Extended radio emission in BL Lac objects - I: the images

We have observed 28 sources selected from the 1Jy sample of BL Lac objects (Stickel et al. 1991) with the Very Large Array (VLA) in A, B and D configurations at 1.36, 1.66 and 4.85 GHz, and/or with the Westerbork Synthesis Radio Telescope (WSRT) at 1.40 GHz. In this paper we present high sensitivity images at arcsecond resolution of the 18 objects showing extended structure in our images, and of another source from the FIRST (Faint Images of the Radio Sky at Twenty-cm) survey (Becker et al. 1995). In general our high sensitivity images reveal an amount of extended emission larger than previously reported. In some objects the luminosity of the extended structure is comparable with that of FR~II radio sources. A future paper will be devoted to the interpretation of these results.Comment: 12 pages, 35 figures, to appear on A&A Supp. Ser., postscript file with figures included available at http://www.ira.noto.cnr.it/staff/carlo/ds1030.ps.g

Extended emission around GPS radio sources

Extended radio emission detected around a sample of GHz Peaked Spectrum (GPS) radio sources is discussed. Evidence for extended emission which is related to the GPS source is found in 6 objects out of 33. Three objects are associated with quasars with core-jet pc-scale morphology, and three are identified with galaxies with symmetric (CSO) radio morphology. We conclude that the core-jet GPS quasars are likely to be beamed objects with a continuous supply of energy from the core to the kpc scale. It is also possible that low surface brightness extended radio emission is present in other GPS quasars but the emission is below our detection limit due to the high redshifts of the objects. On the other hand, the CSO/galaxies with extended large scale emission may be rejuvenated sources where the extended emission is the relic of previous activity. In general, the presence of large scale emission associated with GPS galaxies is uncommon, suggesting that in the context of the recurrent activity model, the time scale between subsequent bursts is in general longer than the radiative lifetime of the radio emission from the earlier activity.Comment: 18 paged, 18 figures, accepted for publication on A&

Bendings of radio jets in BL Lacertae objects I: EVN and MERLIN observations

Several blazars, and BL Lac objects in particular, show a misalignment between the jet orientation on parsec and kiloparsec scales. Some authors (i.e. Conway & Murphy, 1993) have attempted to explain this behaviour invoking helical jets for misalignment angles around 90\degr, showing how in this case there are interesting implications for the understanding of the medium into which the jet is expanding. By comparing sensitive VLA observations (Cassaro et al., 1999) with images available in the literature for the BL Lac objects from the 1-Jy Sample (Stickel et al., 1991), it is clear that there is a wide range of misalignments between the initial jet direction and the kpc-scale jet, when detected. We have carried out VLBI observations of these BL Lac objects, in order to investigate the spatial evolution of the radio jets from few tens to hundreds of mas, and to search for helical jets in this class of sources. We present here the first dataset obtained from EVN+MERLIN observations at 5 GHz for seven objects. From these observations we never have a clear detection of helical jets, we only have a possible signature of their presence in 2 objects. In only one of the sources with a misalignment angle around 90\degr the presence of helical jets can be ruled out. This implies that it is not possible to invoke helical jets to explain the morphology of all the sources showing a misalignment of about 90\degr between the parsec and the kiloparsec scale jets.Comment: 12 pages, 9 figures, latex, accepted by Astronomy & Astrophysic

Características morfogênicas e estruturais de gramíneas com potencial de uso em Sistemas de Integração - Lavoura - Pecuária - Floresta em Rondônia.

Este trabalho apresenta as principais características morfogênicas e estruturais de gramíneas com potencial de uso em sistemas de integração Lavoura-Pecuária-Floresta (iLPF?s). Este sistema surge como alternativa promissora, por apresentarem várias vantagens quando comparados aos sistemas convencionais de produção. Nos iLPF's as pastagens além de servirem como a base alimentar dos rebanhos, oportunizando a geração de produtos de origem animal, passam a exercer importante papel na ciclagem de nutrientes.bitstream/item/46764/1/cot364-gramineas.pd

Noto Station Status Report

The Noto VLBI station was fully operational in 2012, and the upgrade projects could be restarted, involving mainly the receiver area. Another important improvement was the activation of the 1 Gbps network

Características morfogênicas e estruturais de gramíneas forrageiras tropicais.

Em experimento conduzido na Embrapa Rondônia em Porto Velho, foram determinadas e comparadas as características morfogênicas e estruturais de cinco gramíneas forrageiras (Brachiaria ruziziensis, B. brizantha cultivares-cvs. Marandu, Xaraés, e Piatã, e Panicum maximum x P. infestum cultivar-cv. Massai), estabelecidas em vasos contendo solo Podzólico Vermelho-Amarelo, mantidos em bancada sob condições ambientais. As cvs. de B. brizantha apresentaram características morfogênicas e estruturais semelhantes, à exceção do filocrono, duração de vida de folha e número de folhas por perfilho. As cvs. Xaraés e Marandu demandaram maior tempo para emitirem uma nova folha do que a Piatã, e essa a B. ruziziensis e ao Massai, as quais não diferiram entre si. As folhas da cv. Marandu persistiram mais em relação as das cvs. Xaraés e Piatã, com folhas mais longevas do que as da B. ruziziensis e essa as do Massai. A taxa de expansão de folhas foi semelhante para todas as gramíneas, mas quanto à de senescência, as cvs. de B. briz ntha senesceram à menores taxas do que as de B. ruziziensis e as do Massai. As cvs. de B. brizantha mantiveram menor quantidade de folhas por perfilho e perfilharam menos, mas em contrapartida, suas folhas e perfilhos foram maiores que os da B. ruziziensis e os do Massai. Com base nessas características as cvs. de B. brizantha devem ser submetidas a freqüência e intensidade de desfolha mais lenientes em relação ao Massai e a B. ruziziensis

The high brightness temperature of B0529+483 revealed by RadioAstron and implications for interstellar scattering

The high brightness temperatures, $T_\mathrm{b}\gtrsim 10^{13}$ K, detected in several active galactic nuclei by RadioAstron space VLBI observations challenge theoretical limits. Refractive scattering by the interstellar medium may affect such measurements. We quantify the scattering properties and the sub-mas scale source parameters for the quasar B0529+483. Using RadioAstron correlated flux density measurements at 1.7, 4.8, and 22 GHz on projected baselines up to 240,000 km we find two characteristic angular scales in the quasar core, about 100 $\mu$as and 10 $\mu$as. Some indications of scattering substructure are found. Very high brightness temperatures, $T_\mathrm{b}\geq 10^{13}$ K, are estimated at 4.8 GHz and 22 GHz even taking into account the refractive scattering. Our findings suggest a clear dominance of the particle energy density over the magnetic field energy density in the core of this quasar.Comment: 14 pages, 9 figure

Optical Nuclei of Radio-loud AGN and the Fanaroff-Riley Divide

We investigate the nature of the point-like optical ``cores'' that have been found in the centres of the host galaxies of a majority of radio galaxies by the Hubble Space Telescope. We examine the evidence that these optical cores are relativistically beamed, and look for differences in the behaviour of the cores found in radio galaxies of the two Fanaroff-Riley types. We also attempt to relate this behaviour to the properties of the optical nuclei in their highly beamed counterparts (the BL Lac objects and radio-loud quasars) as hypothesized by the simple Unified Scheme. Simple model-fitting of the data suggests that the emission may be coming from a non-thermal relativistic jet. It is also suggestive that the contribution from an accretion disk is not significant for the FRI objects and for the narrow-line radio galaxies of FRII type, while it may be significant for the Broad-line objects, and consistent with the idea that the FRII optical cores seem to suffer from extinction due to an obscuring torus while the FRI optical cores do not. These results are in agreement with the Unified Scheme for radio-loud AGNs.Comment: 16 pages including 7 figures and 6 tables, v3: Accepted for publication in A&

Reflections in a Pool: Lully's Ballet des Saisons and the Court of Louis XIV

Excerpt from an unpublished MA thesis (Musicology, Cornell University, 1993). Lully's Ballet des saisons of 1661, a French ballet de cour, focuses on the progression of the four seasons at the royal château of Fontainebleau. The work also incorporates deeper levels of meaning that would have been apparent to the courtiers at the time. Uncovering these layers requires an exploration of the ballet's various subtexts and the relationship between its surface and political meaning. A close examination allows a more fluid view of the court hierarchy. The ballet, then, acts as a mirror of the society that created it