Pub Date : 2024-11-13DOI: 10.1016/j.newast.2024.102330
Ligang Yu , Shaung Wang , Michel Raúl , Liyun Zhang
We carried out a low resolution spectrum, the first ground-based multi-color light curves (LCs) analysis, and Transiting Exoplanet Survey Satellite (TESS) data analysis for the binary V1393 Tau. We determined its spectral type of K2V and updated an orbital period 0.24738715 days. By the Wilson-Devinney program, we solved ten sets of light curves. From the BVRcIc-band , we obtained a mass ratio and a fill-out factor , which implies that V1393 Tau is a W-type shallow-contact binary. We traced the spot migration and evolution through modeling light curves during the past four years. The spot’s size alternately becomes smaller or bigger, and its longitude intervenes between in and in except for .
{"title":"A comprehensive study on the K2-type binary V1393 Tau in four-year observations","authors":"Ligang Yu , Shaung Wang , Michel Raúl , Liyun Zhang","doi":"10.1016/j.newast.2024.102330","DOIUrl":"10.1016/j.newast.2024.102330","url":null,"abstract":"<div><div>We carried out a low resolution spectrum, the first ground-based multi-color light curves (LCs) analysis, and Transiting Exoplanet Survey Satellite (TESS) data analysis for the binary V1393 Tau. We determined its spectral type of K2V and updated an orbital period 0.24738715 days. By the Wilson-Devinney program, we solved ten sets of light curves. From the <em>BVRcIc</em>-band <span><math><mrow><mi>L</mi><msub><mrow><mi>C</mi></mrow><mrow><mn>2022</mn><mo>.</mo><mn>11</mn></mrow></msub></mrow></math></span>, we obtained a mass ratio <span><math><mrow><mi>q</mi><mo>=</mo><mn>2</mn><mo>.</mo><mn>500</mn><mrow><mo>(</mo><mn>3</mn><mo>)</mo></mrow></mrow></math></span> and a fill-out factor <span><math><mrow><mi>f</mi><mo>=</mo><mn>11</mn><mo>.</mo><mn>73</mn><mrow><mo>(</mo><mn>6</mn><mo>)</mo></mrow><mtext>%</mtext></mrow></math></span>, which implies that V1393 Tau is a W-type shallow-contact binary. We traced the spot migration and evolution through modeling light curves during the past four years. The spot’s size alternately becomes smaller or bigger, and its longitude intervenes between <span><math><mrow><mi>λ</mi><mo>=</mo><mn>82</mn><mo>.</mo><mn>3</mn><msup><mrow><mn>9</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span> in <span><math><mrow><mi>L</mi><msub><mrow><mi>C</mi></mrow><mrow><mi>S</mi><mn>70</mn></mrow></msub></mrow></math></span> and <span><math><mrow><mn>102</mn><mo>.</mo><mn>5</mn><msup><mrow><mn>6</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span> in <span><math><mrow><mi>L</mi><msub><mrow><mi>C</mi></mrow><mrow><mn>2022</mn><mo>.</mo><mn>10</mn></mrow></msub></mrow></math></span> except for <span><math><mrow><mi>L</mi><msub><mrow><mi>C</mi></mrow><mrow><mi>S</mi><mn>32</mn></mrow></msub></mrow></math></span>.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102330"},"PeriodicalIF":1.9,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654163","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 : 2024-11-07DOI: 10.1016/j.newast.2024.102328
Noraiz Tahir , Martín López-Corredoira , Francesco De Paolis
The halo of our Galaxy is populated with a significant number of high-velocity clouds (HVCs) moving with a speed up to 500 km/s. It is suggested that these HVCs might contain a non-negligible fraction of the missing baryons. The main aim of the current paper is to estimate the baryonic mass of the Milky Way halo in the form of HVCs in order to constrain a fraction of missing baryons in the form of these clouds. Such findings would give substantial help in the studying halo dynamics of our Galaxy.
We first estimate the HVCs distance. We consider the most recent and updated HVC catalog, namely the Galactic All Sky Survey (GASS), which, however, covers the southern sky declinations, south of . Following a model presented in the literature, we assume that most of the HVCs (not all of the HVCs in the Milky Way) were ejected from the Magellanic Clouds (MCls) which is at a distance of about 50 kpc. We assume that the HVCs have a temperature in the range of about – K, and are distributed in the Galactic halo as the Navarro–Frenk–White (NFW) profile. Since the GASS survey covers a small portion of the sky, we estimate the number of missing clouds by using Monte Carlo (MC) simulations. The next step will be to estimate the total mass of the Milky Way contained in the form of these HVCs. The total mass resulted to be in the form of HVCs and compact high-velocity clouds (CHVCs).
{"title":"The baryonic mass estimates of the Milky Way halo in the form of high-velocity clouds","authors":"Noraiz Tahir , Martín López-Corredoira , Francesco De Paolis","doi":"10.1016/j.newast.2024.102328","DOIUrl":"10.1016/j.newast.2024.102328","url":null,"abstract":"<div><div>The halo of our Galaxy is populated with a significant number of high-velocity clouds (HVCs) moving with a speed up to 500 km/s. It is suggested that these HVCs <em>might</em> contain a non-negligible fraction of the missing baryons. The main aim of the current paper is to estimate the baryonic mass of the Milky Way halo in the form of HVCs in order to constrain a fraction of missing baryons in the form of these clouds. Such findings would give substantial help in the studying halo dynamics of our Galaxy.</div><div>We first estimate the HVCs distance. We consider the most recent and updated HVC catalog, namely the Galactic All Sky Survey (GASS), which, however, covers the southern sky declinations, south of <span><math><mrow><mi>b</mi><mo>≤</mo><mn>6</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>∘</mo></mrow></msup></mrow></math></span>. Following a model presented in the literature, we assume that most of the HVCs (not all of the HVCs in the Milky Way) were ejected from the Magellanic Clouds (MCls) which is at a distance of about 50 kpc. We assume that the HVCs have a temperature in the range of about <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msup></mrow></math></span>–<span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>4</mn></mrow></msup></mrow></math></span> K, and are distributed in the Galactic halo as the Navarro–Frenk–White (NFW) profile. Since the GASS survey covers a small portion of the sky, we estimate the number of missing clouds by using Monte Carlo (MC) simulations. The next step will be to estimate the total mass of the Milky Way contained in the form of these HVCs. The total mass resulted to be <span><math><mrow><mo>∼</mo><mrow><mo>(</mo><mn>7</mn><mo>±</mo><mn>2</mn><mo>)</mo></mrow><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>9</mn></mrow></msup><msub><mrow><mi>M</mi></mrow><mrow><mo>⊙</mo></mrow></msub></mrow></math></span> in the form of HVCs and compact high-velocity clouds (CHVCs).</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102328"},"PeriodicalIF":1.9,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654251","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}
There are some traces of the existence of internal ocean in some icy moons, such as the vapor plumes of Europa and Enceladus. This implies a region of liquid water beneath the surface ice shell. Since liquid water would be essential for the origin of life, it is important to understand the development of these internal oceans, particularly their temperature distribution and evolution. The balance between tidal heating and radiative cooling is believed to sustain liquid water beneath an icy moon’s surface. We aim to simulate the tidal heating of an internal ocean in an icy moon using 3-dimensional numerical fluid calculations with the Smoothed Particle Hydrodynamics (SPH) method. We incorporated viscosity and thermal conduction terms into the governing equations of SPH. However, we encountered two issues while calculating rigid body rotation using SPH with a viscous term: (1) conventional viscosity formulations generated unphysical forces that hindered rotation, and (2) there was artificial internal energy partitioning within the layered structure, which was due to the standard SPH formulations. To address the first issue, we modified the viscosity formulation. For the second, we adopted Density Independent SPH (DISPH) developed in previous studies to improve behavior at discontinuous surfaces. Additionally, we implemented radiative cooling using an algorithm to define fluid surfaces via the particle method. We also introduced an equation of state accounting for phase transitions. With these modifications, we have refined the SPH method to encompass all necessary physical processes for simulating the evolution of icy moons with internal oceans.
{"title":"Modifications of SPH towards three-dimensional simulations of an icy moon with internal ocean","authors":"Keiya Murashima , Natsuki Hosono , Takayuki R. Saitoh , Takanori Sasaki","doi":"10.1016/j.newast.2024.102320","DOIUrl":"10.1016/j.newast.2024.102320","url":null,"abstract":"<div><div>There are some traces of the existence of internal ocean in some icy moons, such as the vapor plumes of Europa and Enceladus. This implies a region of liquid water beneath the surface ice shell. Since liquid water would be essential for the origin of life, it is important to understand the development of these internal oceans, particularly their temperature distribution and evolution. The balance between tidal heating and radiative cooling is believed to sustain liquid water beneath an icy moon’s surface. We aim to simulate the tidal heating of an internal ocean in an icy moon using 3-dimensional numerical fluid calculations with the Smoothed Particle Hydrodynamics (SPH) method. We incorporated viscosity and thermal conduction terms into the governing equations of SPH. However, we encountered two issues while calculating rigid body rotation using SPH with a viscous term: (1) conventional viscosity formulations generated unphysical forces that hindered rotation, and (2) there was artificial internal energy partitioning within the layered structure, which was due to the standard SPH formulations. To address the first issue, we modified the viscosity formulation. For the second, we adopted Density Independent SPH (DISPH) developed in previous studies to improve behavior at discontinuous surfaces. Additionally, we implemented radiative cooling using an algorithm to define fluid surfaces via the particle method. We also introduced an equation of state accounting for phase transitions. With these modifications, we have refined the SPH method to encompass all necessary physical processes for simulating the evolution of icy moons with internal oceans.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102320"},"PeriodicalIF":1.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142654161","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 : 2024-10-31DOI: 10.1016/j.newast.2024.102318
Bin Zhang , Yi-Dan Gao , Zhen Zhong , Bing Lv
We present the new light curve synthesis and orbital period change analysis of V724 And. We found that it is a W-subtype contact binary system with a mass ratio of q = 2.31 and a fill-out factor of f = 10.8%. The weak O’Connell effect can be explained by a cool star-spot on the more massive component star. By analyzing orbital period changes, it is found that the target displays a secular period decrease superimposed on a cyclic oscillation. The orbital period decreases at a rate of dp/dt = −4.13 × 10−8 d yr−1, which can be explained by the mass transfer from the more massive one to the less massive component. The new discovery suggests that the semi-amplitude and period of the cyclic variation are A = 0.0013 d and P = 10.54 yr, respectively, which implies that V724 And is a possibly triple system. The minimum mass of the tertiary companion is estimated as M = 0.054 M, which plays an important role during the formation and evolution of the central binary system.
我们对 V724 And 进行了新的光曲线合成和轨道周期变化分析。我们发现它是一个 W 亚型接触双星系统，质量比为 q = 2.31，填充因子为 f = 10.8%。较弱的奥康纳尔效应可以用质量较大的组成恒星上的冷星点来解释。通过分析轨道周期的变化，可以发现该目标在周期性振荡的基础上又出现了周期性下降。轨道周期的下降速率为 dp/dt = -4.13 × 10-8 d yr-1，这可以用质量较大的成分向质量较小的成分的质量转移来解释。新发现表明，周期变化的半振幅和周期分别为 A = 0.0013 d 和 P = 10.54 yr，这意味着 V724 And 可能是一个三重系统。三级伴星的最小质量估计为 M3min = 0.054 M⊙，它在中心双星系统的形成和演化过程中起着重要作用。
{"title":"Photometric study for the short period contact binary V724 And","authors":"Bin Zhang , Yi-Dan Gao , Zhen Zhong , Bing Lv","doi":"10.1016/j.newast.2024.102318","DOIUrl":"10.1016/j.newast.2024.102318","url":null,"abstract":"<div><div>We present the new light curve synthesis and orbital period change analysis of V724 And. We found that it is a W-subtype contact binary system with a mass ratio of q = 2.31 and a fill-out factor of f = 10.8%. The weak O’Connell effect can be explained by a cool star-spot on the more massive component star. By analyzing orbital period changes, it is found that the target displays a secular period decrease superimposed on a cyclic oscillation. The orbital period decreases at a rate of dp/dt = −4.13 × 10<sup>−8</sup> d yr<sup>−1</sup>, which can be explained by the mass transfer from the more massive one to the less massive component. The new discovery suggests that the semi-amplitude and period of the cyclic variation are A = 0.0013 d and P = 10.54 yr, respectively, which implies that V724 And is a possibly triple system. The minimum mass of the tertiary companion is estimated as M<span><math><msub><mrow></mrow><mrow><mn>3</mn><mi>m</mi><mi>i</mi><mi>n</mi></mrow></msub></math></span> = 0.054 M<span><math><msub><mrow></mrow><mrow><mo>⊙</mo></mrow></msub></math></span>, which plays an important role during the formation and evolution of the central binary system.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102318"},"PeriodicalIF":1.9,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142593906","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 : 2024-10-31DOI: 10.1016/j.newast.2024.102319
Hongfei Yang, Zhongtao Han, Weiwei Na, Hushan Xu, Tingting Yang
We present a photometric analysis of the eclipsing Z Cam-type dwarf nova V416 Dra based on TESS and AAVSO data. The AAVSO light curve, spanning nearly 17 years, shows numerous outbursts recurring approximately every 20.2 and 38.6 days. We examined the amplitude vs. recurrence-time relation in V416 Dra, which appears to reflect the common characteristics of long outbursts in Z Cam stars. The TESS light curves revealed that V416 Dra is a shallow eclipse binary and shows some SU UMa-like superoutbursts, which may be related to the special structure of the accretion disk. The period-searching results show that there are the forest of peaks within the period range of 0.4–2.5 days, related to donor star’s activity. Moreover, we also find the presence of some typical quasi-periodic oscillation (QPO) signals with periods of 14–41 and 177–200 min, respectively. These results will help us locate the origin of the QPOs in V416 Dra accurately.
{"title":"TESS and AAVSO observations of the eclipsing Z Cam-type cataclysmic variable V416 Dra","authors":"Hongfei Yang, Zhongtao Han, Weiwei Na, Hushan Xu, Tingting Yang","doi":"10.1016/j.newast.2024.102319","DOIUrl":"10.1016/j.newast.2024.102319","url":null,"abstract":"<div><div>We present a photometric analysis of the eclipsing Z Cam-type dwarf nova V416 Dra based on TESS and AAVSO data. The AAVSO light curve, spanning nearly 17 years, shows numerous outbursts recurring approximately every 20.2 and 38.6 days. We examined the amplitude vs. recurrence-time relation in V416 Dra, which appears to reflect the common characteristics of long outbursts in Z Cam stars. The TESS light curves revealed that V416 Dra is a shallow eclipse binary and shows some SU UMa-like superoutbursts, which may be related to the special structure of the accretion disk. The period-searching results show that there are the forest of peaks within the period range of 0.4–2.5 days, related to donor star’s activity. Moreover, we also find the presence of some typical quasi-periodic oscillation (QPO) signals with periods of 14–41 and 177–200 min, respectively. These results will help us locate the origin of the QPOs in V416 Dra accurately.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102319"},"PeriodicalIF":1.9,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586112","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 : 2024-10-20DOI: 10.1016/j.newast.2024.102316
Moonzarin Reza
Dark matter subhalos play an important role in galaxy formation and evolution. However, accurate prediction of dark matter properties remains a challenge of modern-day astronomy. In recent times, machine learning (ML) tools have shown promising results in solving numerous astrophysical problems. In this paper, we use data from the EAGLE simulations to determine the total mass and the half-mass radius of dark matter subhalos using structural properties of gas, star, black hole, and photometric features using gradient boosted decision trees (GBDT) and dense neural network. GBDT does not require data preprocessing, and results in better performance compared to the neural network. According to GBDT, the most important feature for subhalo radius and mass estimation is gas radius and black hole mass respectively. The all-features combined approach results in the highest test accuracy — Pearson’s correlation coefficient = 0.947 and 0.981, coefficient of determination = 0.898 and 0.962, normalized median absolute deviation = 0.111 and 0.114 for radius and mass respectively. We evaluate our model for masses and redshifts beyond its training range and find that GBDT demonstrates significantly better extrapolation capabilities than the neural network. We also test our model on simulations with different resolutions, and find that the discrepancies lie within 10% if the resolution is changed. This novel study incorporates the structural parameters of gas and black hole to determine the dark matter properties using a ML-based approach. The promising results of this study prove that ML tools can improve our current understanding of dark matter, and answer some of the basic cosmological questions.
{"title":"Predicting the Physical Properties of Dark Matter Subhalos from Baryonic Parameters Using Machine Learning","authors":"Moonzarin Reza","doi":"10.1016/j.newast.2024.102316","DOIUrl":"10.1016/j.newast.2024.102316","url":null,"abstract":"<div><div>Dark matter subhalos play an important role in galaxy formation and evolution. However, accurate prediction of dark matter properties remains a challenge of modern-day astronomy. In recent times, machine learning (ML) tools have shown promising results in solving numerous astrophysical problems. In this paper, we use data from the EAGLE simulations to determine the total mass and the half-mass radius of dark matter subhalos using structural properties of gas, star, black hole, and photometric features using gradient boosted decision trees (GBDT) and dense neural network. GBDT does not require data preprocessing, and results in better performance compared to the neural network. According to GBDT, the most important feature for subhalo radius and mass estimation is gas radius and black hole mass respectively. The all-features combined approach results in the highest test accuracy — Pearson’s correlation coefficient = 0.947 and 0.981, coefficient of determination = 0.898 and 0.962, normalized median absolute deviation = 0.111 and 0.114 for radius and mass respectively. We evaluate our model for masses and redshifts beyond its training range and find that GBDT demonstrates significantly better extrapolation capabilities than the neural network. We also test our model on simulations with different resolutions, and find that the discrepancies lie within 10% if the resolution is changed. This novel study incorporates the structural parameters of gas and black hole to determine the dark matter properties using a ML-based approach. The promising results of this study prove that ML tools can improve our current understanding of dark matter, and answer some of the basic cosmological questions.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"115 ","pages":"Article 102316"},"PeriodicalIF":1.9,"publicationDate":"2024-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142527652","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 : 2024-10-04DOI: 10.1016/j.newast.2024.102314
Adnan Malik , Zoya Asghar , M. Farasat Shamir , Fatemah Mofarreh
This paper is devoted to investigating the dynamics of charged stellar structures with Bardeen exterior geometry. For this purpose, firstly a proposed metric coefficient is utilized, which is defined as . Here, and are arbitrary constants determined from matching conditions and is a positive integer. The pressure and density profiles are found to be positive and monotonically decreasing, with maximum values occurring at the center. Furthermore, the energy conditions and causality conditions are satisfied, and the adiabatic index falls within an acceptable range. The second part of the paper focuses on the dynamics of rotating stars. Numerical values for relevant parameters are assumed to obtain the masses and radii of stars within the desired range. Five different compact stars, namely, , , , , and , are considered. The behavior of the moment of inertia of the sphere against the solar mass is investigated, revealing an increase in the moment of inertia with an increase in solar mass. Furthermore, the relationships of mass and energy density against the radius of the compact structure exhibit natural behavior, supporting the acceptability of the analysis. Overall, the study supports the existence of realistic charged compact structures with Bardeen exterior geometry.
本文致力于研究具有巴丁外部几何形状的带电恒星结构的动力学。这里，h 和 N 是根据匹配条件确定的任意常数，m 是正整数。研究发现，压力和密度曲线均为正值且单调递减，最大值出现在中心位置。此外，还满足了能量条件和因果关系条件，绝热指数也在可接受的范围内。论文的第二部分侧重于旋转恒星的动力学。假定了相关参数的数值，以便在所需范围内获得恒星的质量和半径。本文考虑了五颗不同的紧凑型恒星，即 VelaX-1、CenX-3、4U1820-30、4U1608-52 和 PSR1903+327。研究了球体惯性矩与太阳质量的关系，发现惯性矩随着太阳质量的增加而增加。此外，质量和能量密度与紧凑结构半径的关系表现出自然的行为，支持了分析的可接受性。总之，这项研究支持了具有巴丁外部几何形状的现实带电紧凑结构的存在。
{"title":"Slowly rotating charged Bardeen stellar structure","authors":"Adnan Malik , Zoya Asghar , M. Farasat Shamir , Fatemah Mofarreh","doi":"10.1016/j.newast.2024.102314","DOIUrl":"10.1016/j.newast.2024.102314","url":null,"abstract":"<div><div>This paper is devoted to investigating the dynamics of charged stellar structures with Bardeen exterior geometry. For this purpose, firstly a proposed metric coefficient is utilized, which is defined as <span><math><mrow><mi>a</mi><mo>=</mo><mi>N</mi><msup><mrow><mfenced><mrow><mn>1</mn><mo>+</mo><mn>2</mn><mi>h</mi><msup><mrow><mi>r</mi></mrow><mrow><mn>2</mn></mrow></msup></mrow></mfenced></mrow><mrow><mi>m</mi><mo>/</mo><mn>2</mn></mrow></msup></mrow></math></span>. Here, <span><math><mi>h</mi></math></span> and <span><math><mi>N</mi></math></span> are arbitrary constants determined from matching conditions and <span><math><mi>m</mi></math></span> is a positive integer. The pressure and density profiles are found to be positive and monotonically decreasing, with maximum values occurring at the center. Furthermore, the energy conditions and causality conditions are satisfied, and the adiabatic index falls within an acceptable range. The second part of the paper focuses on the dynamics of rotating stars. Numerical values for relevant parameters are assumed to obtain the masses and radii of stars within the desired range. Five different compact stars, namely, <span><math><mrow><mi>V</mi><mi>e</mi><mi>l</mi><mi>a</mi><mi>X</mi><mo>−</mo><mn>1</mn></mrow></math></span>, <span><math><mrow><mi>C</mi><mi>e</mi><mi>n</mi><mi>X</mi><mo>−</mo><mn>3</mn></mrow></math></span>, <span><math><mrow><mn>4</mn><mi>U</mi><mn>1820</mn><mo>−</mo><mn>30</mn></mrow></math></span>, <span><math><mrow><mn>4</mn><mi>U</mi><mn>1608</mn><mo>−</mo><mn>52</mn></mrow></math></span>, and <span><math><mrow><mi>P</mi><mi>S</mi><mi>R</mi><mn>1903</mn><mo>+</mo><mn>327</mn></mrow></math></span>, are considered. The behavior of the moment of inertia of the sphere against the solar mass is investigated, revealing an increase in the moment of inertia with an increase in solar mass. Furthermore, the relationships of mass and energy density against the radius of the compact structure exhibit natural behavior, supporting the acceptability of the analysis. Overall, the study supports the existence of realistic charged compact structures with Bardeen exterior geometry.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"114 ","pages":"Article 102314"},"PeriodicalIF":1.9,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418764","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 : 2024-10-01DOI: 10.1016/j.newast.2024.102315
Noah Ferich , Anna C. Childs , Jason H. Steffen
Previous research suggests that impacts between planetary embryos and planetesimals during the late stages of planet formation can often determine the percentages of core and mantle material that compose the newly formed planets in a system. Previous studies have attempted to include the composition-changing effects of these collisions in N-body simulations of planet formation, often as post-processing codes. In this paper, we present the Differentiated Body Composition Tracker, a new post-processing tool that uses collisional data collected from the N-body integrator REBOUND to determine the amount of core and mantle material that is transferred between colliding objects and the resulting fragments during an impact. We demonstrate how this code works using the data from 50 REBOUND simulations of planet formation and explore how the parameters in the code affect the core mass fractions of the remaining objects from these simulations. We then investigate how non-uniform distributions of core material across an initial disc affect the final core mass fractions of planets. Under ideal conditions, we find that a combination of giant impacts and planetary embryos enriched in core material could create some of the iron-rich planets that have been discovered.
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Pub Date : 2024-09-27DOI: 10.1016/j.newast.2024.102313
Jérémy Couturier, Alice C. Quillen, Miki Nakajima
NcorpiN is a general purpose N-body software initially developed for the time-efficient integration of collisional and fragmenting systems of planetesimals or moonlets orbiting a central mass. It features a fragmentation model, based on crater scaling and ejecta models, able to realistically simulate a violent impact.
The user of NcorpiN can choose between four different built-in modules to compute self-gravity and detect collisions. One of these makes use of a mesh-based algorithm to treat mutual interactions in time. Another module, much more efficient than the standard Barnes–Hut tree code, is a tree-based algorithm called FalcON. It relies on fast multipole expansion for gravity computation and we adapted it to collision detection as well. Computational time is reduced by building the tree structure using a three-dimensional Hilbert curve. For the same precision in mutual gravity computation, NcorpiN is found to be up to 25 times faster than the famous software REBOUND.
NcorpiN is written entirely in the C language and only needs a C compiler to run. A python add-on, that requires only basic python libraries, produces animations of the simulations from the output files. NcorpiN can communicate with REBOUND’s webGL viewer via MPI for 3D visualization. The name NcorpiN, reminding of a scorpion, comes from the French N-corps, meaning N-body, and from the mathematical notation , due to the running time of the software being almost linear in the total number of bodies. NcorpiN detects collisions and computes mutual gravity faster than REBOUND, and unlike other N-body integrators, it can resolve a collision by fragmentation. The fast multipole expansions are implemented up to order eight to allow for a high precision in mutual gravity computation.
NcorpiON 是一款通用 N 体软件，最初是为高效整合环绕中心质量的类地行星或小行星的碰撞和碎裂系统而开发的。NcorpiON 的用户可以选择四种不同的内置模块来计算自重力和检测碰撞。其中一个模块利用基于网格的算法在 O(N) 时间内处理相互影响。另一个模块比标准的巴恩斯-胡特树代码更高效，它是一种基于树的 O(N) 算法，名为 FalcON。它依靠快速多极扩展进行重力计算，我们也将其用于碰撞检测。通过使用三维希尔伯特曲线构建树形结构，计算时间得以缩短。在相互重力计算精度相同的情况下，NcorpiON 比著名软件 REBOUND 快 25 倍。NcorpiON 完全由 C 语言编写，只需一个 C 编译器即可运行。一个只需基本 Python 库的 Python 附加组件可从输出文件中生成模拟动画。NcorpiON 可通过 MPI 与 REBOUND 的 webGL 浏览器通信，实现 3D 可视化。NcorpiON 的名字让人联想到蝎子，它来自法文 N-corps，意为 N 个体，也来自数学符号 O(N)，因为软件的运行时间几乎与 N 个体的总数成线性关系。NcorpiON 检测碰撞和计算相互引力的速度比 REBOUND 更快，而且与其他 N 体积分器不同，它可以通过碎裂来解决碰撞问题。快速多极扩展的阶数高达 8 阶，从而实现了高精度的相互引力计算。
{"title":"NcorpiON : A O(N) software for N-body integration in collisional and fragmenting systems","authors":"Jérémy Couturier, Alice C. Quillen, Miki Nakajima","doi":"10.1016/j.newast.2024.102313","DOIUrl":"10.1016/j.newast.2024.102313","url":null,"abstract":"<div><div>Ncorpi<span><math><mi>O</mi></math></span>N is a general purpose N-body software initially developed for the time-efficient integration of collisional and fragmenting systems of planetesimals or moonlets orbiting a central mass. It features a fragmentation model, based on crater scaling and ejecta models, able to realistically simulate a violent impact.</div><div>The user of Ncorpi<span><math><mi>O</mi></math></span>N can choose between four different built-in modules to compute self-gravity and detect collisions. One of these makes use of a mesh-based algorithm to treat mutual interactions in <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>N</mi><mo>)</mo></mrow></mrow></math></span> time. Another module, much more efficient than the standard Barnes–Hut tree code, is a <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>N</mi><mo>)</mo></mrow></mrow></math></span> tree-based algorithm called FalcON. It relies on fast multipole expansion for gravity computation and we adapted it to collision detection as well. Computational time is reduced by building the tree structure using a three-dimensional Hilbert curve. For the same precision in mutual gravity computation, Ncorpi<span><math><mi>O</mi></math></span>N is found to be up to 25 times faster than the famous software REBOUND.</div><div>Ncorpi<span><math><mi>O</mi></math></span>N is written entirely in the C language and only needs a C compiler to run. A python add-on, that requires only basic python libraries, produces animations of the simulations from the output files. Ncorpi<span><math><mi>O</mi></math></span>N can communicate with REBOUND’s webGL viewer via MPI for 3D visualization. The name Ncorpi<span><math><mi>O</mi></math></span>N, reminding of a scorpion, comes from the French <em>N-corps</em>, meaning N-body, and from the mathematical notation <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>N</mi><mo>)</mo></mrow></mrow></math></span>, due to the running time of the software being almost linear in the total number <span><math><mi>N</mi></math></span> of bodies. Ncorpi<span><math><mi>O</mi></math></span>N detects collisions and computes mutual gravity faster than REBOUND, and unlike other N-body integrators, it can resolve a collision by fragmentation. The fast multipole expansions are implemented up to order eight to allow for a high precision in mutual gravity computation.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"114 ","pages":"Article 102313"},"PeriodicalIF":1.9,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418759","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 : 2024-09-24DOI: 10.1016/j.newast.2024.102312
A Ansar Ahamed , S Prasanna Subramanian , A Mujiber Rahman , A Kubera Raja , K Mahalakshmi , TK Thirumalaisamy
In the present work, propagation of an earth directed fast and wide Coronal Mass Ejection event on 17 February 2023 is studied in detail. The complex magnetic configuration in the Active Region (AR) 13229 at N25E64 caused an intensive X2.3 flare with a peak at 19:38 UT. It is followed by a massive halo CME event observed in the LASCO C3 coronagraph with a linear speed of 930 km/s and shock speed of 1300 km/s. A low frequency Type II emission was detected in the frequency range 10 MHz – 180 kHz during 20:30 UT-04:45 UT on 18 Feb 2023 by space borne Wind/WAVES instrument. From the OMNI data, the IP shock and the ICME reached earth's magnetosphere on 20 Feb 2023. A fast forward type shock was observed using OMNI high resolution data. The IP shock and ICME affected the Galactic Cosmic ray (GCR) detection. This event caused large magnetic turbulences in sheath region caused a major geomagnetic storm (∼-100 nT).
{"title":"Study of solar activities associated with a Halo CME on 17 Feb 2023 event","authors":"A Ansar Ahamed , S Prasanna Subramanian , A Mujiber Rahman , A Kubera Raja , K Mahalakshmi , TK Thirumalaisamy","doi":"10.1016/j.newast.2024.102312","DOIUrl":"10.1016/j.newast.2024.102312","url":null,"abstract":"<div><div>In the present work, propagation of an earth directed fast and wide Coronal Mass Ejection event on 17 February 2023 is studied in detail. The complex magnetic configuration in the Active Region (AR) 13229 at N25E64 caused an intensive X2.3 flare with a peak at 19:38 UT. It is followed by a massive halo CME event observed in the LASCO C3 coronagraph with a linear speed of 930 km/s and shock speed of 1300 km/s. A low frequency Type II emission was detected in the frequency range 10 MHz – 180 kHz during 20:30 UT-04:45 UT on 18 Feb 2023 by space borne Wind/WAVES instrument. From the OMNI data, the IP shock and the ICME reached earth's magnetosphere on 20 Feb 2023. A fast forward type shock was observed using OMNI high resolution data. The IP shock and ICME affected the Galactic Cosmic ray (GCR) detection. This event caused large magnetic turbulences in sheath region caused a major geomagnetic storm (∼-100 nT).</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"114 ","pages":"Article 102312"},"PeriodicalIF":1.9,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418763","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}
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