Challenge 1: A Catalog of HII regions
This challenge asks students to create a catalog of HII regions,
the star forming regions of galaxies. SDSS astronomers could use such a
catalog to study star formation and to test future updates of SDSS software.
Students write a query - a short computer program - to search through SDSS
for objects classified as galaxies that might be HII regions. Students will
have to visually examine every object to verify that it
is a HII region. This challenge is best undertaken by a group of
students, so they can divide up their list of potential candidates as they
verify them.
Project Goals
By the end of the project, students should be able to:
- Define an HII region and
explain its importance to astronomers
- Describe the color
characteristics of an HII region and how its colors differ from the colors
of a typical galaxy
- Create SQL queries to search and
retrieve information on likely HII regions
- Sort data to find the objects
most likely to be HII regions
- Identify prominent
spectral lines in HII regions
- Create a useful catalog of
astronomical objects
- Effectively communicate how their
data were collected so that others may use and refer to their catalog
- Create and carry out a complex
independent research project
Background Knowledge
Students should be familiar with the types of galaxies and with some of
their characteristics. They also should be comfortable working with
the SDSS color system and know about the magnitude scale. Students
will need to use this knowledge to make educated guesses about the colors of HII
regions. The Colors and
Galaxies projects give good introductions to these concepts.
In this challenge, students will look at the spectra of candidate HII regions. They
should know how to retrieve spectra from SkyServer using the Get Plates
tool. Students should be familiar with spectral emission lines, since these
lines are the dominant feature in the spectrum of an HII region.
Computer skills are very important for this challenge. Students will need
to create SQL queries that return data that are likely to include HII
regions. Students will need to know how to filter data in the "where"
block of the query, and how to retrieve data from multiple tables in the
same database. You may wish to work through one of the SQL tutorials so that you
may answer student questions.
Students will need to know how to use SkyServer's Navigation tool and
Object Explorer to look up images and Spectra of various objects. For some objects, they may
wish to download the images and look at them using an image processing
program such as IRIS
to get a better view. See the Image Processing
project for more information on how to use IRIS.
Project Structure
The first page of the student project teaches students what HII regions are.
The second page describes some of the
characteristics of HII regions so students can form some ideas on the best
way to search the data. The third page teaches students how to query SDSS data
with SkyServer's Query tool. The fourth page tells students how to tell if a candidate
object is actually an HII region.
The goal of this challenge is to create a catalog of HII regions that
could be used for research. SDSS astronomers just published a similar
catalog of quasars from SDSS's early data release. You can see the research paper
where they explain their results
here. (The paper is a .pdf file, and you will need Adobe Acrobat Reader to view it.
If you do not already have the reader, you can download it free from
Adobe's
web site.) You may wish to show this paper to students to give them an idea
of what their catalogs could be used for.
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