Looking Sharp: Images from New Gemini Spectrograph Rival View from Space

A longslit spectrum of HCG87a (box/peanut galaxy). The slit was placed along the major axis (long dimension) of the galaxy and the light was dispersed with a 400 line/mm diffraction grating to detect three emission lines from gas in the galaxy. Halpha is the brightest line emitted by Hydrogen gas at 6563A. The [NII] lines are emitted by ionized nitrogen gas. Doppler shift due to movement of the gas causes the observed wavelengths of the lines to shift with position along the slit. The gas to the rights of the galaxy's center is moving away from us at 350 km/sec with respect to the center of the galaxy while gas to the left is moving towards us. This shows that the galaxy is rotating. The bright vertical spectrum along the right edge is from a nearby star. The horizontal lines along the top of the image are emission lines from gas in the earth's atmosphere.