117518735
A note on geometry of the new cosmology.
118556020
The mesotrons of eddington
SummarySome aspects of Eddington’s fundamental theory are reviewed. It is shown that an electrically neutral particle of rest mass close to that of π0-meson can be predicted using a quadruple phase reference frame. An attempt is made to calculate the lifetimes of the π-mesons using an extension of Eddington’s arguments.RiassuntoSi considerano alcuni aspetti della teoria fondamentale di Eddington. Si dimostra che si può prevedere una particella elettricamente neutra con massa a riposo prossima a quella del mesone π0 usando un sistema di riferimento della fase quadruplo. Si tenta di calcolare la vita dei mesoni π con un’estensione degli argomenti di Eddington.РеэюмеЗаново рассматриваются некоторые аспекты фундаментальной теории Эддингтона. Покаэывается, что может быть предскаэана масса покоя злектрически нейтральной частицы, блиэкая к массе π0 меэона, при испольэовании системы отсчета квадруплетной фаэы. Предпринимается попытка вычислить времена жиэни π меэонов, испольэуя обобшение аргументов Эддингтона.
124396676
A COMMENT ON A CRITICISM OF THE NONSYMMETRIC UNIFIED FIELD THEORY
122325575
An exact solution of the Einstein-Dirac equations
An exact solution to the Einstein-Dirac equations is obtained for a space-time with metric of the anisotropic cosmological type, the gravitational field having as its source a (massive) Dirac electron field.
120241964
Is Rainich’s theory tenable?
121499433
The field equations of a conformally invariant, scalar-tensor theory
A general, conformally invariant theory of the general relativistic, gravitational field coupled with a scalar field is considered. The field equations of the theory are derived from a variational action principle and also from the assumption of the geodesic motion of test particles. These are shown to be identical. The scalar field is assumed to be a long-range field with the view to establishing a cosmological theory. An upper bound for the background scalar field is estimated.
10205544
The Zadko Telescope: A Southern Hemisphere Telescope for Optical Transient Searches, Multi-Messenger Astronomy and Education
The new 1-m f/4 fast-slew Zadko Telescope was installed in June 2008 about 70 km north of Perth, Western Australia. It is the only metre-class optical facility at this southern latitude between the east coast of Australia and South Africa, and can rapidly image optical transients at a longitude not monitored by other similar facilities. We report on first imaging tests of a pilot program of minor planet searches, and Target of Opportunity observations triggered by the Swift satellite. In 12 months, 6 gamma-ray burst afterglows were detected, with estimated magnitudes; two of them, GRB 090205 (z = 4.65) and GRB 090516 (z = 4.11), are among the most distant optical transients imaged by an Australian telescope. Many asteroids were observed in a systematic 3-month search. In September 2009, an automatic telescope control system was installed, which will be used to link the facility to a global robotic telescope network; future targets will include fast optical transients triggered by high- energy satellites, radio transient detections, and LIGO gravitational wave candidate events. We also outline the importance of the facility as a potential tool for education, training, and public outreach.
118423870
Towards an optimal search strategy of optical and gravitational wave emissions from binary neutron star coalescence
Observations of an optical source coincident with gravitational wave emission detected from a binary neutron star coalescence will improve the confidence of detection, provide host galaxy localization and test models for the progenitors of short gamma-ray bursts. We employ optical observations of three short gamma-ray bursts, 050724, 050709 and 051221, to estimate the detection rate of a coordinated optical and gravitational wave search of neutron star mergers. Model R-band optical afterglow light curves of these bursts that include a jet-break are extrapolated for these sources at the sensitivity horizon of an Advanced LIGO/Virgo network. Using optical sensitivity limits of three telescopes, namely TAROT (m = 18), Zadko (m = 21) and an 8–10 m class telescope (m = 26), we approximate detection rates and cadence times for imaging. We find a median coincident detection rate of 4 yr−1 for the three bursts. GRB 050724 like bursts, with wide opening jet angles, offer the most optimistic rate of 13 coincident detections per year, and would be detectable by Zadko up to 5 d after the trigger. Late-time imaging to m = 26 could detect off-axis afterglows for GRB 051221 like bursts several months after the trigger. For a broad distribution of beaming angles, the optimal strategy for identifying the optical emissions triggered by gravitational wave detectors is rapid response searches with robotic telescopes followed by deeper imaging at later times if an afterglow is not detected within several days of the trigger.
119101179
The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel/HIFI*
In contrast with numerous studies on the physical and chemical structure of low- and high-mass protostars, much less is known about their intermediate-mass counterparts, a class of objects that could help to elucidate the mechanisms of star formation on both ends of the mass range. We present the first results from a rich HIFI spectral dataset on an intermediate-mass protostar, OMC2-FIR4, obtained in the CHESS (Chemical HErschel Survey of Star forming regions) key programme. The more than 100 methanol lines detected between 554 and 961 GHz cover a range in upper level energy of 40 to 540 K. Our physical interpretation focusses on the hot core, but likely the cold envelope and shocked regions also play a role in reality, because an analysis of the line profiles suggests the presence of multiple emission components. An upper limit of 10^(-6) is placed on the methanol abundance in the hot core, using a population diagram, large-scale source model and other considerations. This value is consistent with abundances previously seen in low-mass hot cores. Furthermore, the highest energy lines at the highest frequencies display asymmetric profiles, which may arise from infall around the hot core.
18597318
Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes
Context. The theory of stellar evolution can be more closely tested if we have the opportunity to measure new quantities. Nowadays, observations of galactic RR Lyr stars are available on a time baseline exceeding 100 years. Therefore, we can exploit the possibility of investigating period changes, continuing the pioneering work started by V. P. Tsesevich in 1969. Aims. We collected the available times of maximum brightness of the galactic RR Lyr stars in the GEOS RR Lyr database. Moreover, we also started new observational projects, including surveys with automated telescopes, to characterise the O‐C diagrams better. Methods. The database we built has proved to be a very powerful tool for tracing the period variations through the ages. We analyzed 123 stars showing a clear O‐C pattern (constant, parabolic or erratic) by means of different least‐squares methods. Results. Clear evidence of period increases or decreases at constant rates has been found, suggesting evolutionary effects. The median values are �=+0.14 d Myr −1 for the 27 stars showing a period increase and �=‐0.20 d Myr −1 for the 21 stars showing a period decrease. The large number of RR Lyr stars showing a period decrease (i.e., blueward evolution) is a new and intriguing result. There is an excess � � � �
33144366
Herschel/HIFI observations of spectrally resolved methylidyne signatures toward the high-mass star-forming core NGC 6334I
Context. In contrast to the more extensively studied dense star-forming cores, little is known about diffuse gas surrounding star-forming regions. Aims: We study the molecular gas in the Galactic high-mass star-forming region NGC 6334I, which contains diffuse, quiescent components that are inconspicuous in widely used molecular tracers such as CO. Methods: We present Herschel/HIFI observations of methylidyne (CH) toward NGC 6334I observed as part of the "Chemical HErschel Survey of Star forming regions" (CHESS) key program. HIFI resolves each of the six hyperfine components of the lowest rotational transition (J = 3/2 - 1/2) of CH, observed in both emission and absorption. Results: The CH emission features appear close to the systemic velocity of NGC 6334I, while its measured FWHM linewidth of 3 km s-1 is smaller than previously observed in dense gas tracers such as NH3 and SiO. The CH abundance in the hot core is ~7 × 10-11, two to three orders of magnitude lower than in diffuse clouds. While other studies find distinct outflows in, e.g., CO and H2O toward NGC 6334I, we do not detect any outflow signatures in CH. At least two redshifted components of cold absorbing material must be present at -3.0 and +6.5 km s-1 to explain the absorption signatures. We derive a CH column density (NCH) of 7 × 1013 and 3 × 1013 cm-2 for these two absorbing clouds. We find evidence of two additional absorbing clouds at +8.0 and 0.0 km s-1, both with NCH ≈ 2 × 1013 cm-2. Turbulent linewidths for the four absorption components vary between 1.5 and 5.0 km s-1 in FWHM. We constrain the physical properties and locations of the clouds by matching our CH absorbers with the absorption signatures seen in other molecular tracers. Conclusions: In the hot core, molecules such as H2O and CO trace gas that is heated and dynamically influenced by outflow activity, whereas the CH molecule traces more quiescent material. The four CH absorbing clouds have column densities and turbulent properties that are consistent with those of diffuse clouds: two are located in the direct surroundings of NGC 6334, and two are unrelated foreground clouds. Local density and dynamical effects influence the chemical composition of the physical components of NGC 6334, which causes some components to be seen in CH but not in other tracers, and vice versa. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Acknowledgements (page 5) are only available in electronic form at http://www.aanda.org