AST 101

The Realm of the Nebulae

Meet the Neighbors

Large Magellanic Cloud

Large Magellanic Cloud

Small Magellanic Cloud

The Local Group

Contents of the Local Group

About 47 galaxies

• 3 large galaxies

• 44 smaller galaxies

The Local Group

Big Galaxies

M31 - Andromeda

Big Galaxies

M33 Triangulum

IC 10 M 32

Sextans ALeo I

Morphological Classification(Hubble Types)

• Spirals– Barred Spirals

• Ellipticals– Dwarf Ellipticals

• Irregulars

Spirals• Sa

• Sb

• Sc

• Sd

Barred Spirals• SBa

• SBb

• SBc

• SBd

Properties of Spirals

Sa Sb Sc Sd

• Bulge decreases in prominence

• Spiral arms increase in prominence

• Dust/gas content increases

• Prominence of population I increases

• Star formation rate increases

Ellipticals

• E0

• E2

• E6

• S0 spheroidal galaxy

Properties of Ellipticals

E0 E7

• Flattening increases

S0: has a disk, but no arms

Little, if any, gas and dust

Mostly the old stellar population (pop II)

Tuning Fork Diagram