NOAO >   Observing Info >   Approved Programs >   2009B-0467

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Proposal Information for 2009B-0467


PI: Todd Hillwig, Valparaiso University, todd.hillwig@valpo.edu
Address: Physics Department, 1610 Campus Drive, Valparaiso, IN 46383, USA

CoI: David Frew, Macquarie University
CoI: Orsola De Marco, Macquarie University
CoI: Sam Schaub, Valparaiso University

Title: Determining the Nature of EGB1 and its Central Star

Abstract: We have recently found the central star of the planetary nebula EGB 1 to be photometrically variable with a period of about 0.147 days. The variability suggests that the central star is a close binary system exhibiting either an irradiation effect due to a close cool companion, or an ellipsoidal effect due to one or both components filling a significant fraction of their Roche lobe. The central star (WD 0103+732) has been identified as a hot DA white dwarf. The nebula itself is clearly asymmetric, presumably due to interaction with the ISM. However, some studies suggest that EGB 1 may \it not be a planetary nebula but is instead ISM ionized by the hot WD. We request time resolved long-slit spectroscopic observations with the KPNO Mayall 4-meter. These observations will allow us to identify the nature of the photometric variability of the central star and provide a more certain classification of the surrounding nebulosity. In addition, if the variability is due to irradiation the spectra will also provide radial velocity measurements for both components in the binary system. If the variability is due to an ellipsoidal effect, then radial velocities for at least the white dwarf will be obtained. The spectroscopic observations will be supported by photometric observations using the 0.9m SARA telescope at KPNO.


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NOAO >   Observing Info >   Approved Programs >   2009B-0467

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