Additional spectra of asteroid 1996 FG3, backup target of the ESA MarcoPolo-R mission

Near-Earth binary asteroid (175706) 1996 FG3 is the current backup target of the ESA MarcoPolo-R mission, selected for the study phase of ESA M3 missions. It is a primitive (C-type) asteroid that shows significant variation in its visible and near-infrared spectra. Here we present new spectra of 1996 FG3 and we compare our new data with other published spectra, analysing the variation in the spectral slope. The asteroid will not be observable again over the next three years at least. We obtained the spectra using DOLORES and NICS instruments at the Telescopio Nazionale Galileo (TNG), a 3.6m telescope located at El Roque de los Muchachos Observatory in La Palma, Spain. To compare with other published spectra of the asteroid, we computed the spectral slope S', and studied any plausible correlation of this quantity with the phase angle (alpha). In the case of visible spectra, we find a variation in spectral slope of Delta S' = 0.15 +- 0.10 %/10^3 A/degree for 3 < alpha < 18 degrees, in good agreement with the values found in the literature for the phase reddening effect. In the case of the near-infrared, we find a variation in the slope of Delta S' = 0.04 +- 0.08 %/10^3 A/degree for 6 < alpha < 51 degrees. Our computed variation in S' agrees with the only two values found in the literature for the phase reddening in the near-infrared. The variation in the spectral slope of asteroid 1996 FG3 shows a trend with the phase angle at the time of the observations, both in the visible and the near-infrared. It is worth noting that, to fully explain this spectral variability we should take into account other factors, like the position of the secondary component of the binary asteroid 1999 FG3 with respect to the primary, or the spin axis orientation at the time of the observations. More data are necessary for an analysis of this kind.Comment: 4 pages, 3 figures, Accepted in A&A 25 June 201

Subcritical Flow Over Various Weir Shapes

Submerged flow exists for any given structure when a change in flow depth downstream from the structure causes a change in flow depth upstream from the structure for any given constant value of discharge. The two flow depths, normally measured when submerged flow exists, consist of a depth upstream from the structure, which is used also for free flow conditions, and a depth of flow located any place downstream from the structure. The initial studies in which the submerged flow analysis was developed were made on flat-bottomed flumes (Hyatt, 1965; and Skogerboe, Walker, and Robinson, 1965). Later studies verified the method of analysis for Parshall flumes (Skogerboe, Hyatt, England, and John son, 1965; and Hyatt, Skogerboe, and Eggleston, 1966). Because of previous findings, it was felt this method of analyzing submerged flow could be applied to various types and kinds of weirs. Original development of the parameters and relationships which describe submerged flow came from a combination of dimensional analysis and empiricism. Further verification of the parameters developed in this manner are obtained by employing momentum relationships. Both approaches to the submerged flow problem are discussed in this report. Considerable effort and study has been expended on free and submerged flow weirs by other authors in previous years. For this reason the authors of this report went to the literature as a source of data. Various studies typifying a particular type of weir structure were investigated and the data selected from these studies were subjected to the submerged flow analysis developed by the authors. The data from these studies provide further verification of validity of the approach to the submerged flow problem made by the authors. Acknowledgement is given and appreciation expressed to those authors whose studies provided the data used in the analysis presented in this report. Although no investigation was made of a contracted weir, the authors feel that the submerged flow analysis as explained in this report would be just as valid for this type of structure

Stage-Fall-Discharge Relations For Flood Flows Over Highway Embankments

At Utah State University, considerable effort has been devoted to the analysis of submerged flow at open channel constrictions. A method of analyzing submerged flow was first developed for a trapezoidal flume by Hyatt (1965). Later studies verified the method of analysis for a rectangular flume (Skogerboe, Walker, and Robinson, 1965) and Parshall flumes (Skogerboe, Hyatt, England, and Johnson, 1965). Because of the previous findings, it was felt this method of analyzing submerged flow could be applied to highway embankments. A highway embankment is a form of broad-crested weir when overtopped by flood waters. Being a weir, the flood discharge over the embankment is only a function of the upstream depth for free flow conditions. This report will present a method for determining the discharge under submerged flow conditions using the upstream and downstream depths. Thus, post flood field measurements and observations, when properly obtained, will provide the necessary information for an accurate determination of the flood discharge for either free or submerged flow conditions. The concepts involved in the analysis of submerged flow at open channel constrictions were originally developed by dimensional analysis for flow measuring flumes. The parameters describing submerged flow in flumes have been further verified by the development of theoretical submerged flow equations which utilize momentum theory and energy relationships. The experimental models studied by Kindsvater (1964) are comparable to a secondary highway embankment. The models were constructed to a scale of 1/9 a typical secondary roadway. The data resulting from the model studies has been subjected to the method of submerged flow analysis previously employed with flow measuring flumes. The consistency of the data, both fro free flow and submerged flow, reflects the quality of the experimental design and produces employed in collecting the data. Although the data presented in this report applies only various forms of secondary road embankments, the methods of analysis are general. The development of calibration curves for other embankment geometries requires only the generation of additional data employing model studies

Long-term variability of the optical spectra of NGC 4151: II. Evolution of the broad Ha and Hb emission-line profiles

Results of the long-term (11 years, from 1996 to 2006) H$\alpha$ and H$\beta$ line variations of the active galactic nucleus of NGC 4151 are presented. High quality spectra (S/N>50 and R~8A) of H$\alpha$ and H$\beta$ were investigated. We analyzed line profile variations during monitoring period. Comparing the line profiles of H$\alpha$ and H$\beta$, we studied different details (bumps, absorption features) in the line profiles. The variations of the different H$\alpha$ and H$\beta$ line profile segments have been investigated. Also, we analyzed the Balmer decrement for whole line and for line segments. We found that the line profiles were strongly changing during the monitoring period, showing blue and red asymmetries. This indicates a complex BLR geometry of NGC 4151 with, at least, three kinematically distinct regions: one that contributes to the blue line wing, one to the line core and one to the red line wing. Such variation can be caused by an accelerating outflow starting very close to the black hole, where the red part may come from the region {closer to the black hole than the blue part, which is coming} from the region having the highest outflow velocities. Taking into account the fact that the BLR of NGC 4151 has a complex geometry (probably affected by an outflow) and that a portion of the broad line emission seems to have not a pure photoionization origin, one can ask the question whether the study of the BLR by reverberation mapping may be valid in the case of this galaxy.Comment: 24 pages, 18 figures, accepted for publications in A&

Effective spacetime from multi-dimensional gravity

We study the effective spacetimes in lower dimensions that can be extracted from a multidimensional generalization of the Schwarzschild-Tangherlini spacetimes derived by Fadeev, Ivashchuk and Melnikov ({\it Phys. Lett,} {\bf A 161} (1991) 98). The higher-dimensional spacetime has $D = (4 + n + m)$ dimensions, where $n$ and $m$ are the number of "internal" and "external" extra dimensions, respectively. We analyze the effective $(4 + n)$ spacetime obtained after dimensional reduction of the $m$ external dimensions. We find that when the $m$ extra dimensions are compact (i) the physics in lower dimensions is independent of $m$ and the character of the singularities in higher dimensions, and (ii) the total gravitational mass $M$ of the effective matter distribution is less than the Schwarzshild mass. In contrast, when the $m$ extra dimensions are large this is not so; the physics in $(4 + n)$ does explicitly depend on $m$, as well as on the nature of the singularities in high dimensions, and the mass of the effective matter distribution (with the exception of wormhole-like distributions) is bigger than the Schwarzshild mass. These results may be relevant to observations for an experimental/observational test of the theory.Comment: A typo in Eq. (24) is fixe

Spectral optical monitoring of the double peaked emission line AGN Arp 102B: II. Variability of the broad line properties

We investigate a long-term (26 years, from 1987 to 2013) variability in the broad spectral line properties of the radio galaxy Arp 102B, an active galaxy with broad double-peaked emission lines. We use observations presented in Paper I (Shapovalova et al. 2013) in the period from 1987 to 2011, and a new set of observations performed in 2012--2013. To explore the BLR geometry, and clarify some contradictions about the nature of the BLR in Arp 102B we explore variations in the H$\alpha$ and H$\beta$ line parameters during the monitored period. We fit the broad lines with three broad Gaussian functions finding the positions and intensities of the blue and red peaks in H$\alpha$ and H$\beta$. Additionally we fit averaged line profiles with the disc model. We find that the broad line profiles are double-peaked and have not been changed significantly in shapes, beside an additional small peak that, from time to time can be seen in the blue part of the H$\alpha$ line. The positions of the blue and red peaks { have not changed significantly during the monitored period. The H$\beta$ line is broader than H$\alpha$ line in the monitored period. The disc model is able to reproduce the H$\beta$ and H$\alpha$ broad line profiles, however, observed variability in the line parameters are not in a good agreement with the emission disc hypothesis. It seems that the BLR of Arp 102B has a disc-like geometry, but the role of an outflow can also play an important role in observed variation of the broad line properties.Comment: 17 pages, Accepted for publication in A&