Aims. We report the discovery of a strong outburst of the embedded young stellar object (YSO) UKIDSS−J185318.36+012454.5, located in the star-forming region associated with IRAS 18507+0121 and the ...ultra-compact H II region GAL 034.4+00.23. Methods. Using archival photometric data and images, we determined the amplitude and the epoch of the outburst as well as the evolution stage and the basic parameters of the object. Results. According to the near- and mid-infrared colors and spectral energy distribution, we classify the object as an intermediate-mass YSO with Class 0/I evolution stage. The outburst apparently started between May 2003 and April 2004. The amplitude of the outburst is at least ΔKs = 5.0 mag. The summation of the photometric and spectral data does not allow classifying UKIDSS−J185318.36+012454.5 as an FU Orionis (FUor) or EX Orionis (EXor) object. We can consider it as an eruptive variable with mixed characteristics or as an MNor type object.
The work describes the production of investment material on the basis of β cristobalite obtained from β quartz at 1100°C in the presence of mineralizers. The obtained mixture is characterized by ...beginning of solidification of 9 min and compressive strength of 6.1 mPa; it provides a smooth surface and easy extraction from the mold of chromium nickel alloys.
The interaction between dacitic tuff and calcium hydroxide under hydrothermal conditions has been investigated. At a ratio of CaO/SiO
2
= 0.3–1.5 : 1 and at a ratio between the liquid phase and the ...solid phase amounting to 10 : 1, after 2 h at 220°C, calcium hydroxide is completely bound. As a result of the destruction of potassium feldspar in tuff, potassium can be transformed into a plant-digestible form.
A study is performed of the mechanism behind the effect high-voltage nanosecond electromagnetic pulses and dielectric barrier discharges have on surfaces of ilmenite in air at atmospheric pressure. ...Fourier-transform infrared spectroscopy, scanning electron microscopy, electron microprobe analysis, microhardness testing, contact angles of surface wetting, and streaming potentials are used to examine the morphology of ilmenite, its physicochemical properties (microhardness, contact angle, and electrokinetic potential), and the structural state of ilmenite surfaces. Advantages are shown of using brief energy treatments (
t
treat
= 10–30 s) to modify the chemical structure of surfaces of ilmenite and its physicochemical properties in order to improve the efficiency of processing complex titanium ores.
Alluvial diamonds from the Juina area in Mato Grosso, Brazil, have been characterized in terms of their morphology, syngenetic mineral inclusions, carbon isotopes and nitrogen contents. ...Morphologically, they are similar to other Brazilian diamonds, showing a strong predominance of rounded dodecahedral crystals.
The results of a search for compact clusters in the vicinity of 19 IRAS sources based on data from the GPS UKIDSS and Spitzer GLIMPSE surveys are presented. Overall, clusters have been identified in ...15 regions. Clusters are identified for the first time in 4 regions (IRAS 18151-1208, IRAS 18316-0602, 18517+0437, 19110+1045). In 5 regions (IRAS 05168+3634, 05358+3543, IRAS 18507+0121, IRAS 20188+3928, IRAS 20198+3716) the compact groups we have identified are substructures within more extended clusters. The radii of the identified groups and the surface star density are widely scattered with ranges of 0.3-2.7 pc and 4-1360 stars/pc2, respectively. In 11 of the clusters, the IRAS sources are associated with a pair or even a group of YSOs. The groups identified in the NIR range include representatives of a later II evolutionary class among the stellar objects associated with the IRAS sources.
The review discusses intramolecular cyclization of ammonium salts containing a 4-hydroxybut-2- yn-1-yl group in combination with various π
4
-fragments, as well as mechanisms of cyclization and ...intramolecular recyclization of the resulting 4-(hydroxymethyl)dihydroisoindolium salts and their fused analogs. The process is accompanied by neither ring expansion nor contraction, and a pharmacophoric 1,3-dihydrofuran ring is formed instead of dihydroisoindolium fragment. The effects of electronic and structural factors on the intramolecular cyclization and recyclization processes are considered.
Results are presented from a statistical analysis of ~200 stars with Hα emission in the cluster IC 348. The sample of emission objects extends to R ≤ 20.0. The optical radius of the cluster is ~11'. ...The percentage of emission stars increases from bright to fainter objects and reaches 80% for objects within the interval 13.0 ≤ R − A
R
≤ 19.0. The fraction of WTTS and CTTS is 64% and 36%, respectively. 70% of the x-ray sources are WTTS objects. The age of the WTTS and CTTS is ~2·10
6
yr. The nonemission stars with masses lower than that of the sun also have an age of ~2·10
6
yr, while the age of the brighter objects is ~7·10
6
yr. The most massive stars with a low level of activity are concentrated in a small dense central core of the cluster with a radius of ~1' and appear to have been generated in an earlier wave of star formation.
Astronomical plate archives created on the basis of numerous observations at many observatories are important part of the astronomical heritage. Byurakan Astrophysical Observatory (BAO) plate archive ...consists of 37,000 photographic plates and films, obtained at 2.6m telescope, 1m and 0.5m Schmidt telescopes and other smaller ones during 1947--1991. In 2002-2005, the famous Markarian Survey (First Byurakan Survey, FBS) 2000 plates were digitized and the Digitized FBS (DFBS) was created. New science projects have been conducted based on these low-dispersion spectroscopic material. In 2015, we have started a project on the whole BAO Plate Archive digitization, creation of electronic database and its scientific usage. The project will run during 3 years in 2015--2017 and the final result will be an electronic database and online interactive sky map to be used for further research projects.
PDF
