arXiv subjects

Pascal le Dû

Publications and source records attributed to Pascal le Dû.

2 recordsLinked to original sources

arXiv2026

Analysis of the Gaia DR3 planetary nebula candidates and the possible symbiotic stars among them

The Gaia DR3, released in June 2022, included low-resolution BP/RP (XP) spectra that have been exploited for the classification of various types of emission-line objects using machine-learning techniques. The Gaia Extended Stellar Parametrizer for Emission-Line Stars (ESP-ELS) algorithm identified 273 sources as potential planetary nebulae (PNe). We aim to analyze the PN sample produced by the ESP-ELS algorithm to investigate the true nature of the objects classified as PNe. We extracted all sources from the catalog classified as PNe by the ESP-ELS algorithm and filtered out 200 objects with secure classifications available in the literature. Of these, $\sim$65% correspond to known Galactic or Magellanic compact PNe, and $\sim$20% to D- or D'-type symbiotic systems. The XP spectra of the remaining sources were visually inspected, leading to a subset of 14 promising candidates showing strong emission features attributable to H$α$ and [O III] $λ$5007. Although typical of PNe, such features are also consistent with D- or D'-type symbiotics, known to mimic compact PNe. We obtained spectroscopic follow-up observations for these objects with the 2SPOT facilities in Chile and France, complemented by an analysis of archival photometric data to further constrain their nature. We report the identification of nine bona-fide or likely D- or D'-type symbiotic systems, one planetary nebula in the LMC, one polar cataclysmic variable, and three possible Be stars in (or in the direction of) the SMC, within our sample of 14 objects.

astro-ph.SR↗

arXiv2025

Spectral evolution of the narrow emission line components in optical during the 2022 nova eruption of U Scorpii

There remains debate over whether the accretion disk survives or is entirely disrupted after the nova eruption. In our previous paper, Muraoka et al. (2024, PASJ, 76, 293) have photometrically demonstrated that the surviving accretion disk was expanded close to the L1 point during the optical plateau stage and then drastically shrank to the tidal truncation radius after the optical plateau stage ended. To approach the clarification of the physical mechanism that drives these structural changes, we have then conducted systematic analyses of the spectral evolution of the narrow emission line components in optical over 22 d following the optical peak during the 2022 nova eruption of U Scorpii (U Sco). Additionally, we present its optical spectrum in quiescence 794 d after the 2022 nova eruption. We find that the single-peaked narrow components of H$α$ and He II 4686 appeared almost simultaneously between roughly days 6 and 8, preceding the onset of the disk eclipses observed after day 11. This finding suggests that the nova wind near the binary system may be the primary origin of these narrow components and even remained active several days after the nova eruption with a velocity of approximately 1000 km s$^{-1}$, likely driving the expansion of the accretion disk until the end of the optical plateau stage. While the contribution of the rotating accretion disk might be dominated by that of the nova wind in the H$α$ line profile, the outward surface flow from the expanded disk might also contribute to these narrow features during the optical plateau stage, making the single-peaked narrow line profiles more pronounced.

astro-ph.SR↗