Lab #12: Charting the Milky Way's Center (continued) Page 2 of 4 Galactic Galactic Distance Distance NGC No Longitude Latitude from Sun polar view (deg) (deg) (kpc) (kpc) Galactic Galactic Distance Distance NGC No. Longitude Latitude from Sun (polar view (deg) (deg) (kpc) (kpc) 1904 227 -30 13 11 21 15 9 36 10 8 -6 6 4590 5024 5272 6402 6626 6637 6656 80 18 2 -10 9 10 -8 3 300 333 42 4 353 351 79 47 10 7 6681 3 9 5904 6093 -12 10 20 6356 7 15 6121 16 6284 358 10 15 6171 3 23 6838 57 -5 4 6205 59 41 8 20 -26 21 6218 16 26 5 6864 6981 7078 17 6254 15 23 4 35 65 53 -33 -27 -36 10 7 7089 12 6266 6273 6341 354 357 NONO NA 00000000 9 7099 -47 8 27 74 68 35 6229 40 30 6333 6 11 22 32 333 327 342 -16 5824 5927 1261 5 6584 6752 8 337 -26 271 16 -52 -35 6256 348 3 1851 246 12 341 -7 Pal 1 130 19 11 6352 6749 36 -2 6235 359 14 11 288 152 -89 9 Lat. Cos 1.00 2 1.00 4 1.00 6 0.99 8 0.99 10 0.98 12 0.98 14 0.97 16 0.96 18 0.95 20 0.94 Lat. Cos 22 0.93 24 0.91 26 0.90 28 0.88 30 0.87 32 0.85 34 0.83 36 0.81 38 0.79 0.77 Lat. Cos 42 0.74 44 0.72 46 0.69 48 0.67 50 0.64 52 0.62 54 0.59 56 0.56 58 0.53 60 0.50 Lat. Cos 82 0.14 84 0.11 86 0.07 88 0.04 90 0.00 Lat. Cos 62 0.47 64 0.44 66 0.41 68 0.38 70 0.34 72 0.31 74 0.28 76 0.24 78 0.21 80 0.17 Find the nearest Galactic Latitude in these Cosine tables and multiply the Distance from the Sun in kiloparsecs by the value in the Cos column, which applies for both negative and positive latitudes. 40 Lab #12: Charting the Milky Way's Center (continued) Page 4 of 4 The plane of the galaxy in the polar graph lies across the page's surface, so it depicts a view from above the disk of stars that constitute the Milky Way. The Earth is at the center of the graph. What do you notice about the plotted points? Are they scattered everywhere on the graph or are they concentrated in a particular region? Are the clusters distributed fairly equally on either side of a particular galactic longitude? If so, what longitude would you say points in that direction? Assume that the distribution of globular clusters is roughly uniform in the Milky Way's halo. Draw a small, distinct circle where you estimate the center of the galaxy would lie. How many kiloparsecs separate the Milky Way's center (the circle you drew) from the Earth's location in the galaxy (the center of the polar graph)? _kpc What do you estimate the uncertainty would be in your distance value (For example, five percent, twenty percent, fifty percent)? Use reputable Internet sites to find the accepted distance and find the percent difference between your distance estimate and the actual one. (Accepted value - your distance estimate)/ Accepted value) x 100- % Lab #12: Charting the Milky Way's Center (continued) Page 2 of 4 Galactic Galactic Distance Distance NGC No Longitude Latitude from Sun polar view (deg) (deg) (kpc) (kpc) Galactic Galactic Distance Distance NGC No. Longitude Latitude from Sun (polar view (deg) (deg) (kpc) (kpc) 1904 227 -30 13 11 21 15 9 36 10 8 -6 6 4590 5024 5272 6402 6626 6637 6656 80 18 2 -10 9 10 -8 3 300 333 42 4 353 351 79 47 10 7 6681 3 9 5904 6093 -12 10 20 6356 7 15 6121 16 6284 358 10 15 6171 3 23 6838 57 -5 4 6205 59 41 8 20 -26 21 6218 16 26 5 6864 6981 7078 17 6254 15 23 4 35 65 53 -33 -27 -36 10 7 7089 12 6266 6273 6341 354 357 NONO NA 00000000 9 7099 -47 8 27 74 68 35 6229 40 30 6333 6 11 22 32 333 327 342 -16 5824 5927 1261 5 6584 6752 8 337 -26 271 16 -52 -35 6256 348 3 1851 246 12 341 -7 Pal 1 130 19 11 6352 6749 36 -2 6235 359 14 11 288 152 -89 9 Lat. Cos 1.00 2 1.00 4 1.00 6 0.99 8 0.99 10 0.98 12 0.98 14 0.97 16 0.96 18 0.95 20 0.94 Lat. Cos 22 0.93 24 0.91 26 0.90 28 0.88 30 0.87 32 0.85 34 0.83 36 0.81 38 0.79 0.77 Lat. Cos 42 0.74 44 0.72 46 0.69 48 0.67 50 0.64 52 0.62 54 0.59 56 0.56 58 0.53 60 0.50 Lat. Cos 82 0.14 84 0.11 86 0.07 88 0.04 90 0.00 Lat. Cos 62 0.47 64 0.44 66 0.41 68 0.38 70 0.34 72 0.31 74 0.28 76 0.24 78 0.21 80 0.17 Find the nearest Galactic Latitude in these Cosine tables and multiply the Distance from the Sun in kiloparsecs by the value in the Cos column, which applies for both negative and positive latitudes. 40 Lab #12: Charting the Milky Way's Center (continued) Page 4 of 4 The plane of the galaxy in the polar graph lies across the page's surface, so it depicts a view from above the disk of stars that constitute the Milky Way. The Earth is at the center of the graph. What do you notice about the plotted points? Are they scattered everywhere on the graph or are they concentrated in a particular region? Are the clusters distributed fairly equally on either side of a particular galactic longitude? If so, what longitude would you say points in that direction? Assume that the distribution of globular clusters is roughly uniform in the Milky Way's halo. Draw a small, distinct circle where you estimate the center of the galaxy would lie. How many kiloparsecs separate the Milky Way's center (the circle you drew) from the Earth's location in the galaxy (the center of the polar graph)? _kpc What do you estimate the uncertainty would be in your distance value (For example, five percent, twenty percent, fifty percent)? Use reputable Internet sites to find the accepted distance and find the percent difference between your distance estimate and the actual one. (Accepted value - your distance estimate)/ Accepted value) x 100- %