Class Notes (809,509)
Astronomy (153)
ASTRON 2B03 (116)
Lecture

# Sep 20 – 2B03.docx

6 Pages
118 Views

School
McMaster University
Department
Astronomy
Course
ASTRON 2B03
Professor
Todd Alway
Semester
Fall

Description
Sep 20 – 2B03 20/09/2011 9:25:00 AM Two main types of galaxies:  Spirals: o Our milky war o Think, disk-like (similar to a frizbee) [2d] o Have spiral arms o Stars are being formed today  Ellopticals o Compared to a frizbee, they are 3d. Similar to a balloon. o Similar, as well, to a cloud of bees.  Within galaxy, stars move around like bees flying about. o Not much rotation and star formation  Most galaxies are one or the other Galxies don’t live in isolation -> they have nearby neighbours.  They live in galaxy grouos. o Feel each other’s gravitational forces.  Our milky way have tiny galaxies orbiting around us, as well as have other large galaxies around us (Andromeda)  Some live in isolation, but most common is in groups Compact (galaxy) groups – distances between galaxies are smaller than galaxies themselves.  Incredibly compact.  Really feeling eachother’s forces. Two spirals colliding (galaxies) -> may create an ellicptical galaxy.  Two ellicptical galaxies colliding will create a larger elliptical.  These are when galxies collidge. Cluster vs group  Different in magnitude : o Group has like 30-50 (no rigid boundary) o Cluster may have like 1000 (much more) Biggest galaxies are the ones in the centre of the cluster (we think it is a result of, over time, colliding and merging with other galaxies) Gravitational lensing -> background galaxies, their light that is, is stretched out by the other galaxies. We will come back to this. Spinning of spiral galaxies – left on its own will stay spiral – the spiral means that it is stable.  When interacted with others galaxies, it will change shape. Galaxy clusters - biggest places in the universe  (Two kinds of clusters:) o Made up of stars, and also made up of galaxies. Most of the mass we see is invisible to the key  Most of the mass of a galaxy is in its dark matter -> invisible. o (we were speaking about the edge of the universe; edge is
More Less

Related notes for ASTRON 2B03

OR

Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Join to view

OR

By registering, I agree to the Terms and Privacy Policies
Just a few more details

So we can recommend you notes for your school.