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Jacoby G.H.,WIYN Observatory | Kronberger M.,Deepskyhunters Collaboration | Patchick D.,Deepskyhunters Collaboration | Teutsch P.,Deepskyhunters Collaboration | And 10 more authors.
Publications of the Astronomical Society of Australia | Year: 2010

Recent Hα surveys such as SHS and IPHAS have improved the completeness of the Galactic planetary nebula (PN) census. We now know of ∼3000 PNe in the Galaxy, but this is far short of most estimates, typically ∼25 000 or more for the total population. The size of the Galactic PN population is required to derive an accurate estimate of the chemical enrichment rates of nitrogen, carbon, and helium. In addition, a high PN count (>20 000) is strong evidence that most main-sequence stars of mass 1-8 M⊙ will go through a PN phase, while a low count (<10 000) argues that special conditions (e.g. close binary interactions) are required to form a PN. We describe a technique for finding hundreds more PNe using the existing data collections of the digital sky surveys, thereby improving the census of Galactic PNe. © Astronomical Society of Australia 2010.

Kronberger M.,CERN | Reegen P.,University of Vienna | Reegen P.,Tricentis | Alessi B.S.,Deepskyhunters Collaboration | And 2 more authors.
Astrophysics and Space Science Proceedings | Year: 2012

We present 27 open cluster candidates, including 24 previously unknown, that were found during an ongoing visual inspection of First and Second Generation Digitized Sky Survey (DSS) and Two Micron All Sky Survey (2MASS) images. Employing 2MASS and UKIDSS photometry, 10 of these candidates and three earlier published objects have physical parameters determined by isochrone fitting of their [J,J-H] and [J,J-K] colour-magnitude diagrams (CMDs) and [J-H, J-K] colour-colour diagrams. In order to decontaminate the cluster CMDs from stars belonging to the Milky Way fore- and background, a statistical approach is applied that determines the statistical significance of the density differences between the cluster CMD and the CMD of the Milky Way background. The studied clusters have ages ranging from a few Myr to≈1Gyr, are only moderately reddened (E(B-V)≤ 1:1) and are situated at distances between 0.95 and 5.5 kpc. © Springer-Verlag Berlin Heidelberg 2012.

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