NOAO >   Observing Info >   Approved Programs >   2005A-0085

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Proposal Information for 2005A-0085


PI: Thomas E Harrison, New Mexico State University, tharriso@nmsu.edu
Address: Astronomy Department, Box 30001/MSC 4500, Las Cruces, New Mexico 88003, USA

CoI: G. Fritz Benedict, University of Texas
CoI: Hugh C. Harris, United States Naval Observatory
CoI: Barbara McArthur, University of Texas
CoI: Robin Ciardullo, Pennsylvania State University
CoI: Edmund Nelan, Space Telescope Science Institute
CoI: Howard Bond, Space Telescope Science Institute
CoI: Richard Patterson, University of Virginia

Title: Precise Distances to Nearby Planetary Nebula from HST/FGS Parallaxes

Abstract: We have just been awarded 20 orbits in Cycle 13 to obtain parallaxes for four planetary nebulae using the Fine Guidance Sensors (FGS) on HST. The main result of this program will be distances accurate to +/- 6%. It has been noted that one of the outstanding problems in the field of Galactic planetary nebulae (PN) is their uncertain distances. Because PN distances are so poorly known, our understanding of their luminosities, masses, scale heights, birth rates, and evolutionary status is limited. To produce high-precision parallaxes with the Fine Guidance Sensors on the \it HST requires us to estimate the parallaxes of the reference frame stars. We do this by determining the spectral type of each reference star, and then using \it UBVRIJHK photometry to estimate A_\rm V and M_\rm V. We request four nights on the KPNO 4m with the RC spectrograph, to obtain moderate resolution spectroscopy of the 27 reference stars to perform MK classification.


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