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Full-Text Articles in Physical Sciences and Mathematics
The Initial-Final Mass Relation Among White Dwarfs In Wide Binaries, Jingkun Zhao, T. D. Oswalt, Lee Anne Wilson, Qian Wang, Gang Zhao
The Initial-Final Mass Relation Among White Dwarfs In Wide Binaries, Jingkun Zhao, T. D. Oswalt, Lee Anne Wilson, Qian Wang, Gang Zhao
Aerospace, Physics, and Space Science Faculty Publications
We present the initial–final mass relation derived from 10 white dwarfs in wide binaries that consist of a main-sequence star and a white dwarf. The temperature and gravity of each white dwarf were measured by fitting theoretical model atmospheres to the observed spectrum using a χ2 fitting algorithm. The cooling time and mass were obtained using theoretical cooling tracks. The total age of each binary was estimated from the chromospheric activity of its main-sequence component to an uncertainty of about 0.17 dex in log t. The difference between the total age and white dwarf cooling time is taken as the …
A Selection Of Hot Subluminous Stars In The Galex Survey – I. Correlation With The Guide Star Catalog, S. Vennes, A. Kawka, P. Nemeth
A Selection Of Hot Subluminous Stars In The Galex Survey – I. Correlation With The Guide Star Catalog, S. Vennes, A. Kawka, P. Nemeth
Aerospace, Physics, and Space Science Faculty Publications
We assembled a catalogue of bright, hot subdwarf and white dwarf stars extracted from a joint ultraviolet, optical and infrared source list. The selection is secured using colour criteria that correlate well with effective temperatures Teff≳ 12 000 K. We built a NUV− V versus V − J diagram for ≳60 000 bright sources using the Galaxy Evolution Explorer (GALEX) NUV magnitude (NUV < 14), the associated Guide Star Catalog (GSC2.3.2) photographic quick-V magnitude and the Two-Micron All-Sky Survey J and H magnitudes. This distillation process delivered a catalogue of ≈700 sources with NUV− V < 0.5 comprising ∼160 known hot subdwarf stars and another ∼60 known white dwarf stars. A reduced proper-motion diagram built using the proper-motion measurements extracted from the Naval Observatory Merged Astrometric Dataset allowed us to identify an additional ∼120 new hot subdwarf candidates and ∼10 hot white dwarf candidates. We present a spectroscopic study of a subset of 52 subdwarfs, 48 of them analysed here for the first time, and with nine objects brighter than V ∼ 12. …
The Structure Of X-Ray Emissions Fromtriggered Lightning Leadersmeasured By A Pinhole-Type X-Ray Camera, M. M. Schaal, J. R. Dwyer, S. Arabshahi, E. S. Cramer, R. J. Lucia, N. Y. Liu, H. K. Rassoul, D. M. Smith, J. W. Matten, A. G. Reid, J. D. Hill, D. M. Jordan, M. A. Uman
The Structure Of X-Ray Emissions Fromtriggered Lightning Leadersmeasured By A Pinhole-Type X-Ray Camera, M. M. Schaal, J. R. Dwyer, S. Arabshahi, E. S. Cramer, R. J. Lucia, N. Y. Liu, H. K. Rassoul, D. M. Smith, J. W. Matten, A. G. Reid, J. D. Hill, D. M. Jordan, M. A. Uman
Aerospace, Physics, and Space Science Faculty Publications
We investigate the structure of X-ray emissions from downward triggered lightning leaders using a pinhole-type X-ray camera (XCAM) located at the International Center for Lightning Research and Testing. This study builds on the work of Dwyer et al. (2011), which reported results from XCAM data from the 2010 summer lightning season. Additional details regarding the 2010 data are reported here. During the 2011 summer lightning season, the XCAM recorded 12 out of 17 leaders, 5 of which show downward leader propagation. Of those five leaders, one dart-stepped leader and two chaotic dart leaders are the focus of this paper. These …