New Astronomy最新文献

We present the discovery of $\gamma$ Doradus-type pulsations in the eclipsing binary TIC 140736015. We obtained the physical and geometrical parameters of this detached eclipsing binary hosting a pulsating component. Based on the Transiting Exoplanet Survey Satellite (TESS) observation and Gaia DR3 data of TIC 140736015, we refined the light elements of the system using $(O-C)$ analysis and found that the eclipse times varied with a period of $\sim 2048$ days, probably linked to the multiperiodic pulsational nature. We showed that essentially, only secondary eclipse is seen in the phased light curve. The frequency analysis using the out-of-eclipse data reveals that all the pulsational frequencies are located in the region lower than $5d^{-1}$. After removing the pulsational variation from the observations we analysed the residual light curve together with the radial velocity data obtained from Gaia DR3 and find the masses and radii of the primary and secondary components as $M_1=1.429\pm 0.022$ $M_{\odot }$, $M_2=1.402\pm 0.022$ $M_{\odot }$and $R_1=1.685\pm 0.001$ $R_{\odot }$, $R_2=1.393\pm 0.001$ $R_{\odot }$, respectively. Regarding the location of the components on the Hertzsprung–Russell diagram both components can be a $\gamma$ Dor/solar-like pulsator.

In this study, new CCD photometric observations and photometric analysis of BK Vul and V699 Cep systems, which are classified as contact binaries in the literature, are presented. For the V699 Cep, the TESS light curve was also used in the photometric analysis. We determined the basic astrophysical parameters of the BK Vul and V699 Cep systems from photometric analysis using the Wilson–Devinney method. Due to the lack of spectroscopic data for both systems in the literature, these absolute parameters were approximately calculated as to be $M_2$ = 0.73 $M_{\odot }$, $R_1$ = 1.39 $R_{\odot }$ and $R_2$ = 1.09 $R_{\odot }$ for BK Vul, and $M_2$ = 0.36 $M_{\odot }$, $R_1$ = 2.40 $R_{\odot }$ and $R_2$ = 1.33 $R_{\odot }$ for V699 Cep after estimating the mass of the primary component. The period decrease rate (dP/dt) and cyclic variation period of BK Vul were determined from the $O-C$ analysis as -3.86 $\times 10^{-7}$ day yr⁻¹ and 27 yrs., respectively. The evolutionary status of components of both systems were discussed.

OPTICAM is a triple-band optical system developed for the 2.1 m telescope of the National Astronomical Observatory in the Sierra de San Pedro Mártir (OAN-SPM). Partial engineering tests were conducted in 2019, with the complete system experiencing its first light in March 2022. The system incorporates two beam splitters, enabling simultaneous observations on three channels. Users can choose three out of the five available filters from the SDSS filter set ($u^{\prime }{g}^{\prime }{r}^{\prime }{i}^{\prime }{z}^{\prime }$), covering the wavelength range from 320 to 1000 nm. It offers an effective field of view of approximately 4.7, 4.7, and 5.6 arcminutes in each of its arms, respectively. Due to its design and capabilities, OPTICAM is suitable for coordinated observations with other ground-based and space-based observatories. This document presents the final instrument design and the current system status. Some of the optical tests carried out are described. We also present the results of scientific observations conducted during its first light and first year of operations.

The future space-borne Laser Interferometer Space Antenna (LISA) is expected to detect gravitational waves (GW) from Extreme Mass Ratio Inspiral (EMRI) binaries which may live in nontrivial environments such as accretion disks. In this work, we apply the Fisher matrix Principal Component Analysis (PCA) method to assess how well LISA observations can jointly constrain the source parameters and environmental densities around EMRIs. Specifically, we calculate the Fisher matrix from the post-Newtonian parameters of an EMRI binary embedded in a fluid with a constant density profile. We determine that the most dominant measurable parameter combination is dominated by contributions from environmental effects, namely, gravitational drag, accretion, and gravitational pull (in order of contribution). The proposed reparameterization of the PN parameters can be used to improve the power and efficiency of future detection and parameter estimation methods.

We present ab initio global general-relativistic Particle-in-cell (GR-PIC) simulations of compact millisecond neutron star magnetospheres in the axisymmetric aligned rotator configuration. We investigate the role of GR and plasma supply on the polar cap particle acceleration efficiency – the precursor of coherent radio emission – employing a new module for the PIC code OSIRIS, designed to model plasma dynamics around compact objects with fully self-consistent GR effects. We provide a detailed description of the main sub-algorithms of the novel PIC algorithm, including a charge-conserving current deposit scheme for curvilinear coordinates. We demonstrate efficient particle acceleration in the polar caps of compact neutron stars with denser magnetospheres, numerically validating the spacelike current extension provided by force-free models. We show that GR relaxes the minimum required poloidal magnetospheric current for the transition of the polar cap to the accelerator regime, thus justifying the observation of weak pulsars beyond the expected death line. We denote that spin-down luminosity intermittency and radio pulse nullings for older pulsars might arise from the interplay between the polar and outer gaps. Also, narrower radio beams are expected for weaker low-obliquity pulsars.

In the present work we consider three modified Chevallier–Polarski–Linder (CPL) models with considering non-cold dark matter in the background of homogeneous and isotropic FLRW space–time model. From the observational data set ((Pantheon+)+BAO+HST) we find that all the parameters involved in the models having equation of dark energy state ${\omega }_{de}={\omega }_0+{\omega }_1\frac{a}{{(1+a)}^p}$ (Model II) and ${\omega }_{de}={\omega }_0+{\omega }_1\frac{1-a}{{(1+a)}^p}$ (Model III) do not depend on $p$. We also find that for all the models equation of state for dark matter is almost same and observe that Model I is more preferable than the other two proposed models.

We analyzed the light curve of the total eclipse contact binary V1320 Cas, obtained reliable photometric solutions, confirmed it to be a W-type contact binary with a mass ratio of 3.404 and a contact degree of 23.9%, a cool spot is discovered on the less massive component. Orbital period analysis indicates that the period of V1320 Cas is decreasing at a rate of $\frac{dP}{dt}=1.78\times 10^{-7}$ day yr⁻¹, superimposed with a cyclic modulation with a period of 1.425 yr, long-term period decrease may be caused by the combination of mass transfer and angular momentum loss, and the cyclic modulation may be caused by the third companion. Using the photometric solutions and Gaia distance, we calculated the absolute physical parameters and plotted mass-luminosity and mass–radius diagrams to analyze the evolutionary status of V1320 Cas, the more massive component is a main sequence star, while the less massive component has higher luminosity and radius than those of main sequence stars with the same mass. With the decreasing orbital period, the two components of V1320 Cas will be gradually closer, while the binary may evolve toward deep contact.

This paper presents properties of the intracluster medium (ICM) in the environment of a cool core cluster Abell 2566 (redshift $z$ $=$ 0.08247) based on the analysis of 20 ks Chandra X-ray data. 2D imaging analysis of the Chandra data from this cluster revealed spiral structures in the morphology of X-ray emission from within the central 109 kpc formed due to gas sloshing. This analysis also witness sharp edges in the surface brightness distribution along the south-east and north-west of the X-ray peaks at 41.6 kpc and 77.4 kpc, respectively. Spectral analysis of 0.5 – 7 keV X-ray photons along these discontinuities exhibited sharp temperature jumps from 2.3 to 3.1 keV and 1.8 to 2.8 keV, respectively, with consistency in the pressure profiles, implying their association with cold fronts due to gas sloshing of the gas. Further confirmation for such an association was provided by the deprojected broken power-law density function fit to the surface brightness distribution along these wedge shaped sectorial regions. This study also witness an offset of 4.6${}^{\prime \prime }$  (6.8 kpc) between the BCG and the X-ray peak, and interaction of the BCG with a sub-system in the central region, pointing towards the origin of the spiral structure due to a minor merger.

This study explores the impact of $f\left(\mathrm{G,T}\right)$ gravity, where $G$ is the Gauss Bonnet invariant and $T$ is the trace of the energy–momentum tensor, on the adiabatic anisotropic spherical gravitating source under the expansion-free condition. We coupled the relativistic matter with spherical symmetric structure by applying $f\left(\mathrm{G,T}\right)=\alpha G^n+\lambda T$ Gauss–Bonnet model with a linear trace. To derive the collapse equation, we used the perturbation method on the field equations and the contracted Bianchi identities. The dynamics of instability range is depicted in Newtonian ($N$) and post-Newtonian (pN) regimes. Furthermore, instead of using the adiabatic index, we establish the instability range by looking at the density profile and anisotropic pressure configuration. We investigate the analytic solutions that meets the expansion-free condition. Finally, we have successfully achieved the original results obtained by Herrera et al. (2012) in General Relativity by setting $\alpha =\lambda =0$ in proposed cosmological model.