Milky Way Galaxy: embryonic development

How galaxies like the Milky Way grow from nothing into dazzling structures has been something of a mystery until now. While a hypothetical way of figuring out their origins existed, it was impossible to put into practice until astrophysicist Pablo G. Pérez-González of the Instituto de Astrofísica de Canarias and his international team of scientists put together observations from Hubble and SHARDS (Survey for High-z Absorption Red and Dead Sources) spectroscopy to shed light on the formation of these entities.

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There are some nexus parallels between embryonic galaxies and a developing embryo. 

The data analyzed by Pérez-González and his team is something like a sonogram from space. Embryos are formed after enough cells have multiplied in the zygote phase, with the main difference being that zygotes keep dividing to produce more cells, while galaxies start off as smaller galaxies that merge with other small galaxies until their future selves began to take shape. Star formation within those galaxies is more comparable to cells, though stars grow through accretion of dust and gas rather than splitting.

What is now the majestic Milky Way was probably unrecognizable (as most living embryos are) at this point.

Zygotes that become embryos begin cephalocaudal development, from the head down, which is why they look like one giant head early on. Sometimes it is almost impossible to tell one species from another in this phase. Galaxies that haven’t developed much further than their inner cores do appear something like huge glowing heads. Proximodistal development, which stars months later when the embryo has turned into a fetus, is growth from the center of the body outwards, such as the development of limbs.

Most galaxies like our own tend to show more of a proximodistal pattern of growth once they have had enough mergers, their outer reaches extending further into the void as more stars spawn. Maybe that explains why some scientists are convinced that our brains are mirrors of the universe, however New Age-y it sounds.

Please click above image for larger version.

“The universe was more efficient in forming stars than expected at early epochs,” said Pérez-González. “Now we need to understand why some galaxies start forming very early in the history of the Universe. For that, we need to look for the progenitors of the bulges, and even beyond. Only then we can understand what these galaxies have that speeds up their formation.”  [Entire article available here.]