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Astrometry With the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, ABELL 31, and DeHt 5We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC 6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1r and FGS 3, white-light interferometers on the Hubble Space Telescope. Proper motions, spectral classifications and VJHKT2M and DDO51 photometry of the stars comprising the astrometric reference frames provide spectrophotometric estimates of reference star absolute parallaxes. Introducing these into our model as observations with error, we determine absolute parallaxes for each PNN. Weighted averaging with previous independent parallax measurements yields an average parallax precision, sigma (sub pi)/ pi = 5%. Derived distances are: d(sub NGC6853) = 405(exp +28 sub -25) pc, d(sub NGC7293) = 216(exp +14 sub -12) pc, d(sub Abell31) = 621(exp +91 sub -70) pc, and d(sub DeHt5) = 345(exp +19 sub -17) pc. These PNNi distances are all smaller than previously derived from spectroscopic analyses of the central stars. To obtain absolute magnitudes from these distances requires estimates of interstellar extinction. We average extinction measurements culled from the literature, from reddening based on PNNi intrinsic colors derived from model SEDs, and an assumption that each PNN experiences the same rate of extinction as a function of distance as do the reference stars nearest (in angular separation) to each central star. We also apply Lutz-Kelker bias corrections. The absolute magnitudes and effective temperatures permit estimates of PNNi radii through both the Stefan-Boltzmann relation and Eddington fluxes. Comparing absolute magnitudes with post-AGB models provides mass estimates. Masses cluster around 0.57 solar Mass, close to the peak of the white dwarf mass distribution. Adding a few more PNNi with well-determined distances and masses, we compare all the PNNi with cooler white dwarfs of similar mass, and confirm, as expected, that PNNi have larger radii than white dwarfs that have reached their final cooling tracks.
Document ID
20100007286
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Benedict, G. F.
(Texas Univ. Austin, TX United States)
McArthur, Barbara E.
(Texas Univ. Austin, TX United States)
Napiwotzki, Ralf
(Hertfordshire Univ. Hatfield, United Kingdom)
Harrison, Thomas E.
(New Mexico State Univ. Las Cruces, NM, United States)
Harris, Hugh C.
(Naval Observatory Flaggstaff, AZ, United States)
Nelan, Edmund
(Space Telescope Science Inst. Baltimore, MD, United States)
Bond, Howard E
(Space Telescope Science Inst. Baltimore, MD, United States)
Patterson, Richard J.
(Virginia Univ. Charlottesville, VA, United States)
Ciardullo, Robin
(Pennsylvania State Univ. University Park, PA, United States)
Date Acquired
August 25, 2013
Publication Date
December 1, 2009
Publication Information
Publication: The Astronomical Journal
Publisher: American Astronomical Society
Volume: 138
Subject Category
Astronomy
Report/Patent Number
AD-A510418
Funding Number(s)
CONTRACT_GRANT: NAS5-26555
CONTRACT_GRANT: GO-10432
CONTRACT_GRANT: GO-10611
CONTRACT_GRANT: NAG5-1603
Distribution Limits
Public
Copyright
Other
Keywords
STARS
STARS
WHITE DWARFS
GENERAL
ASTROMETRY
DISTANCES
FUNDAMENTAL PARAMETERS
PLANETARY NEBULAE

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