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Deuterated Water Abundance in the Young Hot Core RCW 120 S2 年轻热岩心rcw120s2中氘化水丰度
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700252
M. S. Kirsanova, A. A. Farafontova
{"title":"Deuterated Water Abundance in the Young Hot Core RCW 120 S2","authors":"M. S. Kirsanova,&nbsp;A. A. Farafontova","doi":"10.1134/S1063773725700252","DOIUrl":"10.1134/S1063773725700252","url":null,"abstract":"<p>Emission of water molecules cannot be observed from Earth, less abundant isotopologues, such as H<span>({}_{2}^{18})</span>O and HDO, are used to trace water in star-forming regions. The main aim of this study is to determine HDO abundance in the hot core RCW 120 S2. We performed observations of the hot core in the 200–255 GHz range using the nFLASH230 receiver on the APEX telescope. Two HDO lines were detected toward RCW 120 S2. Their intensities are described by excitation temperature <span>({approx}290)</span> K and gas number density <span>({geq}10^{9})</span> cm<span>({}^{-3})</span>. The emission originates from the hot core rather than the warm dense envelope surrounding a central young stellar object. The HDO column density ranges from <span>((3.9{-}7.9)times 10^{13})</span> cm<span>({}^{-3})</span> with the best-fit model value of <span>(5.6times 10^{13})</span> cm<span>({}^{-3})</span>. The HDO abundance relative to hydrogen is <span>(1.7times 10^{-9})</span>. This HDO abundance value is among the lowest reported for hot cores. Combined with the non-detection of the H<span>({}_{2}^{18})</span>O line, we conclude that protostellar heating in RCW 120 S2 is still in its early stages.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"111 - 117"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011832","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Helical Randomization of Magnetized Galaxy Clusters Plasmas Observed in Faraday Rotation Sky 法拉第旋转天空中观测到的磁化星系团等离子体的螺旋随机化
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700215
A. Bershadskii
{"title":"Helical Randomization of Magnetized Galaxy Clusters Plasmas Observed in Faraday Rotation Sky","authors":"A. Bershadskii","doi":"10.1134/S1063773725700215","DOIUrl":"10.1134/S1063773725700215","url":null,"abstract":"<p>Using results of numerical simulations and galaxy clusters observations, it is shown that the transition from deterministic chaos to hard turbulence in the galaxy clusters magnetized plasmas occurs via a randomization process. The notion of distributed chaos has been used to describe the randomization process. The randomization can be quantified with the main parameter of the distributed chaos, which in turn can be related to magnetic helicity. Spontaneous breaking of local reflectional symmetry (an intrinsic property of chaotic/turbulent motions) generates local helicity even when the global helicity is negligible. It is shown that the magnetic fields can impose their level of randomization on the Faraday rotation maps. Results of the numerical simulations of the galaxy clusters dynamos are in good agreement with this approach, as well as with the results obtained using observations of the Faraday rotation sky.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"65 - 72"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Supernova in Lost Common Envelope and SN 2006gy 消失的普通包层中的超新星和SN 2006gy
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700227
N. N. Chugai
{"title":"Supernova in Lost Common Envelope and SN 2006gy","authors":"N. N. Chugai","doi":"10.1134/S1063773725700227","DOIUrl":"10.1134/S1063773725700227","url":null,"abstract":"<p>A mechanism is proposed for synchronizing core-collapse supernova with a recent loss of a red supergiant (RSG) envelope in the common envelope regime. A prerequisite for the synchronization is a moderate RSG expansion during final decade. This scenario is based on the phenomenon of preSN II dense shell formed at the final stage of 10–20 yr as a result of powerfull mass loss. The energy deposition into the RSG envelope that powers the enormous mass loss rate is able to expand the RSG. The moderate expansion is sufficient for the close secondary component to plunge into the common envelope with a subsequent explosion of stripped helium core. Superluminous SN 2006gy is suggested to be the outcome of this scenario.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"73 - 78"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Formation of an Optimal Scenario for Observations with an Orbital Space Telescope to Reduce Fuel Consumption 轨道空间望远镜观测最优方案的形成以减少燃料消耗
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700264
O. S. Chernenko, N. A. Eismont, V. A. Zubko
{"title":"Formation of an Optimal Scenario for Observations with an Orbital Space Telescope to Reduce Fuel Consumption","authors":"O. S. Chernenko,&nbsp;N. A. Eismont,&nbsp;V. A. Zubko","doi":"10.1134/S1063773725700264","DOIUrl":"10.1134/S1063773725700264","url":null,"abstract":"<p>We consider the optimization of the attitude control strategy for orbital telescopes in the vicinity of the Sun–Earth libration point L2 to minimize the propellant consumption of the motion control system. We analyze the changes in the mission profile that lead to a growth of the requirements for correcting maneuvers and propose the methods of their reduction by choosing an optimal space observatory positioning scenario. Our attention is focused on finding a balance between the reaction-wheel offloading of the attitude control system, the reduction of fuel consumption, and the fulfilment of the requirements for scientific observations. We show that applying the proposed approach allows one to increase the stability of the orbit and to prolong the active lifetime of the telescopes by reducing the frequency of corrections and rationally using the control impulses.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"118 - 126"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Disk Wind as a Source of the Photometric Activity of Young Stars in the Optical and Infrared Spectral Ranges 盘风在光学和红外光谱范围内作为年轻恒星光度活动的来源
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700276
M. A. Albrant, V. P. Grinin
{"title":"Disk Wind as a Source of the Photometric Activity of Young Stars in the Optical and Infrared Spectral Ranges","authors":"M. A. Albrant,&nbsp;V. P. Grinin","doi":"10.1134/S1063773725700276","DOIUrl":"10.1134/S1063773725700276","url":null,"abstract":"<p>The influence of the dust component of a magnetocentrifugal disk wind on the circumstellar extinction and the infrared thermal radiation of T Tauri stars is investigated. The wind models from Safier’s papers, which are analytical approximations of the solutions for a magnetocentrifugal dusty disk wind, are taken as a basis. An accretion spot whose luminosity is scaled in accordance with the accretion rate and stellar parameters is added to the stellar spectrum. The radiative transfer in the wind and the circumstellar disk has been simulated by the Monte Carlo method using the RADMC3D code. The results of our simulations are applied to T Tauri stars with UX Ori-type variability. We show that when such stars are observed at a small angle to the disk plane, an increase in the accretion rate can cause an optical fading of the stars and, simultaneously, an enhancement of their infrared radiation. We also show that the results of our simulations are sensitive to the magnetic field topology in the disk in the wind formation zone. The results of our calculations are discussed in connection with the observations of deep minima in the T Tauri stars V1184 Tau and RW Aur accompanied by an enhancement of their radiation in the near-infrared spectral range. In the Conclusions we briefly discuss alternative mechanisms for the uplift of dust above the disk capable of causing an enhancement of the infrared radiation from young stars.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"89 - 100"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011557","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On Accretion in the Polar V379 Vir 关于极地V379 Vir的吸积
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700239
M. V. Suslikov, A. I. Kolbin, N. V. Borisov
{"title":"On Accretion in the Polar V379 Vir","authors":"M. V. Suslikov,&nbsp;A. I. Kolbin,&nbsp;N. V. Borisov","doi":"10.1134/S1063773725700239","DOIUrl":"10.1134/S1063773725700239","url":null,"abstract":"<p>Based on optical and infrared survey data spanning <span>(approx 20)</span> years of observations, the long-term variability of the polar V379 Vir with a brown dwarf secondary has been studied. By modeling the spectral energy distribution, we constrain the white dwarf’s mass to <span>(M_{1}=0.61pm 0.05;M_{odot})</span> and its effective temperature to <span>(T_{textrm{eff}}=10,930pm 350text{ K})</span>. Near-infrared photometry yields a donor radius of <span>(R_{2}=0.095pm 0.018;R_{odot})</span> and temperature <span>(T_{textrm{eff}}=1600pm 180text{ K})</span>. Modeling of the cyclotron emission from the accretion spot, detected with the <i>Spitzer</i> infrared telescope, gives an accretion rate of <span>(dot{M}approx 3times 10^{-13};M_{odot}/textrm{yr})</span>. This rate is consistent with polars in a low accretion state, but significantly higher than expected from wind-driven mass transfer.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"79 - 88"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
IRAS 22272+5435 (V354 Lac): Multicolor Photometry of a Variable Carbon-rich Post-AGB Star and a Dust Formation Episode IRAS 22272+5435 (V354 Lac): agb后富碳变星和尘埃形成事件的多色光度测定
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700240
N. P. Ikonnikova, V. I. Shenavrin, G. V. Komissarova, M. A. Burlak
{"title":"IRAS 22272+5435 (V354 Lac): Multicolor Photometry of a Variable Carbon-rich Post-AGB Star and a Dust Formation Episode","authors":"N. P. Ikonnikova,&nbsp;V. I. Shenavrin,&nbsp;G. V. Komissarova,&nbsp;M. A. Burlak","doi":"10.1134/S1063773725700240","DOIUrl":"10.1134/S1063773725700240","url":null,"abstract":"<p>We present new <span>(UBV)</span> photometric observations (2009–2024) of the carbon-rich post-AGB star IRAS 22272+5435 (V354 Lac), combined with our data spanning over 30 years (1991–2024). The star shows pulsations with two closely spaced periods, 127 and 132 d, which cause brightness variations of variable amplitude. We also detect low-amplitude oscillations with a 661-day period, of uncertain origin. Color analysis reveals both temperature variations during pulsations and spectral anomalies. For the first time, we analyze long-term <span>(JHKLM)</span> photometry (1994–2024), showing increased <span>(KLM)</span>-band brightness from 1996 to 2004—likely due to dust emission following a sudden mass ejection. The absence of strong optical variability suggests either a large angle between the ejection direction and the line of sight or a low optical depth of the ejected material. We discuss possible mechanisms and observational signatures of this dust-formation event.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"101 - 110"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Exploring the Dynamics of Dark Energy in (boldsymbol{f(Q,C)}) Gravity: A Comprehensive Analysis Using Cosmological Datasets 探索(boldsymbol{f(Q,C)})重力中的暗能量动力学：使用宇宙学数据集的综合分析
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-09-08 DOI: 10.1134/S1063773725700203
Amit Samaddar, S. Surendra Singh
{"title":"Exploring the Dynamics of Dark Energy in (boldsymbol{f(Q,C)}) Gravity: A Comprehensive Analysis Using Cosmological Datasets","authors":"Amit Samaddar,&nbsp;S. Surendra Singh","doi":"10.1134/S1063773725700203","DOIUrl":"10.1134/S1063773725700203","url":null,"abstract":"<p>We study the <span>(f(Q,C))</span> gravity model by finding a power-law solution for the Hubble parameter <span>(H(z)=H_{0}(1+z)^{{3}/{2n}})</span> and examine its consequences using a variety of cosmological datasets. Our approach involves the fitting of the model parameters to datasets from Hubble, BAO and Phantom that are in good agreement with observations. Upon analyzing the energy density <span>(rho(z))</span>, we discover that it provides evidence for a dynamic dark energy theory. The <span>(Om(z))</span> diagnostic and the statefinder parameters <span>(r)</span> and <span>(s)</span> show the behaviours that is compatible with quintessence models. According to our findings, the <span>(f(Q,C))</span> gravity model offers a feasible substitute for the conventional <span>(Lambda)</span>CDM model and offer a valuable understanding into the dynamic characteristics of dark energy and cosmic expansion.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 2","pages":"49 - 64"},"PeriodicalIF":0.8,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145011629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
To the Origin of the Fast X-ray Precursors of Solar Flares 太阳耀斑快速x射线前体的起源
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-07-20 DOI: 10.1134/S1063773725700185
V. V. Zaitsev, A. V. Stepanov
{"title":"To the Origin of the Fast X-ray Precursors of Solar Flares","authors":"V. V. Zaitsev,&nbsp;A. V. Stepanov","doi":"10.1134/S1063773725700185","DOIUrl":"10.1134/S1063773725700185","url":null,"abstract":"<p>We study the origin of the soft X-ray precursors that arise before the impulsive phase of a flare and testify to the rapid heating of the footpoints of flaring magnetic loops to temperatures of 10–15 MK. We show that the precursor heating rate at an observed duration <span>({sim})</span>10 s must exceed the quasi-steady-state coronal heating rate at comparable electric currents by three orders of magnitude. We suggest that the preflare heating is associated with a sharp increase in the longitudinal electric current as the Rayleigh-Taylor instability develops at the chromospheric footpoints of the flaring loops. We show that if the pulse current exceeds <span>(10^{11}{-}10^{12})</span> A, then the plasma Joule heating leads the ionization. In this case, a relatively large fraction of neutrals, <span>(n_{a}/n=10^{-5})</span>, which significantly exceeds the fraction of neutrals in a quasi-steady-state corona, is retained in the precursor plasma during the heating process. This ensures the rapid heating of the precursor region through an increase in the current dissipation rate under the Cowling resistivity associated with ion-atom collisions.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 1","pages":"34 - 37"},"PeriodicalIF":0.8,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Method for Estimating the Spatial Period of Energy Release in Solar Flares II 一种估算太阳耀斑能量释放空间周期的方法2
IF 0.8 4区 物理与天体物理
Astronomy Letters-A Journal of Astronomy and Space Astrophysics Pub Date : 2025-07-20 DOI: 10.1134/S1063773725700161
L. S. Ledentsov
{"title":"A Method for Estimating the Spatial Period of Energy Release in Solar Flares II","authors":"L. S. Ledentsov","doi":"10.1134/S1063773725700161","DOIUrl":"10.1134/S1063773725700161","url":null,"abstract":"<p>The method for estimating the spatial period of energy release in solar flares based on the application of a Fourier analysis to the difference images of flare arcades in the far ultraviolet is applied to the observations of the large solar flare on November 4, 2003. The flare occurred at the solar limb; the flare arcade extending along the solar limb was imaged in detail in the ultraviolet 195 Å channel of the TRACE satellite. The Fourier analysis of its difference images has shown the presence of a series of harmonics in the spatial distribution of the regions of flare energy release with characteristic periods lying in the range from 3.3 to 18.6 Mm. Such periodization may result from the decay of the preflare current layer accumulating the solar flare energy in coronal magnetic fields due to some instability of thermal, plasma, or other nature.</p>","PeriodicalId":55443,"journal":{"name":"Astronomy Letters-A Journal of Astronomy and Space Astrophysics","volume":"51 1","pages":"38 - 48"},"PeriodicalIF":0.8,"publicationDate":"2025-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145167205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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