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.
14536809
A multiwavelength study of Swift GRB 060111B constraining the origin of its prompt optical emission
In this work, we present the results obtained from a multi-wavelength campaign, as well as from the public Swift/BAT, XRT, and UVOT data of GRB 060111B for which a bright optical emission was measured with good temporal resolution during the prompt phase. We identified the host galaxy at R~25 mag; its featureless spectral continuum and brightness, as well as the non-detection of any associated supernova 16 days after the trigger and other independent redshift estimates, converge to z~1-2. From the analysis of the early afterglow SED, we find that non-negligible host galaxy dust extinction, in addition to the Galactic one, affects the observed flux in the optical regime. The extinction-corrected optical-to-gamma-ray spectral energy distribution during the prompt emission shows a flux density ratio $F_{\gamma}/F_{opt}$=0.01-0.0001 with spectral index $\beta_{\gamma,opt}> \beta_{\gamma}$, strongly suggesting a separate origin of the optical and gamma-ray components. This result is supported by the lack of correlated behavior in the prompt emission light curves observed in the two energy domains. The properties of the prompt optical emission observed during GRB 060111B favor interpretation of this optical light as radiation from the reverse shock in a thick shell limit and in the slow cooling regime. The expected peak flux is consistent with the observed one corrected for the host extinction, likely indicating that the starting time of the TAROT observations is very near to or coincident with the peak time. The estimated fireball initial Lorentz factor is >260-360 at z=1-2, similar to the Lorentz factors obtained from other GRBs. GRB 060111B is a rare, good test case of the reverse shock emission mechanism in both the X-ray and optical energy ranges.
17272445
The CFHTLS real time analysis system: "optically selected GRB afterglows" Overview and performance
Aims. We describe a deep and wide search for optical GRB afterglows in images taken with MegaCAM at the Canada France Hawaii Telescope, within the framework of the CFHT Legacy Survey. Methods. This search is performed in near real-time thanks to a Real Time Analysis System (RTAS) called ”Optically Selected GRB Afterglows”, which has been installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images to construct catalogs of astronomical objects, and compares catalogs made from images taken at different epochs to produce a list of astrometrically and photometrically variable objects. These objects are then displayed on a web page to be characterized by a member of the collaboration. Results. In this paper, we comprehensively describe the RTAS process from image acquisition to the final characterization of vari able sources. We present statistical results based on one full year of oper ation, showing the quality of the images and the performance of the RTAS. The limiting magnitude of our search is r’ =22.5 on average and the observed area amounts to 1178 square degrees. We have detected about 13.10 6 astronomical sources of which about 0.01% are found to vary by more than one tenth of a magnitude. We discuss the performance of our instrumental setup with a sample of simulated afterglows. This sample allows us to compare the effi ciency of our search with previous works, to propose an optimal observational strategy, and to discuss general considerations on the searches for GRB optical afterglows. We postpone to a forthcoming paper the discussion of the characterizati on of variable objects we have found, and a more detailled analysis of the nature of those resembling GRB afterglows. Conclusions. The RTAS has been continuously operating since November 2004. Each month 15-30 square degrees are observed many times over a period of 2-3 nights. The real-time analysis of the data has revealed no convincing afterglow candidate so far.
7878763
Limits on the early afterglow phase of gamma-ray burst sources from TAROT-1
The Telescope a Action Rapide pour les Objets Transitoires (TAROT-1) has as prime objective the observation of the prompt and delayed emission of cosmic gamma-ray bursts (GRBs). We have performed a search for optical emission from 6 GRBs detected by BATSE. The positioning error circle was fully covered within typically thirty minutes after the trigger. No detection of the early afterglow phase was made, and magnitude limits in the range of $ \\mathrm{m}_{\\mathrm{R}} = 13-15 $ were estimated using 20s exposures. These limits are compared to optical afterglow data obtained in later phases and the results are interpreted in terms of source distances. They correspond to a median redshift of z = 0.5. With HETE-2 and the planned instrument upgrade, TAROT-1 will be able to detect the early optical emission of GRBs up to a redshift of the order of 5.
118513531
Instrumental methods for professional and amateur collaborations in planetary astronomy
Amateur contributions to professional publications have increased exponentially over the last decades in the field of planetary astronomy. Here we review the different domains of the field in which collaborations between professional and amateur astronomers are effective and regularly lead to scientific publications.We discuss the instruments, detectors, software and methodologies typically used by amateur astronomers to collect the scientific data in the different domains of interest. Amateur contributions to the monitoring of planets and interplanetary matter, characterization of asteroids and comets, as well as the determination of the physical properties of Kuiper Belt Objects and exoplanets are discussed.
118950262
Detection of a very bright optical flare from a gamma-ray burst at redshift 6.29
In this letter we discuss the flux and the behavior of the bright optical flare emission detected by the 25 cm TAROT robotic telescope during the prompt high-energy emission and the early afterglow. We combine our data with simultaneous observations performed in X-rays and we analyze the broad-band spectrum. These observations lead us to emphasize the similarity of GRB 050904 with GRB 990123, a remarkable gamma-ray burst whose optical emission reached 9th magnitude. While GRB 990123 was, until now, considered as a unique event, this observation suggests the existence of a population of GRBs which have very large isotropic equivalent energies and extremely bright optical counterparts. The luminosity of these GRBs is such that they are easily detectable through the entire universe. Since we can detect them to very high redshift even with small aperture telescopes like TAROT, they will constitute powerful tools for the exploration of the high-redshift Universe and might be used to probe the first generation of stars.
119929847
The nonsymmetric unified field theory
This paper reviews the recent progress in the nonsymmetric unified field theory of Einstein and Straus and its current status as a theory of macrophysics of gravitation and electromagnetism.
120241964
Is Rainich’s theory tenable?
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.
116491269
Spherical symmetry in Rainich's theory
121340458
Some cosmological solutions of a scalar-tensor theory of gravitation
Some cosmological solutions of the scalar-tensor theory of gravitation are derived. The results differ from Friedmann and Brans-Dicke cosmologies, though not sufficiently to enable an immediate decision between these theories to be made. In the case of the solar system the new theory is a special case of theories discussed by Bergmann and Wagoner.