Using slitless spectroscopy to study the kinematics of the planetary nebula population in M94 |
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| Authors: | N G Douglas J Gerssen K Kuijken M R Merrifield |
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| Institution: | Kapteyn Astronomical Institute, PO Box 800, 9700 AV Groningen, Netherlands;School of Physics &Astronomy, University of Nottingham, Nottingham NG7 2RD |
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| Abstract: | The planetary nebula populations of relatively nearby galaxies can be easily observed and provide both a distance estimate and a tool with which dynamical information can be obtained. Usually the requisite radial velocities are obtained by multi-object spectroscopy once the planetary nebulae have been located by direct imaging. Here we report on a technique for measuring planetary nebula kinematics using the double-beam ISIS spectrograph at the William Herschel Telescope in a novel slitless mode, which enables the detection and radial velocity measurements to be combined into a single step. The results on our first target, the Sab galaxy NGC 4736, allow the velocity dispersion of the stellar population in a disc galaxy to be traced out to four scalelengths for the first time and are consistent with a simple isothermal sheet model. |
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| Keywords: | instrumentation: spectrographs techniques: radial velocities planetary nebulae: general galaxies: individual: M94 galaxies: individual: NGC 4736 galaxies: kinematics and dynamics |
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