New Astronomy最新文献

{"title":"Slowly rotating charged Bardeen stellar structure","authors":"","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":null,"pages":null},"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}

{"title":"Composition tracking for collisions between differentiated bodies in REBOUND","authors":"","doi":"10.1016/j.newast.2024.102315","DOIUrl":"10.1016/j.newast.2024.102315","url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142418252","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":"NcorpiON : A O(N) software for N-body integration in collisional and fragmenting systems","authors":"","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":null,"pages":null},"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}

{"title":"Study of solar activities associated with a Halo CME on 17 Feb 2023 event","authors":"","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":null,"pages":null},"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}

{"title":"Discovery of 226 δ Scuti and γ Doradus Stars near NGC 6871 with TESS","authors":"","doi":"10.1016/j.newast.2024.102297","DOIUrl":"10.1016/j.newast.2024.102297","url":null,"abstract":"<div><p>We present the discovery of 269 pulsating variable stars of <span><math><mi>δ</mi></math></span> Scuti, <span><math><mi>γ</mi></math></span> Doradus, and Maia types in the vicinity of the open cluster NGC 6871, using data from the Transiting Exoplanet Survey Satellite (<em>TESS</em>). Our small-scale regional survey centered on the <span><math><mi>δ</mi></math></span> Scuti star V1821 Cyg in the open cluster NGC 6871, covering a radius of one degree. The results include a remarkable total of 1512 newly classified variable stars, comprising the following categories: 105 <span><math><mi>δ</mi></math></span> Scuti stars, 121 <span><math><mi>γ</mi></math></span> Doradus stars, 50 Maia variables, 198 eclipsing binary systems, with 12 exhibiting pulsating or rotating components, 500+ rotating variable stars, and dozens of other types. Out of 1512 newly discovered variable stars, 108 are confirmed members of NGC 6871 with a membership probability exceeding 50%. Notably, dedicated Fourier analyses were applied to eight representative stars from the newly discovered variables. Among these, one star exhibits a rich and complex pulsation spectrum characterized by amplitude variations in dominant pulsations. To contextualize the new pulsators, we plotted them in the Hertzsprung–Russell diagrams alongside the largest known group of class member stars. Surprisingly, both <span><math><mi>δ</mi></math></span> Scuti and <span><math><mi>γ</mi></math></span> Doradus stars occupy nearly the same region in the diagrams, hinting at a potential unified pulsation mechanism. This study contributes valuable insights into the variability census of NGC 6871 and sheds light on the pulsation behavior of different stellar types. Further investigations into the physical properties and evolutionary status of these stars are warranted.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001118/pdfft?md5=e35b0e69d33cf80078eb497ada72afa1&pid=1-s2.0-S1384107624001118-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259947","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}

{"title":"Investigation of motion around out-of-plane points in the restricted three-body problem with variable shape and masses","authors":"","doi":"10.1016/j.newast.2024.102311","DOIUrl":"10.1016/j.newast.2024.102311","url":null,"abstract":"<div><p>The paper examines out-of-plane equilibrium points (OEPs) of the restricted three-body problem with variable masses and shape. The bigger primary varies it shape as the lengths of the semi-axes vary with time. For the autonomized system, two pair of OEPs <span><math><msub><mi>L</mi><mrow><mn>6</mn><mo>,</mo><mn>7</mn><mi>κ</mi></mrow></msub></math></span> and <span><math><msub><mi>L</mi><mrow><mn>8</mn><mo>,</mo><mn>9</mn><mi>κ</mi></mrow></msub></math></span>, are obtained and differ from those of the non-autonomous system due to time <span><math><mi>t</mi></math></span>. The stability of OEPs of both systems is found to be unstable. Further, numerical illustrations is provided when variations in shape of the bigger primary is, a triaxial prolate, a sphere and a triaxial oblate shape. The positions, stability and zero velocity curves (ZVC) of the particle around the OEPs are explored. It is seen that when the bigger primary is a triaxial prolate body, the OEPs <span><math><msub><mi>L</mi><mrow><mn>8</mn><mo>,</mo><mn>9</mn><mi>κ</mi></mrow></msub></math></span> are closer to the primaries than <span><math><msub><mi>L</mi><mrow><mn>6</mn><mo>,</mo><mn>7</mn><mi>κ</mi></mrow></msub></math></span>. However, the converse happens when it is a triaxial oblate body. Also, when the bigger primary is a triaxial oblate body, the OEPs are farther away from the primaries than when it is a triaxial prolate. In the case of the ZVC, it is seen that when the bigger primary is a triaxial prolate body, there is a petal around it, and region of allowed motion of the particle increases, while the region reduces when the bigger primary evolves from a sphere to a triaxial oblate body. This study can be used to describe motion of a dust grain in the vicinity of Betelgeuse, a red giant star whose mass and shape changes with time and its stellar companion.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001258/pdfft?md5=26357da594ce5af4c57b885884db352e&pid=1-s2.0-S1384107624001258-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142241731","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}

{"title":"Analysis of relativistic stellar model under the influence of dark energy equation of state","authors":"","doi":"10.1016/j.newast.2024.102310","DOIUrl":"10.1016/j.newast.2024.102310","url":null,"abstract":"<div><p>Dark energy, one of the mysterious and impactful forms of energy in the cosmos has a crucial role in propelling the rapid expansion of the cosmos. As a result it is highly likely that dark energy interacts with astrophysical objects in some direct or indirect way. The present paper introduces a simplified method to simulate the interaction between energy and conspicuous baryonic matter. It is accomplished by using a dense pulsar named PSRJ1614-2230 as a representative model star. The study involves solving Einsteins field equations within the stars interior using the Kuchowicz spacetime framework. The solutions obtained are then analyzed across physical as well as geometrical parameters such as metric potentials, pressure, density and energy conditions. Based on this analysis, it is suggested that the formation of the star embraced with dark energy equation of state exhibits stability. Importantly the proposed stellar model does not have any singularities, meets the stability criteria. Additionally, numerical results for the adiabatic and abreu index indicate that the model star displays stiffness and resilience against radial adiabatic perturbations.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001246/pdfft?md5=ed059197a5627dc332f85ea383aa12b4&pid=1-s2.0-S1384107624001246-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142169152","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}

{"title":"Exploration of bulk viscous Bianchi type cosmological model in f(T) theory of gravity","authors":"","doi":"10.1016/j.newast.2024.102300","DOIUrl":"10.1016/j.newast.2024.102300","url":null,"abstract":"<div><p>In the present paper, the expansion of Locally Rotational Symmetric (LRS) Bianchi type - I cosmological model have been investigated with Bulk Viscous matter in the context of <span><math><mrow><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></mrow></math></span> theory of gravity, where <span><math><mi>T</mi></math></span> signifies the torsion scalar. The power model, exponential model and linear functional model of the universe have been discussed for choices of <span><math><mrow><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></mrow></math></span>with utilization of the special form of time dependent varying deceleration parameter. The discussion involves the examination of the dynamical behaviour of these models using some dynamical parameters and its graphical representation.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001143/pdfft?md5=c0e8a0ea414cfb13a9d5a191e9c87626&pid=1-s2.0-S1384107624001143-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270676","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}

{"title":"Identifying a point-symmetric morphology in supernova remnant Cassiopeia A: Explosion by jittering jets","authors":"","doi":"10.1016/j.newast.2024.102307","DOIUrl":"10.1016/j.newast.2024.102307","url":null,"abstract":"<div><p>We identify a point-symmetric morphology of the supernova remnant (SNR) Cassiopeia A compatible with shaping by at least two, and more likely more than four, pairs of opposite jets, as expected in the jittering jets explosion mechanism (JJEM) of core-collapse supernovae. Using an old Spitzer Telescope infrared map of argon, we identify seven pairs of opposite morphological features that we connect with lines that cross each other at the same point on the plane of the sky. The opposite morphological features include protrusions, clumps, filaments, and funnels in the main SNR shell. In addition to these seven symmetry axes, we find two tentative symmetry axes (lines). These lines form a point-symmetric wind-rose. We place this point-symmetric wind-rose on a new JWST and X-ray images of Cassiopeia A. We find other morphological features and one more symmetry axis that strengthen the identified point-symmetric morphology. Not all symmetry axes correspond to jets; e.g., some clumps are formed by the compression of ejecta between two jet-inflated lobes (bubbles). The robust point-symmetric morphology in the iconic Cassiopeia A SNR strongly supports the JJEM and poses a severe challenge to the neutrino-driven explosion mechanism.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001210/pdfft?md5=f7430818de058d178d1331b818492af6&pid=1-s2.0-S1384107624001210-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142164222","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}

{"title":"A study of an X-ray flare on the solar analogue V895 Tau","authors":"","doi":"10.1016/j.newast.2024.102295","DOIUrl":"10.1016/j.newast.2024.102295","url":null,"abstract":"<div><p>Using observations with <em>XMM-Newton</em>, we study the characteristics of a flare emanating from a solar analogous V895 Tau. At the peak of the flare, its luminosity reached <span><math><mrow><mn>3</mn><mo>.</mo><mn>3</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>30</mn></mrow></msup></mrow></math></span> <span><math><mrow><mi>erg</mi><mspace></mspace><msup><mrow><mi>s</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math></span>, which is <span><math><mo>∼</mo></math></span> 600 times more energetic than the X10 class flare on the Sun. The quiescent state corona of V895 Tau is depicted by a two-temperature plasma model with temperatures of 3.9 and 11 MK. The flare’s evolution was carefully scrutinized through time-resolved X-ray spectroscopy, unveiling the variations in temperature, emission measure, abundance and luminosity during the flare. The temperature peaked at 36.1 MK, which is approximately four times higher than the pre-flare temperature. Employing a hydrodynamic loop model, we have estimated the half length of the flaring loop to be <span><math><mrow><mn>5</mn><mo>.</mo><mn>9</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>10</mn></mrow></msup></mrow></math></span> cm. Using the loop scaling laws, other loop parameters like density, pressure, volume, and minimum magnetic field are also estimated, and are found to be similar to those of other flares from similar type of stars.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":null,"pages":null},"PeriodicalIF":1.9,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S138410762400109X/pdfft?md5=e95ec425e573cf00bf487479b6b6cf0b&pid=1-s2.0-S138410762400109X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148733","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}