54637934
The puzzling temporally variable optical and X-ray afterglow of GRB 101024A
Aims. We present the optical observations of the afterglow of the Swift burst GRB 101024A and try to reconcile these observations with the X-ray afterglow data of GRB 101024A using current afterglow models Methods. We employ early optical observations, using the Zadko Telescope combined with X-ray data, to compare them with the reverse shock/forward shock model. Results. The early optical light curve reveals a very unusual steep decay index of α ∼ 5. This is followed by a flattening and possibly a plateau phase coincident with a similar feature in the X-ray. We discuss these observations in the framework of the standard reverse shock/forward shock model and energy injection. The plateau phase might also be the signature of the formation of a new magnetar.
85444481
Detection of interstellar oxidaniumyl : Abundant H2O+ towards the star-forming regions DR21, Sgr B2, and NGC6334
Aims: We identify a prominent absorption feature at 1115 GHz, detected in first HIFI spectra towards high-mass star-forming regions, and interpret its astrophysical origin. Methods: The characteristic hyperfine pattern of the H2O+ ground-state rotational transition, and the lack of other known low-energy transitions in this frequency range, identifies the feature as H2O+ absorption against the dust continuum background and allows us to derive the velocity profile of the absorbing gas. By comparing this velocity profile with velocity profiles of other tracers in the DR21 star-forming region, we constrain the frequency of the transition and the conditions for its formation. Results: In DR21, the velocity distribution of H2O+ matches that of the [C ii] line at 158 μm and of OH cm-wave absorption, both stemming from the hot and dense clump surfaces facing the H ii-region and dynamically affected by the blister outflow. Diffuse foreground gas dominates the absorption towards Sgr B2. The integrated intensity of the absorption line allows us to derive lower limits to the H2O+ column density of 7.2 × 1012 cm-2 in NGC 6334, 2.3 × 1013 cm-2 in DR21, and 1.1 × 1015 cm-2 in Sgr B2. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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.
117717977
Optically Selected GRB Afterglows, a Real Time Analysis System at the CFHT
We attempt to detect optical GRB afterglows on images taken by the Canada France Hawaii Telescope for the Very Wide survey, component of the Legacy Survey. To do so, a Real Time Analysis System called "Optically Selected GRB Afterglows" has been installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images and extracts from them a list of variable objects which is displayed on a web page for validation by a member of the collaboration. The Very Wide survey covers 1200 square degrees down to i'=23.5. This paper briefly explain the RTAS process.
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
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 � � � �
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.
118183813
A revised nonsymmetric unified field theory.
117518735
A note on geometry of the new cosmology.
123579352
A note on the cylindrically symmetric, static solutions of the weak field equations
The general solution of the weak field equations of the nonsymmetric unified field theory in the magnetic case is reduced to the solution of a second-order differential equation with movable critical points. Some special solutions are discussed.
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.