Search Publications
Global fitting of globular cluster age indicators
Weiss, A.; Meissner, F.
Context: .Stellar models and the methods for the age determinations of globular clusters are still in need of improvement.
Aims: .We attempt to obtain a more objective method of age determination based on cluster diagrams, avoiding the introduction of biases due to the preference of one single age indicator.
Methods: .We compute new stella…
The Dwarf Novae during Quiescence
Sion, Edward M.; Urban, Joel A.
We present a synthetic spectral analysis of nearly the entire far-ultraviolet (FUV) IUE archive of spectra of dwarf novae (DNe) in or near their quiescence. We have examined all of the systems for which the signal-to-noise ratio permitted an analysis. The study includes 53 systems of all DN subtypes both above and below the period gap. The spectra…
Could electron-positron annihilation lines in the Galactic center result from pulsar winds?
Wang, W.; Pun, C. S. J.; Cheng, K. S.
Observations of a strong and extended positron-electron annihilation line emission in the Galactic center (GC) region by the Spectrometer on the International Gamma-Ray Astrophysical Laboratory (SPI/INTEGRAL) are challenging to the existing models of positron sources in the Galaxy. In this paper, we study the possibility that pulsar winds in the G…
MOIRCS Deep Survey. I: DRG Number Counts
Ouchi, Masami; Tanaka, Ichi; Yamada, Toru +11 more
We use very deep near-infrared imaging data taken with Multi-Object InfraRed Camera and Spectrograph (MOIRCS) on the Subaru Telescope to investigate the number counts of Distant Red Galaxies (DRGs). We have observed a 4x7 arcmin^2 field in the Great Observatories Origins Deep Survey North (GOODS-N), and our data reach J=24.6 and K=23.2 (5sigma, Ve…
Hubble Space Telescope STIS Spectroscopy and Modeling of the Long-Term Cooling of WZ Sagittae following the 2001 July Outburst
Szkody, Paula; Sion, Edward M.; Godon, Patrick +3 more
We present the latest Hubble Space Telescope Space Telescope Imaging Spectrograph (HST STIS) E140M far-ultraviolet (FUV) spectrum of the dwarf nova WZ Sge, obtained in 2004 July, 3 yr following the early superoutburst of 2001 July. With a temperature T~15,000 K, the white dwarf (WD) is still ~1500 K above its quiescent temperature, it has a FUV fl…
Microlensing of the Lensed Quasar SDSS 0924+0219
Kochanek, C. S.; Morgan, Nicholas D.; Morgan, Christopher W. +1 more
We analyze V-, I-, and H-band HST images and two seasons of R-band monitoring data for the gravitationally lensed quasar SDSS 0924+0219. We clearly see that image D is a point-source image of the quasar at the center of its host galaxy. We can easily track the host galaxy of the quasar close to image D because microlensing has provided a natural c…
Astrophysical constraints from gamma-ray spectroscopy
Diehl, Roland; von Ballmoos, Peter; Prantzos, Nikos
Gamma-ray lines from cosmic sources provide unique isotopic information, since they originate from energy level transitions in the atomic nucleus. Gamma-ray telescopes explored this astronomical window in the past three decades, detecting radioactive isotopes that have been ejected in interstellar space by cosmic nucleosynthesis events and nuclei …
Spectral Modeling of SNe Ia Near Maximum Light: Probing the Characteristics of Hydrodynamical Models
Baron, E.; Branch, David; Hauschildt, Peter H. +1 more
We have performed detailed non-local thermodynamic equilibrium (NLTE) spectral synthesis modeling of two types of one-dimensional hydrodynamical models: the very highly parameterized deflagration model W7, and two delayed-detonation models. We find that, overall, both models do about equally well at fitting well-observed SNe Ia near maximum light.…
Physical Conditions in Orion's Veil. II. A Multicomponent Study of the Line of Sight toward the Trapezium
Abel, N. P.; O'Dell, C. R.; Ferland, G. J. +2 more
Orion's Veil is an absorbing screen that lies along the line of sight to the Orion H II region. It consists of two or more layers of gas that must lie within a few parsecs of the Trapezium cluster. Our previous work considered the Veil as a whole and found that the magnetic field dominates the energetics of the gas in at least one component. Here …
In situ dust measurements in the inner Saturnian system
Grande, M.; Beckmann, U.; Kempf, S. +38 more
In July 2004 the Cassini-Huygens mission reached the Saturnian system and started its orbital tour. A total of 75 orbits will be carried out during the primary mission until August 2008. In these four years Cassini crosses the ring plane 150 times and spends approx. 400 h within Titan's orbit. The Cosmic Dust Analyser (CDA) onboard Cassini charact…