Astrophysics最新文献

{"title":"Correction to: A Search for New Dwarf Galaxies Outside the Nearby Groups","authors":"I. D. Karachentsev, V. E. Karachentseva, S. S. Kaisin, E. I. Kaisina","doi":"10.1007/s10511-025-09864-3","DOIUrl":"10.1007/s10511-025-09864-3","url":null,"abstract":"","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"150 - 151"},"PeriodicalIF":0.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929954","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}

{"title":"A Study on Geodesics and Lifespan of the Rindler-Modified Schwarzschild Black Hole. I. Time-Like Geodesics","authors":"T. Huo,&nbsp;C. Liu","doi":"10.1007/s10511-025-09862-5","DOIUrl":"10.1007/s10511-025-09862-5","url":null,"abstract":"<p>We study the time-like geodesics in the spacetime of the Rindler-modified Schwarzschild black hole (RMSBH) with a cosmological constant. We find that for massive particles, whether undergoing radial motion or orbital motion, are unable to escape the black hole. Meanwhile, at larger orbital radii, the cosmological constant significantly modifies the proper velocity of particles. Additionally, in the case where Λ = 0, we have presented a special solution: if the particle is located on a specific circular orbit, its proper velocity will remain unaffected by the Rindler acceleration. Furthermore, we discuss the stability of circular orbits by employing the Lyapunov exponent, and draw the dividing line between stable and unstable circular orbits.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"120 - 139"},"PeriodicalIF":0.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930168","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}

{"title":"Doppler Velocity and Spectral Line Width Variations in Solar Spicules and Prominences","authors":"M. Sikharulidze,&nbsp;D. Khutsishvili,&nbsp;E. Khutsishvili,&nbsp;V. Kakhiani,&nbsp;T. Tsinamdzgvrishvili","doi":"10.1007/s10511-025-09859-0","DOIUrl":"10.1007/s10511-025-09859-0","url":null,"abstract":"<p>The objective of the study is to investigate the dynamic behaviors of solar spicules and prominences and the relationship between them. An analysis of spicules and prominences and comparison of the obtained results should provide some novelty to the description of physical processes governing these phenomena. For this purpose, spectrograms in the helium D₃ line were obtained at a height of 8000 km using the large coronagraph at the Abastuman Astrophysical Observatory. The D₃ line spectrograms were derived in the second order, with an inverse dispersion of 0.96 Å/mm. The standard errors of the Doppler velocities and spectral line widths are 0.35 km/s and 0.04 Å, respectively. The lifetime of almost all measured spicules was about 20 min, which defines them as type I spicules. The Doppler shifts and variations of line widths over time were analyzed using the Lomb-Scargle periodogram algorithm for irregular data series. The primary results of the observational data reduction and analysis are as follows. The Doppler velocities in the prominence legs vary in the range of about 17–18 km/s, and in spicules in the range of 16–24 km/s. We observe a temporal asymmetry in the variation of Doppler velocities and line widths in four out of the five studied spicules. For D₃ prominences, the oscillation period of the Doppler velocities on average ranges from three to four minutes, and the period of line width oscillation from two to three minutes. For D₃ spicules, the period of Doppler velocity oscillations varies on average between two and five minutes, and the period of line width oscillation between two and five minutes. In the prominence legs, the anticorrelation between Doppler velocities and line widths is more pronounced in the region where solar plasma moves from lower atmospheric layers to higher ones. The observed anti-phase oscillations with longer periods can be explained by the upward and downward motion of turbulent plasma in type I spicules. Oscillations with shorter periods may be caused by the helical motion of the spicule axis resulting from the superposition of two linearly polarized magnetohydrodynamic kink waves.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"69 - 83"},"PeriodicalIF":0.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930169","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}

{"title":"A Cosmological Model with Second Law of Thermodynamics in f(R, T) Gravity","authors":"R. K. Tiwari,&nbsp;J. Bharali,&nbsp;B. Cherty,&nbsp;A. Beesham","doi":"10.1007/s10511-025-09860-7","DOIUrl":"10.1007/s10511-025-09860-7","url":null,"abstract":"<p>In the context of <i>f (R, T)</i> modified gravity theory, we investigate a cosmological model with homogeneous and anisotropic properties, specifically the Locally Rotationally Symmetric (LRS) Bianchi type-I model. By considering Einstein’s field equations in <i>f (R, T)</i> gravity, we solve them with the choice <i>f (R, T) = R + 2f (T)</i>, where <i>R</i> represents the Ricci scalar and <i>T</i> denotes the trace of the stress-energy momentum tensor <i>T</i>_<i>ij</i>. In this case, we set <i>f</i> (<i>T</i> ) = -λ<i>T</i>, with λ being an arbitrary constant. It is worth noting that the cosmic jerk parameter j is directly proportional to the negative value of the deceleration parameter <i>q</i>, namely <i>j</i> ∝ - <i>q</i>. We analyze the physical and geometrical properties of the models, and also employ the statefinder diagnostic pair to gain insight into the geometrical nature of the model. We also investigate the validity of the generalized second law of thermodynamics (GSLT) on the apparent and event horizons. Our findings reveal that GSLT holds on both the horizons.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"84 - 107"},"PeriodicalIF":0.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929953","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}

{"title":"Electromagnetic Radiation from a Relativistic Jet Induced by a Plane Gravitational Wave","authors":"V. Epp,&nbsp;K. Oosetrin,&nbsp;E. Osetrina","doi":"10.1007/s10511-025-09863-4","DOIUrl":"10.1007/s10511-025-09863-4","url":null,"abstract":"<p>Electromagnetic radiation of a relativistic gas or plasma jet in the field of a plane gravitational wave is investigated. The gravitational wave is considered as a weak (linearized) field on flat Minkowski spacetime. It is assumed that the relativistic jet has large regions with uncompensated electric charge. The deformation of these areas under the action of a gravitational wave leads to the appearance of electric currents that generate electromagnetic radiation. The angular distribution of the intensity of this radiation is found. Cases are considered when the jet and the gravitational wave move in the same direction or towards each other.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"140 - 149"},"PeriodicalIF":0.6,"publicationDate":"2025-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143930170","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}

{"title":"LGV Analysis of Hydroperoxy Radical (HO2): Spectral Lines for Its Detection in a Cosmic Object","authors":"S. Chandra","doi":"10.1007/s10511-025-09861-6","DOIUrl":"10.1007/s10511-025-09861-6","url":null,"abstract":"<p>Knowing rotational and centrifugal distortion constants in conjunction with electric dipole moment for HO₂ radical, we have calculated energies for rotational levels (without fine-structure splitting), and probabilities for radiative transitions between the levels. The radiative transition probabilities in conjunction with the scaled values for rate coefficients for collisional transitions between the levels, the Large Velocity Gradient (LVG) analysis for HO₂ is performed. Two observed lines, 2₀₂-1₀₁ and 4₀₄-3₀₃ of HO2 are found to show MASER action. Seven lines 1₁₀-1₁₁, 2_{1. 1}-2_{1. 2}, 3_{1. 2}-3_{1. 3}, 4_{1. 3}-4_{1. 4}, 5_{1. 4}-5_{1. 5}, 6_{1. 5}-6_{0. 6} and 7_{1. 6}-7_{0. 7} are found to show anomalous absorption and five more lines, 7_{1. 6}-7_{1. 7}, 1_{1. 0}-1_{0. 1}, 2_{2. 1}-3_{1. 2}, 4_{2. 3}-3_{1. 2} and 4_{4. 1}-3_{3. 0} are found to show MASER action. These 14 lines are analyzed here and they may play key role in the identification of HO₂ in a cosmic object.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"108 - 119"},"PeriodicalIF":0.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929946","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}

{"title":"Spectral Variations and Physical Conditions of by Draconis in the Ultraviolet","authors":"M. R. Sanad","doi":"10.1007/s10511-025-09857-2","DOIUrl":"10.1007/s10511-025-09857-2","url":null,"abstract":"<p>We present International Ultraviolet Explorer (IUE) observations during the period (1980 - 1994) of the double lined spectroscopic binary BY Dra to show the spectral behavior and physical conditions in its atmosphere. The observations reveal indication of flare activity in their flux values in years (1981-1990-1994) in the chromosphere and transition region of the primary star. Beside the flaring activity the emission lines show a range of variations between high, intermediate and low. There is a relation between the fluxes and rotational phase. The reddening of BY Dra was estimated from 2200 Å absorption feature to be <i>E</i>(<i>B</i> - <i>V</i>) = 0. The average mass loss rate is found to be ~4.9⋅10^-8 <i>M</i>_⨀ yr^-1, the average temperature of the emitting region to be ~9.2⋅10⁴ K, energy of flare to be ~6.2⋅10³⁷ erg. We attributed the spectral variations to a cyclic behavior of the underlying magnetic field and the flaring activity to three component model.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"40 - 50"},"PeriodicalIF":0.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929944","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}

{"title":"Variability of Planetary Nebulae: Results of Long-Term Observations","authors":"L. N. Kondratyeva,&nbsp;E. K. Denissyuk,&nbsp;S. A. Shomshekova,&nbsp;I. V. Reva,&nbsp;A. K. Aimanova,&nbsp;M. A. Krugov","doi":"10.1007/s10511-025-09858-1","DOIUrl":"10.1007/s10511-025-09858-1","url":null,"abstract":"<p>The results of spectroscopic and photometric observations of 14 compact planetary nebulae are presented. Observations were conducted at the V.G. Fesenkov Astrophysical Institute (Kazakhstan) since 1973. The aim of this study is to obtain data on the variability of the studied objects over long time spans. The criterion for determining the nebular excitation class was the intensity of the [OIII] lines normalized to the intensity of Hβ. Analysis of the data collected over 40–50 years revealed significant spectral changes in most of the observed objects, likely associated with an increase in the temperature of the central stars and/or changes in the internal structure of the nebular envelopes.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"51 - 68"},"PeriodicalIF":0.6,"publicationDate":"2025-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929945","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}

{"title":"Astrometric and Photometric Studies for Some Selected Open Star Clusters","authors":"R. M. Hariry,&nbsp;A. A. Haroon,&nbsp;A. A. Malawi","doi":"10.1007/s10511-025-09855-4","DOIUrl":"10.1007/s10511-025-09855-4","url":null,"abstract":"<p>In this study, we conducted a detailed astrometric, and photometric study of four open clusters (SAI 43, SAI 47, SAI 63, and SAI 113) using data from Gaia DR3. The ASteCA code enabled the identification of the astrometric and photometric parameters. The new centers of these clusters were redetermined and from Radial Density Profile (RDP), the cluster radii, are between 3.13- and 6.6 arcmin for all clusters. The astrophysical parameters are as follows: the number of star members N are 141 (SAI 43), 153 (SAI 47), 198 (SAI 63), and 188 (SAI 113); parallax (ϖ) for SAI 43, SAI 47, SAI 63, and SAI 113 are between 0.275 and 0.506 mas; proper motion parameters (μ_<i>a</i> cosδ, μ_δ) are (0.57, -0.54 mas/yr), (0, -0.34 mas/yr), (-0.24, 0.26 mas/yr), and (-5.61, 2.84 mas/yr) for SAI 43, SAI 47, SAI 63, and SAI 113, respectively. The photometric parameters include the color magnitude diagram (CMD), ages, reddening, and distances. The ages are provided as log (age), and they are between (7.172-8.659); the color excess E(B-V) is 0.476±0.017 mag for SAI 43, 0.375±0.014 mag for SAI 47, 0.510±0.009 mag for SAI 63, and 1.265±0.011 mag for SAI 113, the distance modules of the clusters are between 11.177-13.439 mag, and the distances from the sun to each of the clusters (SAI 43, SAI 47, SAI 63, and SAI 113) are calculated as 4900±100 pc, 2360±30 pc, 1720±20 pc, and 3720±50 pc, respectively.</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"17 - 31"},"PeriodicalIF":0.6,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929942","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}

{"title":"Total C+N+O Abundances in the Atmospheres of Red Giants of Different Metallicities","authors":"L. S. Lyubimkov,&nbsp;D. V. Petrov","doi":"10.1007/s10511-025-09856-3","DOIUrl":"10.1007/s10511-025-09856-3","url":null,"abstract":"<p>The sum of C+N+O in red giants presents interest due to its steady nature during stellar evolution of the star, although the abundance of its components, especially C and N, undergoes significant evolutionary changes. It is shown that there is a pronounced correlation between the total log ε(C+N+O) abundances in red giants and their metallicity index [Fe/H]. The linear relationship between log ε (C + N + O) and [Fe/H] indicates an increase in log ε (C+N+O) from 7.0 with [Fe/H] = -2.5 to 9.2 with [Fe/H] = +0.3, i.e., by more than 2 dex. In contrast, the abundance of (C+N+O) relative to Fe decreases by 0.7 dex over the same [Fe/H] interval. It is shown that the ratio between [(C+N+O)/Fe] and [Fe/H] is almost completely determined by the ratio between [O/Fe] and [Fe/H]; hence, it is confirmed that oxygen is the main contributor to C+N+O. Since current models of Galactic evolution explain the observed dependence of [O/Fe] on [Fe/H] reasonably well, they thereby also explain the observed dependence of [(C+N+O)/Fe] on [Fe/H].</p>","PeriodicalId":479,"journal":{"name":"Astrophysics","volume":"68 1","pages":"32 - 39"},"PeriodicalIF":0.6,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143929943","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}