Date: September 1st, 2012
Title: Encore: A Closer Look at Galaxy Clusters
Podcaster: Thomas Hofstätter
Organization: http://hidden-space.at.tf (The Hidden Space Project)
Originally aired on September 25, 2010
http://365daysofastronomy.org/2010/09/25/september-25th-a-closer-look-at-galaxy-clusters/
Description: Galaxy Clusters are the largest known structures in the universe. They are bound together by gravity and contain huge amounts of matter such as gas and dust. They oppose the general expansion of the universe due to high amounts of dark matter. If you have any questions, comments or suggestions to the podcast, feel free to write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf!
Bio: Born in 1993 near Vienna, Austria, Europe. Upper High School with focus on Computer Science.Interested in extreme small and extreme big, devious and uninvestigated things. My main aim is to bring astronomy to public and to establish secular interest in astronomy, physics and mathematics. Hoster of :: The Hidden Space Project :: at http://hidden-space.at.tf.”
Today’s Sponsor: This episode of 365 days of Astronomy is sponsored by iTelescope.net – Expanding your horizons in astronomy today. The premier on-demand telescope network, at dark sky sites in Spain, New Mexico and Siding Spring, Australia.
Transcript:
Hello and welcome to this episode of 365 Days of Astronomy. My name is Thomas Hofstätter and I am the hoster of :: The Hidden Space Project :: at www.hidden-space.at.tf.
[Leon:] And I’m Leon Dombroski from the state of Connecticut in the United States.
In this episode, we’ll have a closer look on Galaxy Clusters. Unfortunately, we cannot show you images on this podcast. But you can find some images in the article about this topic at www.hidden-space.at.tf/articles.php. There you can find an article named equally to this podcast as well as some other ones.
[Leon:] Gravity affects every massive particle in the universe. Due to this gravitational effect, matter is bound together to form structures. These structures begin with small molecules and then go to larger objects such as planets, galaxies … and galaxy clusters. Galaxy clusters are huge collections of galaxies bound together by gravity. They are the largest objects/structures in the known universe.
Looking at the whole universe, we can see large structures of matter forming dense regions all over the universe. They oppose the general expansion of the universe known since Edwin Powell Hubble has detected it in the first quarter of the last century. It says that the universe is expanding at the time due to energy set free during the big bang.
[Leon:] When looking at galaxies, scientists classify these known structures in the following groups:
*) Local Groups,
*) Galaxy Clusters and
*) Galaxy Superclusters
As a Local Group, scientists define the local structures of galaxies. Our local group the Milky Way is part of contains about 30 galaxies and dwarf galaxies. These are e.g. the Milky Way itself, the Small and Large Magellanic Cloud [dwarf galaxies orbiting the Milky Way], the Andromeda Galaxy (M31) together with her satellite (dwarf) galaxy M32 and the Triangulum Galaxy. Also halos around galaxies and their satellites are counted to the local group. All together, it’s about four million light years wide.
[Leon:] The next larger step are Galaxy Clusters. They are the largest known structures in the universe and are often called Galaxy Group. They contain about ten to 1000 galaxies and their satellites. If more galaxy clusters are bound together, it’s called a Galaxy Supercluster.
A cluster contains not only galaxies and dwarfs but also a high amount of dark matter. Such dark matter doesn’t contain any baryonic material. That means, no particles we got to know as electrons, protons, neutrons and so on. Hence, we are not able to see it in any part of the spectrum. The only affect that makes us know this form of matter is it’s gravitational pull. Dark matter makes the clusters hold together and forces the general expansion of the universe.
[Leon:] The cluster we live in is the so-called Virgo Supercluster. It contains 100 galaxy clusters and galaxy groups. Moreover, there is a high amount of gas and dust between and around the galaxies and galaxy clusters. The width is about 110 million light years. It’s mass is about 2*10^45kg. Most of the mass comes from dark matter.
Due to this high amount of mass, galaxies and galaxy clusters contain and due to the general theory of relativity by Albert Einstein, galaxy clusters mostly produce gravitational lenses when the light is bend outwards. These gravitational lenses make us see far away galaxies much nearer. Hence, galaxy clusters work for us as a most intensive telescope and help us understanding the universe shortly after the big bang.
That’s it for today. I hope, you enjoyed it. If you have any questions, comments or suggestions, write me an email to hidden-space (at) gmx (dot) at or visit me at my website at www.hidden-space.at.tf and observe basic questions of astronomy’s past and future as well as hidden and devious facts.
Thanks for listening and clear-skies!
[Leon:] Good bye for now!
End of podcast:
365 Days of Astronomy
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