Navigating the Milky Way Galaxy

With partiview_mw running, grab the lower right corner of the window and expand it to a comfortable size. Do not make it full size. It helps to be able to see the original terminal window as well as the visual display. The stellar database is quite large, and on some computers the display may not be as responsive as you are accustomed to. The larger the window, the slower the display can update when it is running this process.

Figure: The Partiview window with its Milky Way database.

You navigate through the 3-D space using the mouse and an occasional keystroke in one of three modes: orbit, translate, and rotate. By default, the program will start in orbit mode with you at the Sun looking toward Orion. Orbit allows you to ``orbit'' around the reference point, and to move logarithmically in and out of the screen. However, it does not allow you to move off the reference point initially. Try this:

1. Hold the left mouse button down and move the mouse over the image. This moves you around the Sun, but since you are also on the Sun, the effect is let you look around the universe as seen from the center of our solar system. Direct your view above and to the right of Orion toward Taurus and you will see the red giant Aldebaran and the galactic star cluster the Pleiades. Try pressing on the buttons ``g4=constell'' to toggle on and off the constellation maps, ``g15=radec'' to toggle the right ascension and declination grid, and ``g16=eclip'' to toggle the ecliptic coordinate grid.

2. Select the translate mode either using the third arrow button on the top of the interface window, or by pressing ``t'' on the keyboard while the window is active (if necessary, left click on the top of the window bar to make it active). The navigation mode will be displayed under the arrow on the bar, and should show [t]tran for ``translate'' or [o]rbit for ``orbit''.

3. Hold the right mouse button down and move the mouse up over the image. This will move you away from Orion. If you release the button while you are moving the mouse, you will continue to move (you have ``inertia''). Left click anywhere on the image to stop the motion.

4. Now that you are no longer at the Sun (it should have receded into the distance in front of you) you can switch back to ``orbit'' mode. This has the advantage of using logarithmic scaling which will allow you to make a fast journey out of the Milky Way.

5. Since we are interested in galaxies now, let's select the objects that are useful for us. Groups are turned on or off with the buttons along the top of the window. Click off everything (it comes up with ``g1=stars'' and some others on). If you need to see all 32 groups, use the slider underneath the group list to scroll it left or right. Now click on
   • ``g6=oc'' open clusters
   • ``g8=gc'' globular clusters
   • ``g9=pul'' pulsars
   • ``g12=snr'' supernova remnants
   • ``g27=mwpoly'' milky way spiral structure
   • ``g28=bar'' milky way central bar
   • ``g30=lgrp'' local group

   Figure: Stars are off, clusters on.

   
6. Set the clipping planes so that they will be able to include both near and far objects. Usually the command clip 100 1e11 entered in the ``Cmd:'' field of the window will do it. You may need to change the clipping at some point if objects of interest disappear, but for now this will do.
7. Add axes centered on the Sun with lengths of 10000 parsecs with the command censize 10000
8. In ``orbit'' mode move the mouse down over the image with the right button depressed, and while moving it release the button. Inertia will carry you out of the Milky Way. As it recedes in front of you, left click on the image when it is obviously far in front of you. By holding the left button down and moving the mouse you can orbit around the Sun and see the Milky Way from different directions.
9. Notice that the open clusters, globular clusters, pulsars, and supernova remnants are color coded. You can identify which is which by clicking off/on each group. It might help now to turn off g9 and g12, leaving just the open and globular clusters.
10. Move out farther to see the Local Group galaxies. They will appear in green with blue labels.
11. If you center click on any object, its (x,y,z) coordinates and other information will be displayed both in the information box on the display, and on the terminal window from which you started Partiview. Explore the Local Group and see if you can find the Andromeda galaxy, M31.
12. A shift and right click on any active group button will select it so that you can control some the display parameters specific to that group. Try this on the local group. Now left click on the small arrowhead labeled ``slum'' near center at the top of the window. This will provide a list of things that can be connected to the slider on the right. Select ``alpha'' and you will see a label under the slider that says ``[lgrp] alpha''. As you move the slider you will have control on the brightness of the local group galaxies in the display. ``[lgrp] polysize'' will make the marker for the object change size logarithmically as you move the slider.
13. Return to the center of the Milkyway and look for labels that mark the Hyades and Pleiades. Turn the stars back on. It may help to turn on the ``Box'' feature that is set to bound these clusters. Set the clipping planes to limit the display; something like ``clip .1 1000'' may work once you are close to the Pleiades. Hold the shift key down and center click in orbit mode to move the center of the orbit to the selected object. For example, select the bright star Atlas in the Pleiades in this way and the motion will be around a point within the cluster. Change to ``censize 1'' to see a 1 parsec distance scale within the Pleiades. What is the separation between Atlas and Merope?

Figure: The Tully Nearby Galaxies Catalog.