Our goal is to obtain a set of global transonic accretion solutions for magnetized dissipative accretion flows around non-rotating black holes. To achieve this, we have considered a steady state, axisymmetric, and viscous advection-dominated accretion disc. Additionally, we have investigated the effects of thermal conduction and bremsstrahlung cooling on hot accretion flow. We also have examined the properties of the dynamical variables of the flow in their presence. We have found that the nature of transonic solutions is modified by changing the thermal conduction parameter and cooling factor. We have determined the critical values of the thermal conduction and cooling parameters that provide the global accretion solutions. Furthermore, we have estimated the disc’s luminosity in our model and have applied it to Sgr A
{"title":"Global Transonic Solution of magnetized dissipative accretion flow around non-rotating black holes with thermal conduction","authors":"Sakine Rezaie , Maryam Ghasemnezhad, Mojtaba Golshani","doi":"10.1016/j.newast.2024.102348","DOIUrl":"10.1016/j.newast.2024.102348","url":null,"abstract":"<div><div>Our goal is to obtain a set of global transonic accretion solutions for magnetized dissipative accretion flows around non-rotating black holes. To achieve this, we have considered a steady state, axisymmetric, and viscous advection-dominated accretion disc. Additionally, we have investigated the effects of thermal conduction and bremsstrahlung cooling on hot accretion flow. We also have examined the properties of the dynamical variables of the flow in their presence. We have found that the nature of transonic solutions is modified by changing the thermal conduction parameter and cooling factor. We have determined the critical values of the thermal conduction and cooling parameters that provide the global accretion solutions. Furthermore, we have estimated the disc’s luminosity in our model and have applied it to Sgr A<span><math><msup><mrow></mrow><mrow><mo>∗</mo></mrow></msup></math></span></div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102348"},"PeriodicalIF":1.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095036","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 : 2024-12-17DOI: 10.1016/j.newast.2024.102342
Yun Zhou, Zhongmu Li
Open clusters (OCs) play an important role in the study of star formation and the structural evolution of the Milky Way. This paper fits the color-magnitude diagrams (CMDs) of 17 OCs using a tool called Powerful CMD, with the aim of studying the effect of inclusion of binary stars on the fitting of cluster CMDs with clear giant branches. The fitting results of these star clusters were analyzed and compared under two scenarios, i.e., single-star isochrone fitting and binary-star isochrone fitting. In the binary-star isochrone fitting, the binary fraction is greater than 0 and no larger than 1, which is determined by Powerful CMD based on the goodness of fit to the CMD. The research findings indicate that binaries enhance the goodness of fit for all sample star clusters. In particular, the fit to giant branches becomes better when binary stars are considered. Furthermore, binaries contribute to improving accuracy in determining the fundamental parameters such as age, color excess, and distance modulus for star clusters, because the parameter uncertainties become smaller when binary stars are included in theoretical models. Moreover, the distance modulus and age of clusters become larger when binary-star isochrones are used instead single-star isochrones. The results suggest that one should not neglect the influence of binaries on the shape of giant branches and their role in determining fundamental parameters, in the CMD studies of star clusters.
{"title":"How inclusion of binaries affects the fitting of giant branches and determination of fundamental parameters of star clusters","authors":"Yun Zhou, Zhongmu Li","doi":"10.1016/j.newast.2024.102342","DOIUrl":"10.1016/j.newast.2024.102342","url":null,"abstract":"<div><div>Open clusters (OCs) play an important role in the study of star formation and the structural evolution of the Milky Way. This paper fits the color-magnitude diagrams (CMDs) of 17 OCs using a tool called Powerful CMD, with the aim of studying the effect of inclusion of binary stars on the fitting of cluster CMDs with clear giant branches. The fitting results of these star clusters were analyzed and compared under two scenarios, i.e., single-star isochrone fitting and binary-star isochrone fitting. In the binary-star isochrone fitting, the binary fraction is greater than 0 and no larger than 1, which is determined by Powerful CMD based on the goodness of fit to the CMD. The research findings indicate that binaries enhance the goodness of fit for all sample star clusters. In particular, the fit to giant branches becomes better when binary stars are considered. Furthermore, binaries contribute to improving accuracy in determining the fundamental parameters such as age, color excess, and distance modulus for star clusters, because the parameter uncertainties become smaller when binary stars are included in theoretical models. Moreover, the distance modulus and age of clusters become larger when binary-star isochrones are used instead single-star isochrones. The results suggest that one should not neglect the influence of binaries on the shape of giant branches and their role in determining fundamental parameters, in the CMD studies of star clusters.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102342"},"PeriodicalIF":1.9,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095023","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 : 2024-12-16DOI: 10.1016/j.newast.2024.102345
Mohammed Tobrej, Binay Rai, Manoj Ghising, Ruchi Tamang, Bikash Chandra Paul
We present broadband X-ray observations of the High Mass X-ray Binary (HMXB) pulsar SMC X-2, using concurrent NuSTAR and NICER observations during its 2022 outburst. The source is found to be spinning with a period of 2.37281(3) s. We confirm the existence of cyclotron resonant scattering feature (CRSF) at 31 keV in addition to the iron emission line in the X-ray continuum of the source. Spectral analysis performed with the physical bulk and thermal Comptonization model indicates that the bulk Comptonization dominates the thermal Comptonization. Using phase-resolved spectroscopy, we have investigated the variations of the spectral parameters relative to pulse phase that may be due to the complex structure of magnetic field of the pulsar or the impact of the emission geometry. It is observed that the spectral parameters exhibit significant variabilities relative to the pulsed phase. Time-resolved spectroscopy is employed to examine the evolution of the continuum and changes in the spectral characteristics. Measurements of luminosity along with variations in cyclotron line energy and photon index suggest that the source may be accreting in the super-critical regime.
{"title":"Spectro-timing analysis of Be X-ray pulsar SMC X-2 during the 2022 outburst","authors":"Mohammed Tobrej, Binay Rai, Manoj Ghising, Ruchi Tamang, Bikash Chandra Paul","doi":"10.1016/j.newast.2024.102345","DOIUrl":"10.1016/j.newast.2024.102345","url":null,"abstract":"<div><div>We present broadband X-ray observations of the High Mass X-ray Binary (HMXB) pulsar SMC X-2, using concurrent NuSTAR and NICER observations during its 2022 outburst. The source is found to be spinning with a period of 2.37281(3) s. We confirm the existence of cyclotron resonant scattering feature (CRSF) at <span><math><mo>∼</mo></math></span> 31 keV in addition to the iron emission line in the X-ray continuum of the source. Spectral analysis performed with the physical bulk and thermal Comptonization model indicates that the bulk Comptonization dominates the thermal Comptonization. Using phase-resolved spectroscopy, we have investigated the variations of the spectral parameters relative to pulse phase that may be due to the complex structure of magnetic field of the pulsar or the impact of the emission geometry. It is observed that the spectral parameters exhibit significant variabilities relative to the pulsed phase. Time-resolved spectroscopy is employed to examine the evolution of the continuum and changes in the spectral characteristics. Measurements of luminosity along with variations in cyclotron line energy and photon index suggest that the source may be accreting in the super-critical regime.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102345"},"PeriodicalIF":1.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095038","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 : 2024-12-16DOI: 10.1016/j.newast.2024.102344
Bess Rioborue Agbogidi , Aguda Ekele Vincent , Benson Ade Eniola Afere , Sani Doro Ibrahim
This paper discusses the existence, location, and liner stability of equilibrium points around a rotating dipole in the framework of the circular restricted three-body problem. The rotating dipole system consists of two finite bodies of masses and rigidly connected by a massless rod in a constant characteristic distance. The idea is to consider that the bigger primary body is an oblate spheroid and the smaller one is a point mass together with small perturbations in the Coriolis and centrifugal forces of the primaries. Firstly, these equilibria are determined numerically and, depending on the force ratio and mass factor values, their number may be three or five. It is found that the positions of these equilibria depend on all the system parameters except small perturbation in the Coriolis force. The linear stability of each equilibrium point is also examined. A simulation is done by using two typical highly irregular shaped asteroids, 216-Kleopatra and 1620-Geographos, for which it is found that three collinear and two non-collinear equilibria exist for each system. The positions of these equilibria and their stability as well as the zero-velocity curves under variations of the aforementioned perturbations have been determined numerically. It is seen that the positions of the equilibria are affected by the parameters of the problem, since they are shifted from the classical restricted three-body problem on the –axis and out of the –axis, respectively. The linear stability of these equilibria is investigated for the asteroid systems, and they are found to be linearly unstable.
{"title":"Equilibrium points in the perturbed rotating mass dipole system with oblateness","authors":"Bess Rioborue Agbogidi , Aguda Ekele Vincent , Benson Ade Eniola Afere , Sani Doro Ibrahim","doi":"10.1016/j.newast.2024.102344","DOIUrl":"10.1016/j.newast.2024.102344","url":null,"abstract":"<div><div>This paper discusses the existence, location, and liner stability of equilibrium points around a rotating dipole in the framework of the circular restricted three-body problem. The rotating dipole system consists of two finite bodies of masses <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>1</mn></mrow></msub></math></span> and <span><math><msub><mrow><mi>m</mi></mrow><mrow><mn>2</mn></mrow></msub></math></span> rigidly connected by a massless rod in a constant characteristic distance. The idea is to consider that the bigger primary body is an oblate spheroid and the smaller one is a point mass together with small perturbations in the Coriolis and centrifugal forces of the primaries. Firstly, these equilibria are determined numerically and, depending on the force ratio and mass factor values, their number may be three or five. It is found that the positions of these equilibria depend on all the system parameters except small perturbation in the Coriolis force. The linear stability of each equilibrium point is also examined. A simulation is done by using two typical highly irregular shaped asteroids, 216-Kleopatra and 1620-Geographos, for which it is found that three collinear and two non-collinear equilibria exist for each system. The positions of these equilibria and their stability as well as the zero-velocity curves under variations of the aforementioned perturbations have been determined numerically. It is seen that the positions of the equilibria are affected by the parameters of the problem, since they are shifted from the classical restricted three-body problem on the <span><math><mi>x</mi></math></span>–axis and out of the <span><math><mi>x</mi></math></span>–axis, respectively. The linear stability of these equilibria is investigated for the asteroid systems, and they are found to be linearly unstable.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102344"},"PeriodicalIF":1.9,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095037","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}
We obtained newly BV light curves for the contact binary BO Ari in 2023. The multi-color light curves were analyzed using the Wilson–Devinney (2013) program, which solutions reveal that BO Ari is a middle contact binary with q = 0.1778, f = 48% and a small temperature difference of 92 K. All minimum times were collected to re-calculated O-C. The O-C curves show a cyclic oscillation ( = 0.00337 d, = 16.35 yr) superimposed on a long-term decreasing (dP/dt = d ). This secular period decrease may be due to mass transfer from the more massive component to the less massive one. The cyclic trend was explained by the light-travel time effect due to the presence of a third body or magnetic activity. With this long-term mass transferring, the fill-out degree will increase. Furtherly, BO Ari will evolve into a deeply contact binary. In addition, during the monitoring of the space telescope Transiting Exoplanet Survey Satellite (TESS), it is the first time to discover continuous variation of the O’Connell effect in each cycle, obviously the positive O’Connell effect changes to a negative one over a short time. These phenomena imply the presence of possible magnetic activity on the surface of the component. Based on these fitting parameters, the hot spot and dark spot were found on the components.
{"title":"Continuous O ’Connell effect and period variations of solar-like totally eclipsing contact binary BO Ari","authors":"Meng Guo , Jingjing Wang , Jing Zhang , Xiaoman Tian","doi":"10.1016/j.newast.2024.102341","DOIUrl":"10.1016/j.newast.2024.102341","url":null,"abstract":"<div><div>We obtained newly BV<span><math><mrow><msub><mrow><mi>R</mi></mrow><mrow><mi>c</mi></mrow></msub><msub><mrow><mi>I</mi></mrow><mrow><mi>c</mi></mrow></msub></mrow></math></span> light curves for the contact binary BO Ari in 2023. The multi-color light curves were analyzed using the Wilson–Devinney (2013) program, which solutions reveal that BO Ari is a middle contact binary with <em>q</em> = 0.1778, <em>f</em> = 48% and a small temperature difference of 92 K. All minimum times were collected to re-calculated <em>O-C</em>. The <em>O-C</em> curves show a cyclic oscillation (<span><math><msub><mrow><mi>A</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> = 0.00337 d, <span><math><msub><mrow><mi>T</mi></mrow><mrow><mn>3</mn></mrow></msub></math></span> = 16.35 yr) superimposed on a long-term decreasing (<em>dP/dt</em> = <span><math><mrow><mo>−</mo><mn>1</mn><mo>.</mo><mn>63</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>7</mn></mrow></msup></mrow></math></span> d <span><math><msup><mrow><mi>yr</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>). This secular period decrease may be due to mass transfer from the more massive component to the less massive one. The cyclic trend was explained by the light-travel time effect due to the presence of a third body or magnetic activity. With this long-term mass transferring, the fill-out degree will increase. Furtherly, BO Ari will evolve into a deeply contact binary. In addition, during the monitoring of the space telescope Transiting Exoplanet Survey Satellite (TESS), it is the first time to discover continuous variation of the O’Connell effect in each cycle, obviously the positive O’Connell effect changes to a negative one over a short time. These phenomena imply the presence of possible magnetic activity on the surface of the component. Based on these fitting parameters, the hot spot and dark spot were found on the components.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102341"},"PeriodicalIF":1.9,"publicationDate":"2024-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103877","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}
This study investigates the orbital period variation and physical parameters of the eclipsing binary system V2802 Orionis. Observations were conducted at the Regional Observatory for the Public, Nakhon Ratchasima (ROP-NMA), under the National Astronomical Research Institute of Thailand (NARIT), using Johnson-Cousins B, V, RC, and IC filters. Light curves obtained between 2021 and 2023 were analyzed with the Wilson–Devinney (W-D) code, revealing a mass ratio of q = 2.902(±0.006), an inclination of i = 88.6(±0.4) degree, and a secondary star temperature T2 = 5030(±3) K. Our results indicate that V2802 Orionis is a W-type W UMa binary star with a shallow degree of contact (16.6 %) and variability due to a spot on the primary component. The orbital period shows a secular decrease at a rate of 1.12(±0.09)×10−7 day year−1, attributed to mass transfer from the more massive to the less massive component. Additionally, a period variation with a cycle 5.1(±0.1) years suggests the presence of a third body, with a mass of 0.14(±0.01) M☉ and a separation of 3.2(±0.1) AU from the binary system. The masses, radii, and luminosities of the primary and secondary stars are estimated as M1 = 0.65(±0.001) M☉, M2 = 0.77 M☉, R1 = 0.56(±0.01) R☉, R2 = 0.91(±0.01) R☉, L1 = 0.21(±0.01) L☉, and L2 = 0.48(±0.01) L☉. Evolutionary analysis on the Hertzsprung-Russell diagram shows that the primary star (less massive) has evolved away from the main-sequence, while the secondary (more massive) remains on the main sequence star.
{"title":"Orbital period variation of W UMa binary star V2802 Orionis","authors":"Ronnakrit Rattanamala , Pornapa Artsang , Supachai Awiphan","doi":"10.1016/j.newast.2024.102343","DOIUrl":"10.1016/j.newast.2024.102343","url":null,"abstract":"<div><div>This study investigates the orbital period variation and physical parameters of the eclipsing binary system V2802 Orionis. Observations were conducted at the Regional Observatory for the Public, Nakhon Ratchasima (ROP-NMA), under the National Astronomical Research Institute of Thailand (NARIT), using Johnson-Cousins <em>B, V, R</em><sub>C</sub>, and <em>I</em><sub>C</sub> filters. Light curves obtained between 2021 and 2023 were analyzed with the Wilson–Devinney (W-D) code, revealing a mass ratio of <em>q</em> = 2.902(±0.006), an inclination of <em>i</em> = 88.6(±0.4) degree, and a secondary star temperature <em>T</em><sub>2</sub> = 5030(±3) K. Our results indicate that V2802 Orionis is a W-type W UMa binary star with a shallow degree of contact (16.6 %) and variability due to a spot on the primary component. The orbital period shows a secular decrease at a rate of 1.12(±0.09)×10<sup>−7</sup> day year<sup>−1</sup>, attributed to mass transfer from the more massive to the less massive component. Additionally, a period variation with a cycle 5.1(±0.1) years suggests the presence of a third body, with a mass of 0.14(±0.01) M<sub>☉</sub> and a separation of 3.2(±0.1) AU from the binary system. The masses, radii, and luminosities of the primary and secondary stars are estimated as <em>M</em><sub>1</sub> = 0.65(±0.001) M<sub>☉</sub>, <em>M</em><sub>2</sub> = 0.77 M<sub>☉</sub>, <em>R</em><sub>1</sub> = 0.56(±0.01) R<sub>☉</sub>, <em>R</em><sub>2</sub> = 0.91(±0.01) R<sub>☉</sub>, <em>L</em><sub>1</sub> = 0.21(±0.01) L<sub>☉</sub>, and <em>L</em><sub>2</sub> = 0.48(±0.01) L<sub>☉</sub>. Evolutionary analysis on the Hertzsprung-Russell diagram shows that the primary star (less massive) has evolved away from the main-sequence, while the secondary (more massive) remains on the main sequence star.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102343"},"PeriodicalIF":1.9,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103876","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 : 2024-12-12DOI: 10.1016/j.newast.2024.102317
Lajos G. Balázs , Gábor B. Kovács
Recent space-borne and ground-based observations provide photometric measurements as time series. The data points are nearly continuous over a limited observational interval or randomly scattered over a long period. The effect of interstellar dust extinction in the near-infrared range is only 10% of that measured in the visual (V) range. However, the sensitivity of the light curve shape to the physical parameters in the near-infrared is significantly lower. So, interpreting these types of data sets requires new approaches like the different large-scale surveys, which create similar problems with big data. Using a selected data set, we provide a method for applying routines implemented in R to extract most information of measurements to determine physical parameters, which can also be used in automatic classification schemes and pipeline processing.
We made a multivariate classification of 131 Cepheid light curves (LC) in J,H, and K colors by applying routines of R, where all the LCs were represented in 20D parameter space in these colors separately. Performing a Principal Component Analysis (PCA), we got an orthogonal coordinate system and squared Euclidean distances between LCs. The PCA resulted in 6 significant eigenvalues, which allowed us to reduce the 20-dimension to 6. We also estimated the optimal number of partitions of similar objects and obtained it equal to 7 in each color; their dependence on the period, absolute magnitude, amplitude, and metallicity are also discussed. We computed the Spearman rank correlations, and concerning periods and absolute magnitudes, the first three PCs had correlations at a very high significance level. Similar computations revealed significant relationships between the amplitude and the first two PCs, but the LCs depend only marginally on the metallicity in H and K colors.
The method shown can be generalized and implemented in unsupervised classification schemes and analysis of mixed and biased samples. The analysis of a sample of classical Cepheids observed only in near-infrared bands resulted in the information coded in the light curves being insufficient to determine the stars’ metallicity and identified the mass as the dominating quantity to form the shape of LCs in our sample.
{"title":"Estimation of classical Cepheid’s physical parameters from NIR light curves","authors":"Lajos G. Balázs , Gábor B. Kovács","doi":"10.1016/j.newast.2024.102317","DOIUrl":"10.1016/j.newast.2024.102317","url":null,"abstract":"<div><div>Recent space-borne and ground-based observations provide photometric measurements as time series. The data points are nearly continuous over a limited observational interval or randomly scattered over a long period. The effect of interstellar dust extinction in the near-infrared range is only 10% of that measured in the visual (V) range. However, the sensitivity of the light curve shape to the physical parameters in the near-infrared is significantly lower. So, interpreting these types of data sets requires new approaches like the different large-scale surveys, which create similar problems with big data. Using a selected data set, we provide a method for applying routines implemented in R to extract most information of measurements to determine physical parameters, which can also be used in automatic classification schemes and pipeline processing.</div><div>We made a multivariate classification of 131 Cepheid light curves (LC) in J,H, and K colors by applying routines of R, where all the LCs were represented in 20D parameter space in these colors separately. Performing a Principal Component Analysis (PCA), we got an orthogonal coordinate system and squared Euclidean distances between LCs. The PCA resulted in 6 significant eigenvalues, which allowed us to reduce the 20-dimension to 6. We also estimated the optimal number of partitions of similar objects and obtained it equal to 7 in each color; their dependence on the period, absolute magnitude, amplitude, and metallicity are also discussed. We computed the Spearman rank correlations, and concerning periods and absolute magnitudes, the first three PCs had correlations at a very high significance level. Similar computations revealed significant relationships between the amplitude and the first two PCs, but the LCs depend only marginally on the metallicity in H and K colors.</div><div>The method shown can be generalized and implemented in unsupervised classification schemes and analysis of mixed and biased samples. The analysis of a sample of classical Cepheids observed only in near-infrared bands resulted in the information coded in the light curves being insufficient to determine the stars’ metallicity and identified the mass as the dominating quantity to form the shape of LCs in our sample.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102317"},"PeriodicalIF":1.9,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143095024","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 : 2024-12-06DOI: 10.1016/j.newast.2024.102340
Evgeny Griv , Michael Gedalin , Luis Martinez-Medina , Angeles Pérez-Villegas , Ing-Guey Jiang
In the concluding work of a series of studies, the disk’s spiral structure of the Milky Way is anew considered as a Lin–Shu-type density-wave pattern. As a step forward, a sample of stars from a total of 656161 sources within 3 kpc from the Sun and pc from the disk’s mean plane identified in the Gaia EDR3 is examined. The parameters of Galactic rotation and solar peculiar motion corrected for the effects of 3D density waves, and the radial, azimuthal, and vertical components of the streaming motion of stars due to the spiral arms are derived from the measured velocities of objects. The parameters of the waves are also estimated. Two almost equal scales of periodic compression/rarefaction irregularity of the streaming velocity field with the radial and vertical wavelengths of kpc in the form of a spiral density wave propagating in the disk at the Sun are revealed, which are reasonably related to the global spiral pattern. The Sun is located between the central part and the inner edge of the Orion (Local) wave arm. The spiral pattern in the kinematics of stars is consistent with the spatial distribution of the nearby arm segments traced by young populations. In agreement with the original Lin and Shu proposal, the gravitational field associated with the arms is a small deviation from the total gravitational field of the Galaxy that is axisymmetric in the mean. The very existence of the spiral arrangement in the velocity field suggests that the localized disk is gravitationally unstable.
{"title":"Characterizing the spiral Lin–Shu-type density-wave structure of the Milky Way in the 3-kpc-scale solar neighborhood: Astrophysical conclusions","authors":"Evgeny Griv , Michael Gedalin , Luis Martinez-Medina , Angeles Pérez-Villegas , Ing-Guey Jiang","doi":"10.1016/j.newast.2024.102340","DOIUrl":"10.1016/j.newast.2024.102340","url":null,"abstract":"<div><div>In the concluding work of a series of studies, the disk’s spiral structure of the Milky Way is anew considered as a Lin–Shu-type density-wave pattern. As a step forward, a sample of <span><math><mrow><mo>∼</mo><mn>500000</mn></mrow></math></span> stars from a total of 656161 sources within 3 kpc from the Sun and <span><math><mrow><mo>±</mo><mn>250</mn></mrow></math></span> pc from the disk’s mean plane identified in the <em>Gaia</em> EDR3 is examined. The parameters of Galactic rotation and solar peculiar motion corrected for the effects of 3D density waves, and the radial, azimuthal, and vertical components of the streaming motion of stars due to the spiral arms are derived from the measured velocities of objects. The parameters of the waves are also estimated. Two almost equal scales of periodic compression/rarefaction irregularity of the streaming velocity field with the radial and vertical wavelengths of <span><math><mrow><mo>≲</mo><mn>2</mn></mrow></math></span> kpc in the form of a spiral density wave propagating in the disk at the Sun are revealed, which are reasonably related to the global spiral pattern. The Sun is located between the central part and the inner edge of the Orion (Local) wave arm. The spiral pattern in the kinematics of stars is consistent with the spatial distribution of the nearby arm segments traced by young populations. In agreement with the original Lin and Shu proposal, the gravitational field associated with the arms is a small deviation from the total gravitational field of the Galaxy that is axisymmetric in the mean. The very existence of the spiral arrangement in the velocity field suggests that the localized disk is gravitationally unstable.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102340"},"PeriodicalIF":1.9,"publicationDate":"2024-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143103874","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 : 2024-11-26DOI: 10.1016/j.newast.2024.102329
Qing Dong , Raúl Michel , Zhi-Hua Wang , Iván Mora Zamora
We reported spectroscopy and photometry for five ultra-short period W UMa-type contact binaries. Eleven sets of low resolution spectra are obtained from the Large Sky Area Multiobject Fiber Spectroscopic Telescope (LAMOST) database and analyzed. It has been determined that these systems are late G- to K-type stars: G7V for J0658, G9V for LINEAR 3562115, K0V for PS Com, and K5V for LINEAR 11570575. Additionally, it was observed that the cooler the star, the stronger the sodium absorption line. Seven sets of complete light curves, including two sets of TESS data for PS Com and V0568 Peg, were analyzed using the W-D code. All the five targets are W-subtype systems with mass ratios () greater than 1. The light curves of the two medium contact systems (J0658 and LINEAR 11570575) are symmetric. In contrast, the light curves of the three shallow contact binaries (LINEAR 3562115, PS Com, and V0568 Peg) show differences between their two maxima, Max.I and Max.II, suggesting the presence of cool or hot spots on their surfaces. According to the H-R diagram, the more massive components of these targets are situated between the ZAMS and TAMS, while the less massive ones are overheated due to energy transfer within the common envelope. As these binaries lose angular momentum, they will evolve into deep, low mass ratio contact binaries.
我们报告了五颗超短周期W UMa型接触双星的光谱和测光结果。我们从大天区多天体光纤光谱望远镜（LAMOST）数据库中获得了11组低分辨率光谱，并对其进行了分析。经测定，这些系统都是晚期G型到K型恒星：J0658为G7V，LINEAR 3562115为G9V，PS Com为K0V，LINEAR 11570575为K5V。此外，还观察到恒星温度越低，钠吸收线就越强。利用 W-D 代码分析了七组完整的光变曲线，包括 PS Com 和 V0568 Peg 的两组 TESS 数据。五个目标都是质量比（q）大于 1 的 W 亚型系统。两个中等接触系统（J0658 和 LINEAR 11570575）的光变曲线是对称的。相比之下，三个浅接触双星（LINEAR 3562115、PS Com和V0568 Peg）的光曲线在两个最大值（Max.I和Max.II）之间存在差异，这表明它们的表面存在冷点或热点。根据H-R图，这些目标中质量较大的部分位于ZAMS和TAMS之间，而质量较小的部分则由于共同包层内的能量转移而过热。随着这些双星失去角动量，它们将演变成深层的低质量比接触双星。
{"title":"Spectroscopic and photometric study for five late G- to K-type short-period contact binaries","authors":"Qing Dong , Raúl Michel , Zhi-Hua Wang , Iván Mora Zamora","doi":"10.1016/j.newast.2024.102329","DOIUrl":"10.1016/j.newast.2024.102329","url":null,"abstract":"<div><div>We reported spectroscopy and photometry for five ultra-short period W UMa-type contact binaries. Eleven sets of low resolution spectra are obtained from the Large Sky Area Multiobject Fiber Spectroscopic Telescope (LAMOST) database and analyzed. It has been determined that these systems are late G- to K-type stars: G7V for J0658, G9V for LINEAR 3562115, K0V for PS Com, and K5V for LINEAR 11570575. Additionally, it was observed that the cooler the star, the stronger the sodium absorption line. Seven sets of complete light curves, including two sets of TESS data for PS Com and V0568 Peg, were analyzed using the W-D code. All the five targets are W-subtype systems with mass ratios (<span><math><mi>q</mi></math></span>) greater than 1. The light curves of the two medium contact systems (J0658 and LINEAR 11570575) are symmetric. In contrast, the light curves of the three shallow contact binaries (LINEAR 3562115, PS Com, and V0568 Peg) show differences between their two maxima, Max.I and Max.II, suggesting the presence of cool or hot spots on their surfaces. According to the H-R diagram, the more massive components of these targets are situated between the ZAMS and TAMS, while the less massive ones are overheated due to energy transfer within the common envelope. As these binaries lose angular momentum, they will evolve into deep, low mass ratio contact binaries.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102329"},"PeriodicalIF":1.9,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142747807","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 : 2024-11-23DOI: 10.1016/j.newast.2024.102331
Yves-Henri Sanejouand
Magnitude predictions of CDM, as parametrized by the Planck collaboration, are not consistent with the supernova Ia data of the whole Pantheon+ sample even when, in order to take into account the uncertainty about its value, the Hubble constant is adjusted. This is a likely consequence of the increase of the number of low-redshift supernovae in the Pantheon+ sample, with respect to previous such samples.
In order to find directions in the sky where the Hubble flow is quiet, that is, where model predictions are consistent with both low and high-redshift supernova data, predicted magnitudes of several models were compared to the corrected B band magnitudes of the supernovae of the Pantheon+ sample.
When supernovae at redshifts below 0.035 are ignored, with kmsMpc−1, CDM predictions become consistent with Pantheon+ data. This is also the case when subsets of low-redshift supernovae roughly centered on the direction of the CMB dipole are considered, together with high-redshift ones, at least when CMB and peculiar velocities corrections are taken into account for the redshifts. These results seem robust, since they are also obtained with a simple, single-parameter tired-light model.
{"title":"A robust assessment of the local anisotropy of the Hubble constant in the Pantheon+ sample","authors":"Yves-Henri Sanejouand","doi":"10.1016/j.newast.2024.102331","DOIUrl":"10.1016/j.newast.2024.102331","url":null,"abstract":"<div><div>Magnitude predictions of <span><math><mi>Λ</mi></math></span>CDM, as parametrized by the Planck collaboration, are not consistent with the supernova Ia data of the whole Pantheon+ sample even when, in order to take into account the uncertainty about its value, the Hubble constant is adjusted. This is a likely consequence of the increase of the number of low-redshift supernovae in the Pantheon+ sample, with respect to previous such samples.</div><div>In order to find directions in the sky where the Hubble flow is quiet, that is, where model predictions are consistent with both low and high-redshift supernova data, predicted magnitudes of several models were compared to the corrected B band magnitudes of the supernovae of the Pantheon+ sample.</div><div>When supernovae at redshifts below 0.035 are ignored, with <span><math><mrow><msub><mrow><mi>H</mi></mrow><mrow><mn>0</mn></mrow></msub><mo>=</mo><mn>73</mn><mo>.</mo><mn>4</mn></mrow></math></span> km<span><math><mi>⋅</mi></math></span>s<span><math><mrow><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup><mi>⋅</mi></mrow></math></span>Mpc<sup>−1</sup>, <span><math><mi>Λ</mi></math></span>CDM predictions become consistent with Pantheon+ data. This is also the case when subsets of low-redshift supernovae roughly centered on the direction of the CMB dipole are considered, together with high-redshift ones, at least when CMB and peculiar velocities corrections are taken into account for the redshifts. These results seem robust, since they are also obtained with a simple, single-parameter tired-light model.</div></div>","PeriodicalId":54727,"journal":{"name":"New Astronomy","volume":"116 ","pages":"Article 102331"},"PeriodicalIF":1.9,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721320","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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