Diya T. Kumar | Searcharxiv

arXiv2026

V347 Aurigae: from Peak to Quiescence

We present an analysis of eight epochs of high-resolution optical spectra of the YSO (young stellar object) V347 Aur. The source exhibits periodic brightness variations spanning $\sim$2 mag over several months, interpreted as cyclic accretion-burst and quiescent phases, making V347 Aur a useful probe of the broad range of accretion and outflow variability in YSOs. When faint, V347 Aur shows an M-type photospheric absorption spectrum; when bright, it exhibits a strong emission-line spectrum. Our Keck/HIRES spectroscopy was obtained during the decay of an accretion burst. The emission spectrum includes the strong H I, Ca II, and He I transitions commonly seen in YSOs, as well as numerous weaker metal lines, for which we provide a complete inventory. As the star fades, photospheric absorption lines deepen, consistent with decreasing veiling from the accretion continuum. H I and He I emission, which trace accretion, strengthen relative to the continuum as it fades, but show the expected decline in strength with decreasing accretion after correcting for the strong early veiling. Ca II behaves similarly, with line profiles that alternate between red- and blueshifted dominance, which we interpret as the rotation of the magnetospheric accretion flows. Narrow, slightly blueshifted absorption in Ca II, Na I, and K I indicates disk winds with localized density enhancements. Forbidden [O I] and [S II] emission is blueshifted, with broad shoulders and low- and high-velocity narrow peaks, consistent with a disk geometry that obscures much of the receding outflow. Their behavior as the continuum fades is similar to that of the broad accretion lines. The V347 Aur system is a useful proxy both for the ubiquitous short-term accretion variability observed in YSOs, and for their secular evolution on longer time scales.

astro-ph.SR↗

arXiv2026

Detection of 27 candidate circumbinary planets through apsidal precession of eclipsing binaries observed by TESS

Most circumbinary planets have been discovered by their transits, limiting our understanding of such systems to those with mutually coplanar architectures. This bias makes it difficult to infer the true circumbinary planet population, highlighting the need for alternative detection methods that do not rely on transits. In this work, we explore one such approach by leveraging apsidal precession as a dynamical signature of planetary companions. We analyse TESS photometry of a sample of 1590 eclipsing binaries from the Gaia DR3 Catalogue of Eclipsing Binary Candidates to identify systems exhibiting measurable apsidal precession that cannot be explained by general relativistic, tidal, or rotational effects alone. These excess precession signals point to the presence of additional gravitational perturbers and allow constraints to be placed on the masses and orbital separations of potential companions. We present a new set of 27 candidate circumbinary planets identified through this precession-based method, as well as 6 candidate companions with a higher minimum mass. Their inferred properties remain degenerate, as the same dynamical signatures can arise from lower-mass planets at less than 1 AU or from more massive companions on wider, few-AU orbits, reflecting the current uncertainty in characterising these systems. Radial velocities can help break this degeneracy and provide direct confirmation.

astro-ph.EP↗