The Jurassic Prehodavci Formation of the Julian Alps: easternmost outcrops of Rosso Ammonitico in the Southern Alps (NW Slovenia)

The Julian Alps are located in NW Slovenia and structurally belong to the Julian Nappe where the Southern Alps intersect with the Dinarides. In the Jurassic, the area was a part of the southern Tethyan continental margin and experienced extensional faulting and differential subsidence during rifting of the future margin. The Mesozoic succession in the Julian Alps is characterized by a thick pile of Upper Triassic to Lower Jurassic platform limestones of the Julian Carbonate Platform, unconformably overlain by Bajocian to Tithonian strongly condensed limestones of the Prehodavci Formation of the Julian High. The Prehodavci Formation is up to 15 m thick, consists of Rosso Ammonitico type limestone and is subdivided into three members. The Lower Member consists of a condensed red, well-bedded bioclastic limestone with Fe–Mn nodules, passing into light-grey, faintly nodular limestone. The Middle Member occurs discontinuously and consists of thin-bedded micritic limestone. The Upper Member unconformably overlies the Lower or Middle Members. It is represented by red nodular limestone, and by red-marly limestone with abundant Saccocoma sp. The Prehodavci Formation unconformably overlies the Upper Triassic to Lower Jurassic platform limestone of the Julian Carbonate Platform; the contact is marked by a very irregular unconformity. It is overlain by the upper Tithonian pelagic Biancone (Maiolica) limestone. The sedimentary evolution of the Julian High is similar to that of Trento Plateau in the west and records: (1) emergence and karstification of part of the Julian Carbonate Platform in the Pliensbachian, or alternatively drowning of the platform and development of the surface by sea-floor dissolution; (2) accelerated subsidence and drowning in the Bajocian, and onset of the condensed pelagic sedimentation (Prehodavci Formation) on the Julian High; (3) beginning of sedimentation of the Biancone limestone in the late Tithonian.     

Submerged caves of Croatia: distribution,classification and origin

Presently, 235 submerged caves and pits have been recorded along the Croatian coast and islands, partly or completely submerged by sea water. Contrary to the inland situation, recorded submerged features are predominantly horizontal (60%), though there are indications that the real situation is similar to that of the continental part where 69% are vertical pits. Completely marine conditions are established in 126 caves and the rest are anchihaline caves and submarine springs. Speleothems are found in more than 140 caves. By their origin, the investigated caves are all continental features formed in Mesozoic and Palaeogene carbonates, subsequently submerged owing to sea transgression. Due to the relatively low wave energy, rapid sea level rise and maturity of the host rock, they do not fit into concepts of a sea cave or a flank margin cave development, but they fulfil several conditions for being the blue holes. Since the term ‘blue hole’ is mainly associated with the Bahamian karst, our attempt is only to show the possible similarities with no intention of ascribing that term to the Croatian caves. Beside karstological issues, Croatian submerged caves are unique environmental, archaeological and tourism assets.     

Environmental risk assessment of some potentially toxic elements in El-Tabbin region (Cairo, Egypt)

As much as 24 soil samples and 6 stream sediments from the River Nile were studied in El-Tabbin region (Great Cairo, Egypt). Twelve chemicals, potentially toxic elements posing potential environmental risk, were the object of concern in this study. Mean contents of analysed elements (in mg kg^?1) in soils and the River Nile stream sediments were the following: As_s 3.6/As_ss 1.5, Cd_s 0.33/Cd_ss 0.12, Cr_s 87.7/Cr_ss 141.5, Cu_s 40.3/Cu_ss 43.8, Hg_s 0.03/Hg_ss 0.13, Pb_s 33.3/Pb_ss 20.2, Zn_s 150/Zn_ss 109, Se_s 0.24/Se_ss 0.05, Ni_s 37.2/Ni_ss 48, Sb_s 1.25/Sb_ss 1, Ba_s 892/Ba_ss 431, V_s 103.3/V_ss 167.8. Furthermore, geochemical background values were derived for soil and stream sediment samples. The values are as follows (in mg kg^?1): As_s 1.33/As_ss 1, Cd_s 0.48/Cd_ss 0.05, Cr_s 54.7/Cr_ss 106.5, Cu_s 23.8/Cu_ss 23, Hg_s 0.025/Hg_ss 0.095, Pb_s 15.3/Pb_ss 13.5, Zn_s 70/Zn_ss 55, Se_s 0.13/Se_ss 0.05, Ni_s 19.5/Ni_ss 32.5, Sb_s 1/Sb_ss 1, Ba_s 266/Ba_ss 275, V_s 50.7/V_ss 119. More than two-thirds of soil and sediment samples exceeded established (based on literature data) risk limit values for non-polluted environment. Based on environmental risk assessment for potentially toxic elements in soils and sediments in more than 45% of total area disturbed environment (I _ER = 1–3) was documented and more than 13% of territory was characterised with highly disturbed environment (I _ER > 3).     

Orbital Parameters of the Binary Companion in o and Using Spectrum Disentangling

o And is one of the most frequently observed Be stars, both in photometry and spectroscopy. It is a multiple system of at least four stars (a Be star, a close binary of spectral types B7 and B8, and an A star). For over a century, numerous observers report a highly variable spectrum, photometric changes, and a substantial range of radial velocity. The star has changed back and forth between a shell-type and a normal B-type star. The last emission phase started in 1992 and ended in 2000. Analysis of the dynamical spectra at spectral lines Mg II 4481 Å and He I 6678 Å and radial velocity curves shows that the two binary components can be resolved. We decomposed the triple star spectra and computed orbital parameters of the binary companion using the KOREL code for spectrum disentangling.     

Confirmation of Cometary Features of Newly Discovered Bodies

The majority of new ground-based discoveries of comets comes from large surveys devoted, predominantly, to Near Earth Asteroids. The first step in distinguishing these newly discovered members of the population of cometary bodies consists inconfirmatory astrometric observations along with detection of their cometaryfeatures. Although both amateur and professional stations take part in suchconfirmatory observations, only some of them do a preliminary analysis of thecometary activity of a particular newly discovered body. A timely recognitionof cometary features of a particular body having an unusual orbit can help inplanning further observing campaigns.A main goals of the Klet Observatory NEO astrometric follow-upprogramme consists of an analysis of possible cometary activity of newlydiscovered unusual bodies. Here, we describe several examples (comets C/1999 S4 (LINEAR) and so on). We also mention an extension of our programme to fainterobjects after the completion ofa new 1-m telescope at the Klet Observatory.     

Collisional velocities and rates in resonant planetesimal belts

We consider a belt of small bodies (planetesimals, asteroids, dust particles) around a star, captured in one of the external or 1:1 mean-motion resonances with a massive perturber (protoplanet, planet). The objects in the belt collide with each other. Combining methods of celestial mechanics and statistical physics, we calculate mean collisional velocities and mean collisional rates, averaged over the belt. The results are compared to collisional velocities and rates in a similar, but non-resonant belt, as predicted by the particle-in-a-box method. It is found that the effect of the resonant lock on the velocities is rather small, while on the rates more substantial. At low to moderate eccentricities and libration amplitudes of tens of degrees, which are typical of many astrophysical applications, the collisional rates between objects in an external resonance are by about a factor of two higher than those in a similar belt of objects not locked in a resonance. For Trojans under the same conditions, the collisional rates may be enhanced by up to an order of magnitude. The collisional rates increase with the decreasing libration amplitude of the resonant argument, depend on the eccentricity distribution of objects, and vary from one resonance to another. Our results imply, in particular, shorter collisional lifetimes of resonant Kuiper belt objects in the solar system and higher efficiency of dust production by resonant planetesimals in debris disks around other stars.     

14 July 2000, a near-global coronal event and its association with energetic electron events detected in the interplanetary medium

On 14 July 2000, the LASCO coronagraphs showed a very fast halo coronal mass ejection in association with the radio bursts seen shortly after 10:00 UT. Radio imaging observations by the Nançay radioheliograph (NRH) of these bursts showed a very complex event that can be regarded as global: the sources encompassed all the visible range in longitude and a huge span in latitude. Another interesting feature of the radio event is its recurrent nature: after the most intense phase shortly after 10:00 UT, two other strong outbursts are detected, one at about 12:50 UT and another at about 13:48 UT. All of these sub-events showed similar development and likely evidence for CMEs. The launch of a CME in association with the 14:00 UT sub-event is inferred from WIND/WAVES, with interplanetary type II signatures in the hectometric wavelength range at that time. These later events were not detected by LASCO due to energetic particles hitting the CCD. During the Bastille Day event, energetic particle observations measured in situ by ACE/EPAM are dominated by energetic electrons. Changes in anisotropy and energy spectrum of the ～38–350 keV electrons suggest a good correlation with the coronal radio observations. In addition to the three main radio events and particle observations, the NRH data reveal moving features in the southern hemisphere. These moving features, located at about 45 deg south and with an angular extent of about 45 deg, are illuminated by non-thermal electrons and are seen at distances up to 2.5 solar radii from the Sun center. More generally, we interpret the global and recurrent coronal activity, revealed by the radio data, as responsible for populating the interplanetary medium with energetic electrons.     

Kinematics of Interacting ICMEs and Related Forbush Decrease: Case Study

We study heliospheric propagation and some space weather aspects of three Earth-directed interplanetary coronal mass ejections (ICMEs), successively launched from the active region AR 11158 in the period 13?–?15 February 2011. From the analysis of the ICME kinematics, morphological evolution, and in situ observations, we infer that the three ICMEs interacted on their way to Earth, arriving together at 1 AU as a single interplanetary disturbance. Detailed analysis of the in situ data reveals complex internal structure of the disturbance, where signatures of the three initially independent ICMEs could be recognized. The analysis also reveals compression and heating of the middle ICME, as well as ongoing magnetic reconnection between the leading and the middle ICME. We present evidence showing that the propagation of these two, initially slower ICMEs, was boosted by the fastest, third ICME. Finally, we employ the ground-based cosmic ray observations, to show that this complex disturbance produced a single cosmic ray event, i.e., a simple Forbush decrease (FD). The results presented provide a better understanding of the ICME interactions and reveal effects that should be taken into account in forecasting of the arrival of such compound structures.     

Comparative Study of MHD Modeling of the Background Solar Wind

Knowledge about the background solar wind plays a crucial role in the framework of space-weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are located, therefore we have to rely on heliospheric models to derive the distribution of solar-wind parameters in interplanetary space. We test the performance of different solar-wind models, namely Magnetohydrodynamic Algorithm outside a Sphere/ENLIL (MAS/ENLIL), Wang–Sheeley–Arge/ENLIL (WSA/ENLIL), and MAS/MAS, by comparing model results with in-situ measurements from spacecraft located at 1 AU distance to the Sun (ACE, Wind). To exclude the influence of interplanetary coronal mass ejections (ICMEs), we chose the year 2007 as a time period with low solar activity for our comparison. We found that the general structure of the background solar wind is well reproduced by all models. The best model results were obtained for the parameter solar-wind speed. However, the predicted arrival times of high-speed solar-wind streams have typical uncertainties of the order of about one day. Comparison of model runs with synoptic magnetic maps from different observatories revealed that the choice of the synoptic map significantly affects the model performance.