Search Publications
V421 Pegasi: a detached eclipsing binary with a possible γ Doradus component
Akan, C.; Çakırlı, Ö.; Özdarcan, O.
We present spectroscopic and photometric study of V421 Peg. This eclipsing binary displays lines from both components that are well separated. This allowed us to classify the primary and secondary component as F(1 ± 0.5) V and F(2 ± 0.5) V, respectively. We use our radial velocity measurements together with Hipparcos and ASAS photometry and apply …
Averaged universe confronted with cosmological observations: A fully covariant approach
Ishak, Mustapha; Lin, Weikang; Wijenayake, Tharake
One of the outstanding problems in general relativistic cosmology is that of the averaging, that is, how the lumpy universe that we observe at small scales averages out to a smooth Friedmann-Lemaître-Robertson-Walker (FLRW) model. The root of the problem is that averaging does not commute with the Einstein equations that govern the dynamics of the…
Resolving Gas Flows in the Ultraluminous Starburst IRAS 23365+3604 with Keck LGSAO/OSIRIS
Martin, Crystal L.; Soto, Kurt T.
Keck OSIRIS/LGSAO observations of the ultraluminous galaxy IRAS 23365+3604 resolve a circumnuclear bar (or irregular disk) of semimajor axis 0.″42 (520 pc) in Paα emission. The line-of-sight velocity of the ionized gas increases from the northeast toward the southwest; this gradient is perpendicular to the photometric major axis of the infrared em…
Spectral behavior of Nova GQ Mus in the ultraviolet
Sanad, M. R.; Abdel-Sabour, M. A.
We present ultraviolet spectroscopic study of nova GQ Mus observed with the International Ultraviolet Explorer (IUE) during the period 1983–1985. Different spectra showing the changes in line fluxes at different times are presented. The outflow velocity of the ionized ejecta was calculated to be 1010–2900
Origin of the X-ray broad iron spectral feature in GRS 1915+105
Tsujimoto, Masahiro; Ebisawa, Ken; Mizumoto, Misaki +1 more
The X-ray spectrum of GRS 1915+105 is known to have a "broad iron spectral feature" in the spectral hard state. Similar spectral features are often observed in active galactic nuclei (AGNs) and other black-hole binaries (BHBs), and several models have been proposed for explaining it. In order to distinguish spectral models, time variation provides…
Time-of-flight mass spectrographs—From ions to neutral atoms
Galvin, A. B.; Kistler, L. M.; Kucharek, H. +2 more
After their introduction to space physics in the mid 1980s time-of-flight (TOF) spectrographs have become a main staple in spaceborne mass spectrometry. They have largely replaced magnetic spectrometers, except when extremely high mass resolution is required to identify complex molecules, for example, in the vicinity of comets or in planetary atmo…
Peculiarities of the accretion flow in the system HL CMa
Lutovinov, A. A.; Revnivtsev, M. G.; Semena, A. N. +2 more
The properties of the aperiodic luminosity variability for the dwarf novaHLCMa are considered. The variability of the system HL CMa is shown to be suppressed at frequencies above 0.7 × 10-2 Hz. Different variability suppression mechanisms related to the radiation reprocessing time, partial disk evaporation, and characteristic variabilit…
Variability of the nitric oxide nightglow at Venus during solar minimum
Montmessin, F.; Marcq, E.; Royer, E. M.
We present results from a NO airglow inversion method based on Venus Express data acquired from 2006 to 2010, during the last solar minimum period. We retrieve an altitude of 114 ± 10 km for the emission peak of the NO layer, with an associated scale height of 20 ± 10 km and an average limb brightness of 59.3 kR with a standard deviation of 63 kR.…
The Global Implications of the Hard Excess. II. Analysis of the Local Population of Radio-quiet AGNs
Turner, T. J.; Reeves, J. N.; Gofford, J. +5 more
Active galactic nuclei (AGNs) show evidence for reprocessing gas, outflowing from the accreting black hole. The combined effects of absorption and scattering from the circumnuclear material likely explain the “hard excess” of X-ray emission above 20 keV, compared with the extrapolation of spectra from lower X-ray energies. In a recent Suzaku study…
Penetration of magnetosheath plasma into dayside magnetosphere: 2. Magnetic field in plasma filaments
Goldstein, Melvyn L.; Pollock, Craig; Lyatsky, Wladislaw +2 more
In this paper, we examined plasma structures (filaments), observed in the dayside magnetosphere but containing magnetosheath plasma. These filaments show the stable antisunward motion (while the ambient magnetospheric plasma moved in the opposite direction) and the existence of a strip of magnetospheric plasma, separating these filaments from the …