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JournalISSN: 1539-2996

Highlights of Astronomy 

Cambridge University Press
About: Highlights of Astronomy is an academic journal. The journal publishes majorly in the area(s): Galaxy & Stars. It has an ISSN identifier of 1539-2996. Over the lifetime, 1917 publications have been published receiving 4705 citations.


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Journal ArticleDOI
Richard Schilizzi1
TL;DR: The Square Kilometre Array (SKA) as discussed by the authors is the next generation radio telescope at metre-to-centimetre wavelengths with high angular and time resolution, which will have a collecting area of order one million square metres, a sensitivity 100 times higher than the extended VLA, an instantaneous field of view (FOV) larger than the full moon, and, in some designs, more than one FOV allowing multiple simultaneous use.
Abstract: The Square Kilometre Array is a global project to develop the next generation radio telescope at metre to centimetre wavelengths. It will have a collecting area of order one million square metres, a sensitivity 100 times higher than the extended VLA, an instantaneous field of view (FOV) larger than the full moon, and, in some designs, more than one FOV allowing multiple simultaneous use. It will be an extremely powerful survey telescope with the capability to follow up individual objects with high angular and time resolution. The SKA will reach a point source sensitivity of 25 nano-Jy in 1 hour of integration, and a maximum resolution of better than 1 milli-arcsecond at 20 GHz with excellent imaging over several orders of magnitude at any given frequency. The SKA science reach will be enormous, allowing new discoveries in astroparticle physics and cosmology, fundamental physics, galactic and extragalactic astronomy, and solar system science. Technological innovation, closely paralleling commercial IT developments, is key to the design concepts under investigation and to the cost goal of USD 1000/m2 . The selection of technologies for the SKA is scheduled in early 2008. A number of possible locations for the telescope are under investigation with a choice scheduled in early 2006. Construction of the array will take most of the next decade.

148 citations

Journal ArticleDOI
TL;DR: In this article, the properties of solar-like oscillations, excited by stochastic processes, in other stars are discussed, as well as the current state of investigations of such oscillations.
Abstract: The physics of solar and stellar oscillations determine their observable characteristics. I provide a brief overview of the properties of solar-like oscillations, excited by stochastic processes, in other stars. In addition, I consider the current state of investigations of such oscillations, as well as the prospects for an improved understanding of their physics and the properties of the pulsating stars.

136 citations

Journal ArticleDOI
Hagai Netzer1
TL;DR: Kaspi et al. as mentioned in this paper presented a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 and showed that the spectral variations are not related to the brightening or fading of the short wavelength continuum, as observed in other objects.
Abstract: We present a detailed analysis of the 900 ks spectrum of NGC3783 obtained by Chandra in 2000-2001 (Kaspi et al. 2002). We split the data in various ways to look for time dependent and luminosity dependent spectral variations. This analysis, the measured equivalent widths of a large number of X-ray lines, and our photoionization calculations, lead us to the following conclusions: 1) NGC 3783 fluctuated in luminosity, by a factor N 1.5, during individual 170 ks observations. The fluctuations were not associated with significant spectral variations. 2) On a longer time scale, of 20-120 days, we discovered two very different spectral shapes that are noted the high state and the low state spectra. The observed changes between the two can be described as the appearance and disappearance of a soft continuum component. The spectral variations are not related, in a simple way, to the brightening or the fading of the short wavelength continuum, as observed in other objects. NGC3783 seems to be the first AGN to show this unusual behavior. 3) The appearance of the soft continuum component is consistent with beeing the only spectral variation and there is no need to invoke changes in the absorber s opacity. In particular, all absorption lines with reliable measurements show the same equivalent width, within the observational uncertainties, during high and low states. 4) Photoionization model calculations show that a combination of three ionization components, each split into two kinematic components, explain very well the intensity of almost all absorption lines and the bound-free absorption. The components span a large range of ionization and a total column of about 3 x 10(exp 22) per square centimeter Moreover, all components are thermally stable and are situated on the vertical branch of the stability curve.. This means that they are in pressure equilibrium and perhaps occupy the same volume of space. This is the first detection of such a multi-component equilibrium gas in AGN. 5) The only real discrepancy between the model and the observations is the wavelength of the iron M-shell UTA feature. This is most likely due to an underestimation of the dielectronic recombination O VI and discuss its possible origin. 6) The lower limit on the distance of the absorbing gas in NGC3783 is between 0.2 and 3.2 pc, depending of the specific ionization component. The constant pressure assumption imposes an upper limit of about 25 pc on the distance of the least ionized gas from the central sourec.

118 citations

Journal ArticleDOI
TL;DR: The Planetary Data System (PDS) as mentioned in this paper was developed and supported by the Solar System Exploration Division of the National Aeronautics and Space Administration (NASA) and has now successfully operated for a few years.
Abstract: The “Planetary Data System” (PDS) was developed and supported by the Solar System Exploration Division of the National Aeronautics and Space Administration (NASA) and has now successfully operated for a few years. Its primary objectives are to preserve data obtained from previous, current and future space missions; to help individual scientists in the analysis of planetary data by preparing them in a usable form and making them easily accessible to the community; and to assist the National Space Science Data Center (NSSDC) managing, archiving and distributing data obtained by NASA missions. The principal goals and general structure of the PDS have been summarized in several brochures issued by the PDS and articles such as e.g., “The Planetary Data System” by S.W. Lee, published in the IUGG U.S. National Report on Planetology 1987-1990 or by the Jet Propulsion Laboratory. Additional information can be obtained e.g., by the current author; the PDS Project Manager, S. McMahon at JPL; the PDS Project Scientist, S. Lee at the Laboratory for Atmospheric and Space Physics, University of Colorado or from any of the seven Discipline Nodes listed below.

98 citations

Book ChapterDOI
TL;DR: The fate of nuclear energy carried by matter accreted onto a neutron star was considered by Rosenbluth et al. as mentioned in this paper, who examined pycnonuclear reactions on an originally cold star, and found that the whole star is thereby heated up to 106-107°K.
Abstract: The fate of nuclear energy carried by matter accreted onto a neutron star was considered e.g. by Rosenbluth et al.(1973). They examined pycnonuclear reactions on an originally cold star, and found that the whole star is thereby heated up to 106–107°K. The thermonuclear reactions that can be ignited then, have been studied by Hansen and Van Horn (1975), who computed stationary burning shells, finding, however, that in most cases the shells are thermally unstable.

88 citations

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Performance
Metrics
No. of papers from the Journal in previous years
YearPapers
20151
2012138
20103
2009170
20081
20075