Summer 2001 Astronomy Internship

Jessy Lancaster Lancaster High School

M57

THE RING NEBULA   False color composite from V, R, and I filters with a linear scale. Three 300s exposures in R and I and two 300s exposures in V were added to make the combined image. The image measures 914.4 arcsec by 676.80 arcsec. North is up, East is right.   Introduction Planetary nebulae are the remains of a dying star. When a star with a mass less than eight suns nears the end of its life, it blows off its outer gas layers, forming a halo around the star's core. At this point the star is called a white dwarf and is no longer producing heat, but slowly losing it.   Observations Images of the planetary nebula M57 were taken on the night of July 14 with the 10" Meade Schmidt-Cassegrain Great Ohio Telescope and the SBIG ST-8 CCD camera. The nebula measures 84.24 arcsec x 64.80 arcsec. Data was taken in all five filters (V, R, I, H-alpha, H-continuum)  , with 300 second exposures in each. Also, the weather was photometric.   Reduction The images of M57 were reduced using IRAF (Image Reduction and Analysis Facility) . In order to reduce noise, the dark frames were subtracted. Then the data was flat-corrected with ccdproc using the twilight flats. Cosmic rays were removed using xzap. The images taken in each filter were registered (xregister)  and then combined (imexpression) . These combined images of the V, R, and I filters were registed with each other and then cropped. The registered, cropped images were combined to make a color composite image using the CIAO program dmimg2jpg. The I data was coded to red, the R data to green, and the V data to blue.   Results In the combined V, R, and I images the central star is easily visible and very blue. I attempted to image the central star in H-alpha to determine its temperature, but was not able to see it.   The H-alpha image in inverted greyscale coloring. This is a combined image of three 300s exposures in the H-alpha filter.   H-continuum subtracted from H-alpha in inverted greyscale coloring. Acknowledgements Tom Statler, Katheen Moore, Tim Lester, Anca Constantine, Robert Salow, and Russell Ryan are all sincerely thanked for their help and advice with this project.   Links M57 Planetray Nebulae Ohio University Physics Page STARS Homepage datawaslost   False color composite from V, R, and I filters with a linear scale and slightly different coloring.    False color composite from V, R, and I with a log  scale.  
  copyright 2001 Ohio University