Astrometry With The Hubble Space Telescope: Trigonometric Parallaxes Of Planetary Nebula Nuclei NGC 6853, NGC 7293, Abell 31, And Deht 5

dc.contributor.utaustinauthorBenedict, G. Fritzen_US
dc.contributor.utaustinauthorMcArthur, Barbara E.en_US
dc.creatorBenedict, G. Fritzen_US
dc.creatorMcArthur, Barbara E.en_US
dc.creatorNapiwotzki, Ralphen_US
dc.creatorHarrison, Thomas E.en_US
dc.creatorHarris, Hugh C.en_US
dc.creatorNelan, Edmunden_US
dc.creatorBond, Howard E.en_US
dc.creatorPatterson, Richard J.en_US
dc.creatorCiardullo, Robinen_US
dc.description.abstractWe 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 VJHKT(2)M 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(pi)/pi = 5%. Derived distances are: d(NGC6853) = 405(-25)(+28) pc, d(NGC7293) = 216(-12)(+14) pc, d(Abell 31) = 621(-70)(+91) pc, and d(DeHt 5) = 345(-17)(+19) 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 M-circle dot, 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.en_US
dc.description.sponsorshipNASA NAG5-1603, GO-10432, GO-10611, NAS5-26555en_US
dc.identifier.citationBenedict, G. Fritz, Barbara E. McArthur, Ralf Napiwotzki, Thomas E. Harrison, Hugh C. Harris, Edmund Nelan, Howard E. Bond, Richard J. Patterson, and Robin Ciardullo. >Astrometry with the Hubble Space Telescope: Trigonometric Parallaxes of Planetary Nebula Nuclei NGC 6853, NGC 7293, Abell 31, and DeHt 5.> The Astronomical Journal Vol, 138, No. 6 (Dec., 2009): 1969.en_US
dc.relation.ispartofserialAstronomical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.subjectplanetary nebulae: generalen_US
dc.subjectstars: distancesen_US
dc.subjectfundamental parametersen_US
dc.subjectwhite dwarfsen_US
dc.subjectfine guidance sensoren_US
dc.subjectda white-dwarfsen_US
dc.subjectbalmer line problemen_US
dc.subjectinterferometric astrometryen_US
dc.subjectold planetariesen_US
dc.subjectproxima centaurien_US
dc.subjectastronomy & astrophysicsen_US
dc.titleAstrometry With The Hubble Space Telescope: Trigonometric Parallaxes Of Planetary Nebula Nuclei NGC 6853, NGC 7293, Abell 31, And Deht 5en_US
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