Night Flight to the Stars

Activity 4B: Seeing the Invisible!

The W51 star formation region is about 25,000 light years from earth. It contains hundreds of bright young stars surrounded by a thick dust cloud within or beyond the Milky Way's spiral arm. Use a ruler to mark the exact center of this star field. That's the location of W51. What do you see in the visible light photograph?

Explain your observation.

During the flight, watch as the Tracker Operator aims the telescope at W51 by using the locations of stars in this field. Why can the KAO "see" this dust cloud, but you can't find it in the photograph?

The image to the right was made by the IRAS infrared satellite. Notice that the W51 nebula is bright in IR even though it cannot be seen in the visible spectrum.

Compare the IR photograph of W51 with the IR photographs of M17, the Ring Nebula, and the galaxy M33.

Which object does W51 most resemble?

How would you describe W51 based on these comparisons?

As data are collected, watch where the telescope is pointing and record infrared measurements the KAO makes. Indicate on the top photo the locations of each brightness measurement. Use the KAO guide stars to position your observations.

This page was created by Daniel Helfman, a junior at Mission San Jose High School in Fremont, CA.

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