DUNIYAR TAURARON BOYAJIAN MAI GIRMAN DA YA WUCE KIMA MAI YIWUWA TANA SANYE DA ZOBE

A ranakun 3–4 ga Satumba 2019, tauraron ɗan adam TESS ya kalli wani tauraro mai suna KIC 8462852 yana rasa kusan 1.1% na haskensa na tsawon kusan awa 21, sannan ya dawo. Raguwar ta kasance mai santsi kuma daidai a ɓangarorin biyu (symmetric): daidai abin da jiki mai ƙarfi, kusan zagaye, ke haifarwa idan ya wuce gaban tauraronsa. Ga wannan tauraro, wannan babban sauyi ne mai jan hankali.

Raguwa mai tsabta a kan tauraro mara natsuwa

Wanda aka fi sani da tauraron Boyajian ko tauraron Tabby, KIC 8462852 in ba don wannan ba tauraro ne na al’ada. Duk da haka, a cikin shekaru huɗu da aikin Kepler ya sa ido a kansa, haskensa ya ragu farat ɗaya ba bisa tsari ba, har zuwa 15% da 22% — zurfi fiye da yadda kowace duniya za ta iya haifarwa. Raguwar sun fi ƙarfi a haske mai shuɗi, alamar ƙananan ƙwayoyin ƙura maimakon jiki mai ƙarfi. Waɗanda ake zargi sun haɗa da taurari masu wutsiya (comets) da ke tarwatsewa, duniyar da aka haɗiye, har ma da “manyan gine-gine” (megastructures) waɗanda ba na halitta ba; babu ɗayansu da aka yarda da shi gaba ɗaya. Manyan samfurorin suna buƙatar wani abokin tafiya mai nauyi da ba a gani ba, wanda ƙarfin janyewarsa (gravity) ke tura jikunan da ke samar da ƙura zuwa kewaye da ke goga tauraron.

Wani bincike na baya-bayan nan da Madurga-Favieres da abokan aikinsa suka yi ya haɗa wannan wucewa (transit) mai tsabta da bayanan saurin layin gani (radial velocity) na ajiya: ɗan ƙaramin motsi gaba da baya da abokin tafiya ke ɗora wa tauraronsa. Sun sami abokin tafiya mai nauyin Jupiter 9.4 (wani wuri tsakanin kusan 5 da 14), radius na ninki 1.7 ± 0.1 na radius ɗin Jupiter, da kewaya ta aƙalla kusan kwanaki 1,030. Idan an tabbatar, zai iya zama jikin da aka daɗe ana nema wanda ke tura taurari masu wutsiya na tauraron.

Faɗi fiye da nauyinsa

Wei Zhu da Quanyi Liu, masana falaki a Tsinghua University da ke Beijing, sun nuna wata matsala a cikin waɗannan lambobi. Katuwar duniyar iskar gas (gas giant) da ta fi Jupiter nauyi tana tsayuwa ne galibi saboda electrons da suka cunkushe sosai waɗanda ke tsayayya da matsewa; idan ta yi sanyi, ƙara nauyi da ƙyar yake canza radius ɗinta. Samfurori da dangantakar nauyi da radius (mass–radius relation) da aka auna ta katuwar duniyoyi masu sanyi sun yarda: ninki 1.0 zuwa 1.1 na radius ɗin Jupiter daga kusan nauyin Jupiter 2 zuwa 12.

Hanyoyin da aka saba bi don kumbura duniya ba sa aiki a nan. Hasken tauraro mai tsanani yana kumbura “Jupiter masu zafi” (hot Jupiters) da ke kan kewaye na kusa, amma zafin da aka ƙiyasta na wannan abokin tafiya kusan kelvin 270 ne kawai, kusan −3 °C. Da shekaru kusan biliyan 1.2, tauraron kuma ya tsufa sosai har zafin da ya rage daga samuwar duniyar ba zai iya taimakawa ba. Saboda haka radius na 1.7 ya wuce kima da 60–70%.

Jadawalin log-log na radius ɗin duniya idan aka kwatanta da nauyi, da murabba’i ja ga Boyajian’s star b can sama da layukan. Sanannun duniyoyin da ke wucewa gaban taurarinsu bisa nauyi da radius: abokin tafiyar tauraron Boyajian (murabba’i ja) yana can sama nesa da girman da ake tsammani ga katuwar duniya mai sanyi (baƙin layi da ratsin ruwan lemu). — Figure 1, Zhu & Liu (2026), arXiv:2610.34806.

Ɓoye wani ɓangare na inuwar a cikin zobe

Shawarar ta shafi siffa (geometry) ne: zobe da haske ba ya ratsawa a kewayen ƙaramar duniya yana tare ƙarin hasken tauraro, kuma daga nesa ma’auratan suna kama da duniya ɗaya mai girman da ya wuce kima. An taɓa ba da shawarar katuwar duniya mai zobe ga wannan tauraro a 2018, amma a matsayin zane kawai, ba tare da daidaita ma’aunan zoben da bayanan ba.

Masana falakin biyu sun sake nazarin bayanan TESS, da aka ɗauka kowane minti 2. Duniya tsirara mara zobe (bare sphere) tana dacewa, amma tana buƙatar kusan ninki 1.74 na radius ɗin Jupiter kuma tana barin wani ɗan bambanci mara ƙarfi mai tsari kusa da ƙasan raguwar. Sai suka faɗaɗa manhajar lissafin wucewarsu, JoJo, zuwa duniya mai zobe shimfiɗaɗɗe da ake gani daga kowace kusurwa. Sun kafa duniyar a girman da ake tsammani ga nauyinta, ninki 1.1 na radius ɗin Jupiter, kuma suka sa zoben ya zama wanda haske ba ya ratsawa kwata-kwata. Iyakar wajensa dole ne ta kasance cikin iyakar Roche (Roche limit), nisan da a cikinsa ƙarfin janyewa (tides) na duniyar ke hana abubuwa marasa haɗuwa taruwa su zama wata (moon); a wajen wannan nisa, zobe ba zai daɗe ba. An ɗauki zobe da ya wuce kusan radius 5 na duniyar a matsayin abu mai wuyar yiwuwa sosai.

Zobe a tsaye da duniya a kwance a gefenta

Mafi kyawun mafita masu zobe suna musanya mafi yawan girman da duniyar ke bayyana da shi da zobe mai faɗi kuma shimfiɗaɗɗe:

iyakar waje a radius 3.1 zuwa 4.4 na duniyar, kusan a iyakar Roche;
ana ganinsa kusan ta gefe, karkace da 78–84° daga fuskantar mu kai tsaye;
yana tsaye kusan a kusurwa madaidaiciya (right angle) da hanyar duniyar a gaban tauraron.

Tunda muna ganin kewayar kusan ta gefe (duniyar tana wucewa gaban tauraronta), irin wannan zobe yana karkace kusan 80° daga kewayar. Idan yana kewaye da ɗamarar tsakiya (equator) ta duniyar, kamar na Saturn, to wannan katuwar Jupiter (super-Jupiter) tana juyawa a kwance a gefenta, kamar Uranus. Idan gaskiya ne, zoben tarkace (debris ring) mai kusanci haka mai yiwuwa taurari masu wutsiya da suka farfashe ko ƙananan watanni ne ke ciyar da shi — wataƙila rukuni ɗaya da ake zargi da tsofaffin raguwar hasken tauraron.

Zanen duniya mai duhu mai siririn zobe a tsaye tana wucewa gaban tauraro, a saman layin haske (light curve) da samfura biyu da aka daidaita da ragowarsu (residuals). Mafi kyawun duniya mai zobe tana shiga, tana wucewa, tana fita daga gaban tauraron (sama), raguwar TESS da samfurin zobe da ja da samfurin duniya tsirara da shuɗi (tsakiya), da abin da samfurin duniya tsirara ya bari ba a bayyana ba (ƙasa). — Figure 2, Zhu & Liu (2026), arXiv:2610.34806.

Kusan kunnen doki, wanda ilimin kimiyyar lissafi (physics) ya warware

A ƙididdiga, gasar tana da kusanci. Zoben yana inganta wani ma’aunin rashin dacewa da aka saba amfani da shi (χ²) da kusan 14, amma yana amfani da ƙarin saituna biyu masu daidaituwa. Da zarar an yi amfani da wani ma’auni da ke hukunta ƙarin saituna (BIC), fifikonsa yana raguwa zuwa maki 0.4 zuwa 1.3: kusan kunnen doki.

Fuskantar zoben ta dogara galibi kan wani ɗan dawowar haske kusan kwanaki 0.25 bayan tsakiyar wucewar, wanda zobe mai karkata sosai ke haifarwa ta hanyar fara barin gaban tauraron da wuri. Amma wucewar duniyar a kan wani tabo mai duhu a jikin tauraron zai iya haifar da irin wannan kumburi: yayin da take rufe wani yanki mai duhu, tana ɓoye ƙarancin haske. Idan aka cire wannan kumburin, marubutan sun yarda, fifikon yana juyawa.

Abin da ya rage wata hujja ce mai sauƙi. Don tare haske kamar yadda aka lura, dole zoben ya kai aƙalla radius 1.6 na duniyar — mafi ƙanƙanci da ke ɗauka cewa ana ganin zoben kai tsaye daga gaba kuma yana taɓa duniyar. Idan ya karkata kamar na Saturn, yana buƙatar aƙalla kusan 2.4 — tuni kusa da iyakar Roche, wadda ke tsakanin kusan radius 2.5 da 5 na duniyar gwargwadon yawan matsewar (density) ƙwayoyin zoben idan aka kwatanta da na duniyar. Ko ta yaya, idan zobe ne ke bayyana radius ɗin, dole ya zama mai faɗi.

Hotunan biyu sun fi bambanta yayin da duniyar ke shiga da fita daga faifan tauraron, da ’yan sassa cikin 10,000 na haskensa, abin da na’urorin hangen nesa na sararin samaniya da ake da su za su iya kaiwa. A yanzu, komai ya dogara ne kan wucewa ɗaya kawai, a cikin bayanan da marubutan kansu suka bayyana a matsayin masu ɗan ƙarancin inganci.