Andromeda ( M31 ) , our closest astronomical neighbor at 2.5 million clear years away , is slated to collide with the Milky Way in about 4 billion years to form one huge elliptic Galax urceolata . However , this wo n’t be the first collision in Andromeda ’s history . New computer simulations have indicate that a dwarf galaxy with a supermassive black hole at the center collided with Andromeda , causing the orotund extragalactic nebula to spring its whorled arms , which appear like ring from Earth ’s perspective . Understanding how this happens could help astronomer understand spiral wandflower , including the Milky Way . The promulgation come from researchers at Harvard led by Avi Loeb . The results will appear in the journal Astrophysical Journal Letters and is available in preprint onarXiv.org .
Andromeda is a bit of an optical magic trick , as it does n’t have distinctly defined arm like other spiraling galaxies . Instead , it sort of looks like it has concentric rings , like Saturn . This leftover appearing has led many stargazer to job that Andromeda used to be a disk beetleweed , but a collision with midget galaxy M32 fundamentally create a ripple gravitative effect , creating the appearance of rings or arm .
This is n’t the first prison term computer simulations have attempted to excuse Andromeda ’s appearance with a collision . A team from the University of Witwatersrand in South Africa developed a pretence that was published inNaturein 2006 . A central difference between that field and the one completed by Loeb ’s squad was that the 2006 report assumed M32 crashed very near the gist of Andromeda . They also reason out that Andromeda has true rings , not volute munition . However , Loeb ’s squad feel it is fairly unlikely that M32 would have hit the bullseye like that , when the odds would suggest it would hit anywhere else .
Loeb ’s simulation cast the hit in the outer regions of the disc . They believe that over the course of two billion age , M32 break up into Andromeda and continued to pass through , though the rippling effect deplumate up the platter and begin to form arms . It then take M32 about 900 million geezerhood to slow down , reverse charge , and total back where it will tear through Andromeda again . They also determined that Andromeda does have true spiral arm , but they just look like ring from Earth ’s perspective because of the slant and the fact that they are tightly wrapped arms .
to boot , the model revealed newfangled item of how M32 may have bear during the collision . Traditionally , astronomer believe that gravitational violence would have pulled off a dwarf galaxy ’s outer star , gun , and dark thing , which would reduce its size . However , the simulation paint a picture that M32 was already so thick , Andromeda was n’t able to pull off that outer envelope of material . This must mean that M32 ’s compendious elliptical nature was formed by some other means .
Despite Andromeda being our closest neighbor , there is n’t a whole lot known about it . As observational data continues to be collected , more simulations will have to melt in parliamentary procedure to simulate situations that can actually be essay .
[ Hat pourboire : Katia Moskvitch , Nature News ]
