Evidence of a star formation burst in a spheroidal dwarf galaxy

We present here the luminosity profile and the colour distribution of the irregular dwarf galaxy UGC 5423 = M81 dwB. Using digital surface photometry we show that UGC 5423 is a burst of young stars in the central body of a larger spheroidal dwarf galaxy.     

UW Persei

This object consists of two visible components; it is not quite sure if the brighter one is variable. An examination on 314 plates gave no further maximum in addition to the three already known historical eruptions. A relationship of the brighter component to the cataclysmic variables is not very probable because of the observed UV weakness.     

V 361 Lyrae: An exotic binary system with a “Hot Spot” between the components?

A phenomenological model for V 361 Lyr is proposed. Probably it is a binary system which consists of a mass accreting primary star with mass of about M₁ ≈ 0·81 M⊙ and radius R₁ ≈ (6.1 ± 0·4) · 10¹⁰ cm and a mass losing secondary with about M₂ ≈ 0·77 M⊙ and R₂ ≈ 5.8 · 10¹⁰ cm. The secondary fills its Roche lobe, but the primary is something smaller than this lobe, contrary to the models of W UMa-type systems. So the hot spot appears in the atmosphere of the primary, but not in a disk, like in cataclysmic variables. The luminosity of the hot spot, L = (6-15) · 10³² erg/s, is large enough to be the main emission source of the system in visible light. So phenomenologically the object may be somewhat between W UMa-type stars and cataclysmic variables.     

Dynamic modeling of long-term sedimentation in the Yadkin River basin

Modeling of sediment transport in relation to changing land-surface conditions against a background of considerable natural variability is a challenging area in hydrology. Bayesian dynamic linear models (DLMs) however, offer opportunities to account for non-stationarity in relationships between hydrologic input and basin response variables. Hydrologic data are from a 40 years long record (1951–1990) from the 5905 km² Yadkin River basin in North Carolina, USA. DLM regressions were estimated between log-transformed volume-weighted sediment concentration as a response and log-transformed rainfall erosivity and river flow, respectively, as input variables. A similar regression between log-transformed river flow and log-transformed basin averaged rainfall was also analyzed. The dynamic regression coefficient which reflects the erodibility of the basin decreased significantly between 1951 and 1970, followed by a slowly rising trend. These trends are consistent with observed land-use shifts in the basin. Bayesian DLMs represent a substantial improvement over traditional monotonic trend analysis. Extensions to incorporate multiple regression and seasonality are recommended for future applications in hydrology.     

H II emission line region in LEDA 212995, a small neighboring galaxy of Mrk 1040

We present here new spectroscopic observations of Mrk 1040 and LEDA 212995 (Mrk 1040 companion) obtained with the Isaac Newton Telescope (INT). The intensity ratios and widths for the narrow emission lines found in LEDA 212995 are typical of H II regions. The red‐shift (0.0169 ± 0.00015) of the object derived from these emission lines is very close to the red‐shift of Mrk 1040 (z = 0.01665). The weak narrow and broad absorption lines were detected in the Hα wavelength band of LEDA 212995 spectra. These absorptions indicate that the companion might be at least partly obscured by Mrk 1040. Using this and previous observations we discuss the possible physical relationship between these two galaxies. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Photometry of groups of galaxies. II. The NGC 972 group

A nearby group of galaxies, centered at the spiral galaxy NGC 972 and conspicuously rich in faint dwarf spheroidal galaxies, has been investigated photometrically on the B and V plates, obtained with the Tautenburg 2m Schmidt telescope. For ten certain and probable group members the equivalent B and V brightness profiles have been extracted. Integrated magnitudes and mean colours of faint group members have been estimated. Typically, the dwarfs show a “subexponential” (i.e. a convex curvature over the linear radius) surface brightness profile and often a central excess. Their equivalent profiles are reasonably well fitted by modified isothermal (King) models.     

Biophysical Parameter Estimation With a Semisupervised Support Vector Machine

This letter presents two kernel-based methods for semisupervised regression. The methods rely on building a graph or hypergraph Laplacian with both the available labeled and unlabeled data, which is further used to deform the training kernel matrix. The deformed kernel is then used for support vector regression (SVR). Given the high computational burden involved, we present two alternative formulations based on the Nystrom method and the incomplete Cholesky factorization to achieve operational processing times. The semisupervised SVR algorithms are successfully tested in multiplatform leaf area index estimation and oceanic chlorophyll concentration prediction. Experiments are carried out with both multispectral and hyperspectral data, demonstrating good generalization capabilities when a low number of labeled samples are available, which is usually the case in biophysical parameter retrieval.     

A scanning microphotometer with an on-line data reduction for large field Schmidt plates

The mechanical and electronic device of the microphotometer is described. The on-line data compression is performed in the domain of the HAAR transform of the measurement points. This method provides a fast treatment of the measurement data in the computer and changes the large data material sampled in equidistant steps whose width can be chosen by the seeing condition into a non-equidistant grid whose widths depend only on the characteristic length of the signal. The grain noise is eliminated. An automatical discrimination between stars and galaxies is possible. The accuracy of the photometry was tested by comparing with the photoelectrically determined B-brightness distribution of M 81.     

A closure study of sub-micrometer aerosol particle hygroscopic behaviour

The hygroscopic properties of sub-micrometer aerosol particles were studied in connection with a ground-based cloud experiment at Great Dun Fell, in northern England in 1995. Hygroscopic diameter growth factors were measured with a Tandem Differential Mobility Analyser (TDMA) for dry particle diameters between 35 and 265 nm at one of the sites upwind of the orographic cloud. An external mixture consisting of three groups of particles, each with different hygroscopic properties, was observed. These particle groups were denoted less-hygroscopic, more-hygroscopic and sea spray particles and had average diameter growth factors of 1.11–1.15, 1.38–1.69 and 2.08–2.21 respectively when taken from a dry state to a relative humidity of 90%. Average growth factors increased with dry particle size. A bimodal hygroscopic behaviour was observed for 74–87% of the cases depending on particle size. Parallel measurements of dry sub-micrometer particle number size distributions were performed with a Differential Mobility Particle Sizer (DMPS). The inorganic ion aerosol composition was determined by means of ion chromatography analysis of samples collected with Berner-type low pressure cascade impactors at ambient conditions. The number of ions collected on each impactor stage was predicted from the size distribution and hygroscopic growth data by means of a model of hygroscopic behaviour assuming that only the inorganic substances interacted with the ambient water vapour. The predicted ion number concentration was compared with the actual number of all positive and negative ions collected on the various impactor stages. For the impactor stage which collected particles with aerodynamic diameters between 0.17–0.53 μm at ambient relative humidity, and for which all pertinent data was available for the hygroscopic closure study, the predicted ion concentrations agreed with the measured values within the combined measurement and model uncertainties for all cases but one. For this impactor sampling occasion, the predicted ion concentration was significantly higher than the measured. The air mass in which this sample was taken had undergone extensive photochemical activity which had probably produced hygroscopically active material other than inorganic ions, such as organic oxygenated substances.