The Spectral Type of the Ionizing Stars and the Infrared Fluxes of HII Regions

The 20 cm radio continuum fluxes of 91 HII regions in a previously compiled catalog have been determined. The spectral types of the ionizing stars in 42 regions with known distances are estimated. These spectral types range from B0.5 to O7, corresponding to effective temperatures of 29 000-37 000 K. The dependences of the infrared (IR) fluxes at 8, 24, and 160 $\mu$m on the 20 cm flux are considered. The IR fluxes are used as a diagnostic of heating of the matter, and the radio fluxes as measurements of the number of ionizing photons. It is established that the IR fluxes grow approximately linearly with the radio flux. This growth of the IR fluxes probably indicates a growth of the mass of heated material in the envelope surrounding the HII region with increasing effective temperature of the star.Comment: 16, pages, 10 figures, published in Astronomy Report

Global photometric analysis of galactic regions of ionized hydrogen

Проанализированы данные о потоках излучения в различных инфракрасных фотометрических полосах для 99 зон HII, включенных в каталог Топчиевой и др. (2017). Получены оценки массовой доли ПАУ (qPAH) и интенсивности излучения в ультрафиолетовом диапазоне по сетке моделей, предложенной в статье Дрейна и Ли (2007).We analyze data on emission fluxes in different infrared photometric bands for 99 HII regions, included in the catalog by Topchieva et al. (2017). A mass fraction of PAH (qPAH) and the ultraviolet radiation intensity are estimated using the grid of models, presented in Draine and Li (2007).Работа выполнена при поддержке Программы ОФН

Determination of Physical Parameters of Infrared Radiation in HII Regions

We present fluxes from inner parts and outer rings of the IR ring nebulae at seven wavelengths from 8 to 500 μm based on Spitzer and Herschel data. We define spectral indices, which are the best indicators of dust temperature and small dust mass fraction.Мы представляем потоки от внутренних частей и внешних колец инфракрасных кольцевых туманностей на семи длинах волн от 8 до 500 мкм на основе данных Spitzer и Herschel. Определены спектральные индексы, являющиеся лучшими индикаторами температуры пыли и массовой доли мелких пылинок.Работа поддержана грантом РФФИ 18-32-00384 и грантом Фонда развития теоретической физики и математики «БАЗИС»

IR ring nebulae in the Milky Way and M33 galaxies

Изучение образования массивных звезд в нашей и других галактиках является одной из возможностей связать информацию, полученную для областей звездообразования в целом. В данной работе представлены статистические и теоретические данные по инфракрасным кольцевым туманностям (ИККТ) в Галактике и галактике М33, которая расположена недалеко от нас и в картинной плоскости удобна для выделения отдельных объектов. В данной работе показаны сравнения потоков для 258 комплексов звездообразования в М33, внегалактических комплексов звездообразования и для ИККТ в нашей Галактике. Проведен теоретический расчет распределения полициклических ароматических углеводородов с использованием программы DustEM.Studying the formation of massive stars in our Galaxy and in other galaxies is one of the possibilities to connect the information obtained for the regions of star formation in general. This study presents statistical and theoretical data on infrared ring nebulae (IRRN) in our Galaxy and the galaxy M33, which is located not far from us and in the plane of sky, which is convenient for selecting individual objects. In this paper, comparisons of fluxes for 258 star-forming complexes in M33, extragalactic of star formation complexes, and for IRRN in our Galaxy are shown. A theoretical calculation of the distribution of polycyclic aromatic hydrocarbons using DustEM has been carried out.Работа выполнена при поддержке гранта РФФИ 20-02-00643 А. Также данная работа была поддержана грантом Фонда развития теоретической физики и математики «БАЗИС»

Spectral Types of Ionizing Stars and the Infrared Morphology of HII Regions

A previously developed catalog is presented, which includes 99 regions of ionized hydrogen (HII). Results of the flux measurements in the infrared (IR) and radio continua in the direction of the HII region are presented. Estimated fluxes of IR emission are compared to results from other catalogs. Spectral types of ionizing stars are determined for 42 regions with distance estimates available.Представлены данные ранее разработанного каталога, включающего 99 областей ионизованного водорода (HII). Отражены результаты определения потоков в инфракрасном (ИК) и радиоконтинуумах в направлении на области HII. Проведено сравнение оценок ИК-потоков с другими каталогами. Определены примерные спектральные классы ионизующих звезд 42 областей, для которых известны оценки расстояний.Работа поддержана грантом РФФИ 17-02-00521

Effect of Dust Evaporation and Thermal Instability on Temperature Distribution in a Protoplanetary Disk

The thermal instability of accretion disks is widely used to explain the activity of cataclysmic variables, but its development in protoplanetary disks has been studied in less detail. We present a semi-analytical stationary model for calculating the midplane temperature of a gas and dust disk around a young star. The model takes into account gas and dust opacities, as well as the evaporation of dust at temperatures above 1000 K. Using this model, we calculate the midplane temperature distributions of the disk under various assumptions about the source of opacity and the presence of dust. We show that when all considered processes are taken into account, the heat balance equation in the region r<1 au has multiple temperature solutions. Thus, the conditions for thermal instability are met in this region. To illustrate the possible influence of instability on the accretion state in a protoplanetary disk, we consider a viscous disk model with alpha parameterization of turbulent viscosity. We show that in such a model the disk evolution is non-stationary, with alternating phases of accumulation of matter in the inner disk and its rapid accretion onto the star, leading to an episodic accretion pattern. These results indicate that this instability needs to be taken into account in evolutionary models of protoplanetary disks.Comment: Published in Astronomy Reports Vol. 67, No. 5, pp. 470-482 (2023

Infrared Morphology of Regions of Ionized Hydrogen

A search for infrared ring nebulae associated with regions of ionized hydrogen has been carried out. The New GPS Very Large Array survey at 20 cm forms the basis of the search, together with observations obtained with the Spitzer Space Telescope at 8 and 24 $\mu$m and the Herschel Space Telescope at 70 $\mu$m. Objects having ring-like morphologies at 8 $\mu$m and displaying extended emission at 20 cm were selected visually. Emission at 24 $\mu$m having the form of an inner ring or central peak is also observed in the selected objects. A catalog of 99 ring nebulae whose shapes at 8 and 70 $\mu$m are well approximated by ellipses has been compiled. The catalog contains 32 objects whose shapes are close to circular (eccentricities of the fitted ellipses at 8 $\mu$m no greater than 0.6, angular radius exceeding 20). These objects are promising for comparisons with the results of one-dimensional hydrodynamical simulations of expanding regions of ionized hydrogen.Comment: Astronomy Reports, Volume 61, Issue 12, pp.1015-1030 (ARep Homepage

Analysis of the interstellar matter at the periphery of the supershell surrounding the CYG OB1 association in 2.12 micron molecular hydrogen line

We present observations of the vdB 130 cluster vicinity in a narrow-band filter centered at a $2.12\,\mu$m molecular hydrogen line performed at the Caucasus Mountain Observatory of the Lomonosov Moscow State University. The observations reveal an H$_2$ emission shell around vdB 130, coincident with a bright infrared shell, visible in all \textit{Spitzer} bands. Also, numerous H$_{2}$ emission features are detected around infrared Blobs E and W and in the vicinity of a protocluster located to the east of the shell, in a tail of a cometary molecular cloud. H$_2$ emission in the vicinity of the vdB~130 cluster is mostly generated in well-developed \HII\ regions and is of fluorescent nature. In the protocluster area, isolated spots are observed, where H$_2$ emission is collisionally excited and is probably related to shocks in protostellar outflows. Obtained results are discussed in the context of possible sequential star formation in the vicinity of the vdB 130 cluster, triggered by the interaction of the expanding supershell surrounding the Cyg OB1 association with the molecular cloud and an associated molecular filament.Comment: Accepted by Astrophysical Bulleti

Dust Opacities in Protoplanetary Disks for FEOSAD Code

Представлены рассчитанные сетки непрозрачностей пыли для различных температур с учетом вариации пылевой компоненты по размерам от 0.005 мкм до 1 см. Также учтен химический состав пылевой компоненты в зависимости от температуры и наличие ледяной мантии массой от 10 до 90 % от массы пылинки. Эти сетки будут использоваться для расчета тепловой структуры в гидродинамической модели газопылевого протопланетного диска FEOSAD.Calculated grids of dust opacities for various temperatures are presented, with sizes of the dust component varying from 0.005 μm to 1 cm. The chemical composition of the dust component depending on temperature and the presence of an ice mantle weighing from 10 to 90 % of the mass of a dust grain are also taken into account. These grids will be used to calculate the thermal structure in the hydrodynamic model of the FEOSAD model of a protoplanetary disk with gas and dust components.Работа выполнена при поддержке гранта РНФ 22-72-10029