Searching for Data
You can see that searching the data by hand is tedious and time
consuming. To make a good H-R diagram for a globular cluster, you might need a
couple of hundred stars or more. To make a diagram with hundreds of stars, you
would need some tool to search through SDSS data automatically.
Fortunately, SkyServer includes several tools to search through SDSS data. The simplest
is the Radial Search tool,
which finds all objects in a region of sky. You can search more precisely with the
SQL Search tool, which uses a
programming language called SQL to make requests, or queries, from the SDSS database.
Searching for Stars in Palomar 5
You can use either of the search tools to find stars near Palomar 5. You can use the radial
search tool to find all objects, then use Excel to pare the list down to the stars. Or you can
use the SQL Search tool to look for stars, and only stars.
Click one of the links below to learn one of the two methods for finding stars. Your teacher
might tell you which one he or she wants you to use. Either link will bring up a new page in
this window.
Use the Radial Search tool and Excel
Use the SQL Search tool
Regardless of which method you chose, you should now have a table of data for all stars in
the region around Palomar 5.
| Exercise 7.
Using the data from your search, create an H-R diagram for Pal
5. Graph r on the y-axis and g-r on the x-axis. Remember
to reverse the values on the y-axis so brighter stars are at the top.
You may also want to adjust the min and max values of the axes to
give a better view of the H-R diagram. |
| Question 12.
Can you see the main sequence on this diagram? Can you see
any of the giants and supergiants? If so, identify these groups
of stars on your diagram. |
|
