WhatFinger


I Zwicky 18, Fritz Zwicky

Young Galaxy not as Young as First Thought



In the world of science, nothing is absolutely certain for very long. Einstein's theories of relativity and general relativity are already being rethought. Evolution is always up in the air. And now, I Zwicky 18--a dwarf irregular galaxy--appears not to be as young as first thought.

Support Canada Free Press


Named for the Swiss astronomer Fritz Zwicky, who discovered it from a series of 1930s photographic galaxy survey, the little galaxy was later to become a harbinger of misled scientific enlightenment. Observations from the Palomar Observatory some 40 years ago seemed to suggest that the galaxy was a lot younger than anticipated. Towards the end of 2004, Hubble was used to measure the age of this galaxy. The press release described it as "a mere toddler seemingly out of place among the grown-up galaxies around it" and the scientists were looking forward to getting a glimpse in to what early galaxies may have looked like. It was originally thought to be some 500 million years old. Granted, we're still talking about millions of years here, but cosmologically, that's nothing. Take the Milky Way for example; which are aged at some 12 billion years old, a basic average age for galaxies. They also believed that the galaxy was only 45 million light-years away. Once again, seems a lot, but it's still pretty much in our own backyard. Well, my use of the past tense hasn't been for nothing, as Hubble scientists have just announced findings that blow these theories out of the...sky (sorry). Even if you are not the world's greatest authority on astronomy, you'll most likely be aware of the fact that a young star is very blue, and an old star is a dying red. Well Hubble has found red stars within I Zwicky 18, faint, but there nonetheless. This discovery, at the very least, doubles the age of the galaxy to 1 billion years old, and could be stretched as far as 10 billion. In other words, the galaxy essentially formed at the same time as everyone else did. "Although the galaxy is not as youthful as was once believed, it is certainly developmentally challenged and unique in the nearby Universe," said astronomer Alessandra Aloisi from the European Space Agency/Space Telescope Science Institute, who led the new study. New data from the Hubble telescope has also reshaped the distance between the Milky Way and I Zwicky 18. The new distance seems to sit at 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. Almost at the limit of Hubble's ageing resolution, Zwicky is still in our backyard, but just a bit further out than the swing and sandpit. The method of distance detection is really quite fascinating. Massive stars called Cepheid variables pulse with a regular rhythm, a rhythm that is directly tied to their brightness. By determining the brightness of three such stars within Zwicky using prediction models created specifically for Zwicky, the Aloisi and her scientists were able to determine how far away the galaxy actually is. All of this scientific-fact quashing aside though, Zwicky still holds secrets that scientists want to unwrap. For example, though the galaxy is now believed to be of similar age to our own--thus, relatively average--it is still mostly composed of hydrogen and helium. These two materials are part of the original big bang, and that the galaxy hasn't created heavier elements suggests that its rate of star formation has been much slower than the average. As always, the scientists end their press release with the note that these discoveries "may provide unique new insights" into the properties of certain stars. We will continue to keep you all updated on these unique new insights as soon as we hear about them. Joshua Hill, a Geek’s-Geek from Melbourne, Australia, Josh is an aspiring author with dreams of publishing his epic fantasy, currently in the works, sometime in the next 5 years. A techie, nerd, sci-fi nut and bookworm.


View Comments

Guest Column Joshua Hill -- Bio and Archives

Items of notes and interest from the web.


Sponsored