned to ask to observe Betelgeuse with ALMA in June and July, when the winter skies in the Southern Hemisphere are most free of turbulence. But ALMA closed in March and was still closed in September.

“When I realized ALMA will not get the time in June, I thought … we are never going to solve it,” he says. “We may never be completely certain, because of COVID.”

Any other star

Montargès and his colleagues have submitted their analysis of the SPHERE pictures from March for publication. Though he’s not yet willing to share the results, he thinks they could pull the two camps together.

Ultimately, if Betelgeuse did cough out a cloud of dust last year, it could teach us about the origins of life in the universe, Montargès says. If the dust camp is even partially right, Betelgeuse’s dimming may have been the first time humans have watched the seeds of life being launched into the cosmos.

In the meantime, he’s relieved to see his favorite star shining bright again. “I must admit that since [last] December, since this whole stuff started, every time I see it, I am like, phew, it’s still there,” he says.

People keep asking him if he would like ​Betelgeuse to go supernova so he can study it. “I would like another star to go supernova,” he says. “Antares, I don’t care about it it can explode anytime. But not Betelgeuse.”

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A version of this article appears in the December 5, 2020 issue of Wetenskapnuus.


Astroquizzical: What happens when Betelgeuse explodes?

It’s one of the nearest red supergiants to us, and a supernova is only a matter of time. What are we in for when it happens?

Question: If Betelgeuse explodes right now, could we see it with naked eye? It is over 400 light years away, so you might think that people would see it long after it actually happens?

Betelgeuse is already one of the brightest stars in the night sky, sitting somewhere around the 8th or 9th brightest star in the night sky. (These lists don’t include the Sun, which is somewhat obviously always the brightest object in the sky.) It sits in the constellation Orion, along with a number of other bright stars, and makes up the left hand shoulder of the warrior. It looks visibly orange in the night sky, and is classified as a red supergiant star, in the later stages of its life. It’s also one of the few stars that’s close enough for us to resolve in more detail than a point source, and the pictures are pretty fun.

If Betelgeuse were to go supernova right now — as in, if you could break physics and travel to the star instantaneously to check on it — you’re absolutely correct to think that it would take us quite a while to notice. Betelgeuse is about 600 light years away from our solar system, so the light traveling from Betelgeuse has about 600 years of travel before it will reach us. If the star had physically exploded in 2015, we wouldn’t spot the light from that explosion until 2615. We’re constantly observing this star (and pretty much everything in the Universe) as it was, a significant period of time ago. This is also why astronomers say that in studying the night sky, we study the past. The more distant the object, the further in the past we observe. 600 light years, in the grand scheme of things, is pretty close we’re still dealing with our local neighborhood inside our own galaxy.

Supernovae are incredibly bright phenomena. At the brightest point of the explosion, a supernova can outshine the whole galaxy it lives in. A single star has managed to, for a short time, be a brighter source of light than the several billion other stars in its galaxy combined. This is tremendously bright. Supernovae do have a “rising time” of about a week, when the star is increasing in brightness — it stays at its peak brightness for a few days, and then slowly declines into obscurity over a period of a couple of weeks.

But how bright would Betelgeuse specifically be? We can do some math to work this out, making the assumption that Betelgeuse explodes as a Type II supernova. The exact style of supernova is still up for a bit of debate, depending on the exact rotation speed and mass loss of the star over the next hundred thousand years. Regardless of the exact method of its explosion, all the supernovae options for this star have a peak brightness of approximately the same value, so for a quick calculation that’s good enough to determine what we’d see with the naked eye.

There are two ways of measuring brightness in the astronomy world the first is absolute magnitude, which is the brightness of the star, as it would be measured from a fixed distance. (It’s arbitrary, but the fixed distance chosen is 10 parsecs, or about 33 light years.) This is trying to get to a measure of intrinsic brightness — as though we could line up everything in the sky at equal distance from us, and compare them to each other that way. We can’t actually measure the brightness of a star this way, but we can apply some corrections based on the distance to the star to get to it. The absolute magnitude of a Type II supernova is around -17. Because astronomers have the worst conventions in the world (for largely “historical reasons”), negative numbers mean brighter objects. The sun has an absolute magnitude of 4.83, which, once we translate out of “magnitudes”, means that the sun is 500 million times fainter than the supernova, when measured at the same distance. This huge difference in relative brightness is why a supernova can outshine an entire galaxy.

The other method of measuring brightness is a bit more straightforward. It’s the apparent brightness — i.e., how bright does it appear to us as viewed from the Earth. In this frame of reference, more distant objects will always appear fainter, regardless of how intrinsically bright they are. Because Betelgeuse is still fairly distant from us, the apparent brightness would be significantly less than the absolute magnitude. Based on the distance to Betelgeuse, we can work out that the apparent magnitude of the peak of the explosion would be -10. The sun, in apparent magnitude, is the brightest thing in our sky, and is checking in at an apparent magnitude of -26.74. Once again translated out of magnitudes, this means that the Sun as seen from the Earth is a whopping

5 million times brighter than Betelgeuse’s explosion, so our supernova certainly won’t be anywhere near as bright as our sun in the daytime. That’s not to say you wouldn’t be able to see it — it would definitely be bright enough to see during the daytime, as long as you were looking in the right direction. (After all, you can still see Venus in the daytime, if you know where to look!)

Nighttime will be a different story. The brightness of Betelgeuse’s supernova is about the same as the quarter moon. It would also be about 16 times brighter than the brightest supernova known to have been seen from earth, which occurred in 1006, and was recorded by a number of early civilizations. (An image of what remains of that supernova is shown below.)

It was said that the supernova in 1006 was bright enough to cast a shadow at night. Betelgeuse, being significantly brighter, would likely also cast shadows — which, if you think about the brightness of a quarter moon, would make sense!

All that said, Betelgeuse isn’t expected to explode for another 100,000 years or so. We do expect a few supernova in our galaxy every few hundred years, so there are a number of stars that are nearing the ends of their lifetimes within our galaxy. It’s hard to predict exactly when a star will transition from “close to the end of its life” to “exploding in the next week”, so while we expect that none of these will be exploding in the next little while, it’s difficult to predict which one of the stars will be the first to go. In the mean time, we can take wonderful pictures of the more nearby stars, like the one below taken by Hubble, and watch them cast off their outer layers at an incredible rate.

If you have your own questions you’d like Astroquizzical to cover, you can submit them at Astroquizzical’s ask page!


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Astronomer and BBC Sky at Night presenter Chris Lintott says the star's light is variable, which means it's not likely to go supernova in the near future.

'Lots of people are either excited or scared that Betelgeuse is about to go supernova. The fact it’s dimming is amazing - so weird that Orion looks different - but it’s no more likely to go bang in a dip like this than before.

'Betelgeuse just does this from time to time. It’s hard being a constant brightness when you’re big enough to engulf the inner solar system.'

If it were at the centre of the Solar System in place of the Sun its surface would engulf the inner planets from Mercury to Mars and possibly even Jupiter

If it does go supernova, as some scientists predict, it will appear much brighter than Venus when looked at by the naked eye - says data scientist Jason Baumgartne.

'Venus has an apparent magnitude of -4.4. Betelgeuse going super nova would probably get to around -12.4 apparent magnitude.

'Imagine looking at Venus in the sky but it was over 1,500 times brighter. That's how bright Betelgeuse would appear.'

Science writer and astronomy imaging specialist Jason Major says speculating about a supernova is like imagining what you'd do if you won the lottery

Sky at Night presenter Chris Lintott is among a number of astronomers explaining that Betelgeuse is a variable star that dips in brightness regularly

ABOUT BETELGEUSE

Betelgeuse is a Red Super Giant star and is one of the largest in the Milky Way Galaxy.

  • It has a diameter of about 700 million miles
  • It's brightness is 7,500 times greater than the Sun
  • It can be seen from Earth on the shoulder of the Orion constellation
  • It can be easily found in the night sky through most of the year
  • It is is estimated to have a maximum mass of around 20 to 30 times that of the sun
  • It's surface temperature is thought to be about 6,000 F
  • It is about 100,000 times more bright than the Sun
  • It's about 640 light years from the Earth
  • When it explodes it will appear as bright as the moon in the night sky for several weeks

It takes about 642 years for the star's light to get to Earth so any sign that it might be going supernova that we are seeing now, actually happened in 1377.

'If Betelgeuse goes supernova, the blast will take 20,000-100,000 years to reach us, and the Sun's magnetic bubble will shield us', says science writer Corey S Powell.

'It would be as bright as the full moon, concentrated into a point. Easily visible during the day, and possibly painful to look at directly at night!'

Mr Eagle said that when it does pop it will be 'as bright as the full moon' but the light would be contained with a tiny point of light - making Orion strange to look at.

'After many weeks outshining all the other stars in the sky, the supernova’s light will start to fade.

'From then on our view of Orion will change forever, The Mighty Hunter effectively losing his right shoulder.'

What is not known is whether Betelgeuse will turn into a neutron star or a black hole after its end of life explosion.

To become a black hole it has to leave behind material equalling more than three times the mass of the Sun. Under that and it becomes a neutron star.

SUPERNOVAE OCCUR WHEN A GIANT STAR EXPLODES

A supernova occurs when a star explodes, shooting debris and particles into space.

A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe began.

One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever increasing rate.

Scientists have also determined that supernovas play a key role in distributing elements throughout the universe.

In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy blazing with the power of over 100 million suns (pictured)

There are two known types of supernova.

The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, steals matter from its companion star.

Eventually, the white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.

The second type of supernova occurs at the end of a single star's lifetime.

As the star runs out of nuclear fuel, some of its mass flows into its core.

Eventually, the core is so heavy it can't stand its own gravitational force and the core collapses, resulting in another giant explosion.

Many elements found on Earth are made in the core of stars and these elements travel on to form new stars, planets and everything else in the universe.


Kyk die video: When Betelgeuse goes supernova, what will it look like from Earth? (November 2022).