galaxy are considered active or dead look on the rate at which they mold stars . Young galaxy are bright and produce stars very cursorily but the older , more massive ones tend to fall behind , often being described as red and dead . Sometimes , extragalactic nebula can “ come back from the dead ” if they steal enough material . It appear that the Milky Way is one of these deport - again galaxies .
The study was conducted by Masafumi Noguchi from Japan ’s Tohoku University and published in the journalNature . It focused on the chemic composing of stars in our beetleweed . According to Noguchi ’s calculations , the stars around the Sun formed in two genesis , separated by 5 billion years . No mechanism could create such a local variance without having far - reach effects .
The model used by Noguchi suggests that lead first formed when cold intergalactic gas began flowing into the primaeval Milky Way . This contemporaries of stars ends up as spectacular supernova , which has two outcome . The first is that the supernovae produce heavy constituent , spreading them far and wide . This enriches the interstellar gasoline and change its chemical substance composition .
The other upshot is heat . Supernovae make powerful shockwaves that raise the temperature of the gas from which stars form . It seems counterintuitive but despite being very hot , stars need to form from cold gas . If the gas is not inhuman , it can not contract enough for gravitational attraction to make it break and form a ace .
Noguchi ’s modelhighlights how different type of supernovae spillage different chemical element in different quantities . The unity from short - exist stars , acknowledge as Type II supernovae , are rich in alpha - factor ( such as O , magnesium , and silicon ) and happen speedily . This explains why the older generation is indeed richer in these elements . Then the star - formation foramen happened . Eventually , the more long - lived supernova , called Type I , explode and released iron . The 2d multiplication of wizard is rich in iron . Our Sun is among these stars .
The idea of two distinct full point of intense star formation has already been proposed to explain features of more massive galaxies , so it is interesting to see it apply to an fair - sized one like the Milky Way . Some researchers suppose that Andromeda , our galaxy ’s equal - sized neighbour , also had a exchangeable formation . next observations might elucidate if this is the event and perhaps change what we cognize about how most galaxies evolve .
