ASTR 103 Lecture Notes - Lecture 25: Galaxy Rotation Curve, Parsec, Starburst Galaxy

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School
Department
Course
Professor
Hubble&27
Over&a&quarter-century&of&discovery&with&the&Hubble&Space&Telescope
-
Deep&field&(1995),&ultra&deep&field&(2003/2004),&and&eXstreme&deep&field&(2012)
-
2&trillion&galaxies&in&the&universe
-
The&Edwin&Hubble&"Tuning&Fork&Diagram"
Classification&of&galaxies&shape
-
Elliptical
E0,&E3,&E5,&E7
§
Perfect&sphere&to&elongated&elliptical
§
General&information/Characteristics
Roughly&20%&of&galaxies& we&see
§
No&recognizable&disk
§
Contains&nearly&no&star-forming&dust&and&gas
§
Composed&of&mostly&older&population&II&stars
§
Make&up&both&the&smallest&AND&largest&galaxies&that&we&see
§
-
Spirals
S0
Armless&spiral&(looks&like&a&Frisbee)
§
Sa,&Sb,&Sc
"Classic/normal&spirals"
Large&nucleus&with&tight&arms&to&looser/wider&arms
®
§
Sba,&SBb,&SBc
Barred&spirals
Arms&get&looser&and&looser/wider&and&wider
®
§
General&Information/Characteristics
Display&both&a&spheroidal&AND&disc&component
§
Nearly&80%&of&the&galaxies&we&see
§
Contains&a&good&deal&of&dust&and&gas
§
Active&star&formation&occurring
§
Contains&hot,&young,&population&I&stars
§
Lots&of&blue&and&red&(blue&because&stars&are&so&hot&and&red&because&
of&Nebulae)
§
-
Irregulars
Irr
General&information/Characteristics
For&any&galaxies&that&don't&appear&to&look&like&spirals&or&
ellipticals;& May&have&been&a&spiral&or&an&elliptical& at&some&
point&but&gravitational&pull&moves&them
Category&for&the&galaxies&that&don’t&fit&elsewhere
No&real&subdivisions
Many&known&as&"Starburst&galaxies"&because&a&HUGE&amount&
of&star&formation&is&taking&place
§
-
Galactic& distance
Standard&candles
Cepheid's,&supergiant's,&globular&clusters,&HII&regions,&and&
supernovae
Supernovae
Extreme&brightness&allows&them&to&be&see&at&great&
distances
M=&roughly&19&mag&for&Type&Ia&SN
M=&roughly&17&mag&for&Type&II&SN
®
§
Type&Ia&Supernova
Light&curves
§
Hubble&Expansion&Law
Expansion&of&uniderse
§
Distance-Velocity&relation
§
Vr=&H0D;&H0=&68&km/s
§
Good&for&distances&greater&than&10&Mpc
§
-
Galactic& mass
Rotation&curve
M=&v^2R/G
§
-
Galaxy&formation
Density&and&angular&momentum&during&formation
Collisions&tend&to&make&galaxies&elliptical
-
5.3-Galaxies
Friday,&November& 10,&2017
10:31&AM
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