ﻻ يوجد ملخص باللغة العربية
Some quadruple star systems in the hierarchical 2+2 configuration exhibit orbit-orbit resonances between the two compact binaries. We show that the most important resonances occur at period ratios of 1:1, 3:2 and 2:1. We describe the conditions required for capture and show that they can be satisfied at the 3:2 and 2:1 resonances in binaries that migrate significantly in semimajor axis after circularization, probably through magnetic braking or gravitational radiation.
Analyzing exoplanets detected by radial velocity or transit observations, we determine the multiplicity of exoplanet host stars in order to study the influence of a stellar companion on the properties of planet candidates. Matching the host stars of
Observations of molecular hydrogen (H$_2$) fluorescence are a potentially useful tool for measuring the H$_2$ abundance in exoplanet atmospheres. This emission was previously observed in M$;$dwarfs with planetary systems. However, low signal-to-noise
Using NASA IRTF SpeX data from 0.8 to 4.5 $mu$m, we determine self-consistently the stellar properties and excess emission above the photosphere for a sample of classical T Tauri stars (CTTS) in the Taurus molecular cloud with varying degrees of accr
The orbits of binary stars and planets, particularly eccentricities and inclinations, encode the angular momentum within these systems. Within stellar multiple systems, the magnitude and (mis)alignment of angular momentum vectors among stars, disks,
We have identified a quadruple system with two close eclipsing binaries in TESS data. The object is unresolved in Gaia and appears as a single source at parallax 1.08~$pm$0.01 mas. Both binaries have observable primary and secondary eclipses and were