15 Our Place In The Galaxy Flashcards
What is our Galaxy called?
Milky Way
What is Milky Way in Latin?
Via Lactea
How far is the Sun from the centre of our Galaxy?
~10 kpc
What is the radius of our Galaxy?
~15 kpc
What type of galaxy is the Milky Way?
Barred Spiral Galaxy
Where are open clusters of young stars found?
In the Spiral Arms
Why can’t we see the centre of the Galaxy using visible light?
The Centre of the Galaxy is blocked by dust and dense gas
What is the Doppler Principle?
The Doppler Principle is that relative motion changes the frequency or wavelength of observed waves. We notice this change mainly with sound waves
What does it mean if the observed wavelength is longer than it should be?
The object is moving away from us
What does it mean if the observed wavelength is shorter than it should be?
The source is moving towards us
What can the Doppler Shifts tell us about the Milky Way?
The received wavelengths are supposed to be 21 cm, but they aren’t exactly. This will tell us the relative velocities of the different parts of the Milky Way and how it’s rotating
What is redshift?
Redshift is receding sources of waves
What is blueshift?
Blueshift refers to sources that are approaching us
What is the used system for the classification of Galaxies?
Hubble Classification System
What is the diagram that classifies galaxies?
Tuning Fork Diagram
How many theories are there regarding the formation of galaxies?
2
What is the theory on the formation of galaxies from gas?
Vast clouds of gas and dust collapsed gravitationally, allowing stars to form
What is the theory on the formation of galaxies from lumps of matter?
Lumps of matter were already present in the Universe. They clumped together under their mutual gravitational attraction to form galaxies
What type of galaxy is believed to be the earliest type?
Elliptical
What are ‘active galaxies’?
Active galaxies are galaxies that have a small core of emission in a normal galaxy. It emits huge amounts of radiation in wavebands such as X-ray and radio regions
What is an Active Galactic Nucleus (AGN)?
An Active Galactic Nucleus is a compact region at the centre of a galaxy that have a much higher luminosity over a portion of the electromagnetic spectrum which indicates that the luminosity isn’t produced by stars
What are Seyfert galaxies?
Seyfert Galaxies are galaxies that have a bright nucleus and emit strongly in the IR, UV and X-ray regions
Who discovered Seyfert galaxies?
Seyfert galaxies were discovered by Carl Seyfert in 1943
What are Quasars?
A quasar is an extremely luminous AGN that emits strongly in the UV and X-ray regions.
What do Quasars appear like?
Quasars appear star-like on images and have large redshifts
What are BL Lacertae Objects (Blazars)?
Blazars are compact quasars where the galactic jets are pointing towards us
What is the approximate size of the Local Group?
3 Mpc
Name five galaxies our local group.
Any five of: Andromeda Galaxy Large Magellanic Cloud Small Magellanic Cloud Triangulum Galaxy Milky Way Pegasus Dwarf etc.
Which cluster is the Milky way in?
Virgo Cluster
Which supercluster is the virgo cluster in?
Laniakea Supercluster
