Lab Work

PHY 121-122-123: ElementaryAstronomy Name Portland CommunityCollege

Lab: Galaxy Rotation

Purpose:
In this lab we will study the rotational velocities of galaxies by examining stellar data and making graphs of velocity vs. distance from center of galaxies.

Procedure:
1. Graph the following data tables. You may put them all on one graph if you color code them so you can see them individually. Make the graph large enough for them all to fit! Examine all of the data before settling on a scale. Kpc distance is the distance OUT from the center of the galaxy (which is 0.0 Kpc). RV is the rotational velocity, in Km/sec. For comparison, our galaxy is about 16 Kpc in radius (visiblelight)

2. Google each galaxy and determine its type (spiral, elliptical, irregular) and use a best-fit line or arithmetic average to determine its average RV (rotational velocity). Graph the Milky Way data last. (6 graphs @ 3 points each = 18 points)

NGC 4183 Data: TypeofGalaxy: AverageRV: ________

Distance (kpc) Rotational Velocity (km/s)
1.0 48
2.0 65
3.5 85
4.5 96
7.0 105
9.0 112
13.5 105
15.5 108
18.2 110
20.5 112

NGC 4138 Data: TypeofGalaxy: AverageRV: ________

Distance (kpc) Rotational Velocity (km/s)
0.5 140
1.0 180
3.0 180
6.2 195
9.2 182
12.3 163
15.6 147
21.8 151

NGC 5033 Data: TypeofGalaxy: AverageRV: ________

Distance (kpc) Rotational Velocity (km/s)
1.0 140
2.0 190
4.0 220
5.0 225
9.0 220
14 220
17 220
19 220
22 210
26 190
29 195
32 200

NGC 5533 Data: TypeofGalaxy: AverageRV: ________

Distance (kpc) Rotational Velocity (km/s)
3.0 300
9.0 295
15 270
20 270
26 275
38 250
48 240
55 240
62 240
68 230

NGC 6674 Data: TypeofGalaxy: AverageRV: ________

Distance (kpc) Rotational Velocity (km/s)
3.0 210
10 260
17 275
22 265
26 255
32 250
40 235
50 240
56 240
60 250
65 240

MilkyWay: Type of Galaxy:_spiral_AverageRV: _________

Distance (kpc) Rotational Velocity (km/s)
0.850 240
1.70 222
2.55 209
3.40 210
4.25 220
5.10 231
5.95 242
6.80 253
7.65 260
8.50 (Sun’s location) 257
9.35 250
10.2 245
11.1 248
11.9 254
12.8 261
13.6 271
14.5 280
15.3 289
16.2 300
17.0 310

Questions: (3 points each = 12 points)

1. Whatdoesthedatasuggestabouttherotationofgalaxiesnearandfarfromthegalacticnucleus?

2. Is there a relationship between galactic mass and average galactic rotation speed? What isit?

3. Does the type of galaxy (i.e. spiral, elliptical, irregular) have any effect on galactic rotation speed? If it does, what isit?

4. At what angle to us should galaxies be, for best results? How do we adjust for galaxies being at variousangles?

P(5.u)
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