Introduction Search Fields Author Controlled Index Numerical Chemical Astronomical Tutorials
Then search for a word or phrase to find the controlled term. Here we will search the rather broad term "stars" in order to see how it can be narrowed.
The results may include more than one controlled term and clicking on the "T" will provide you with more information on what a particular term represents.
If you click on the "H" you can view the set of narrower and/or broader controlled terms if your current term is too broad or narrow to represent what you really want.
As you can see, there are many narrower terms that can be used in the place of "stars". If we look at multiple stars, we see that it too has narrower terms, but they are all for binary stars, so a search for three or more stars in a system would use the controlled term "multiple stars", while as search for SS Cyg stars would use "dwarf novae."
Two other narrower terms under "stars" are "giant stars" and "supergiant stars". In a search, one may be more useful than the other so we can click the "T" to compare the scope of the two.
From this you can see that for a search for α Aur stars you would want to use "giant stars". For α Cam stars you would use "supergiant stars" and in the case of a search or barium II stars you would use both. The following examples will demonstrate the usefulness of the controlled index. Please note: how to use the Astronomical and Chemical Indexes are explained later on.
Rather than doing just a search for "alpha Aur", combining it with the controlled term "giant stars" has reduced the number of results to an easier set to browse.
In this case, we can see that a search for "stars" and the element barium yields a large set of results. We can narrow the set with either controlled term, but the best set is from using both terms. From this smaller set you can further limit it with other search terms.
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Photo of Titan by NASA/JPL/Space Science Institute
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