New Astronomy最新文献

Using the TESS and Kepler K2 light curve archives, I have reanalyzed 13 known $\delta$ Scuti stars. AD Ari is now reclassified as a rotating ellipsoidal binary variable. EX Cnc and HD 73712 are reclassified as hybrid $\delta$ Sct-$\gamma$ Dor pulsators. EX Cnc turns out to be an enticing asteroseismic target because of its three distinct groups of pulsation frequencies. The strong beating caused by two close frequencies is present in the star CD-54 7154. More than 71 pulsation frequencies were resolved for $\iota$ Boo and IT Dra with high significant levels, while V1821 Cyg, V2238 Cyg, BR Cnc, BU Cnc, and BV Cnc pulsate with a few dozen frequencies. In particular, K2 data revealed a significantly richer pulsational spectrum for the two $\delta$ Scuti stars BU Cnc and BV Cnc from six to 26. Unlike the other 12 stars, BN Cnc shows the simplest pulsation pattern. With high-precision and long-term space-based photometry, we are able to discern the pulsational contents of these stars more clearly and enhance our knowledge of them. This reanalysis using TESS and Kepler K2 data highlights the diversity of pulsational behavior among $\delta$ Scuti stars and the value of long-duration, high-precision photometry. Further asteroseismic modeling of these stars, particularly EX Cnc with its distinct frequency groups, promises to refine our understanding of their internal structures and pulsational mechanisms.

The present work investigates the general wormhole solution in Einstein gravity with an exponential shape function around an ultrastatic and a finite redshift geometry. The geodesic motion around the wormholes is studied in which the deflection angle of the orbiting photon sphere is found to be negative after a certain region, indicating the presence of repulsive effect of gravity in both the ultrastatic and finite redshift wormholes. Various unbounded and bounded timelike trajectories are presented on the wormhole embedding diagrams, in which some of the bound orbits involve intersection points that may lead to causality violating geodesics. Another class of closed timelike geodesics are obtained in the unstable circular trajectory that appeared at the wormhole throat. Finally, the trajectories are classified in terms of the family of CTG orbits.

The photometric study of the short period contact binary V415 Gem are performed for the first time. We discovered that it is a W-subtype shallow contact binary with a mass ratio of q = 2.297 and a contact degree of f = 3.6%. The light curves of the target exhibit an O’Connell effect, we attached a cool star-spot on its primary component for better fitting results. At the same time, the third light was found during our analysis by using the 2015 version of the Wilson–Devinney ($W-D$) code. And the average luminosity contribution of the third light is 44% of the total light. Besides, the $O-C$ curve of V415 Gem exhibits a cyclic variation, which is due to the light-travel time effect caused by the presence of a third component with an amplitude of 0.0033 days and a period of 11.5 years. The mass of the third body is estimated to be M${}_3\sim 1.08$M${}_{\odot }$.

The astronomical data analysis consists of two crucial process; data reduction of the captured images and data analysis of the derived magnitudes. We present the platform ASIVA, a data analysis platform which comes along with a data reduction pipeline. The data reduction pipeline gives flexibility to analyse the FITS images and also perform image alignment for detecting the correct image coordinates for required objects. It can be custom scheduled with cron jobs so that it picks the latest data and appends the results accordingly. The data analysis platform allows user to effectively analyse the ensemble data and perform accurate data processing and grouping with ease. It is integrated with a custom algorithm to detect the variable stars from an ensemble with its relative standard deviations. The statistical, spectral and non-linear dynamics features can be extracted from time series data which can be eventually used for in-depth analysis. To validate the capability, we have analysed 15 nights of Orion Nebula Cluster field in I filter which had 1585 images. ASIVA reduces manual effort to a great extent thus saves analysis time and excludes human errors.

In this paper, we study the properties of electrically charged anisotropic and spherically symmetric compact stars in $f\left(Q\right)$ gravity theory. The field equations have been solved using the MIT-Bag Equation of State (EoS) along with the Vaidya–Tikekar potential. However, the specific form of charge $E^2\left(r\right)=\frac{q_0{L}^2{r}^2}{{(1+L{r}^2)}^2}$ has been used to study the charged compact star model. The interior charge anisotropic solution has been matched with the charged Schwarzchild-(Anti)-de-Sitter metric. In particular, this study has been conducted on different compact stars viz, EXO 1785-248, PSR J1614-2230, PSR J0740+620 and SMC X-1. The mass–radius ratio of these compact stars has been predicted, and the physical viability of the model has been checked through the behaviour of causality condition, matter variables, energy constraints, modified TOV equation, and adiabatic index of the star. In conclusion, we observe a well-behaved model of a compact star in $f\left(Q\right)$ gravity with charged matter distribution.

We present the first CCD observations of an eclipsing binary, ZTFJ015003.88+534,734.1, which is a member in the open star cluster UBC 188. The observations were taken by the 1.88 m telescope at the Kottamia Astronomical Observatory (KAO) in SDSS griz bands. The latest version of the Wilson-Devinney (W-D) code was employed for photometric analysis and light curve modeling of the eclipsing binary. The results indicate that the binary system is in an over-contact configuration. The mass of the primary star (M1) is determined to be 1.293 M_⊙, and the mass of the secondary star (M2) is directly derived from the system's estimated mass ratio (q = M2/M1) as 0.340 times the solar mass (M_⊙). We investigated the color-magnitude diagram and the membership probability of the open cluster UBC 188 using the Gaia DR3 data. We determined the membership probability of the eclipsing binary ZTFJ015003.88+534,734.1 using the pyUPMASK algorithm and found that its membership probability is one.

We present a photometric analysis of six W Ursae Majoris contact binaries and one semi-detached system using multifilter CCD observations. The data were obtained with the 0.25 m Schmidt Cassegrain telescope at the observatory Stazione Astronomica Betelgeuse (SAB) in Magnago, Italy, and the 30-cm Ritchey Chretien Astrograph at the IRIDA observatory (IO) of the NAO Rozhen in Bulgaria. We applied the Wilson–Devinney code to model the light curves and derive the orbital and physical parameters of the systems. Four of the contact binaries belong to the W sub-type and two to the A sub-type, and all are in thermal contact. 2MASS J23194851+3603503 has a very low mass ratio q = 0.093 and a fill-out factor of f = 71.4%, whereas the other contact binaries have mass ratios between 0.2 and 0.38 and fill-out factors between 8% and 39%. 2MASS J04525351+6246069 is a semi-detached system with q = 0.125 and a temperature difference of 540 K between the components. We also estimated the absolute elements of all seven eclipsing binaries.

In this study, we build a charged star model with three layers with distinct equations of state. The core, intermediate layer, and envelope layer obey linear, polytropic, and Chaplygin equations of state, respectively. The model satisfies the physical requirements for the matter variables, gravitational potentials, and stability conditions. We have generated within-acceptable range masses and radii for stars. We also recover the masses and radii for the stars PSRJ1903+0327, PSRJ1614-2230, SAXJ1808.4-3658, Vela X-1, and EXO1785-248 from earlier investigations which shows astrophysical significance of our model.

The accuracy of absolute parameters’ estimation in contact binary systems is important for investigating their evolution and solving some challenges. The Gaia DR3 parallax is one of the methods used for estimating the absolute parameters, in cases where photometric data is the only one that is available. The use of this method includes advantages and limitations that we have described and examined in this study. We selected 48 contact binary systems whose mass ratios were mostly obtained by spectroscopic data, in addition to a number of photometric studies. The target systems were suitable for $A_V$ and the Re-normalized Unit Weight Error (RUWE), and their absolute parameters were calculated based on Gaia DR3 parallax, observational information, orbital period, and light cure solution from the literature and catalogs. The outcomes of OO Aql differed significantly from those reported in the literature. Upon analyzing the system’s light curve with TESS data, we concluded that the stars’ temperatures were the reason for this difference, and utilizing Gaia DR3 parallax provided reasonable results. We displayed the target systems on the Hertzsprung–Russell (HR), $q-L_{ratio}$, $P-M_V$, and $log{M}_{tot}-log{J}_0$ diagrams, and the systems are in good agreement with the theoretical fits. We showed that the estimation of absolute parameters with this method might be acceptable if $\Delta a\left(R_{\odot }\right)$ is less than $\sim 0.1\left(R_{\odot }\right)$. There are open questions regarding the existence of $l_3$ in the light curve analysis and its effect on the estimation of absolute parameters with this method.

In this study, we investigate the FRW model in the Chern–Simons modified gravity framework, considering holographic dark energy and Kaniadakis holographic dark energy models. Employing the field equation of Chern–Simons gravity, it is analyzed some important cosmological parameters such as density, equation of state, and deceleration parameters for both models. Our findings, presented visually through graphs, reveal that holographic dark energy places the equation of state within $\omega \in (-1,-0.4)$, while Kaniadakis holographic dark energy spans $\omega \in (-0.8,-0.4)$. These results demonstrate the dynamic nature of dark energy’s influence. Our study highlights the interplay of quintessence and $\Lambda \mathrm{CDM}$ across cosmic eras. We identify the ranges of $q\in (-0.89,-0.86)$ and $q\in (-0.9925,-0.9922)$ for Kaniadakis holographic dark energy and holographic dark energy, offering insights into their roles in cosmic inflation which implies that the universe attributes are impacted by both quintessence and the $\Lambda$CDM model in Chern–Simons modified gravity. In addition, this study implies that the universe’s expansion is decelerating in its current state.