Two unusually dumb collections of stars lying in the outer reach of the Milky Way were previously thought to be remnants of nanus galaxy captured by our own . However , a raw analysis of their chemical physical composition shows the stars in each have always been part of the Milky Way , but originated in the galactic disk . Astronomers have conclude they were pulled from their original location by the gravity of a small satellite galaxy that interacted with the Milky Way .
Deep outer space may seem a serene surround , but it can host titanic encounters where galaxiescannibalize each other , or rip neighbor aside . There ’s no reason to believe the Milky Way is immune , and indeed we are headed for acollision with Andromeda , our nearest large neighbor . luckily , therecent discoverythat Andromeda is not in reality larger than our galaxy means it will be a fair scrap .
Even clashes with smaller galaxies can matter , however , and it appear one such case lead to the constitution of A13 and Triangulum - Andromeda ( not to be disconcert with either the Triangulum or Andromeda Galaxies , which are vastly larger and further off ) . These collection of stars sit down around 14,000 light - years above and below the sheet of the Milky Way , in locating where star are carry to be rarefied , forming what astronomers call an “ overdensity ” .
An interrogation , published inNatureof the chemical make - up of 14 stars within the two maculation bump both are very consistent in opus and resemble stars of the Milky Way disk . In dividing line , the component element are unlike those in any known dwarf galaxy . Although home phenomenon can throw the occasional starout of the extragalactic nebula , the only process known to be able to remove such magnanimous groups of star is tidal interactions with substantial other galaxies .
“ These finding are very exciting , as they show that the Milky Way Galaxy ’s platter as a whole can vibrate because of tidal interaction , and its dynamics are importantly more complex than previously thought,”Dr Luca Casagrandeof the Australian National University said in astatement .
Triangulum - Andromeda ’s wizard are estimated to be 6 - 10 billion years old . Casagrande told IFLScience that while the timing of the encounter that extract them away from the disc is difficult to compute , it probably pack post 4 - 8 billion years ago .
Although the size of the galaxy that disrupted these sensation can not be substantiate , Casagrande state IFLScience the squad modeled an encounter with the primogenitor of theSagittarius dwarf galaxy , the faithful planet coltsfoot to the Milky Way , and found it sufficient to do the job .
It remains unknown whether the wizard accumulation will ever come back to the plane of the galactic disk , or how being throw out of the disc would touch planets around these stars .
