RAƘUMAN NAUYI BIYU A TAZARAR AWA 7, DA WATA SUPERNOVA
Idan babban tauraro (massive star) ya rushe, yana fashewa a matsayin supernova kuma yana barin tauraron neutron ko baƙin rami (black hole). Idan wannan ragowar tana cikin ma’aurata (binary) masu dacewa, wata rana za ta iya haɗewa da abokin tafiyarta ta aika raƙuman nauyi (gravitational waves) a faɗin sararin duniya. Amma yawanci wannan rana tana zuwa ne da daɗewa bayan fashewar: aƙalla kusan shekaru 100,000. Rugujewa da farko, haɗewa da daɗewa bayan haka — wannan shi ne hoton da aka saba.
Sabbin abubuwan da aka lura da su sun fara dusashe wannan hoto. Wasu fashe-fashen hasken gamma (gamma-ray bursts) suna kama da haɗewa da rugujewa a lokaci ɗaya, kuma an tattauna supernova biyu na nau’in “Type IIb” — fashewar taurarin da aka cire musu mafi yawan hydrogen ɗinsu — tare da wasu raunanan ’yan takarar raƙuman nauyi a 2025, ba tare da wata tabbatacciyar matsaya ba. Wata dabara ɗaya za ta iya bayyana irin waɗannan lamura: a cikin tauraron da ke juyawa da sauri wanda ya rushe, faifan (disk) abu mai yawa da ke kewaya sabon baƙin ramin zai iya farfashewa zuwa guntaye, waɗanda daga baya za su haɗe da juna ko su faɗa cikin baƙin ramin cikin awanni.
Bincike a cikin ma’ajiyar bayanai
Sheng Yang, na Henan Academy of Sciences a ƙasar Sin, da Zong-Hong Zhu, na Beijing Normal University, tare da abokan aiki 23 a Sin, Taiwan, Amurka, Australia, Italiya da Sweden sun yi bincike bisa tsari. Sun ɗauki faɗakarwar jama’a (public alerts) da na’urorin gano LIGO, Virgo da KAGRA suka fitar daga Afrilu 2019 zuwa Janairu 2025 — 43 daga cikinsu da wata dama ta ƙunsar tauraron neutron — da kuma supernova 676 na taurarin da aka cire wa lulluɓinsu (stripped supernovae) da Zwicky Transient Facility ta hango. Sun nemi supernova da ke cikin filin sararin samaniya na wata faɗakarwa kuma suka kai ƙololuwa kwanaki 10 zuwa 30 bayan ta.
Binciken ya dawo da daidaito biyu — dukkansu da supernova ɗaya, SN 2019rsq. Tana haɗa faɗakarwa biyu daga 10 ga Satumba 2019: S190910d, sannan S190910h, awa 7.1 daga baya. A lokacin, kowace faɗakarwa ta jawo nata bibiyar (follow-up); sai bayan makonni aka gano supernovar. Waɗannan uku sun bayyana ne kawai idan aka waiwaya baya.
Filayen sararin samaniya na S190910d (toka-toka) da S190910h (lemu) sun rufe juna inda SN 2019rsq take (akwatin ja, damin taurarinta a sama dama); a ƙasa dama, kewayon nisansu ya jitu da megaparsec 140.6 na supernovar (layin ja). — Hoto na 1, Yang da abokan aiki (2026), arXiv:2611.00440.
Yaya ƙarancin wannan biyun yake?
Faɗakarwa masu kusa da juna a lokaci suna faruwa. Amma filayen sararin samaniya biyun suna kuma rufe juna a girma uku (three dimensions): kewayon nisansu ya jitu da juna da kuma da nisan supernovar, megaparsec 140.6. Don auna yadda wannan ya saɓa da al’ada, ƙungiyar ta gauraya ranakun faɗakarwar ba bisa tsari ba sau miliyan ɗaya. Biyu marasa alaƙa masu kusanci haka a lokaci da wuri sun fito da yiwuwar 7.6 × 10⁻⁵, kusan ɗaya cikin 13,000. Daga cikin faɗakarwa 43, biyu-biyu goma sun faɗa cikin kwanaki 5 da juna, amma uku kawai suka rufe juna a girma uku (3D), kuma wannan ya haɗa mafi gajeren jinkiri da mafi girman rufewa.
Supernovar ita kaɗai kuwa ba abin mamaki ba ce: damar cewa wata Type IIb mara alaƙa ta fashe a wannan juzu’i (volume) a wannan lokaci kusan 35% ce. Abin da ya saɓa shi ne siginonin biyun; supernovar tana ba da tauraron da ya rushe wanda zai iya haɗa su wuri ɗaya.
Siginonin biyu marasa ƙarfi ne. Idan aka sake nazarinsu, dukkansu suna kama da sigina na gaske kuma sun fi hayaniyar baya (background noise) ta bayanan da ke kewaye da su, amma babu ɗayansu da ake ƙirga shi a matsayin ganowa tabbatacciya. Wata ƙungiya mai zaman kanta ta riga ta sake gano na farkon, da yiwuwar 58% na kasancewa daga sararin samaniya (astrophysical).
Abin da kowace sigina ke faɗi
Siginonin suna ɗauke da nauyin (masses) abubuwan da ke haɗewa. S190910d na nuna rashin daidaito sosai: kusan nauyin Rana 34 tare da abokin tafiya na kusan 3. S190910h mai sauƙi ne: kusan nauyin Rana 2.5 da 1.3, irin na taurarin neutron.
SN 2019rsq, wadda binciken Pan-STARRS ya gano a ranar 1 ga Oktoba 2019, ta kai ƙololuwa kusan kwanaki 24 bayan siginar farko — lokacin hauhawa (rise time) na yau da kullum ga Type IIb idan tauraron ya rushe a wannan lokacin. Bayanan ba za su iya tantance ranar fashewar daidai ba, amma samfuran da ke sanya ta cikin kwanaki uku na S190910d suna sake samar da haskenta. Supernovar mai sauri ce, kuma tana kan wata wutsiyar jan hankali (tidal tail) ta wani damin taurari da ya hargitse wanda ke samar da taurari.
Tauraro ɗaya, haɗewa da dama?
Yanayin da aka gabatar: tauraro mai juyawa ya rushe zuwa baƙin rami wanda faifansa ya farfashe (1); gunta mai nauyin Rana 3 ya faɗa cikin baƙin rami mai nauyin Rana 34, S190910d (2); guntaye biyu masu sauƙi sun haɗe awa 7.1 daga baya, S190910h (3); haɗuwa na baya za su iya samar da sigina masu jinkiri (4). — Hoto na 4, Yang da abokan aiki (2026), arXiv:2611.00440.
Ƙungiyar tana gabatar da asali guda. Wani babban tauraro mai juyawa da sauri ya rushe zuwa baƙin rami mai nauyin Rana na goma-goma da dama, kewaye da faifai da ke farfashewa zuwa guntaye. Gunta da ya girma zuwa kusan nauyin Rana 3 ya yi ta karkacewa zuwa cikin baƙin ramin na tsakiya: wannan shi ne S190910d. A wani wuri a cikin faifan, guntaye biyu masu sauƙi sun haɗa kai sun haɗe: wannan shi ne S190910h. Lokutan karkacewa da aka lissafa — daga kusan awa ɗaya zuwa awanni da dama — sun rufe tazarar awa 7.1 cikin sauƙi.
Marubutan suna taka-tsantsan. Ƙididdigar yiwuwar ba ta la’akari da kowane bincike da mutum zai iya yi ba, kuma wata doguwar fashewar hasken gamma (long gamma-ray burst) da aka gani kwanaki biyar daga baya a wannan babban yanki ba a ƙirga ta a matsayin shaida ba. Binciken rediyo bai ga komai ba, abin da ya sa wani jet mai ƙarfi, mai daɗewa, ya zama da wuya. Ko SN 2019rsq daidaituwa ce da ba kasafai ake samu ba, ko kuma misali na farko na tauraro da ya harba sigina da dama na raƙuman nauyi yayin da yake mutuwa, zagayen kallo (observing runs) na gaba, tare da manyan binciken sararin sama, ya kamata su nuna ko irin waɗannan tarin za su ci gaba da bayyana.