PHYS 005 Lecture Notes - Lecture 11: Virgo Cluster, Great Attractor, Laniakea Supercluster
5 Jul 2018
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Extra credit: audiomachine as music source
4/30 Galactic Clusters and Superclusters
Ch. 24 Sect. 5
CALCULATING THE REDSHIFT
Hubble Law
v= H0*d
v= velocity @ which galaxy is moving away fr us
H0= Hubble constant=71 km/Mpc*s
●For every Mpc farther away, a galaxy is moving 71 km/s faster
●Obtained fr measurements of STANDARD CANDLES (supernovae, cepheids) in galaxies @ diff
distances
D= distance fr galaxy
●d= v/H0
z=λ-λ0/λ0
z= redshift of the object
lambda0= unshifted
wavelength of light
lambda= observed
shifted wavelength of light
●No units, both lambdas have to have the SAME distance
○Angstroms- diff btw 2 cusps
**further the object is, the further back in time
you are looking at the object
A lot of things happen in 5 light seconds-can miss green light, etc.
Tiny error in calculations messes everything up
Look-back time- how old is the light reaching me
●Calculation includes Hubble constant, baryonic matter, curvature of the universe, dark energy
Value of baryonic matter, dark energy/matter CHANGE hubble constant
●No universal value accepted atm
●More refined every year
Clusters of Galaxies
●Members in clusters continually revolve around one another
●10,000,000 ly
Poor v. rich clusters
Document Summary
Hubble law v= h 0 *d v= velocity @ which galaxy is moving away fr us. For every mpc farther away, a galaxy is moving 71 km/s faster. Obtained fr measurements of standard candles (supernovae, cepheids) in galaxies @ diff distances. D= v/h 0 z= - 0 / 0 z= redshift of the object lambda 0 = unshifted lambda= observed wavelength of light shifted wavelength of light. No units, both lambdas have to have the same distance. **further the object is, the further back in time. A lot of things happen in 5 light seconds-can miss green light, etc. Look-back time- how old is the light reaching me you are looking at the object. Calculation includes hubble constant, baryonic matter, curvature of the universe, dark energy. Value of baryonic matter, dark energy/matter change hubble constant. Members in clusters continually revolve around one another. Milky way, andromeda, triangulam, large & small mascellaneous clouds**
