Two-site CCD observations and spectroscopy of HD 207331: A new δ Scuti variable in Cygnus

The results of an observational campaign on the new δ Scuti pulsator HD 207331 are reported. The star was observed photometrically from August 26 to September 2, 2009 from the Observatorio San Pedro Mártir (0.84-m telescope, Mexico) and the Observatorio del Teide (0.80-m telescope, Spain). An overall run of 53.8 h of useful data was collected from the two sites. Four oscillation frequencies for HD 207331 have been found above a 99% confidence level. These results confirm the multiperiodic pulsation nature of the star suggested in previous observations with sparse data. Spectroscopic observations carried out in 2009 allowed us to derive its spectral type and luminosity class as well as to estimate its rotation rate. A simple comparison with models is performed.     

Tidal and wind-induced circulation within the Southeastern limit of the Bay of Biscay: Pasaia Bay,Basque Coast

The Basque coastal area, in the southeastern Bay of Biscay, can be characterised as being more influenced by land climate and inputs, than other typically ‘open sea’ areas. The influence of coastal processes, together with the presence of irregular and steep topography, complicate greatly the water circulation patterns. Water movement along the Basque coastal area is not well understood; observations are scarce and long-term current records are lacking. The knowledge available is confined to the surface currents: the surface water circulation is controlled mainly by wind forcing, with tidal and density currents being weak. However, there is a lack of knowledge available on currents within the lower levels of the water column; likewise, on the main time-scales involved in the water circulation. This study quantifies the contribution of the tidal and wind-induced currents, to the overall water circulation; it identifies the main time-scales involved within the tidal and wind-induced flows, investigating difference in such currents, throughout the water column, within Pasaia Bay (Basque coast). Within this context, extensive oceanographic and meteorological data have been obtained, in order to describe the circulation. The present investigation reveals that the circulation, within the surface and the sub-surface waters, is controlled mainly by wind forcing fluctuations, over a wide range of meteorological frequencies: third-diurnal, semidiurnal and diurnal land–sea breezes; synoptic variability; frequencies, near fortnightly periods; and seasonal. At the lower levels of the water column, the main contribution to the water circulation arises from residual currents, followed by wind-induced currents on synoptic time-scales. In contrast, tidal currents contribute minimally to the overall circulation throughout the water column.     

3D hydrodynamic characterisation of a meso-tidal harbour: The case of Bilbao (northern Spain)

A background knowledge of marine dynamics helps harbour managers to control pollution and to manage dredging and traffic operations. This contribution studies the hydrodynamic conditions within Bilbao Harbour, which is enclosed by the Nervión Estuary (in the Basque Country, Spain). The results obtained from hydrographical surveys are compared with numerical simulations obtained using the Regional Ocean Modelling System (ROMS). Hydrodynamic modelling was carried out to determine the inner harbour currents for a specific period in which data were available. Then, numerical experiments were designed in order to quantify the importance of different driving mechanisms in the harbour hydrodynamics. The results show that, in addition to the strong tidal influence on water circulation, the wind forcing and freshwater discharge also have a non-negligible influence on the currents. The computational domain is complex due to the presence of harbour infrastructures (i.e. breakwaters and piers). As a result, topographic eddies are therefore observed in the results. The freshwater influence of the Nervión river can also be observed in residual currents. This paper presents an improvement to the application of numerical modelling to a complex geometry domain, contributing to our understanding of the behaviour of the marine systems in meso-tidal harbours. This can be used to deal with harbour engineering and management problems.     

LEGRI Science Operation Center. Architecture and Operations

The LEGRI Science Operation Center (SOC) is the single contact pointbetween the MINISAT-01 Centro de Operaciones Científicas (COC)located at Villafranca del Castillo (Madrid) and the LEGRI Consortium.Its architecture, operational procedures and associated software hasbeen developed at the Universities of Valencia and Birmingham on thescope to define a integrated Data Analysis System, able to perform thedaily follow-up of the instrument health, raw data files decompressionand archiving activities (on-line and historical). Pointing and telecommandfiles generation is also a SOC responsibility.The aim of this paper is to report the SOC activities during the two yearsof LEGRI operations. Conclusions about the SOC architecture and proceduresevolution on how to handle the operations for space-borne instrumentation,are also presented.Special attention has been paid to the operative evaluation of the pointingreconstruction solutions from the MINISAT-01 Attitude Control System bycomparing them with those obtained with the LEGRI Star Sensor. The analysisof one year of observations shows the good agreement between both sets ofdata. No systematic deviations have been found with an averaged standarddeviation of 1 degree in alpha and delta coordinates. For most of the timethe MINISAT pointing system is working slightly better than expected andwithin specifications.     

ULTRACAM observations of the black hole X-ray transient XTE J1118+480 in quiescence

We present 450- and 850-μm maps of R Coronae Australis. We compare the maps with previous surveys of the region, and shed new light on the previously unknown nature of the protostellar sources at the centre of the cloud. We clarify the nature of two millimetre sources previously discovered in lower-resolution data. We identify one new Class 0 protostar, which we label SMM 1B, and we measure the envelope masses of a number of more evolved protostars. We identify two new pre-stellar cores, which we call SMM 1A and SMM 6.     

Detection of superhumps in XTE J1118+480 approaching quiescence

We present the results of our monitoring of the halo black hole soft X-ray transient (SXT) XTE J1118+480 during its decline to quiescence. The system has decayed 0.5 mag from 2000 December to its present near-quiescent level at   R ≃18.65  (2001 June). The ellipsoidal light curve is distorted by an additional modulation that we interpret as a superhump of   P _sh=0.17049(1) d  i.e. 0.3 per cent longer than the orbital period. This implies a disc precession period   P _prec∼52 d  . After correcting the average phase-folded light curve for veiling, the amplitude difference between the minima suggests that the binary inclination angle lies in the range   i =71–82°  . However, we urge caution in the interpretation of these values because of residual systematic contamination of the ellipsoidal light curve by the complex form of the superhump modulation. The orbital-mean H α profiles exhibit clear velocity variations with ∼500 km s⁻¹ amplitude. We interpret this as the first spectroscopic evidence of an eccentric precessing disc.     

VLT spectroscopy of XTE J2123−058 during quiescence: the masses of the two components

We present Very Large Telescope (VLT) low-resolution spectroscopy of the neutron star X-ray transient XTE J2123−058 during its quiescent state. Our data reveal the presence of a K7V companion which contributes 77 per cent to the total flux at λ 6300 and orbits the neutron star at     . Contrary to other soft X-ray transients (SXTs), the H _α emission is almost exactly in antiphase with the velocity curve of the optical companion. Using the light-centre technique we obtain     and hence     This, combined with a previous determination of the inclination angle     yields     and     . M ₂ agrees well with the observed spectral type. Doppler tomography of the H α emission shows a non-symmetric accretion disc distribution mimicking that seen in SW Sex stars. Although we find a large systemic velocity of −     this value is consistent with the galactic rotation velocity at the position of J2123−058, and hence a halo origin. The formation scenario of J2123−058 is still unresolved.