P15: Star Formation in Spirals

Observing Goals:

Your goal is to observe \({\rm H_{\alpha}}\) line emission, associated with star formation, and where it occurs in Spiral Galaxies. You need to observe in the narrow band, and also the broad \({\rm R}\) band, so that you can separate the continuum and line emission. Useful Background and References:

Observation Planning:

  • Observation Time

    • You will be observing HALF a night.

  • Target Selection

    • You should find spiral galaxies that you can observe during your designated observing time, they should also be on a scale that fits nicely within the field of view available on our CCD.

    • Spiral galaxies where the arms look blobby or “interesting” are most likely to give you good results!

  • Observations

    • You should observe in the \({\rm R}\) and \({\rm H_{\alpha}}\) bands – note that H_alpha is much narrower that \({\rm R}\) so requires a lot more observing time. (You may also want other filters to construct multi-colour images)

    • You should observe continuum sources (e.g. stars) so that you can remove the continuum emission from the narrow filter. This could be by observing a standard star field with plenty of stars in it (remember some stars will have significant \({\rm H_{\alpha}}\) absorption, and in some wierdd cases, emission, so you need enough stars to make a solid average).

Data Analysis:

  • Data Reduction Basic Steps

  • Further for this project

    • You need to stack your images to get the highest signal to noise possible in each filter for both the galaxy and standard star fields

  • Further Analysis for this project

    • See R3: Line Emission from Narrow Band Observations for steps to measure and map the \({\rm H_{\alpha}}\) flux

Results:

Can you answer these questions with your work?

  • Q1: Where in your observed galay/galaxies is star formation taking place?

  • Q2: Are there other \({\rm H_{\alpha}}\) sources that you don’t attribute to star formation? why?

  • Q3: In your calibrated measurements, can you make an estimate of the star formation rate? or at least the rate from place to place?

  • Q4: Can you map and describe the star formation in the galaxy? Is there overall star formation? Does it just occur in “knots”? What story can you tell?

Presenting your results: