Analysis of spiral arms using anisotropic wavelets: gas, dust and magnetic fields in M51

We have developed a technique of isolating elongated structures in galactic images, such as spiral arms, using anisotropic wavelets and apply this to maps of the CO, infrared and radio continuum emission of the grand-design spiral galaxy M51. Systematic shifts between the ridges of CO, infrared and radio continuum emission that are several \kpc long are identified, as well as large variations in pitch angle along spiral arms, of a few tens of degrees. We find two types of arms of polarized radio emission: one has a ridge close to the ridge of CO, with similar pitch angles for the CO and polarization spirals and the regular magnetic field; the other does not always coincide with the CO arm and its pitch angle differs from the orientation of its regular magnetic field. The offsets between ridges of regular magnetic field, dense gas and warm dust are compatible with the sequence expected from spiral density wave triggered star formation, with a delay of a few tens of millions of years between gas entering the shock and the formation of giant molecular clouds and a similar interval between the formation of the clouds and the emergence of young star clusters. At the position of the CO arms the orientation of the regular magnetic field is the same as the pitch angle of the spiral arm, but away from the gaseous arms the orientation of the regular field varies significantly. Spiral shock compression can explain the generation of one type of arm of strong polarized radio emission but a different mechanism is probably responsible for a second type of polarization arm. (Shortened abstract.

КОМПЛЕКСИРОВАНИЕ РАСПРЕДЕЛЕННЫХ ИНЕРЦИАЛЬНЫХ НАВИГАЦИОННЫХ СИСТЕМ НА БАЗЕ ВОЛОКОННО-ОПТИЧЕСКИХ И МИКРОЭЛЕКТРОМЕХАНИЧЕСКИХ ИЗМЕРИТЕЛЕЙ

The current state of airborne measuring-and-computing complexes (MCCs) is characterized by the inclusion of distributed strapdown inertial navigation systems (SINSs) as components of these complexes. This is associated with the necessity of the provision of navigational support not only for aircraft (Acft), but also for airborne Earth surface surveillance systems in which the SINSs are included as components. Among such systems are radar systems, video monitors, laser scanners (lidars), and other surveillance devices. At the same time, when the DSINSs are united into a single structure, new functional possibilities for such integrated navigation systems appear, namely: redundancy and mutual support of SINSs, and also an increase in MCC information reliability on this basis; mutual monitoring and mutual diagnosis of SINSs; optimization of DSINS structure for providing the required accuracy of navigation and attitude control under severe conditions of Acft operation. Such conditions are connected with Acft maneuvering, with a loss of the signals of satellite navigation systems (SNSs). The purpose of this paper is to study the capabilities of DSINS which are built around fiberoptic and micromechanical sensors when they are united into a closely connected information-measuring structure. In the solution of the problem formulated above, an object-oriented modular technology for the creation of integrated navigation systems was taken as a basis. The use of such a technology has permitted us to realize the new functional possibilities of the DSINSs, and also to take into account the following features of the construction and functioning of DSINSs as components of MCCs: need for mutual information exchange among DSINS modules via an MCC airborne top-level computing system; synchronization of measuring-and-computing procedures that are realized in the DSINS. In addition, due to restrictions on overall dimensions and weight, SINSs of surveillance systems are built on the basis of microelectromechanical sensors (MEMSs). Such sensors have a wide insensitivity zone and low accuracy. Taking into account the above-mentioned features, SINS-MEMSs must rely on a base high-accuracy SINS which forms part of an Acft navigation complex. Moreover, the SINS-MEMSs cannot execute the initial alignment from attitude angles in the autonomous mode. Because of this, the initial alignment of such SINSs is realized from information obtained from the base system. Mutual support of integrated inertial systems which include satellite receivers is necessary not only for continuous updating of SINS-MEMSs coordinates but also for the refinement of attitude angles of the places where surveillance systems are mounted. It should be noted that the frequency of updating the coordinates that are determined by an SNS is several units of hertz, and that are determined by a SINS is several units of kilohertz. The features mentioned earlier were taken into account in a DSINS developed by the NaukaSoft Experimental Laboratory, Ltd. (Moscow) and by the Bauman Moscow State Technical University in cooperation. A breadboard model of the MSINS includes the SINS-500NS system based on fiber-optic gyros developed jointly by the “NaukaSoft EMNS” and by the “Optolink” RPC (Zelenograd); micromechanical SINS-MEMSs built on the basis of the ADIS16488 measuring modules developed by the Analog Devices Co. The paper presents the results of fullscale experiments performed at the Ramenskoye Instrument-Making Plant.Современное состояние бортовых измерительно-вычислительных комплексов (ИВК)  характеризуется включением в их состав распределенных бесплатформенных инерциальных навигационных систем (БИНС). Это связано с необходимостью навигационного обеспечения не только летательных аппаратов (ЛА), но и бортовых систем обзора земной поверхности, в состав которых включаются БИНС. К таким системам относятся радиолокационные, видеоконтрольные, лазерные сканирующие (лидары) и другие обзорные устройства. В то же время при объединении распределенных БИНС (РБИНС) в единую структуру появляются новые функциональные возможности таких комплексных навигационных систем, а именно: резервирование и взаимная поддержка БИНС и повышение на этой основе информационной надежности ИВК; взаимный контроль и диагностирование БИНС; оптимизация структуры РБИНС для обеспечения требуемой точности навигации и ориентации в сложных условиях эксплуатации ЛА. Такие условия связаны с маневрированием ЛА, потерей сигналов спутниковых навигационных систем (СНС). Цель работы – исследование возможностей РБИНС на базе волоконно-оптических и микроэлектромеханических измерителей при их объединении в тесно связанную информационно-измерительную структуру. При решении поставленной задачи за основу взята объектно-ориентированная модульная технология создания интегрированных навигационных систем. Применение такой технологии позволило реализовать новые функциональные возможности РБИНС, а также учесть следующие особенности построения и функционирования РБИНС в составе ИВК: необходимость взаимного обмена информацией между модулями РБИНС через бортовую вычислительную систему верхнего уровня ИВК; синхронизацию измерительно-вычислительных процедур, реализуемых в РБИНС. Из-за ограничений на размеры и массу БИНС обзорных систем строятся на базе микроэлектромеханических (МЭМС) датчиков. Такие датчики имеют большую зону нечувствительности и невысокую точность. С учетом указанных особенностей БИНС-МЭМС должны опираться на базовую высокоточную БИНС, входящую в состав навигационного комплекса ЛА. Кроме того, БИНС-МЭМС не могут автономно выполнить начальную выставку по углам ориентации. Поэтому начальная выставка таких БИНС реализуется по информации от базовой системы. Взаимная поддержка интегрированных инерциальных систем, включающих спутниковые приемники, необходима не только для непрерывной коррекции координат БИНС-МЭМС, но и для уточнения углов ориентации мест установки обзорных систем. Следует отметить, что частота обновления координат, определяемых СНС, – единицы герц, а определяемых БИНС – единицы килогерц. Указанные особенности были учтены в РБИНС совместной разработки ООО «Экспериментальная мастерская НаукаСофт» (Москва) и МГТУ им. Н.Э. Баумана. Макетный образец РБИНС включает систему БИНС-500НС на волоконно-оптических гироскопах совместной разработки «ЭМ НаукаСофт» и НПК «Оптолинк» (Зеленоград); микромеханические БИНС-МЭМС, построенные на базе измерительных модулей ADIS16488 компании Analog Devices. В работе представлены результаты натурных экспериментов, проведенных на Раменском приборостроительном заводе

The spatial distribution of star and cluster formation in M51

Aims. We study the connection between spatially resolved star formation and young star clusters across the disc of M51. Methods. We combine star cluster data based on B, V, and I-band Hubble Space Telescope ACS imaging, together with new WFPC2 U-band photometry to derive ages, masses, and extinctions of 1580 resolved star clusters using SSP models. This data is combined with data on the spatially resolved star formation rates and gas surface densities, as well as Halpha and 20cm radio-continuum (RC) emission, which allows us to study the spatial correlations between star formation and star clusters. Two-point autocorrelation functions are used to study the clustering of star clusters as a function of spatial scale and age. Results. We find that the clustering of star clusters among themselves decreases both with spatial scale and age, consistent with hierarchical star formation. The slope of the autocorrelation functions are consistent with projected fractal dimensions in the range of 1.2-1.6, which is similar to other galaxies, therefore suggesting that the fractal dimension of hierarchical star formation is universal. Both star and cluster formation peak at a galactocentric radius of 2.5 and 5 kpc, which we tentatively attribute to the presence of the 4:1 resonance and the co-rotation radius. The positions of the youngest (<10 Myr) star clusters show the strongest correlation with the spiral arms, Halpha, and the RC emission, and these correlations decrease with age. The azimuthal distribution of clusters in terms of kinematic age away from the spiral arms indicates that the majority of the clusters formed 5-20 Myr before their parental gas cloud reached the centre of the spiral arm.Comment: 14 pages, 21 figures, accepted for publication in A&

ЛЕТНАЯ ОТРАБОТКА РАCПРЕДЕЛЕННОЙ CИCТЕМЫ ИНЕРЦИАЛЬНО-CПУТНИКОВОЙ МИКРОНАВИГАЦИИ ДЛЯ РАДИОЛОКАТОРА C CИНТЕЗИРОВАННОЙ АПЕРТУРОЙ

The current state of the onboard systems is characterized by the integration of aviation and radio-electronic equipment systems for solving problems of navigation and control. These problems include micro-navigation of the anten- na phase center (APC) of the radar during the review of the Earth's surface from aboard the aircraft. Increasing of the reso- lution of the radar station (RLS) by hardware increasing the antenna size is not always possible due to restrictions on the aircraft onboard equipment weight and dimensions. Therefore the implementation of analytic extension of the radiation pattern by "gluing" the images, obtained by RLS on the aircraft motion trajectory is embodied. The estimations are con- verted into amendments to the signals of RLS with synthetic aperture RSA to compensate instabilities. The purpose of the research is building a theoretical basis and a practical implementation of procedures for evaluating the trajectory APS in- stabilities using a distributed system of inertial-satellite micro-navigation (DSMN) taking into account the RSA flight oper- ations actual conditions. The technology of evaluation and compensation of RSA trajectory instabilities via DSMN is con- sidered. The implementation of this technology is based on the mutual support of inertial, satellite and radar systems. Syn- chronization procedures of inertial and satellite measurements in the evaluation of DSMN errors are proposed. The given results of DSMN flight testing justify the possibility and expediency to apply the proposed technology in order to improve the resolution of RSA. The compensation of aircraft trajectory instabilities in RSA signals can be provided by inertial- satellite micro-navigation system, taking into account the actual conditions of the RSA flight operations. The researches show that in order to achieve the required resolution of RSA it seems to be appropriate to define the rational balance be- tween accuracy DSMN characteristics and RSA wavelength range.Современное состояние бортовых комплексов характеризуется интеграцией систем авиационного и радио- электронного оборудования при решении задач навигации и управления. К таким задачам относится микронавига- ция фазового центра антенны (ФЦА) радиолокатора при обзоре земной поверхности с борта летательного аппарата (ЛА). Повышение разрешающей способности радиолокационной станции (РЛС) путем аппаратурного увеличения размера антенны не всегда представляется возможным из-за ограничений на массу и габариты бортового оборудо- вания ЛА. Поэтому реализуют аналитическое расширение диаграммы направленности путем «склейки» изображе- ний, получаемых бортовой РЛС на траектории движения ЛА. Для компенсации нестабильностей оценки преобра- зуются в поправки к сигналам РЛС радиолокатора с синтезированной апертурой (РСА). Цель работы - теоретиче- ское обоснование и практическая реализация процедур оценки траекторных нестабильностей ФЦА с помощью распределенной системы инерциально-спутниковой микронавигации (РСМН) с учетом реальных условий летной эксплуатации РСА. Рассматривается технология оценки и компенсации траекторных нестабильностей РСА с по- мощью РСМН. Реализация такой технологии опирается на взаимную поддержку инерциальной, спутниковой и радиолокационной систем. Предлагаются процедуры синхронизации инерциальных и спутниковых измерений при оценке ошибок РСМН. Приводятся результаты летной отработки РСМН, подтверждающие возможность и целесо- образность применения предлагаемой технологии для повышения разрешающей способности РСА. Компенсация траекторных нестабильностей ЛА в сигналах РСА может быть обеспечена с помощью инерциально-спутниковой системы микронавигации с учетом реальных условий летной эксплуатации РСА. Проведенные исследования пока- зали, что для обеспечения требуемого разрешения РСА целесообразным представляется определение рационально- го соотношения между точностными характеристиками РСМН и диапазоном длин волн РСА

CHARACTERISTICS OF THE INTEGRATED SYSTEM OF NAVIGATION AT COMBINATION OF DIFFERENTIAL STATION WITH THE SOURCE OF THE RADIO NAVIGATIONAL SIGNAL

The article describes the results of the researches of precision characteristics of the integrated system of navigation made on the basis of the model of movement of the navigation satellites of orbital group GLONASS according to the almanac functionally added with the pseudo-satellite

INTEGRATION OF DISTRIBUTED INERTIAL NAVIGATION SYSTEMS BUILT AROUND FIBER-OPTIC AND MICROELECTROMECHANICAL SENSORS

The current state of airborne measuring-and-computing complexes (MCCs) is characterized by the inclusion of distributed strapdown inertial navigation systems (SINSs) as components of these complexes. This is associated with the necessity of the provision of navigational support not only for aircraft (Acft), but also for airborne Earth surface surveillance systems in which the SINSs are included as components. Among such systems are radar systems, video monitors, laser scanners (lidars), and other surveillance devices. At the same time, when the DSINSs are united into a single structure, new functional possibilities for such integrated navigation systems appear, namely: redundancy and mutual support of SINSs, and also an increase in MCC information reliability on this basis; mutual monitoring and mutual diagnosis of SINSs; optimization of DSINS structure for providing the required accuracy of navigation and attitude control under severe conditions of Acft operation. Such conditions are connected with Acft maneuvering, with a loss of the signals of satellite navigation systems (SNSs). The purpose of this paper is to study the capabilities of DSINS which are built around fiberoptic and micromechanical sensors when they are united into a closely connected information-measuring structure. In the solution of the problem formulated above, an object-oriented modular technology for the creation of integrated navigation systems was taken as a basis. The use of such a technology has permitted us to realize the new functional possibilities of the DSINSs, and also to take into account the following features of the construction and functioning of DSINSs as components of MCCs: need for mutual information exchange among DSINS modules via an MCC airborne top-level computing system; synchronization of measuring-and-computing procedures that are realized in the DSINS. In addition, due to restrictions on overall dimensions and weight, SINSs of surveillance systems are built on the basis of microelectromechanical sensors (MEMSs). Such sensors have a wide insensitivity zone and low accuracy. Taking into account the above-mentioned features, SINS-MEMSs must rely on a base high-accuracy SINS which forms part of an Acft navigation complex. Moreover, the SINS-MEMSs cannot execute the initial alignment from attitude angles in the autonomous mode. Because of this, the initial alignment of such SINSs is realized from information obtained from the base system. Mutual support of integrated inertial systems which include satellite receivers is necessary not only for continuous updating of SINS-MEMSs coordinates but also for the refinement of attitude angles of the places where surveillance systems are mounted. It should be noted that the frequency of updating the coordinates that are determined by an SNS is several units of hertz, and that are determined by a SINS is several units of kilohertz. The features mentioned earlier were taken into account in a DSINS developed by the NaukaSoft Experimental Laboratory, Ltd. (Moscow) and by the Bauman Moscow State Technical University in cooperation. A breadboard model of the MSINS includes the SINS-500NS system based on fiber-optic gyros developed jointly by the “NaukaSoft EMNS” and by the “Optolink” RPC (Zelenograd); micromechanical SINS-MEMSs built on the basis of the ADIS16488 measuring modules developed by the Analog Devices Co. The paper presents the results of fullscale experiments performed at the Ramenskoye Instrument-Making Plant