Ngabe iyanwebeka iMilky Way?
Kunezinkanyezi ezizaleka emngceleni wayo
ZIBALELWA ngaphezulu kwezi-100 billion izinkanyezi ezakhe umaxhobelasishingishane ( spiral galaxy), iMilky Way (umthala), lapho kutholakala khona inkanyezi iLanga, ewunina woMhlaba esiphila kuwona.
Lo maxhobela oyizi-100 000 light years umugqankaba ( diameter) - sizokhumbula ukuthi i-light year eyodwa ilingana nezi-9.461 trillion km - uyikhaya lezinkanyezi ezahlukene ngesisindo, wukukhanya kwazo, yiminyaka yobudala kanti kukhona ezintsha ezizalwayo khona lapho.
Kubukeka ukuzaleka kwezinkanyezi kukhombisa ukuqhubeka ngesivinini, lokhu kwenzeka ngasonqenqemeni lomngcele weMilky Way. Lokhu kwenza ososayensi bazibuze ukuthi ngabe lokhu kuzaleka kwazo onqenqemeni lomngcele walo maxhobela, kusho ukunwebeka kwawo yini.
Mhla zintathu kwephezulu, ithimba labacwaningi eliholwa nguCristina Martinez-Lombilla weInstituto de Astrofisica de Canaris eSpain, liveze kwi-European Week of Astronomy and Space Science umphumela wocwaningo lwalo olweseka lo mbono - wokunwebeka komngcele weMilky Way.
Izinkanyezi ezindala, esezinesisindo esiphansi, zitholakala enkabeni yalo maxhobela nasendilingeni emaphakathi yawo kanti ezitsha zikwisishingishanengalo ( spiral arm). Ngenxa yokuthi ukuzaleka kwalezi zinkanyezi ezintsha kwenzeka ngasemngceleni weMilky Way, abacwaningi bafuna ukubheka ukuthi ukuzaleka kwazo kuzoba namuphi umthelela endleleni lo maxhobela ome ngayo.
Inkinga ngokucwaninga ukunwebeka kweMily Way, yindawo esikuyona - kunzima ukuthola indawo ekahle yokuyicubungula kwazise nathi siphakathi kuyona.
Ukuze laba bacwaningi bathole umbono osondele kulokhu abakufunayo, bacubungule omaxhobelasishingishane abaseduze neMilky Way futhi abanezinto ezifanayo nezayo.
Kubona yiNGC 4565, okuwumaxhobela onomugqankaba oyizi-100 000 light years njengayo iMilky Way - okulinganiselwa ukuthi usebangeni eliphakathi kwezi30-50 million light years ukusuka eMhlabeni. Basebenzise omabonemajukujukwini ( telescope) abaseMhlabeni nabasemkhathini ukubheka inkanyezi esonqenqemeni lwethafa ( disk) leNGC 4565.
Umabonemajukujukwini, iSloan Digital Sky Survey, usize leli thimba ukuqoqa imininingwane eqondile ngale nkanyezi kanti iSpitzer neGALEX zona ziqoqe imininingwane yokukhanya namagagasi akhombisa isisindo nendlela le nkanyezi ehamba ngayo.
Likwazile nokukala ukukhanya endaweni le nkanyezi ekuyona ukuthola ukuthi hlobo luni lwezinkanyezi olutholakala kule ndawo.
Lithole ukuthi iningi lazo wuhlobo lweziluhlaza sasibhakabhaka ezisencane, lahlola nendlela ezihamba ngayo ukuthi zithatha isikhathi esingakanani zishoshela ngaphandle kwethafa leNGC 4565.
Izibalo zikhomba ukuthi omaxhobela abafuze iMilky Way banwebeka ngama-500m esikhathini esiwumzuzwana.
“IMilky Way yinkulu ngendlela emangalisayo, kodwa umsebenzi wethu usikhombisa ukuthi ingxenye yayo esiyibonayo iyanwebeka njengoba kuzaleka ezinye izinkanyezi ezinkalweni zayo. Lokhu kakwenzeki ngokushesha kodwa uma ubungathola ithuba lokubuya uzobheka eminyakeni eyizi-3 billion ezayo, lo maxhobela ubuzobe usunwebeke ngesi-5% (okusho ukuthi mhlawumbe umugqankaba uyobe usunwebeke ngezi-5 000 light years), kusho uCristina.
Uma kubhekwa ngasekugcineni impela kweMilky Way, kulindeleke ukuba umngcele wayo ushintshe kakhulu uma kwenzeka ishayisana nomaxhobela owumakhelwane wayo, i-Andromeda - okuqagulwa ukuthi kuyokwenzeka eminyakeni eyizi-4 billion ezayo.
I-Andromeda nayo iwumaxhobelasishingishane, itholakala ebangeni elilinganiselwa ezi-2.5 million light-years ukusuka eMhlabeni. Ibuye yaziwe ngeMessier 31 (M31) noma iNGC 224.
Yiwona maxhobela omkhulu kakhulu oseduze kweMilky Way, unomungqankaba olinganiselwa ezi220 000 million light-years. Umthombo ngabe: en.wikipedia. org; Astronomy Magazine;