AURORA IRIN TA JUPITER A KAN WANI SANYAYYEN DWARF NA KUSA

Ultracool dwarfs (dwarfs masu matuƙar sanyi) suna zaune ne a iyakar da ke tsakanin taurari da duniyoyi. Iyalin ya ƙunshi taurari masu ƙarancin nauyi sosai, brown dwarfs da abubuwa masu nauyin duniya, duk sun fi kusan kelvin 2,700 sanyi — sanyi har ƙwayoyin da suka daskare suna taruwa zuwa tsare-tsare kamar gajimare a cikin sararinsu (atmosphere). Tun lokacin da aka gano fitar rediyo daga irin waɗannan abubuwa ba zato ba tsammani a 2001, ya bayyana filayen maganadisu na gauss dubu kaɗan. Kusan kashi 15 zuwa 20% daga cikinsu suna “da ƙarar rediyo”.

Siginar rediyonsu sau da yawa tana da sassa biyu: haske mai dorewa, “natsattse”, da bugu masu haske, masu juyawa da polarization na da’ira mai ƙarfi. Ana danganta bugun da wani tsari mai suna electron cyclotron maser instability — shi ne dai ke ba wa aurora na rediyo na Jupiter da Saturn ƙarfi.

Nau’ikan aurora biyu a Jupiter

A Jupiter, aurora na rediyo suna fitowa daga manyan tushe biyu. Ɗaya shi ne babban zobe (main oval), zoben aurora a kewayen kowane sandar maganadisu, wanda igiyoyin lantarki da ke da alaƙa da faifan plasma da ke juyawa tare da duniyar ke ciyarwa. Ɗayan yana fitowa daga watannin duniyar, musamman Io: yayin da watan ke ratsa plasma mai maganadisu na Jupiter, yana tura igiyoyin lantarki a kan layukan filin maganadisu da ke haɗa shi da duniyar. Ana kiran waɗannan layukan filin masu aiki (active field lines).

LSPM J0036+1821, wani dwarf na nau’in L da ke nisan parsec 8.7 (kusan shekarun haske 28), an san shi da fitar da raƙuman rediyo tun 2002. Wani bincike na 2008 ya riga ya gano bugunsa suna maimaituwa kusan kowace sa’a 3.08. Hotunan da aka ɗauka a baya sun kuma nuna yiwuwar wani abokin tafiya, wanda ba a taɓa tabbatarwa ba.

Shekaru uku na sauraro

D. Martín-Carrero, J.C. Guirado da abokan aikinsu a Jami’ar Valencia, tare da abokan aiki a Cibiyar Astrobiology a Madrid, Trinity College Dublin, Lowell Observatory, American Museum of Natural History da Jami’ar Colorado, sun haɗa abubuwan lura daga 2019 zuwa 2023:

• zama na sa’o’i 8.7 da Very Large Array a 8–12 GHz, a ranar 7 ga Disamba 2021;
• gajerun zama da yawa da hanyoyin sadarwa biyu na faranti-faranti na rediyo masu nisa da aka haɗa su zama ɗaya, European VLBI Network da Very Long Baseline Array;
• sa ido a hasken da ake gani da tauraron ɗan adam TESS.

A kowane lokaci, tushen yana kama da wuri guda ɗaya. Hotuna mafi kaifi sun iyakance yankin fitarwa zuwa ƙasa da kusan raka’ar sararin samaniya (astronomical unit) 0.025.

Siffar da ta fi dacewa da bugun rediyo: babban zoben aurora a kewayen kowace sandar maganadisu (cyan) da layin filin mai aiki ɗaya (shunayya), kowanne yana watsa raƙuman rediyo a cikin mazurari marasa ciki. Ba a ma’auni ba. — Figure 7, Martín-Carrero et al. (2026), arXiv:2610.09854.

Agogo da aka auna har zuwa daƙiƙa

Bugun rediyo suna ba da lokacin juyawa na sa’a 3.07941 ± 0.00020; hasken da ake gani daga TESS yana ba da sa’a 3.07908 ± 0.00038. Su biyun sun yarda, da daidaiton kusan daƙiƙa ɗaya. A cewar marubutan, ultracool dwarfs kaɗan ne aka auna juyawarsu da wannan daidaito a rediyo da hasken da ake gani duka biyu.

Bugun suna riƙe da siffa ɗaya a tsawon shekaru da na’urori. A wata polarization na da’ira, akwai ƙololuwa biyu a kowane juyawa, ɗaya ta fi ɗayan ƙarfi; a polarization ɗin akasin haka, ƙololuwa ɗaya a tsakaninsu. Fitarwar ba ta nuna yankewa ba har zuwa 12 GHz, abin da ke nuna filin maganadisu na fiye da kilogauss 4.3.

Zobe ɗaya, layi mai aiki ɗaya

Babban zobe shi kaɗai ko layin filin mai aiki shi kaɗai ba za su iya sake samar da bugun ba: kowanne yana ba da lanƙwasan haske masu daidaito. Don haka tawagar ta daidaita wani samfuri na gauraye, wanda Jupiter ta yi wa ilhami:

• babban zobe yana ba da gudummawa mai dorewa, har da yawancin ƙololuwa mafi rauni;
• layin filin mai aiki ɗaya yana samar da ƙololuwa mafi ƙarfi, mai canzawa da kuma bugun polarization na akasin haka.

Daidaitawar ta fi son ginshiƙin maganadisu da ya karkata kusan digiri 3.6 kawai daga ginshiƙin juyawa, wanda ake gani kusan daga mahaɗin (equator).

A lokacin zaman sa’o’i 8.7, wata ƙololuwa ta dushe daga kusan microjansky 600 zuwa 300 yayin da ɗayan ta girma daga kusan 150 zuwa 350. Ƙananan sauye-sauye ne ke bayyana wannan kai da komowa: ko dai kusurwar buɗewar mazurarin fitarwa tana sauyawa da ɗan juzu’in digiri, ko kuma layi mai aikin yana motsawa da kusan digiri 7 zuwa 8 a longitude daga wani juyawa zuwa na gaba. Wannan kai da komowa iri ɗaya ya bayyana a bayanan 2008, kusan shekaru 15 a baya.

Ɓoyayyen abokin tafiya?

A Jupiter, layi mai aiki mai motsi alama ce ta Io da ke kewaya duniyar. A nan, wani abokin tafiya na kusa — a cikin radius kaɗan na dwarf ɗin — zai iya taka rawa iri ɗaya. Amma marubutan sun jaddada cewa wasu yanayi suna aiki ba tare da wani abokin tafiya ba, kamar gungun iskar gas da ƙura da suka maƙale a cikin wani torus na plasma mai juyawa, ko filin maganadisu mai sarƙaƙiya fiye. Abokin tafiya da ake zato da aka ruwaito a baya, a kusan raka’ar sararin samaniya 0.78, ba a gano shi ba a rediyo (ƙasa da microjansky 21) kuma ko ta yaya zai yi nisa da yawa don mu’amala irin ta Io. Kamfen na rediyo masu tsawo da faɗi ya kamata su bambance waɗannan yanayi.