Microvariability of line profiles in the spectrum of the star ι Her

We present the results of a search for and analysis of line-profile variations in the spectrum of the star ι Her. The observations were acquired with the 1.8 m telescope of the Bohyunsan Optical Astronomy Observatory (Republic of Korea) in May–June 2004. We obtained 69 spectra of the star with signal-to-noise ratios ≈300 and a time resolution of 5–7 min. Profile variability was revealed for six lines of HI, HeI, and SiIII, in the central parts of the lines. The variability amplitude is ≈(1–2)% in units of the intensity of the adjacent continuum. Evidence was found for cyclic variations of the lines, with periods from ≈7^h to ≈2.9^d. We conclude that ι Her belongs to the group of slowly pulsating stars.     

Statistics of magnetic fields for OB stars

Based on an analysis of the catalog of magnetic fields, we have investigated the statistical properties of the mean magnetic fields for OB stars. We show that the mean effective magnetic field B of a star can be used as a statistically significant characteristic of its magnetic field. No correlation has been found between the mean magnetic field strength B and projected rotational velocity of OB stars, which is consistent with the hypothesis about a fossil origin of the magnetic field. We have constructed the magnetic field distribution function for B stars, F(B), that has a power-law dependence on B with an exponent of ≈−1.82. We have found a sharp decrease in the function F(B) for B ⩽ 400 G that may be related to rapid dissipation of weak stellar surface magnetic fields.     

Landslide Research at the British Geological Survey:Capture,Storage and Interpretation on a National and Site-Specific Scale

Abstract: Landslide research at the British Geological Survey (BGS) is carried out through a number of activities, including surveying, database development and real-time monitoring of landslides. Landslide mapping across the UK has been carried out since BGS started geological mapping in 1835. Today, BGS geologists use a combination of remote sensing and ground-based investigations to survey landslides. The development of waterproof tablet computers (BGS·SIGMAmobile), with inbuilt GPS and GIS for field data capture provides an accurate and rapid mapping methodology for field surveys. Regional and national mapping of landslides is carried out in conjunction with site-specific monitoring, using terrestrial LiDAR and differential GPS technologies, which BGS has successfully developed for this application. In addition to surface monitoring, BGS is currently developing geophysical ground-imaging systems for landslide monitoring, which provide real-time information on subsurface changes prior to failure events. BGS’s mapping and monitoring activities directly feed into the BGS National Landslide Database, the most extensive source of information on landslides in Great Britain. It currently holds over 14?000 records of landslide events. By combining BGS’s corporate datasets with expert knowledge, BGS has developed a landslide hazard assessment tool, GeoSure, which provides information on the relative landslide hazard susceptibility at national scale.     

Line-profile microvariability in OB-star spectra: the Supergiant λ Cep (O6If(n))

We observed the bright O6If(n) supergiant λ Cep in 1997 with the 6-m optical telescope of the Special Astrophysical Observatory and in 2007 with the 1.8-m telescope of the Bohyunsan Optical Astronomy Observatory (South Korea). A total of 90 spectra of the star were acquired, with good time resolution (10 minutes), signal-to-noise ratios 150–300, and spectral resolutions of 45 000–60 000. We detected line-profile variations of H, HeI, and HeII lines. It is suggested that the detected variations are due to non-radial photospheric pulsations and the star’s rotation (rotational profile modulation).     

Photometric and spectroscopic investigation of the B2E Herbig star HD52721: First results

We present first results of the photometric and spectroscopic investigation of the B1/B2 Herbig star HD52721 performed in 2009–2010 at three observatories: Mountain Astronomical Station (Kislovodsk)—photometry, CrAO (Crimea, Ukraine)—spectroscopy, Observatory San Pedro Martyr (Ensenada, Mexico)—high-resolution echelle-spectroscopy. We have also used photometric data from the ASAS survey for 2003–2009. Our analysis has shown that a) the object is a close binary system with the orbital period of 1.610 days composed of two components of similar spectral type (B1–B2); b) the system is surrounded by the common disk-like envelope containing azimuthal inhomogeneity rotating with the orbital period of the system. We present preliminary estimates of the system parameters and discuss its possible nature.     

Magnetic field evolution in OBA stars

The applications of the spectral analysis methods discovered by Kirchhoff for the investigation of stellar magnetic fields are considered. The statistical properties of the mean magnetic fields for OBA stars have been investigated by analyzing data from two catalogs of magnetic fields. It is shown that the mean effective magnetic field ℬ of a star can be used as a statistically significant characteristic of its magnetic field. The magnetic field distribution functions F(ℬ) have been constructed for B-type and chemically peculiar (CP) stars, which exhibit a power-law dependence on ℬ. A sharp decrease in F(ℬ) in the range of weak magnetic fields has been found. The statistical properties of the magnetic fluxes for main-sequence stars, white dwarfs, and neutron stars are analyzed.     

High-resolution fiber-fed echelle spectrograph for the 6-m telescope. I. Optical scheme,arrangement, and control system

We propose a project of a high-resolution (R = 100 000) fiber-fed spectrograph for comprehensive studies of stellar atmospheres, exoplanet searches, asteroseismological studies, studies of stellar magnetism, active nuclei of bright galaxies, interstellar medium, etc. We present the optical scheme of the instrument. The operating wavelength region spans from 4000 to 7500 Å. We also present the optical scheme of the pre-fiber optic unit of the spectrograph. The unit supports four main modes of spectroscopic observations: the mode of traditional spectroscopy with the spectrum of the studied object taken along with the background spectrum in the immediate vicinity of the object; the mode of the simultaneous recording of the spectrum of the object and that of the wavelength standard; the mode of high-precision spectroscopy with an iodine cell, and the mode of spectropolarimetric observations with the measurement of all the Stokes parameters.     

Exoplanet studies. Spectral confirmation of photometric exoplanet candidates discovered by the “Kepler” mission

We present the results of spectroscopic confirmation of exoplanet candidates from the “Kepler” space mission catalog. We used the NES spectrometer of the 6-m Russian BTA telescope to investigate the Doppler variability of the radial velocities of the host stars of KOI-974.01, KOI-2687.01/02, and KOI-2706.01. According to the derived upper limits, KOI-2706.01 has a mass significantly smaller than 12 Jupiter masses, which directly indicates its planetary nature. We show that KOI-2687.01 and KOI-2687.02, which have Earth-size or white dwarf-size radii according to photometric data, cannot be white dwarfs, and are therefore exoplanets. Radial velocity analysis for KOI-974, an F-type star, has shown noticeable variations with a half-amplitude of 400 ms^?1, which correlate poorly with the phase of its orbital rotation. This can indicate a presence of other massive planets in the system, with orbits closer or farther from the host star than the orbit of KOI-974.01, or a low mass star in a distant outer orbit. Using the method of synthetic spectra, we obtained more accurate atmospheric parameter and radius estimates for all the program host stars, which, in turn, allowed us to refine the radii of the studied exoplanet candidates.     

Search for and study of photometric variability in magnetic white dwarfs

We report the results of photometric observations of a number of magnetic white dwarfs in order to search for photometric variability in these stars. These V-band observations revealed significant variability in the classical highly magnetized white dwarf GRW+70?8247 with a likely period from several days to several dozen days and a half-amplitude of about 0_. ^m 04. Our observations also revealed the variability of the well-known white dwarf GD229. The half amplitude of its photometric variability is equal to about 0_. ^m 005, and the likely period of this degenerate star lies in the 10–20 day interval. This variability is most likely due to the rotation of the stars considered.We also discuss the peculiarities of the photometric variability in a number of other white dwarfs. We present the updated “magnetic field–rotation period” diagram for the white dwarfs.