Spiral Galaxies

• Spiral galaxies have a spiral shape with arms radiating from a central nucleus.

• Examples: Milky Way, Whirlpool Galaxy

Elliptical Galaxies

• Elliptical galaxies have a smooth and extended appearance and range in size from almost circular to extremely elongated.

• Examples: M87 galaxy, Virgo Cluster

Lenticular Galaxies

• Lenticular galaxies lack identifiable spiral arms and resemble spiral and elliptical galaxies in appearance and disk-like structure.

• Examples: Sombrero Galaxy, Cartwheel Galaxy

Irregular Galaxies

• Irregular galaxies have a shape of uneven, chaotic, and lack a distinct structure.

• Examples: Large and Small Magellanic Clouds

Active Galaxies

• Active galaxies are galaxies that there are small emission nucleus embedded in the center of a typical galaxy

• Examples: Radio Galaxies, Seyfert Galaxies, BL Lac Objects, Quasars for examples of active galaxies.

Seyfert Galaxies

• Seyfert Galaxy is a galaxy of a type characterized by a bright compact core that shows strong infrared emission.

• Example: NGC 1097

Quasars

• Quasars are the blazing centers of active galaxies and are powered by a supermassive black hole feeding on humungous quantities of gas.

• Example: TON 618

Blazars

• Blazars are a type of galaxy powered by a ginormous black hole and among the brightest, most energetic object in the sky

• Examples: 3C 454.3, 3C 273, BL Lacertae, PKS 2155-394, Markarian 421, Markarian 501, and S5 0014+81

composition

• crust, mantle, and core

orbital distance from the sun

• 510.1 million km

size

• 510.1 million km^2

orbital periods

• 365 days

composition

• Iron, nickel, and sulfur

orbital distance from the sun

• 142 million miles

• 1.5 astronomical units away from the Sun

size

• 4,212 miles (6,779 kilometers)

orbital periods

• 686.98 days

composition

• 70% metallic and 30% silicate material

orbital distance from the sun

• 43 million miles

size

• 3032 miles (diameter)

orbital periods

• (Sidereal) 87.9691 days

• (Synodic) 115.88 days

composition

• Mostly hydrogen and helium

orbital distance from the sun

• 483 million miles (777 million km)

size

• 23.71 billion mi^2

orbital periods

• 11.86 years

composition

• Central iron core and a rocky mantle

orbital distance from the sun

• 67 million miles

size

• about 7,521 miles

orbital periods

• (Sidereal)- 224.701 days

• (Synodic)- 583.92 days

composition

• water, methane, and ammonia

orbital distance from the sun

• 1.8 billion miles

size

• 31,763 miles

orbital periods

• 84 years

composition

• hydrogen and helium

orbital distance from the sun

• 887 million miles

size

• 42.7 billion km

orbital periods

• 29.4 years

composition

• water, methane, and ammonia

orbital distance from the sun

• 2,795,984,800 miles

size

• 7.618 billion km

orbital periods

• 165 years

composition

• 92.1% hydrogen and 7.9% helium

size

• 865,000 miles

orbital periods

• 225 million years

Main Sequence Stars:

• Luminosity: High

• Spectral: A, B, F, G, K, M

• Evolutionary: Stable phase where hydrogen fusion occurs in the core, lasting for billions of years

Red Giants:

• Luminosity: Very high

• Spectral: K, M

• Evolutionary: Late stage of stellar evolution when the star expands and cools after exhausting its hydrogen fuel

White Dwarfs:

• Luminosity: Low

• Spectral: A, B

• Evolutionary: End stage of stellar evolution for low to medium-mass stars, the core collapses and becomes a very dense star

Neutron Stars:

• Luminosity: Very high

• Spectral: None (electromagnetic radiation is low or absent)

• Evolutionary: Formed after a massive star undergoes a supernova explosion, leaving behind a very dense core made mostly of neutrons

Red Dwarfs:

• Luminosity: Low

• Spectral: M

• Evolutionary: Low-mass and low-temperature stars that burn their fuel very slowly and have long lifetimes

Brown Dwarfs:

• Luminosity: Very low

• Spectral: L, T, Y

• Evolutionary: Substellar objects that are not big enough to sustain hydrogen fusion in their cores, are considered failed stars