New Astronomy最新文献

We present the discovery of 269 pulsating variable stars of $\delta$ Scuti, $\gamma$ Doradus, and Maia types in the vicinity of the open cluster NGC 6871, using data from the Transiting Exoplanet Survey Satellite (TESS). Our small-scale regional survey centered on the $\delta$ 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 $\delta$ Scuti stars, 121 $\gamma$ 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 $\delta$ Scuti and $\gamma$ 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.

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 $L_{6,7\kappa }$ and $L_{8,9\kappa }$, are obtained and differ from those of the non-autonomous system due to time $t$. 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 $L_{8,9\kappa }$ are closer to the primaries than $L_{6,7\kappa }$. 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.

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.