Astronomers Discover When Galaxies Got Their Spirals 56
KentuckyFC writes "The universe today is filled with beautiful spiral galaxies — but it hasn't always been this way. In the early universe, there were no spiral galaxies, raising an interesting question: when did galaxies get their spirals, and how did they emerge? Now astronomers have the answer, thanks to an analysis of galaxies in an image taken by the Hubble Space Telescope known as the Ultra Deep Field. This shows some 10,000 galaxies of various ages. By ordering a subset of these by type and by age, astronomers have worked out how and when spirals must have evolved. It turns out the first spiral galaxies were simple two-armed structures and appeared when the universe was about 3.8 billion years old. But they say the universe had to wait until it was 8 billion years old before more complex multi-armed galaxies emerged, like the Milky Way and Andromeda."
Seems like a small sample (Score:5, Interesting)
The Elmegreens examined 269 spirals in the Hubble Ultra Deep Field and discarded all but 41 because of factors such as an inability to discern a clear spiral structure or the lack of redshift data which gives a galaxy’s age.
They divided these 41 spiral galaxies into five different types, based on features such as the number and clarity of arms, whether well-defined or clumpy and so on.
It sounds like they only found a few of each type, seems more like a good hypothesis than "the answer". It also makes you wonder if they cherry picked some of their data.
So did we help with this report? (Score:4, Interesting)
I recall a few years ago participating with a lot of others in a crowd source effort to categorize fuzzy pictures of possible galaxies. I think it was galaxy zoo.
So is this the result of our effort? Would be nice to know...
Re:Forming accretion disks (Score:5, Interesting)
This.
The mathematics governing many physical phenomena is strikingly similar. Its the frequency and wavelength that make them look radically different. Heat dissipation due to day/night cycles through a structure looks a lot like microwave attenuation in a surface. Same math, different time scale.
It also makes one wonder if the eventual form of a galaxy will resemble a planetary disc, with a bunch of large bodies (black holes?) orbiting a really big central one, surrounded by largely empty space.