New Astronomy最新文献

{"title":"A study of an X-ray flare on the solar analogue V895 Tau","authors":"Gurpreet Singh ,&nbsp;J.C. Pandey ,&nbsp;Umesh Yadava","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":"114 ","pages":"Article 102295"},"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}

{"title":"A temperature scale of 1∼2 eV in the mass–radius relationship of white dwarfs of type DA","authors":"Jin Lim,&nbsp;Ji-Yu Kim,&nbsp;Maurice H.P.M. van Putten","doi":"10.1016/j.newast.2024.102299","DOIUrl":"10.1016/j.newast.2024.102299","url":null,"abstract":"<div><p>The mass–radius relationship of white dwarfs (WDs) is one of their defining characteristics, largely derived from electron degeneracy pressure. We present a model-independent study of the observed mass–radius relationship in WD binaries of Parsons et al. (2017), listing data over a broad temperature range up to about 60,000<!--> <!-->K (5<!--> <!-->eV). The data show an appreciable temperature sensitivity with pronounced intrinsic scatter (beyond measurement uncertainty) for the canonical He-models with proton<span><math><mo>−</mo></math></span>to<span><math><mo>−</mo></math></span>neutron ratio 1:1. We characterize temperature sensitivity by a temperature scale <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>0</mn></mrow></msub></math></span> in model-agnostic power-law relations with temperature normalized radius. For low-mass WDs, the results identify a remarkably modest <span><math><mrow><msub><mrow><mi>T</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mn>1</mn><mo>∼</mo><mn>2</mn></mrow></math></span> <!--> <!-->eV. We comment on a potential interpretation for atmospheres insulating super-Eddington temperature cores from the sub-Eddington photospheres of low-mass WDs.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"114 ","pages":"Article 102299"},"PeriodicalIF":1.9,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001131/pdfft?md5=d857f645e647472fb8bba074407d1ab4&pid=1-s2.0-S1384107624001131-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142148734","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":"Inhibited destruction of dust by supernova in a clumpy medium","authors":"Svyatoslav Yu. Dedikov,&nbsp;Evgenii O. Vasiliev","doi":"10.1016/j.newast.2024.102293","DOIUrl":"10.1016/j.newast.2024.102293","url":null,"abstract":"<div><p>The decrease rate of dust mass due to strong shock waves (<span><math><mrow><msub><mrow><mi>v</mi></mrow><mrow><mi>s</mi></mrow></msub><mo>≥</mo><mn>150</mn></mrow></math></span> km s⁻¹) from supernovae (SNe) estimated for the Milky Way interstellar medium significantly exceeds the overall production rate by both asymptotic giant branch stars and core collapse SNe. The interplay between the production and destruction rates is critically important for evaluation of the net dust outcome from SNe at different conditions. In light of this, we study the dynamics of initially polydisperse dust grains pre-existing in an ambient medium swept up the SN shock front depending on magnitude of inhomogeneity (clumpiness) in the medium. We find that dust destruction inside the bubble is inhibited in more inhomogeneous medium: the larger amount of dust survives for the higher dispersion of density. This trend is set by the interrelation between radiative gas cooling and dust sputtering in different environment. After several radiative times the mass fraction of the survived dust saturates at the level almost independent on the gas mean density. We note that for more clumpy medium the distributions of dust over thermal phases of a gas inside the bubble and over sizes are smoother and flatter in comparison with those in a nearly homogeneous medium.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"114 ","pages":"Article 102293"},"PeriodicalIF":1.9,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001076/pdfft?md5=983f57845804327a2b7b5006fbb6399b&pid=1-s2.0-S1384107624001076-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142129220","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":"Diagnostic approaches for interacting generalized holographic Ricci dark energy models","authors":"Omar Enkhili,&nbsp;Farida Bargach,&nbsp;Dalale Mhamdi,&nbsp;Taoufik Ouali,&nbsp;Ahmed Errahmani","doi":"10.1016/j.newast.2024.102298","DOIUrl":"10.1016/j.newast.2024.102298","url":null,"abstract":"<div><p>In this paper, we present an analytical solution for the interacting generalized holographic dark energy model, assuming a linear interaction rate between dark energy and dark matter. We determine the equation of state parameter, the generalized holographic Ricci dark energy density, the matter density, and the deceleration parameter. By analyzing the behavior of these cosmological parameters, we demonstrate that our model aligns with recent observations and reproduces the late-time accelerated expansion of the Universe. To compare our model with the <span><math><mi>Λ</mi></math></span>CDM model, we use various diagnostic tools including statefinder, <span><math><mrow><mi>O</mi><mi>m</mi><mrow><mo>(</mo><mi>z</mi><mo>)</mo></mrow></mrow></math></span>-diagnostic, statefinder hierarchy, growth rate analysis, and <span><math><msub><mrow><mi>ω</mi></mrow><mrow><mi>H</mi></mrow></msub></math></span>-<span><math><msubsup><mrow><mi>ω</mi></mrow><mrow><mi>H</mi></mrow><mrow><mo>′</mo></mrow></msubsup></math></span> plane. We also analyze the stability of the model by examining the speed of sound. These methods show that the dynamics of the Universe remain very close to that of the standard cosmological model.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102298"},"PeriodicalIF":1.9,"publicationDate":"2024-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142096219","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":"Temporal variability in transmission spectra of H2-dominated exoplanets: The influence of thermal evolution and stellar irradiation on atmospheric composition","authors":"Viktória Kecskeméthy ,&nbsp;Amy Louca ,&nbsp;Yamila Miguel","doi":"10.1016/j.newast.2024.102296","DOIUrl":"10.1016/j.newast.2024.102296","url":null,"abstract":"&lt;div&gt;&lt;p&gt;Planets and their host stars undergo evolutionary changes over time, resulting in variations in internal temperature and incoming radiation, which significantly impact the temperature structure and composition of their atmospheres. These evolving conditions give rise to distinctive features in planetary spectra that are observable only during specific stages of planetary evolution. We aim to understand how the composition of planets with H&lt;sub&gt;2&lt;/sub&gt;-dominated atmospheres changes over longer timescales due to their thermal evolution. We also investigate time-dependent features in the transmission spectra. These features could provide insights in both the formation and evolution of these gaseous planets, as well as the timescales of these changes, enabling us to study the potential variability of exoplanets over time. We evolve a &lt;span&gt;&lt;math&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;0.04 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Jup&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;0.45 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Jup&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; planet around a 1.0 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;⊙&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; and 1.3 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;⊙&lt;/mo&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; star respectively for 10&lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;9&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; years. In both systems, the planets are considered at semi-major axes of 0.1 AU and 1.0 AU. The star-planet systems are evolved by making use of Modules for Experiments in Stellar Astrophysics (MESA). The temperature–pressure profiles are obtained at selected time-steps using an analytical approximation based on the internal and irradiation temperature of the planet at each time step. We then use VULCAN, a photochemical kinetics code, to see how the composition changes with time in the atmosphere due to the thermal evolution of the planets. By making use of the radiative transfer code petitRADTrans, we also simulate the evolution of the transmission spectra of the planets to find potential time-dependent spectral features. Our findings show a prominent change in the CO&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; feature at &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;mn&gt;4&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mi&gt;m&lt;/mi&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. For the 0.45 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Jup&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; case, this feature is visible in the pre-main-sequence phase of the host star, regardless of orbital distance from the host star. In the case of the &lt;span&gt;&lt;math&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;0.04 M&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Jup&lt;/mi&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; planet, this CO&lt;sub&gt;2&lt;/sub&gt; feature is visible until t &lt;span&gt;&lt;math&gt;&lt;mo&gt;≤&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; 10&lt;sup&gt;6&lt;/sup&gt; years, and then it reappears after t &lt;span&gt;&lt;math&gt;&lt;mo&gt;≥&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt; 10&lt;sup&gt;8&lt;/sup&gt; years when the planet is 0.1 AU away the host star. The CH&lt;sub&gt;4&lt;/sub&gt; features ","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102296"},"PeriodicalIF":1.9,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001106/pdfft?md5=d658e35eb5e86085855c30c9d7f75b81&pid=1-s2.0-S1384107624001106-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040012","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":"Pulsation modes of three Delta Scuti stars using Kepler project data: KIC3429637, KIC10451090, KIC2987660","authors":"Amin Shafaeiyeh Hiagh,&nbsp;Nematollah Riazi","doi":"10.1016/j.newast.2024.102294","DOIUrl":"10.1016/j.newast.2024.102294","url":null,"abstract":"<div><p>We have analyzed the light curves of three <span><math><mi>δ</mi></math></span> Scuti stars that were observed by the Kepler Space Telescope. Data collected by the Kepler space telescope, as well as analysis of the light curve of each star and the use of online databases, have been utilized to achieve the objectives of this project. Data has been collected through Kepler's main mission. We compare both data that we get from the Lightkurve package of Python and the KASOC online data centre to verify the data. We select the necessary data like flux, observation date, and the spectral type of the stars. By investigating various types of pulsating variable stars, three Delta Scuti stars have been selected due to their flux, pulsating type, etc. It is observed that most of these stars are pulsating in the p-modes. However, the selected stars pulsate in both p-modes and (possibly) g-modes. We select these stars, due to the lack of articles about them. Furthermore, some physical properties of these stars are deduced from their light curves. In summary, the results of this study indicate that the stars KIC3429637 and KIC10451090 are pulsating only in p-modes, while KIC2987660 is pulsating both in p-modes and g-modes.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102294"},"PeriodicalIF":1.9,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142075885","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":"Combined light curve and radial velocity analysis of the neglected contact binary S Ant","authors":"Olivera Latković,&nbsp;Atila Čeki","doi":"10.1016/j.newast.2024.102291","DOIUrl":"10.1016/j.newast.2024.102291","url":null,"abstract":"<div><p>We present the first combined photometric and spectroscopic solution of the bright southern contact binary S Ant based on the <em>Transiting Exoplanet Survey Satellite</em> (TESS) light curve and the radial velocities from the David Dunlap Observatory survey. S Ant is a W UMa type binary in deep contact, with a mass ratio of 0.34 and a relatively massive and hot F-type primary. Beside the standard modeling of the phase-binned light curve, we also perform “seasonal modeling” where we treat each of the 83 orbital cycles present in the TESS data as a separate light curve. The resulting ensemble of solutions shows evidence of quasi-periodic migration of a long-lived, dark, polar spot. The migration is confirmed independently by eclipse time variations which display remarkably strong correlation with the spot location.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102291"},"PeriodicalIF":1.9,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141978307","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":"The size and shape dependence of the SDSS galaxy bispectrum","authors":"Anindita Nandi ,&nbsp;Sukhdeep Singh Gill ,&nbsp;Debanjan Sarkar ,&nbsp;Abinash Kumar Shaw ,&nbsp;Biswajit Pandey ,&nbsp;Somnath Bharadwaj","doi":"10.1016/j.newast.2024.102292","DOIUrl":"10.1016/j.newast.2024.102292","url":null,"abstract":"&lt;div&gt;&lt;p&gt;We have measured the spherically averaged bispectrum of the SDSS main galaxy sample, considering a volume-limited &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mn&gt;296&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;75&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;Mpc&lt;/mi&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; data cube with mean galaxy number density &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;63&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;Mpc&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; and median redshift &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;102&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. Our analysis considers &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;∼&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;37&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; triangles, for which we have measured the binned bispectrum and analysed its dependence on the size and shape of the triangle. It spans wavenumbers &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;075&lt;/mn&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;434&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;Mpc&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for equilateral triangles, and a smaller range of &lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;/math&gt;&lt;/span&gt; (the largest side) for triangles of other shapes. For all shapes, we find that the measured bispectrum is well modelled by a power law &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mrow&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mi&gt;Mpc&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, where the best-fit values of &lt;span&gt;&lt;math&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; vary with the shape. The parameter &lt;span&gt;&lt;math&gt;&lt;mi&gt;A&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; is the minimum for equilateral triangles and increases as the shape is deformed to linear triangles where the two largest sides are nearly aligned, reaching its maximum value for &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;95&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;75&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;. The values of &lt;span&gt;&lt;math&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;/math&gt;&lt;/span&gt; are all negative, &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;mi&gt;n&lt;/mi&gt;&lt;mo&gt;|&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; is minimum &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;12&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;35&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt; for the shape bin &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mi&gt;μ&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;65&lt;/mn&gt;&lt;mo&gt;,&lt;/mo&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;t&lt;/mi&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;75&lt;/mn&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;, and &lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;8&lt;/mn&gt;&lt;mo&gt;±&lt;/mo&gt;&lt;mn&gt;0&lt;/mn&gt;&lt;mo&gt;.&lt;/mo&gt;&lt;mn&gt;28&lt;/mn&gt;&lt;/mrow","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102292"},"PeriodicalIF":1.9,"publicationDate":"2024-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142006419","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":"Asteroseismology of evolved stars in six star clusters observed by Kepler/K2","authors":"Yun-A Jo,&nbsp;Heon-Young Chang","doi":"10.1016/j.newast.2024.102290","DOIUrl":"10.1016/j.newast.2024.102290","url":null,"abstract":"<div><p>In this study, we have explored the frequency separations, <span><math><mrow><mi>Δ</mi><mi>ν</mi></mrow></math></span> and <span><math><mrow><mi>δ</mi><msub><mrow><mi>ν</mi></mrow><mrow><mn>02</mn></mrow></msub></mrow></math></span>, the height and width of the oscillation power excess, <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>Gauss</mi></mrow></msub></math></span> and <span><math><mrow><mi>δ</mi><msub><mrow><mi>ν</mi></mrow><mrow><mi>env</mi></mrow></msub></mrow></math></span>, as a function of the frequency of maximum power <span><math><msub><mrow><mi>ν</mi></mrow><mrow><mi>max</mi></mrow></msub></math></span> by analyzing 187 evolved stars in six star clusters observed by the <em>Kepler</em>/<em>K2</em> missions. We have also examined the asteroseismic relation in the Christensen-Dalsgaard diagram. Given the importance of scaling relations, the dependency of asteroseismic scaling relations on physical quantities must be verified to reduce systematic errors through the exploration of observational data obtained from various sources. In this context, the star cluster provides a valuable means to assess the age and metallicity. Focusing on evolved stars with <span><math><mrow><mn>30</mn><mspace></mspace><mi>μ</mi><mi>Hz</mi><mo>&lt;</mo><msub><mrow><mi>ν</mi></mrow><mrow><mi>max</mi></mrow></msub><mo>&lt;</mo><mn>220</mn><mspace></mspace><mi>μ</mi><mi>Hz</mi></mrow></math></span>, we have exploited the mass effect without the need for deriving the individual stellar mass. We have found that the considered relations appear to be associated with the age of star clusters, thereby the mass of the stars in a given evolutionary status for star clusters with different ages. By separately considering red giant branch stars and red clump stars, we have found that red clump stars appear more sensitive to the cluster age compared with red giant branch stars. It has been suggested that conclusions regarding the dependency of metallicity should be drawn with due care as outcomes are subject to how to treat metallicity. Finally, we conclude by briefly pointing out implications of our findings on asteroseismic inferences.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102290"},"PeriodicalIF":1.9,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141849232","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":"Further lunar occultations results from the Trebur Observatory, 2021–24","authors":"J.M. Ohlert ,&nbsp;A. Richichi","doi":"10.1016/j.newast.2024.102289","DOIUrl":"10.1016/j.newast.2024.102289","url":null,"abstract":"<div><p>Following up on our initial paper (Richichi and Ohlert, 2021), we report here on 60 lunar occultation events recorded between February 2021 and March 2024 at the Michael Adrian Observatorium. An improved version of the detector was employed for the present work. The program aims mainly at the direct measurement of the angular diameter of late-type stars, and the discovery or confirmation of binary stars with small separations. Among the results, we present first time angular diameter determinations for the late-type M giants IRC +20184 and BL Tau and for the bright carbon star TU Gem. Our diameter result for RX Cnc is the first determination outside the near-IR range. We also discovered or detected directly for the first time companions around SAO 79580, BL Tau again, and SAO 78643. The lunar occultation technique at our facility is capable to reach sources as faint as <span><math><mo>≈</mo></math></span> 10<!--> <!-->V magnitude with an angular resolution at the milliarcsecond level.</p></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"113 ","pages":"Article 102289"},"PeriodicalIF":1.9,"publicationDate":"2024-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S1384107624001039/pdfft?md5=87c54c6a624308f0bc6941d3934cc2c9&pid=1-s2.0-S1384107624001039-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141845323","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}