两层预测的同心新星壳层环绕着矮新星原型 U Geminorum

本文研究了矮新星原型 U Geminorum，该系统由一颗白矮星及其红矮星伴星组成。通过 Condor Array Telescope 的深度窄带 H-alpha 成像，研究人员发现了环绕该系统的两层同心壳层，这与近期发生经典新星爆发的理论模型相吻合。

arXiv:2608.26555v1 Announce Type: new Abstract: In the 170 years since its discovery, U Gem has been intensively studied as the prototypical cataclysmic binary star. Its massive white dwarf (WD) (~ 1.2 Msun) is cannibalizing its ~ 0.42 Msun red dwarf companion. The WD's resulting accreted hydrogen-rich envelope has previously undergone thermonuclear runaways seen as nova eruptions. These weekslong transient events brighten U Gem to m ~ -3 and eject the accreted envelope (~ 0.00001 Msun) at thousands of km/s. Ultraviolet observations show that the accreted envelope of U Gem's WD is greatly enhanced in nitrogen and depleted in carbon relative to solar composition, and that the WD's effective temperature is much hotter than that of most cataclysmic binary WDs. These suggest that U Gem underwent a classical nova eruption quite recently and should therefore still be surrounded by the ejecta of that event. Modeling of U Gem predicts a nova event ~ 1000 years ago, and the existence of two concentric shells, each of order 1 degree in size, surrounding U Gem. We obtained deep narrowband H-alpha imaging of U Gem with the Condor Array Telescope. The two concentric H-alpha-bright shells that we find, centered on U Gem, may be