Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Institution
Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
The Hubble Space Telescope * Cluster Supernova Survey. Ii. The Type Ia Supernova Rate In High-Redshift Galaxy Clusters, K Barbary, G Aldering, R Amanullah, M Brodwin, N Connolly, Ks Dawson, M Doi, P Eisenhardt, L Faccioli, V Fadeyev, Hk Fakhouri, As Fruchter, D G. Gilbank, Md Gladders, G Goldhaber, A Goobar, T Hattori, E Hsiao, Xiaosheng Huang, Y Ihara, K Kashikawa, B Koester, K Konishi, M Kowalski, C Lidman, L Lubin, J Meyers, T Morokuma, T Oda, N Panagia, S Perlmutter, M Postman, P Ripoche, P Rosati, D Rubin, Dj Schlegel, Al Spadafora, Sa Stanford, M Strovink, N Suzuki, N Takanashi, K Tokita, N Yasuda
The Hubble Space Telescope * Cluster Supernova Survey. Ii. The Type Ia Supernova Rate In High-Redshift Galaxy Clusters, K Barbary, G Aldering, R Amanullah, M Brodwin, N Connolly, Ks Dawson, M Doi, P Eisenhardt, L Faccioli, V Fadeyev, Hk Fakhouri, As Fruchter, D G. Gilbank, Md Gladders, G Goldhaber, A Goobar, T Hattori, E Hsiao, Xiaosheng Huang, Y Ihara, K Kashikawa, B Koester, K Konishi, M Kowalski, C Lidman, L Lubin, J Meyers, T Morokuma, T Oda, N Panagia, S Perlmutter, M Postman, P Ripoche, P Rosati, D Rubin, Dj Schlegel, Al Spadafora, Sa Stanford, M Strovink, N Suzuki, N Takanashi, K Tokita, N Yasuda
Physics and Astronomy
We report a measurement of the Type Ia supernova (SN Ia) rate in galaxy clusters at 0.9 < z < 1.46 from the Hubble Space Telescope Cluster Supernova Survey. This is the first cluster SN Ia rate measurement with detected z > 0.9 SNe. Finding 8 ± 1 cluster SNe Ia, we determine an SN Ia rate of 0.50+0.23 –0.19 (stat) +0.10 –0.09 (sys) h 2 70 SNuB (SNuB ≡ 10–12 SNe L –1 ☉, B yr–1). In units of stellar mass, this translates to 0.36+0.16 –0.13 (stat) +0.07 –0.06 (sys) h 2 70 SNuM (SNuM ≡ 10–12 SNe M –1 ☉ yr–1). This represents a …
Orbital Separation Amplification In Fragile Binaries With Evolved Components, K. B. Johnston, Terry D. Oswalt
Orbital Separation Amplification In Fragile Binaries With Evolved Components, K. B. Johnston, Terry D. Oswalt
Publications
The secular stellar mass-loss causes an amplification of the orbital separation in fragile, common proper motion, binary systems with separations of the order of 1000 A.U. In these systems, companions evolve as two independent coeval stars as they experience negligible mutual tidal interactions or mass transfer. We present models for how post-main sequence mass-loss statistically distorts the frequency distribution of separations in fragile binaries. These models demonstrate the expected increase in orbital seapration resulting from stellar mass-loss, as well as a perturbation of associated orbital parameters. Comparisons between our models and observations resulting from the Luyten survey of wide visual …
The 25 Parsec Local White Dwarf Population, Jerry B. Holberg, Terry D. Oswalt, Edward M. Sion, George P. Mccook
The 25 Parsec Local White Dwarf Population, Jerry B. Holberg, Terry D. Oswalt, Edward M. Sion, George P. Mccook
Publications
We have extended our detailed survey of the local white dwarf population from 20 pc to 25 pc, effectively doubling the sample volume, which now includes 232 stars. In the process new stars within 20 pc have been added, a more uniform set of distance estimates as well as improved spectral and binary classifications are available. The present 25 pc sample is estimated to be about 68% complete (the corresponding 20 pc sample is now 86% complete). The space density of white dwarfs is unchanged at 4.8 ± 0.5 x 10-3 pc-3. This new study includes a white dwarf mass …
The White Dwarf Age Of Nfc 2477, Elizabeth J. Jeffery, Ted Von Hippel, Et Al.
The White Dwarf Age Of Nfc 2477, Elizabeth J. Jeffery, Ted Von Hippel, Et Al.
Publications
We present deep photometric observations of the open cluster NGC 2477 using HST/WFPC2. By identifying seven cluster white dwarf candidates, we present an analysis of the white dwarf age of this cluster, using both the traditional method of fitting isochrones to the white dwarf cooling sequence, and by employing a new Bayesian statistical technique that has been developed by our group. This new method performs an objective, simultaneous model fit of the cluster and stellar parameters (namely, age, metallicity, distance, reddening, as well as individual stellar masses, mass ratios, and cluster membership) to the photometry. Based on this analysis, …
The Chromospheric Activity, Age, Metallicity, And Space Motions Of 36 Wide Binaries, J. K. Zhao, T. D. Oswalt, M. Rudkin, G. Zhao, Y. Q. Chen
The Chromospheric Activity, Age, Metallicity, And Space Motions Of 36 Wide Binaries, J. K. Zhao, T. D. Oswalt, M. Rudkin, G. Zhao, Y. Q. Chen
Publications
We present the chromospheric activity (CA) levels, metallicities, and full space motions for 41 F, G, K, and M dwarf stars in 36 wide binary systems. Thirty-one of the binaries contain a white dwarf (WD) component. In such binaries, the total age can be estimated by adding the cooling age of the WD to an estimate of the progenitor’s main-sequence lifetime. To better understand how CA correlates to stellar age, 14 cluster member stars were also observed. Our observations demonstrate for the first time that, in general, CA decays with age from 50 Myr to at least 8 Gyr for …
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. …
Spitzer 24Μm Survey For Dust Disks Around Hot White Dwarfs, You-Hua Chu, Kate Y.L. Su, Jana Bilikova, Robert A. Gruendl, Orsola De Marco, Martin A. Guerrero, Adria Updike, Kevin Volk, Thomas Rauch
Spitzer 24Μm Survey For Dust Disks Around Hot White Dwarfs, You-Hua Chu, Kate Y.L. Su, Jana Bilikova, Robert A. Gruendl, Orsola De Marco, Martin A. Guerrero, Adria Updike, Kevin Volk, Thomas Rauch
Arts & Sciences Faculty Publications
No abstract provided.
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 …