Results 101 to 110 of about 1,914,179 (372)

The 100 pc White Dwarf Sample in the SDSS Footprint. II. A New Look at the Spectral Evolution of White Dwarfs

The Astrophysical Journal
We increase the spectroscopic completeness of the 100 pc white dwarf sample in the Sloan Digital Sky Survey footprint with 840 additional spectra. Our spectroscopy is 86% complete for white dwarfs hotter than T _eff  = 5000 K, where H α remains visible ...
Mukremin Kilic, Pierre Bergeron, Simon Blouin, Adam Moss, Warren R. Brown, Antoine Bédard, Gracyn Jewett, Marcel A. Agüeros   +7 more
doaj   +1 more source

Cool White Dwarfs Identified in the Second Data Release of the UKIRT Infrared Deep Sky Survey

, 2008
We have paired the Second Data Release of the Large Area Survey of the UKIRT Infrared Deep Sky Survey with the Fifth Data Release of the Sloan Digital Sky Survey to identify ten cool white dwarf candidates, from their photometry and astrometry.
A. Nitta, Adelman-McCarthy, Adelman-McCarthy, Bergeron, Bergeron, Bergeron, Bergeron, Bergeron, Bohlin, Eisenstein, Gates, Hall, Hansen, Harris, Harris, Haywood, Holberg, Holberg, Kalirai, Kilic, Kowalski, Leggett, Liebert, Monet, N. Lodieu, P. Bergeron, Reid, S. K. Leggett, Tremblay, Warren, York   +30 more
core   +1 more source

The Ages of the Thin Disk, Thick Disk, and the Halo from Nearby White Dwarfs [PDF]

, 2017
We present a detailed analysis of the white dwarf luminosity functions derived from the local 40 pc sample and the deep proper motion catalog of Munn et al.
M. Kilic, J. Munn, H. Harris, T. Hippel, J. Liebert, K. Williams, E. Jeffery, S. DeGennaro   +7 more
semanticscholar   +1 more source

An irradiated brown-dwarf companion to an accreting white dwarf [PDF]

Nature, 2016
Brown dwarfs and giant planets orbiting close to a host star are subjected to significant irradiation that can modify the properties of their atmospheres. In order to test the atmospheric models that are used to describe these systems, it is necessary to obtain accurate observational estimates of their physical properties (masses, radii, temperatures ...
S. P. Littlefair, M. L. Pretorius, Juan V. Hernández Santisteban, V. S. Dhillon, Rene P. Breton, Rene P. Breton, Boris T. Gänsicke, John Southworth, Christian Knigge, Tom Marsh, Peter H. Hauschildt   +10 more
openaire   +9 more sources

Proton Acceleration with Relativistic Electromagnetic Shock

Advanced Science, EarlyView.
New Ion Acceleration Mechanism! A novel cosmic‐ray proton acceleration mechanism is proposed, where relativistic electromagnetic shocks accelerate protons transversely. Hamiltonian analysis yields a scaling law linking the proton energy to the minimum longitudinal thickness of the shock.
Ting Xiao, Xiaomei Zhang, Fanqiu Kong, Xiaolong Zheng, Zheng Gong, Baifei Shen   +5 more
wiley   +1 more source

The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey

, 2004
Spectrophotometric observations at high signal-to-noise ratio were obtained of a complete sample of 347 DA white dwarfs from the Palomar Green (PG) Survey. Fits of observed Balmer lines to synthetic spectra calculated from pure-hydrogen model atmospheres
Goldschmidt P., Heber U., Homeier D., J. B. Holberg, James Liebert, Kilkenny D., Koester D., Kondo M., Marsh M. C., Marsh T. R., Napiwotzki R., Noguchi T., P. Bergeron, Pottasch S. R., Wegner G., Weidemann V., Weidemann V., Yuan J. W.   +17 more
core   +1 more source

The mass function of hydrogen-rich white dwarfs: robust observational evidence for a distinctive high-mass excess near 1Msun [PDF]

, 2015
The mass function of hydrogen-rich atmosphere white dwarfs has been frequently found to reveal a distinctive high-mass excess near 1Msun. However, a significant excess of massive white dwarfs has not been detected in the mass function of the largest ...
Garcia-Berro, E., Han, Z., Liu, X. -W., Rebassa-Mansergas, A., Rybicka, M.   +4 more
core   +3 more sources

White Dwarf Crystallization [PDF]

International Astronomical Union Colloquium, 1994
AbstractThe inclusion of a detailed treatment of solidification processes in the cooling theory of carbon–oxygen white dwarfs is of crucial importance for the determination of their luminosity function. Carbon–oxygen separation at crystallization yields delays larger than 2 Gyr to cool down to luminosities corresponding to the observed cut–off.
Enrique García-Berro, M. Hernanz
openaire   +2 more sources

The Halo White Dwarf Population [PDF]

The Astrophysical Journal, 1998
29 pages (AASTeX), 7 eps figures included, accepted for publication in ...
Enrique García-Berro, Jordi Isern, Margarita Hernanz, Santiago Torres, R. Mochkovitch   +4 more
openaire   +3 more sources

Observation of 1/f 4 Noise in Organic Bilayer Ambipolar FETs and Proposition of Defect Engineering Method for Ultimate Noise Control

Advanced Electronic Materials, EarlyView.
The low‐frequency noise in organic bilayer ambipolar transistors is investigated, revealing a unique 1/f⁴ noise from correlated trapping/detrapping and generation/recombination processes. Inserting a thin parylene layer between the n/p junction effectively reduces this excess noise, suggesting a practical approach to enhanced device reliability in ...
Youngmin Han, Jaechan Song, Ryun‐Han Koo, Hocheon Yoo, Wonjun Shin   +4 more
wiley   +1 more source