Optical and soft X-ray light-curve analysis during the 2022 eruption of U Scorpii: Structural changes in the accretion disk

作者：Katsuki Muraoka, Naoto Kojiguchi, Junpei Ito, Daisaku Nogami, Taichi Kato, Yusuke Tampo, Kenta Taguchi, Keisuke Isogai, Teófilo Arranz, John Blackwell, David Blane, Stephen M. Brincat, Graeme Coates, Walter R. Cooney, Shawn Dvorak, Charles Galdies, Daniel Glomski, Franz-Josef Hambsch, Barbara Harris, John E. Hodge, José Luis Hernández‐Verdejo, Marco Iozzi, Hiroshi Itoh, S. Kiyota, Darrell Lee, M. H. M. A Larsson, Tapio Lahtinen, Gordon Myers, Berto Monard, Mario Morales Aimar, Masayuki Moriyama, Masanori Mizutani, Kazuo Nagai, Thabet AlQaissieh, Aldrin Gabuya, Mohammad Odeh, C. Perelló, A. Pearce, Juan Miguel Perales, David Quiles, F. D. Romanov, David J. Lane, M. Richmond, N. Ruocco, Y. Sano, Mark Spearman, Richard E. Schmidt, Tonny Vanmunster, Pavol A. Dubovský, R. M. Wagner, Guido Wollenhaupt, J. Lorenz, Gerhard Lehmann, Andrea Salewski, Guy G Williamson · 发表于：Publications of the Astronomical Society of Japan · 年份：2024 · DOI：10.1093/pasj/psae010 · 被引用次数：9 · 研究领域：Astrophysical Phenomena and Observations、Gamma-ray bursts and supernovae、Astrophysics and Cosmic Phenomena

Abstract We present our optical photometric observations of the 2022 eruption of the recurrent nova U Scorpii (U Sco) using 49152 data points over 70 d following the optical peak. We have also analyzed its soft X-ray (0.3–1 keV) light curve by the Neil Gehrels Swift Observatory. During the 2022 eruption, the optical plateau stage started 13.8–15.0 d and ended 23.8–25.0 d after the optical peak. The soft X-ray stage started 14.6–15.3 d and ended 38.7–39.5 d after the optical peak. Both stages started later and had shorter durations, and the soft X-ray light curve peaked earlier and was less luminous compared to those during the U Sco 2010 eruption. These points suggest that there were differences in the envelope mass between the different cycles of the nova eruption. Furthermore, we have analyzed the optical eclipses during the 2022 eruption. The primary eclipse was first observed 10.4–11.6 d after the optical peak, earlier than the beginning of the optical plateau stage. This sequence of events can be explained by the receding ejecta photosphere associated with the expanding nova ejecta. We have determined the ingress and egress phases of the primary eclipses and estimated the outer radius of the optical light source centered at the white dwarf (WD). During the optical plateau stage, the source radius remained ∼1.2 times larger than the Roche volume radius of the primary WD, being close to the L1 point. When the optical plateau stage ended, the source radius drastically shran...