


卷 63, 编号 8 (2019)
- 年: 2019
- 文章: 8
- URL: https://journals.rcsi.science/1063-7729/issue/view/12124
Article
Meteor Detection from the Fireball Moroccan Network: First Orbital Results and Links to Parent Bodies
摘要
A network of meteor stations is being deployed in Morocco with the aim to determine meteor trajectories and their relationships with possible parent bodies. Several meteor showers may be related to known parent bodies, such as the the comet 109P/Swift-Tuttle, which is associated to Perseids. Two stations of meteor observations with Watec cameras were recently installed in Morocco as part of this network, one at the Oukaimeden Observatory and the other at Marrakech. This paper presents the implementation of a software to determine the orientation of the camera, and the preliminary results obtained with the two stations.



The Photolysis of Aromatic Hydrocarbons Adsorbed on the Surfaces of Cosmic Dust Grains
摘要
The results of laboratory mass-spectrometer studies of the laser-induced dissociation of molecules of simple aromatic hydrocarbons adsorbed on a quartz substrate under the conditions of deep vacuum and low temperatures are adapted to the physical and chemical conditions in regions of active star formation in molecular clouds. The main properties of the photolysis of physically adsorbed molecules compared to the photodissociation of isolated molecules in the gas phase are identified. The relevance of molecular photolytic desorption to the real conditions in the interstellar medium is analyzed, in particular, to the conditions in photodissociation regions. It is shown that the photodissociation of adsorbed benzene occurs along other channels and with appreciably lower efficiency than does the corresponding process in the gas phase. The photodissociation of aromatic hydrocarbons adsorbed on the surfaces of interstellar grains cannot make a large contribution to the abundance of hydrocarbons with small numbers of atoms observed in the interstellar medium.



Spectrum and Variability of the Supernova Remnant G21.5-0.9
摘要
Measurements of the flux densities of the supernova remnant G21.5-0.9 at 4840 and 8450 MHz were performed in 2013–2018 on the 32-m telescope of the Svetloe Observatory of the Institute of Applied Astronomy, Russian Academy of Sciences. Multiple measurements revealed source variability. The flux densities of G21.5-0.9 for 1967–2010 from previously published data are used to compare the intensity of G21.5-0.9 and standard sources. An artificial-Moon flux scale is used to bring all the data into a single system and determine a refined spectrum. Analysis of the resulting data indicates that, first, the observed break in the source spectrum is not associated with energy losses of relativistic electrons due to synchrotron emission and, second, the source variability is manifest as flux-density changes described by one of two power-law dependencies for the flux versus frequency. The spectral indices of each of these dependencies have one of two constant values. Possible origins of the detected changes in the spectrum of G21.5-0.9 are discussed.



An Unusually Powerful Water-Maser Flare in the Galactic Source W49N
摘要
The most powerful flare ever registered in the Galactic water-maser source W49N has been detected in long-term monitoring data in the 616–523 transition with line frequency f = 22.235 GHz carried out on the 22-m Simeiz, 32-m Toruń, 100-m Effelsberg, and 32-m Medicina radio telescopes, beginning in September 2017 and continuing in 2018. Some stages of the flare were monitored daily. Detailed variations of the source spectral flux density with time have been obtained. At the flare maximum, the flux exceeded P ≈ 8 × 104 Jy, and this was record highest flux registered over the entire history of observations of this source. Important conclusions related to details of the mechanism for the H2O line emission have been drawn. An exponential increase in the flare flux density was detected during both the rise and decline of the flare. The data obtained indicate that the maser is unsaturated, and remained in this state up to the maximum observed flux densities. Additional support for the idea that the maser is unsaturated is the shape of the dependence of the line width on the flux. The characteristics of the variations of the spectral flux density are probably associated with a sharp increase in the density of the medium and the photon flux that led to an increase in the temperature from an initial level of 10–40 K to hundreds of Kelvins. Interferometric maps of the object during the increase in the spectral flux density of the flare have been obtained. A possible mechanism for the primary energy release in W49N is considered.



Characteristic Features of the Colors of Shower Meteors and Sporadic Meteors from Observations with the Mini-MegaTORTORA System
摘要
Results of BV R observations of meteors in the Perseid, Taurid, Orionid, Geminid, and Lyrid showers, as well as sporadic meteors, carried out with the Mini-MegaTORTORA system are presented. Two-color diagrams for the brightness maxima are constructed. It is shown that meteors in the Perseid, Taurid, and Geminid showers form clusters in the two-color diagrams. Variations in color with a temporal resolution of 0.1 s are considered for some meteors.



Spectroscopy of Globular Clusters in the Spheroidal Dwarf Galaxy IKN
摘要
Moderate resolution spectra of four globular clusters in the dwarf spheroidal galaxy IKN obtained with the 6-m telescope of the Special Astrophysical Observatory have been used to determine the radial velocities, ages, and metallicities of the clusters, and also to derive the first approximate estimates of the abundances of Mg, Ca, and C. Cross-correlation with radial-velocity standards, fitting of the observed spectra with model spectra, diagnostic diagrams based on the Lick absorption indices, and comparison of the spectra and absorption indices with those of Galactic globular clusters are applied. The integrated spectrum of the two bright clusters IKN4 and IKN5, which are close to the center of the galaxy in projection on the celestial sphere, yields the heliocentric radial velocity Vh = 38 ± 30 km/s, age T =12.6 ± 2 Gyr, metallicity [Fe/H] = −2.1 ± 0.2 dex, and abundance of α-process elements [α/Fe] ∼ 0.5 dex. The integrated spectrum of the two weaker clusters IKN1 and IKN3, which are far from the center of the galaxy, yielded the radial velocity Vh = −39 ± 50 km/s. Despite the low signal-to-noise ratio in the integrated spectrum for IKN1 and IKN3, all the analysis methods applied indicate that these two objects have approximately the same age and metallicity as IKN4 and IKN5. According to the measured Lick indices \({{\rm{H}}_{\delta {\rm{F}}}}\) and Hβ, the studied globular clusters in IKN have blue horizontal branches.



Space-Based Gravitational-Wave Detectors: Development of Ground-Breaking Technologies for Future Space-Based Gravitational Gradiometers
摘要
An analysis of modern developments in the area of space-based gravitational-wave detectors is presented, and possible applications of key technologies for future space-based measurements of the gradient of the Earth’s gravitational field are considered. The structure of a space-based gradiometer based on free masses is presented, together with proposals for the reduction and calibration of measurements from such a device.



Erratum
Erratum to: The Spectral Type of the Ionizing Stars and the Infrared Fluxes of HII Regions
摘要
Several errors were found in this paper, which however did not influence its main conclusions. In Table 2 of Section 2, the references for the data in columns (6)–(9) and (10)–(11) were given incorrectly, and incorrect values for Teff were given in column (10). These errors were discovered by the authors in the course of using the data in other studies, and do not make a signficant contributions to the figures, results, or conclusions of this paper.


