INDA SABON TAURARO KE ƘONE CARBON ƊINSA

Carbon shi ne ƙashin bayan rayuwa kamar yadda muka san ta: fiye da rabin busasshen nauyin jikin ɗan adam. Duk da haka Duniya tana da ƙarancinsa ta hanya mai ban mamaki. Galibin duwatsun duniyarmu, gwargwadon nauyinsu, suna ɗauke da carbon ƙasa da na Rana, ko na ƙurar sararin tsakanin taurari (interstellar dust) da Duniya ta samo asali daga gare ta, da kusan matakai huɗu na girma (four orders of magnitude) — ninki dubu goma. An gabatar da bayanai da dama, daga hasken ultraviolet zuwa oxidation, amma babu ɗaya da ya bayyana shi gaba ɗaya.

Wani abin zargi shi ne zafi. Carbon da ke cikin ƙwayoyin ƙura yana zuwa a sifofi da dama — carbon marar tsari (amorphous) mai kama da toka (soot), hydrocarbons, graphite — waɗanda ke rushewa a yanayin zafi daban-daban. Daga kusan kelvin 500, layin toka (soot line), sifofin da suka fi saurin zama tururi suna tserewa; zuwa kusan kelvin 1,200, ko carbon marar tsari ma ya ƙare. Ayyukan baya sun ƙiyasta cewa wannan zafi dole ne ya faru cikin shekaru miliyan ɗaya na farko na samuwar Duniya.

Tauraron da aka kama a “lokacin sifili”

HOPS-68 wani tauraro ne mai ƙuruciya sosai a cikin gajimaren ƙwayoyin sinadarai na Orion (Orion molecular cloud), a nisan kusan parsec 414. Wani bincike mai rakiya da wannan ƙungiya ta yi ya nuna cewa tsakiyar faifansa na ciki yana kaiwa kelvin 1,400 — zafin da ya isa dukkan ƙura ta zama tururi. Tsarin Rana (Solar System) ɗinmu ma ya bi ta irin wannan mataki: shi ne “lokacin sifili” (“time zero”) na tarihin meteorites, lokacin da ƙwayoyi masu wadatar calcium da aluminium suka daskare daga iskar gas mai zafi kusa da Rana a ƙuruciyarta. Taurari biyu ne kawai masu ƙuruciya, masu ƙaramin nauyi, aka sani a matsayin ’yan takarar wannan lokaci, dukkansu a Orion.

F. J. Ballieux, M. K. McClure da abokan aiki, a Leiden University tare da abokan hulɗa a Amurka da Jamus, yanzu sun bincika carbon da ke cikin bakan haskensa (spectrum), wanda aka ɗauka da Mid-Infrared Instrument na JWST, tare da bayanan ma’ajiya daga ALMA, jerin na’urorin hangen nesa na (sub)millimetre.

Bakan haske cike da hydrocarbons

Hasken HOPS-68 yana ɗauke da alamomin yatsu (fingerprints) na ƙwayoyin sinadarai (molecules) masu yawa na carbon:

• hydrogen cyanide da acetylene masu ɗumi, a kusan kelvin 320 da 430, da yawa — kusan ninki 20 fiye da a kewayen ɗayan tauraron “lokacin sifili”. Suna motsawa zuwa gare mu da saurin kilomita 39 zuwa 53 a cikin daƙiƙa idan aka kwatanta da tauraron, kamar iskar gas mai ɗauke da oxygen da ke nuna iska (wind) da ke kaɗawa daga faifan;
• ƙwayoyin sinadarai masu sanyi, kusan kelvin 40 zuwa 55, ciki har da diacetylene (C₄H₂), methyl radical da carbon monosulfide, mai yiwuwa a ɓangaren waje na faifan ko a jikin bangon ramin da fitowar abu (outflow) daga tauraron ta sassaƙa;
• triacetylene (C₆H₂), sarƙar atom na carbon shida, da aka gano a karon farko a kewayen sabon tauraro.

ALMA ta ƙara wata alama: C₂H radical yana lulluɓe bangon ramin fitowar abu, yana motsawa zuwa waje tare da feshin (jet) maimakon faɗawa ciki.

Yankin lalata carbon

Marubutan sun gabatar da wani hasashe (scenario). Tsakanin layin toka da wurin da ko carbon marar tsari ke zama tururi — kusan kelvin 500 zuwa 1,200 — akwai abin da suke kira “yankin lalata carbon mai jure zafi” (refractory carbon destruction zone): a can, dukkan carbon mai ƙarfi (solid) yana barin ƙwayoyin ƙura ya zama gas. A HOPS-68, yankin ciki mai tsananin zafi yana tura wannan yanki zuwa waje kuma yana faɗaɗa shi. Sannan carbon ɗin da aka saki ko dai tauraron ya haɗiye shi ko kuma iskar faifan ta ɗauke shi.

Ko ta wane hali, ƙurar da ke yankin da duniyoyi masu duwatsu ke samuwa tana rasa carbon ɗinta. Wannan tsari ɗaya, a cewar ƙungiyar, mai yiwuwa ya taimaka wajen ƙarancin carbon na Duniya. Yawan carbon da iskar ke cirewa a zahiri har yanzu ba a auna shi ba.

Can nesa, hasken ultraviolet yana farfasa acetylene zuwa C₂H, wanda ke amsawa (react) da ƙarin acetylene don gina sarƙoƙi masu tsayi kamar C₄H₂ da C₆H₂. Tsakanin kelvin 900 da 1,100, yankin lalatar ma zai iya ƙirƙirar polycyclic aromatic hydrocarbons, kamar a cikin harshen wuta — abin da har yanzu ake buƙatar tabbatarwa.

Daga tauraro mai tasowa (protostar) zuwa taurari masu ƙanƙanta (asteroids)

Binciken yana da sakamako biyu masu faɗi. Na farko, sarƙoƙin carbon da aka gani a kewayen wasu sabbin taurari galibi an danganta su ga iskar gas da ke faɗowa daga lulluɓin (envelope) da ke kewaye; a HOPS-68 a fili suna gudana zuwa waje, wanda ke nuna cewa wannan ilmin sinadarai zai iya nuna fitowar abu (outflows) maimakon haka.

Na biyu, samfuran da aka dawo da su daga taurari masu ƙanƙanta (asteroids) Ryugu da Bennu suna ɗauke da kayan halitta (organic matter) masu siffar sarƙa (“aliphatic”) da yawa. Saboda dogayen sarƙoƙin HOPS-68 suna samuwa ne a wajen iskar, ba a hura su ba; za su iya faɗowa daga baya kan ɓangaren waje na faifan. Marubutan sun ba da shawarar cewa irin waɗannan sarƙoƙi za su iya bayar da gudummawa ga kayan halitta na taurari masu ƙanƙanta da meteorites. Idan haka ne, HOPS-68 zai nuna, a cikin tsari ɗaya mai ƙuruciya, duka samuwar waɗannan ƙwayoyin meteorite da kayan da ke da wadatar carbon da aka sanya su a ciki — dutsen Rosetta (Rosetta stone) ga samuwar ƙananan jikunan farko na tsarin duniyoyi (planetary system).