This paper is devoted to the study of curvature properties of Hayward black hole (briefly, HBH) spacetime, which is a solution of Einstein field equations (briefly, EFE) having non-vanishing cosmological constant. We have proved that the HBH spacetime is an Einstein manifold of level 2, 2-quasi Einstein, generalized quasi-Einstein and Roter type manifold. Also, it is shown that the nature of the HBH spacetime is pseudosymmetric and it obeys several types of pseudosymmetries, such as, pseudosymmetry due to concircular, conformal and conharmonic curvature (i.e., for with a smooth scalar function ), and it also possesses the relation . It is engrossing to mention that the nature of energy momentum tensor of the HBH spacetime is pseudosymmetric. On the basis of curvature related properties, we have made a comparison among Reissner–Nordström spacetime, interior black hole spacetime and HBH spacetime. It is noteworthy to mention that the gravitational force of the point-like global monopole spacetime is much stronger than that of HBH spacetime. Also, it is shown that the HBH spacetime admits an almost -Ricci soliton as well as an almost -Ricci-Yamabe soliton. Finally, an elegant comparative study is delineated between the HBH spacetime and the point-like global monopole spacetime with respect to different kinds of symmetry, such as, motion, curvature collineation, curvature inheritance etc.
{"title":"On curvature related geometric properties of Hayward black hole spacetime","authors":"Absos Ali Shaikh, Shyamal Kumar Hui, Biswa Ranjan Datta, Mousumi Sarkar","doi":"10.1016/j.newast.2023.102181","DOIUrl":"10.1016/j.newast.2023.102181","url":null,"abstract":"<div><p>This paper is devoted to the study of curvature properties of Hayward black hole (briefly, HBH) spacetime, which is a solution of Einstein field equations (briefly, EFE) having non-vanishing cosmological constant. We have proved that the HBH spacetime is an Einstein manifold of level 2, 2-quasi Einstein, generalized quasi-Einstein and Roter type manifold. Also, it is shown that the nature of the HBH spacetime is pseudosymmetric and it obeys several types of pseudosymmetries, such as, pseudosymmetry due to concircular, conformal and conharmonic curvature (i.e., <span><math><mrow><mi>F</mi><mi>⋅</mi><mi>F</mi><mo>=</mo><mi>L</mi><mi>Q</mi><mrow><mo>(</mo><mi>g</mi><mo>,</mo><mi>F</mi><mo>)</mo></mrow></mrow></math></span> for <span><math><mrow><mi>F</mi><mo>=</mo><mi>W</mi><mo>,</mo><mi>C</mi><mo>,</mo><mi>K</mi></mrow></math></span> with a smooth scalar function <span><math><mi>L</mi></math></span>), and it also possesses the relation <span><math><mrow><mi>R</mi><mi>⋅</mi><mi>R</mi><mo>−</mo><mi>L</mi><mi>Q</mi><mrow><mo>(</mo><mi>g</mi><mo>,</mo><mi>C</mi><mo>)</mo></mrow><mo>=</mo><mi>Q</mi><mrow><mo>(</mo><mi>S</mi><mo>,</mo><mi>R</mi><mo>)</mo></mrow></mrow></math></span>. It is engrossing to mention that the nature of energy momentum tensor of the HBH spacetime is pseudosymmetric. On the basis of curvature related properties, we have made a comparison among Reissner–Nordström spacetime, interior black hole spacetime and HBH spacetime. It is noteworthy to mention that the gravitational force of the point-like global monopole spacetime is much stronger than that of HBH spacetime. Also, it is shown that the HBH spacetime admits an almost <span><math><mi>η</mi></math></span>-Ricci soliton as well as an almost <span><math><mi>η</mi></math></span>-Ricci-Yamabe soliton. Finally, an elegant comparative study is delineated between the HBH spacetime and the point-like global monopole spacetime with respect to different kinds of symmetry, such as, motion, curvature collineation, curvature inheritance etc.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139026955","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}
Pub Date : 2023-12-22DOI: 10.1016/j.newast.2023.102182
Ashok Mondal , Tanuka Chattopadhyay
Properties of molecular clouds () lying in our Galaxy and their star formation scenarios have been investigated with the help of multivariate unsupervised machine learning techniques concerning several observable parameters. At first, the have been classified into four coherent groups using the standard K-means clustering method. Subsequently, the optimum number of groups has been estimated by applying the Elbow method as well as the computation of Silhouette widths for a robustness check. Later, the properties of the groups are studied through several observable parameters as mentioned along with computed ones e.g. star formation rates (), virial masses, mass-spectra, dynamical time scales (), etc. to get a deeper understanding of the star formation process and dynamical evolution of these clouds. It is found that cluster 1 is suitable for the formation of field stars, binary pairs, or stellar associations, whereas the clouds in cluster 2 and cluster 3 are favorable sites for the formation of Galactic clusters of moderate masses, and cluster 4 may produce massive Galactic clusters as well as a few globular clusters. Surprisingly, for each cluster, clouds at around Galacto-centric radius 8 kpc, and on the near Galactic plane has a significantly low . These occurrences indicate that the star formation phenomenon has yet not started or the proneness to start in that region.
{"title":"Dependence of star formation rate on different properties of molecular clouds","authors":"Ashok Mondal , Tanuka Chattopadhyay","doi":"10.1016/j.newast.2023.102182","DOIUrl":"https://doi.org/10.1016/j.newast.2023.102182","url":null,"abstract":"<div><p><span>Properties of molecular clouds (</span><span><math><mrow><mi>M</mi><mi>C</mi><mi>s</mi></mrow></math></span><span>) lying in our Galaxy and their star formation scenarios have been investigated with the help of multivariate unsupervised machine learning techniques concerning several observable parameters. At first, the </span><span><math><mrow><mi>M</mi><mi>C</mi><mi>s</mi></mrow></math></span><span> have been classified into four coherent groups using the standard K-means clustering method. Subsequently, the optimum number of groups has been estimated by applying the Elbow method as well as the computation of Silhouette widths for a robustness check. Later, the properties of the groups are studied through several observable parameters as mentioned along with computed ones e.g. star formation rates (</span><span><math><mrow><mi>S</mi><mi>F</mi><mi>R</mi><mi>s</mi></mrow></math></span>), virial masses, mass-spectra, dynamical time scales (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>d</mi></mrow></msub></math></span><span><span><span>), etc. to get a deeper understanding of the star formation process and dynamical evolution of these clouds. It is found that cluster 1 is suitable for the formation of field stars, binary pairs, or </span>stellar associations, whereas the clouds in cluster 2 and cluster 3 are favorable sites for the formation of </span>Galactic clusters<span> of moderate masses, and cluster 4 may produce massive Galactic clusters as well as a few globular clusters. Surprisingly, for each cluster, clouds at around Galacto-centric radius </span></span><span><math><mo>∼</mo></math></span>8 kpc, and on the near Galactic plane has a significantly low <span><math><mrow><mi>S</mi><mi>F</mi><mi>R</mi></mrow></math></span>. These occurrences indicate that the star formation phenomenon has yet not started or the proneness to start in that region.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139033851","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}
Pub Date : 2023-12-21DOI: 10.1016/j.newast.2023.102179
M. Sharif, Maryam Shakeel, M. Zeeshan Gul
This manuscript examines how effective matter variables influence the geometry of compact stellar objects with anisotropic matter configuration in modified gravity, where represents the Ricci scalar, is the scalar field and is a kinetic term depending on the scalar field. The unknown constants in the metric potentials are determined by the smooth matching of an interior region with the exterior spacetime. We then check the viability of some selected stars through various physical quantities, i.e., effective matter contents, anisotropy and energy constraints. We also examine the equilibrium and stable states through the Tolman–Oppenheimer–Volkoff equation and sound speed/adiabatic index, respectively. This comprehensive analysis ensures that viable and stable compact stars exist in this modified theory as all the necessary conditions are satisfied.
{"title":"Study of anisotropic stellar structures in f(R,φ,χ) theory","authors":"M. Sharif, Maryam Shakeel, M. Zeeshan Gul","doi":"10.1016/j.newast.2023.102179","DOIUrl":"10.1016/j.newast.2023.102179","url":null,"abstract":"<div><p>This manuscript examines how effective matter variables influence the geometry of compact stellar objects with anisotropic matter configuration in modified <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>R</mi><mo>,</mo><mi>φ</mi><mo>,</mo><mi>χ</mi><mo>)</mo></mrow></mrow></math></span> gravity, where <span><math><mi>R</mi></math></span> represents the Ricci scalar, <span><math><mi>φ</mi></math></span> is the scalar field and <span><math><mi>χ</mi></math></span> is a kinetic term depending on the scalar field. The unknown constants in the metric potentials are determined by the smooth matching of an interior region with the exterior spacetime. We then check the viability of some selected stars through various physical quantities, i.e., effective matter contents, anisotropy and energy constraints. We also examine the equilibrium and stable states through the Tolman–Oppenheimer–Volkoff equation and sound speed/adiabatic index, respectively. This comprehensive analysis ensures that viable and stable compact stars exist in this modified theory as all the necessary conditions are satisfied.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139023469","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}
Pub Date : 2023-12-21DOI: 10.1016/j.newast.2023.102180
Rong-Jia Yang
We analyze parameter data with some conditions by using Lagrange mean value theorem in Calculus. We find that: (1) there exists decelerated phase at 1 confidence level in the redshift range ; (2) the equation of state of dark energy may be less than at 1 confidence level at some redshifts in the redshift range ; (3) there exists accelerated phase at 1 confidence level in the redshift range . These results may provide possible evidences for physics beyond CDM.
{"title":"Possible evidences from H(z) parameter data for physics beyond ΛCDM","authors":"Rong-Jia Yang","doi":"10.1016/j.newast.2023.102180","DOIUrl":"10.1016/j.newast.2023.102180","url":null,"abstract":"<div><p>We analyze <span><math><mrow><mi>H</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span> parameter data with some conditions by using Lagrange mean value theorem in Calculus. We find that: (1) there exists decelerated phase at 1 <span><math><mi>σ</mi></math></span> confidence level in the redshift range <span><math><mrow><mo>(</mo><mn>0</mn><mo>.</mo><mn>38</mn><mo>,</mo><mn>0</mn><mo>.</mo><mn>59</mn><mo>)</mo></mrow></math></span>; (2) the equation of state of dark energy may be less than <span><math><mrow><mo>−</mo><mn>1</mn></mrow></math></span> at 1 <span><math><mi>σ</mi></math></span> confidence level at some redshifts in the redshift range <span><math><mrow><mo>(</mo><mn>1</mn><mo>.</mo><mn>3</mn><mo>,</mo><mn>1</mn><mo>.</mo><mn>53</mn><mo>)</mo></mrow></math></span>; (3) there exists accelerated phase at 1 <span><math><mi>σ</mi></math></span> confidence level in the redshift range <span><math><mrow><mo>(</mo><mn>1</mn><mo>.</mo><mn>037</mn><mo>,</mo><mn>1</mn><mo>.</mo><mn>944</mn><mo>)</mo></mrow></math></span>. These results may provide possible evidences for physics beyond <span><math><mi>Λ</mi></math></span>CDM.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107623001811/pdfft?md5=cb4f49c0ba75364e3eca93a0e4d11d81&pid=1-s2.0-S1384107623001811-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139019587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-12-21DOI: 10.1016/j.newast.2023.102179
M. Sharif, Maryam Shakeel, M. Zeeshan Gul
This manuscript examines how effective matter variables influence the geometry of compact stellar objects with anisotropic matter configuration in modified gravity, where represents the Ricci scalar, is the scalar field and is a kinetic term depending on the scalar field. The unknown constants in the metric potentials are determined by the smooth matching of an interior region with the exterior spacetime. We then check the viability of some selected stars through various physical quantities, i.e., effective matter contents, anisotropy and energy constraints. We also examine the equilibrium and stable states through the Tolman–Oppenheimer–Volkoff equation and sound speed/adiabatic index, respectively. This comprehensive analysis ensures that viable and stable compact stars exist in this modified theory as all the necessary conditions are satisfied.
{"title":"Study of anisotropic stellar structures in f(R,φ,χ) theory","authors":"M. Sharif, Maryam Shakeel, M. Zeeshan Gul","doi":"10.1016/j.newast.2023.102179","DOIUrl":"https://doi.org/10.1016/j.newast.2023.102179","url":null,"abstract":"<p>This manuscript examines how effective matter variables influence the geometry of compact stellar objects with anisotropic matter configuration in modified <span><math><mrow is=\"true\"><mi is=\"true\">f</mi><mrow is=\"true\"><mo is=\"true\">(</mo><mi is=\"true\" mathvariant=\"double-struck\">R</mi><mo is=\"true\">,</mo><mi is=\"true\">φ</mi><mo is=\"true\">,</mo><mi is=\"true\">χ</mi><mo is=\"true\">)</mo></mrow></mrow></math></span> gravity, where <span><math><mi is=\"true\" mathvariant=\"double-struck\">R</mi></math></span> represents the Ricci scalar, <span><math><mi is=\"true\">φ</mi></math></span> is the scalar field and <span><math><mi is=\"true\">χ</mi></math></span> is a kinetic term depending on the scalar field. The unknown constants in the metric potentials are determined by the smooth matching of an interior region with the exterior spacetime. We then check the viability of some selected stars through various physical quantities, i.e., effective matter contents, anisotropy and energy constraints. We also examine the equilibrium and stable states through the Tolman–Oppenheimer–Volkoff equation and sound speed/adiabatic index, respectively. This comprehensive analysis ensures that viable and stable compact stars exist in this modified theory as all the necessary conditions are satisfied.</p>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139026920","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}
Pub Date : 2023-12-15DOI: 10.1016/j.newast.2023.102178
Leila Asgari, Hossein Sadeghi, Hassan Khalili
In this work, we calculate the S-factor for 9Be Radiative Capture Reaction according to a modified potential model. We consider the sum of all possible electrical and magnetic transitions as a total cross-section. The zero-energy -factor results are in good agreement with previously theoretical studies and the experimentally reported data.
{"title":"The astrophysical S factor of p+9Be radiative capture reaction in a potential model","authors":"Leila Asgari, Hossein Sadeghi, Hassan Khalili","doi":"10.1016/j.newast.2023.102178","DOIUrl":"https://doi.org/10.1016/j.newast.2023.102178","url":null,"abstract":"<div><p>In this work, we calculate the S-factor for <span><math><mrow><mi>p</mi><mo>+</mo></mrow></math></span><sup>9</sup>Be Radiative Capture Reaction according to a modified potential model. We consider the sum of all possible electrical and magnetic transitions as a total cross-section. The zero-energy <span><math><mi>S</mi></math></span>-factor results are in good agreement with previously theoretical studies and the experimentally reported data.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138656807","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}
Pub Date : 2023-12-13DOI: 10.1016/j.newast.2023.102176
C.N. Ofodum , P.N. Okeke , B.I. Okere
We present the result of over 50-h of Johnson-B photometric observation of HD 137949. These high-speed photometric data were acquired between June 12 and August 19 2013 using the 0.5-m telescope of the South African Astronomical Observatory (SAAO). The result of our frequency analysis when compared with that of similar B-light photometric data obtained in 1981 and 1987 using the same telescope reveals the existence of a long-term stability in its principal frequency of oscillation at mHz; even with the excitation of two new secondary oscillations ( mHz; mHz). On the contrary, the signature of its principal amplitude of oscillation () was found to have changed drastically within a time-span of about three decades. However, the aggregate amplitude () of all the detected oscillations was observed to have remained constant within the period under investigation. In addition, HD 137949 was observed to have undergone pulsational energy re-distribution within this time-span of about three decades; with a signature that is suggestive of non-conservation of its total energy (pulsational). We discuss the possible implications of the recently observed dynamics in the oscillation-signature of HD 137949.
我们展示了对 HD 137949 超过 50 小时的约翰逊-B 测光观测结果。这些高速测光数据是在2013年6月12日至8月19日期间利用南非天文台(SAAO)的0.5米望远镜获得的。我们的频率分析结果与 1981 年和 1987 年利用同一望远镜获得的类似 B 光光度测量数据进行了比较,发现其主振荡频率长期稳定在 ν1=2.014781±0.000003 mHz;即使激发了两个新的次级振荡(ν2=2.016787±0.000006 mHz;ν3=2.012628±0.000009 mHz)。相反,其主振幅(A)的特征在大约三十年的时间跨度内发生了急剧变化。然而,所有探测到的振荡的总振幅(∑A)在调查期内保持不变。此外,还观察到 HD 137949 在这大约三十年的时间跨度内经历了脉动能量的重新分配;其特征表明其总能量(脉动)并不守恒。我们将讨论最近观测到的动态对 HD 137949 的振荡特征可能产生的影响。
{"title":"Probing the amplitude modulation and pulsational energy re-distribution in the oscillation of HD 137949","authors":"C.N. Ofodum , P.N. Okeke , B.I. Okere","doi":"10.1016/j.newast.2023.102176","DOIUrl":"10.1016/j.newast.2023.102176","url":null,"abstract":"<div><p><span>We present the result of over 50-h of Johnson-B photometric observation of HD 137949. These high-speed photometric data were acquired between June 12 and August 19 2013 using the 0.5-m telescope of the South African Astronomical Observatory (SAAO). The result of our frequency analysis when compared with that of similar B-light photometric data obtained in 1981 and 1987 using the same telescope reveals the existence of a long-term stability in its principal frequency of oscillation at </span><span><math><mrow><msub><mrow><mi>ν</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>=</mo><mn>2</mn><mo>.</mo><mn>014781</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>000003</mn></mrow></math></span> mHz; even with the excitation of two new secondary oscillations (<span><math><mrow><msub><mrow><mi>ν</mi></mrow><mrow><mn>2</mn></mrow></msub><mo>=</mo><mn>2</mn><mo>.</mo><mn>016787</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>000006</mn></mrow></math></span> mHz; <span><math><mrow><msub><mrow><mi>ν</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>=</mo><mn>2</mn><mo>.</mo><mn>012628</mn><mo>±</mo><mn>0</mn><mo>.</mo><mn>000009</mn></mrow></math></span> mHz). On the contrary, the signature of its principal amplitude of oscillation (<span><math><mi>A</mi></math></span>) was found to have changed drastically within a time-span of about three decades. However, the aggregate amplitude (<span><math><mrow><mo>∑</mo><mi>A</mi></mrow></math></span>) of all the detected oscillations was observed to have remained constant within the period under investigation. In addition, HD 137949 was observed to have undergone pulsational energy re-distribution within this time-span of about three decades; with a signature that is suggestive of non-conservation of its total energy (pulsational). We discuss the possible implications of the recently observed dynamics in the oscillation-signature of HD 137949.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138681853","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}
Pub Date : 2023-12-12DOI: 10.1016/j.newast.2023.102177
Oni Leke, Orum Samuel
This paper investigates motion and zero velocity curves of a dust grain around collinear libration points (CLPs) of the circular restricted three-body problem (R3BP) when both stars IRAS 11472-0800 and G29-38 vary their masses according to the unified Mestschersky law (UML) and their motion is described by the Gylden-Mestschersky problem (GMP) with further assumption that the bigger body is a variable triaxial star. The non-autonomous equations of motion of the model are derived and transformed to the autonomized forms using the Mestschersky transformation (MT), the UML, the particular integral and solutions of the GMP, and a transformation we introduced which enable us to convert the time dependent triaxiality of the bigger star to constant triaxiality. The CLPs are examined and it is seen that when motion takes place on the plane joining the stars, there are three CLPs. To further validate the existence of the CLPs, we obtain three polynomial equations of degree seven for the three CLPs, respectively and we numerically explored the roots. It is seen that only three CLPs exists for all values of the mass parameters coupled with triaxiality of the bigger star. The stability of these points is studied and it is seen that CLPs and are unstable for all mass parameters throughout the interval , where is a constant of the particular integral of the GMP and depicts the mass variation parameter of the stars. However, CLPcan be stable and unstable due to the triaxiality of the bigger star, mass parameters and the mass variation parameter. Further, the zero velocity curves (ZVCs) of the dust grain around the CLPs are investigated and the effects of the system parameters divulged. It is seen that, the mass parameters and mass variation parameter can increase or decrease the region where motion of the dust grain is dynamically forbidden, while triaxiality of the bigger star increases the region where motion is forbidden around the CLPs and it allows the appearance of a petal-shaped ZVC around the bigger star. Finally, the orbits of the dust grain around the CLPs is explored, and it is seen that the paths around each collinear point differs. The deviations in the paths are due to the perturbing effects of the mass parameters, triaxiality of the bigger star and the mass variation parameter of the stars. Our problem could have important physical applications when studying celestial bodies of triaxial shape with changing masses of the bodies. In particular, we can assume that the binary system may describe a host star along with an exoplanet, or a massive exoplanet with an exomoon whose masses vary with time.
{"title":"Motion and zero velocity curves of a dust grain around collinear libration points for the binary IRAS 11472-0800 and G29-38 with a triaxial star and variable masses","authors":"Oni Leke, Orum Samuel","doi":"10.1016/j.newast.2023.102177","DOIUrl":"10.1016/j.newast.2023.102177","url":null,"abstract":"<div><p>This paper investigates motion and zero velocity curves of a dust grain around collinear libration points (CLPs) of the circular restricted three-body problem (R3BP) when both stars IRAS 11472-0800 and G29-38 vary their masses according to the unified Mestschersky law (UML) and their motion is described by the Gylden-Mestschersky problem (GMP) with further assumption that the bigger body is a variable triaxial star. The non-autonomous equations of motion of the model are derived and transformed to the autonomized forms using the Mestschersky transformation (MT), the UML, the particular integral and solutions of the GMP, and a transformation we introduced which enable us to convert the time dependent triaxiality of the bigger star to constant triaxiality. The CLPs are examined and it is seen that when motion takes place on the plane joining the stars, there are three CLPs. To further validate the existence of the CLPs, we obtain three polynomial equations of degree seven for the three CLPs, respectively and we numerically explored the roots. It is seen that only three CLPs exists for all values of the mass parameters coupled with triaxiality of the bigger star. The stability of these points is studied and it is seen that CLPs<span><math><msub><mi>L</mi><mn>1</mn></msub></math></span> and<span><math><msub><mi>L</mi><mn>2</mn></msub></math></span> are unstable for all mass parameters throughout the interval <span><math><mrow><mn>0</mn><mo><</mo><mi>κ</mi><mo><</mo><mi>∞</mi></mrow></math></span>, where<span><math><mi>κ</mi></math></span> is a constant of the particular integral of the GMP and depicts the mass variation parameter of the stars. However, CLP<span><math><msub><mi>L</mi><mn>3</mn></msub></math></span>can be stable and unstable due to the triaxiality of the bigger star, mass parameters and the mass variation parameter. Further, the zero velocity curves (ZVCs) of the dust grain around the CLPs are investigated and the effects of the system parameters divulged. It is seen that, the mass parameters and mass variation parameter can increase or decrease the region where motion of the dust grain is dynamically forbidden, while triaxiality of the bigger star increases the region where motion is forbidden around the CLPs and it allows the appearance of a petal-shaped ZVC around the bigger star. Finally, the orbits of the dust grain around the CLPs is explored, and it is seen that the paths around each collinear point differs. The deviations in the paths are due to the perturbing effects of the mass parameters, triaxiality of the bigger star and the mass variation parameter of the stars. Our problem could have important physical applications when studying celestial bodies of triaxial shape with changing masses of the bodies. In particular, we can assume that the binary system may describe a host star along with an exoplanet, or a massive exoplanet with an exomoon whose masses vary with time.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138580999","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}
Pub Date : 2023-12-12DOI: 10.1016/j.newast.2023.102175
M. Shahbaz Ullah , M. Javed Idrisi , Kumari Shalini
In this paper, we aim to showcase the significant impacts of albedo and eccentricity of the primaries on the infinitesimal mass within the elliptic case of the Sitnikov five-body problem. The Van der Pol transformation and averaging technique were employed to formulate the averaged equations of motion for the infinitesimal mass. Subsequently, the Hamiltonian equations of motion were derived using the action angle variables and . Additionally, we obtained in terms of the Jacobi elliptic function through a canonical transformation. The investigation utilized the first return map to explore various orbits such as regular, periodic, quasi-periodic, chaotic, or stochastic in the presence of albedo and eccentricity. It was observed that chaotic and stochastic regions emerged as the albedo effect increased, disrupting the periodic tubes and islands. Moreover, by escalating the albedo effect and eccentricity of the primaries, several families of periodic orbits were revealed.
在本文中,我们旨在展示在 Sitnikov 五体问题的椭圆情况下,主星的反照率和偏心率对无穷小质量的重大影响。我们采用范德尔波尔变换和平均技术来制定无穷小质量的平均运动方程。随后,利用作用角变量 I 和 θ 推导出哈密顿运动方程。此外,我们还通过对雅各比椭圆函数 sn 进行典型变换,得到了 θ。这项研究利用首次回归图探索了存在反照率和偏心率的各种轨道,如规则轨道、周期轨道、准周期轨道、混沌轨道或随机轨道。研究发现,随着反照率效应的增加,出现了混乱和随机区域,扰乱了周期性的管状和岛状轨道。此外,通过增加反照率效应和主星的偏心率,还发现了几个周期轨道系列。
{"title":"Investigating the albedo effects on the dynamics of infinitesimal mass in the elliptic Sitnikov five-body problem","authors":"M. Shahbaz Ullah , M. Javed Idrisi , Kumari Shalini","doi":"10.1016/j.newast.2023.102175","DOIUrl":"https://doi.org/10.1016/j.newast.2023.102175","url":null,"abstract":"<div><p><span><span>In this paper, we aim to showcase the significant impacts of albedo and eccentricity of the primaries on the infinitesimal mass within the elliptic case of the Sitnikov five-body problem. The Van der Pol transformation and averaging technique were employed to formulate the averaged </span>equations of motion for the infinitesimal mass. Subsequently, the Hamiltonian equations of motion were derived using the action angle variables </span><span><math><mi>I</mi></math></span> and <span><math><mi>θ</mi></math></span>. Additionally, we obtained <span><math><mi>θ</mi></math></span> in terms of the Jacobi elliptic function <span><math><mrow><mi>s</mi><mi>n</mi></mrow></math></span> through a canonical transformation. The investigation utilized the first return map to explore various orbits such as regular, periodic, quasi-periodic, chaotic, or stochastic in the presence of albedo and eccentricity. It was observed that chaotic and stochastic regions emerged as the albedo effect increased, disrupting the periodic tubes and islands. Moreover, by escalating the albedo effect and eccentricity of the primaries, several families of periodic orbits were revealed.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138582325","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}
Pub Date : 2023-12-05DOI: 10.1016/j.newast.2023.102174
A. Franco, A.A. Nucita, F. De Paolis, F. Strafella
Gravitational microlensing is known to be an impressive tool for searching dark, small, and compact objects that are missed by the usual astronomical observations. In this paper, by analysing multiple images acquired by DECam, we present the detection and a complete description of the microlensing event LMC J05074558-65574990 which is most likely due to a sub-solar object with mass M, hence in the mass range between a massive brown dwarf and a red dwarf, whose distance is estimated to be pc thanks to the Gaia observation of the source, leading us to consider this lens as one the closest ever detected.
{"title":"Evidence of a sub-solar star in a microlensing event toward the LMC","authors":"A. Franco, A.A. Nucita, F. De Paolis, F. Strafella","doi":"10.1016/j.newast.2023.102174","DOIUrl":"10.1016/j.newast.2023.102174","url":null,"abstract":"<div><p>Gravitational microlensing is known to be an impressive tool for searching dark, small, and compact objects that are missed by the usual astronomical observations. In this paper, by analysing multiple images acquired by DECam, we present the detection and a complete description of the microlensing event LMC J05074558-65574990 which is most likely due to a sub-solar object with mass <span><math><mrow><mo>(</mo><mn>0</mn><mo>.</mo><mn>16</mn><mspace></mspace><mo>±</mo><mspace></mspace><mn>0</mn><mo>.</mo><mn>10</mn><mo>)</mo></mrow></math></span> M<span><math><msub><mrow></mrow><mrow><mo>⊙</mo></mrow></msub></math></span>, hence in the mass range between a massive brown dwarf and a red dwarf, whose distance is estimated to be <span><math><mrow><mn>7</mn><mo>.</mo><msubsup><mrow><mn>8</mn></mrow><mrow><mo>−</mo><mn>3</mn><mo>.</mo><mn>4</mn></mrow><mrow><mo>+</mo><mn>4</mn><mo>.</mo><mn>1</mn></mrow></msubsup><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span> pc thanks to the Gaia observation of the source, leading us to consider this lens as one the closest ever detected.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":2.0,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107623001756/pdfft?md5=e6ed8875c67802ccbc76806c552ccd21&pid=1-s2.0-S1384107623001756-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543053","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}