ASASSN-24fw: Candidate Gas-rich Circumsecondary Disk Occultation of a Main-sequence Star

作者：Nadia L. Zakamska, Gautham Adamane Pallathadka, Dmitry Bizyaev, Jaroslav Merc, James E. Owen, Henrique Reggiani, Kevin C. Schlaufman, K. Bąkowska, Sławomir Bednarz, Krzysztof Bernacki, A. Gurgul, Kirsten R. Hall, Franz-Josef Hambsch, B. Joachimczyk, Krzysztof Kotysz, Sebastian Kurowski, A. Liakos, P. Mikołajczyk, E. Pakštienė, G. Pojmański, Adam Popowicz, Daniel E. Reichart, Łukasz Wyrzykowski, J. Zdanavičius, Michał Żejmo, Paweł Zieliński, Staszek Zola · 发表于：The Astronomical Journal · 年份：2026 · DOI：10.3847/1538-3881/ae1fd9 · 被引用次数：2 · 研究领域：Astrophysics and Star Formation Studies、Stellar, planetary, and galactic studies、Astronomy and Astrophysical Research

Abstract Dusty disks around planetary and substellar companions in outer reaches of exoplanetary systems can be detected as long-lasting occultations, provided the observer is close to the secondary’s orbital plane. Here we report optical spectroscopy with KOSMOS (Apache Point Observatory), MagE (Magellan), and GHOST (Gemini-S) of ASASSN-24fw (Gaia 07:05:18.97+06:12:19.4), a 4 mag dimming event of a main-sequence star which lasted 8.5 months. We discover multiple low-ionization metal emission lines with velocity dispersion ≲ 10 km s −1 blueshifted by 27 km s −1 with respect to the star, as well as kinematically complex Na D absorption. If associated with the occulter, these detections suggest that the occulter is gas rich. Further, we detect a blueshifted and broad (∼200 km s −1 ) H α line, which likely originates in the inner circumstellar disk. We confirm the previously reported occultations in 1981 and 1937 seen in historic data, yielding a semimajor axis of the occulter’s orbital motion around the star of 14 au. If the occulter is a circumsecondary disk filling 30%–100% of the Hill radius, we estimate the minimum mass of the secondary to be a few Jupiter masses and a disk mass of 1% of the mass of the Moon. Given the age of the star (>2 Gyr), the disk is unlikely to be a survivor of the planet formation stage and may be the result of a planetary collision. If the Na D absorption and/or metal emission lines originate in the disk, the observations presented here are the ...