Abstract <p>At the early stage of the protostar evolution, gas is mostly in the molecular form, while the process of protostars development causes a variety of surrounding matter emission in molecular lines at many frequencies of any ranges. This work is aimed at measuring the parameters of molecular radio lines in the vicinity of some young protostellar objects to expand our understanding of their evolutionary trends. Observations have been carried out with the RT-22 radio telescope at the Pushchino Radio Astronomical Observatory, Lebedev Physical Institute from July 2022 until May 2023. Two standard transistor receivers, which operated at frequencies of 20–24 GHz (13.5-mm range) and 36.2–37.7 GHz (8-mm range), have been used. Emission in the lines of four molecules, each one being a “tracer” of the environmental physical state: water (<InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1659_Article_IEq1.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="33" /> </InlineMediaObject> <EquationSource Format="TEX">\({{{\text{H}}}_{{\text{2}}}}{\text{O}}\)</EquationSource>  </InlineEquation>), methanol (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1659_Article_IEq2.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="57" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{C}}{{{\text{H}}}_{{\text{3}}}}{\text{OH}}\)</EquationSource>  </InlineEquation>), ammonia (<InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1659_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="32" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{N}}{{{\text{H}}}_{{\text{3}}}}\)</EquationSource>  </InlineEquation>), and cyanoacetylene (<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="11444_2025_1659_Article_IEq4.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="44" /> </InlineMediaObject> <EquationSource Format="TEX">\({\text{H}}{{{\text{C}}}_{{\text{3}}}}{\text{N}}\)</EquationSource>  </InlineEquation>) has been studied. Observational results for three IRDC objects, for two CORE-type objects, and for the star forming region Onsala-1 have been obtained. Radio emission in the water vapor line has been detected in all studied objects, except for IRDC G027.94–00.47. For three objects: IRDC G028.37+0.07b, IRDC G024.33+0011, and Onsala-1, the rotational and kinetic temperatures in the radiation region have been determined from the emission spectra of the ammonia molecule, and the concentration of ammonia and the density of molecular hydrogen have been estimated. Emission in lines of cyanoacetylene in the direction of to sources IRDC G028.37+0.07b, and Onsala-1 has been detected, and the column density of this molecule has been determined.</p>

Study of Maser and Thermal Molecular Emission in the Vicinity of Selected Protostellar Objects with the RT-22 Radio Telescope at PRAO

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发表日期：

2025年2月1日

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I. E. Val’tts

摘要

Abstract

At the early stage of the protostar evolution, gas is mostly in the molecular form, while the process of protostars development causes a variety of surrounding matter emission in molecular lines at many frequencies of any ranges. This work is aimed at measuring the parameters of molecular radio lines in the vicinity of some young protostellar objects to expand our understanding of their evolutionary trends. Observations have been carried out with the RT-22 radio telescope at the Pushchino Radio Astronomical Observatory, Lebedev Physical Institute from July 2022 until May 2023. Two standard transistor receivers, which operated at frequencies of 20–24 GHz (13.5-mm range) and 36.2–37.7 GHz (8-mm range), have been used. Emission in the lines of four molecules, each one being a “tracer” of the environmental physical state: water ( \({{{\text{H}}}_{{\text{2}}}}{\text{O}}\) ), methanol ( \({\text{C}}{{{\text{H}}}_{{\text{3}}}}{\text{OH}}\) ), ammonia ( \({\text{N}}{{{\text{H}}}_{{\text{3}}}}\) ), and cyanoacetylene ( \({\text{H}}{{{\text{C}}}_{{\text{3}}}}{\text{N}}\) ) has been studied. Observational results for three IRDC objects, for two CORE-type objects, and for the star forming region Onsala-1 have been obtained. Radio emission in the water vapor line has been detected in all studied objects, except for IRDC G027.94–00.47. For three objects: IRDC G028.37+0.07b, IRDC G024.33+0011, and Onsala-1, the rotational and kinetic temperatures in the radiation region have been determined from the emission spectra of the ammonia molecule, and the concentration of ammonia and the density of molecular hydrogen have been estimated. Emission in lines of cyanoacetylene in the direction of to sources IRDC G028.37+0.07b, and Onsala-1 has been detected, and the column density of this molecule has been determined.