1. Lecture 30- The Structure of the Milky Way Galaxy
Distance to the center of the globular cluster distribution: 8500 parsecs = 8.5 kiloparsecs

2. How far is 8.5 kiloparsecs? Let 1 au = 1cm
Nearest star (1.3 parsecs) = 2.68 km = 1.66 miles
8.5 kiloparsecs = 17,532 km = 10,870 miles (2.74 Earth radii)
Light signal transmitted from the GC would take 27,700 years to reach us

3. Where (on the sky) is the galactic center?
In Sagittarius
RA = 17h45m
DEC=-28.3 degrees
Position on SC1 Chart

4. Location on Sky of Galactic Center

5. At radio wavelengths, we can see to the galactic center
At radio wavelengths, we can see to the galactic center. Interstellar dust has very little effect on radio waves

6. The Galactic Center Lang, Lazio, et al

7. At the Very Center

8. What do we see at the galactic center (radio and infrared wavelengths?
Strong radio source (synchrotron radiation)
At infrared wavelengths, can see stars orbiting very vast around Sgr A
Ten years of observations speeded up

9. The Orbit of Star S2

10. Star S2 passes about as close to Sagittarius A
Star S2 passes about as close to Sagittarius A* as the planet Pluto passes to the Sun. Indicates supermassive object in a very small region
Andrea Ghez paper