Structure of Our Galaxy (The Milky Way) February 20, 2015

Sankha Karunasekara ( BSc Engineering University of Peradeniya (ug)

600

.

, Milky way .

, .

.

Sir

WIlliam Herschal 1875

.

,

. .

Figure 1: Herschals' Universe

Note :

.

.

2 | P a g e

1922 keptayn .

Spheroid ( ) 8.5 * 1.7 kPc . (650,38) Pc

.

harlo shapley

.

.

Sagittarius ( 100kPc)

.

shapley

.

keptayn shapley

( ) .

( Intersteller Extinction) .

1930 Trumpler .

.

8kPc .

:

Shapley

10 0 .

zone of avoidance ,

.

Shapley RR Lyrae

.

Figure 2: Multi wave Length Milkey way

3 | P a g e

( Interstellter Medium)

.

.

.

3 .

1) Halo ( )

2) Bulge

3) Disk ( )

bulge .

.

.

SBc .

( Spiral arms in Milky way)

200 400

disk .

Halo

,

.

,

.

2 3 kPc arms

.

26000 Orion Arm

.

, , Sagittarius Arm

.

4 | P a g e

( Our Neighbors)

, andromeda Local group

( ) . 32

( dwarf Galaxies) .

.

sagittarius dwarf LMC (Large Magalanic Cloud) local

group . 30 -40 .

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Figure 4:Leo 01 Figure 3:LMC (Large Magalanic Cloud)