AI 中文总结
研究三个相互作用星系系统，用双子座/GMOS长缝光谱仪及pPXF方法获取光谱并建模，发现VCC 1748系统有气体流入椭圆目标并引发原位恒星形成，捕捉到椭圆星系向旋涡星系形态转变的中间阶段。
AI 中文摘要
我们展示了对三个相互作用星系系统的光谱观测结果，每个系统都有一个主星系——VCC 1748、SDSS J1106和2MASX J0834，它们被认为是由外部气体吸积驱动的从椭圆型到旋涡型反向形态转变的潜在例子。利用双子座/GMOS长缝光谱仪，我们沿着连接每对星系中感兴趣区域的长缝获取光谱。我们用惩罚像素拟合（pPXF）方法对空间分箱光谱进行建模，以得出气相金属丰度、恒星金属丰度和恒星族群年龄的速度场和径向分布。在这三个系统中，只有VCC 1748系统能提供足够高信噪比（S/N）的光谱，以揭示伴生旋涡星系与其椭圆目标之间延伸的连贯速度和金属丰度结构。该系统气体桥的速度分布从伴生旋臂到目标星系是平滑连续的，椭圆目标VCC 1748在其新形成的盘状区域比中心区域表现出更年轻的恒星族群和高恒星形成率（SFR）。这些发现表明椭圆目标新形成的旋臂上有原位恒星形成，与气体从旋涡伴星持续流入椭圆目标一致。总之，这些结果捕捉到了形态演化的一个中间阶段，即一个原本静止的椭圆星系开始通过相互作用驱动的气体吸积组装一个旋转支撑的盘。
英文摘要
We present results from spectroscopic observations of three interacting galaxy systems, each associated with a primary galaxy - VCC 1748, SDSS J1106, and 2MASX J0834 - which have been proposed as potential examples of reverse morphological transformation from elliptical to spiral types driven by external gas accretion. Using Gemini/GMOS longslit spectroscopy, we obtain spectra along longslits connecting the regions of interest between the two galaxies in each pair. We model the spatially binned spectra with the Penalized Pixel-Fitting (pPXF) method to derive velocity fields and radial profiles of gas-phase metallicity, stellar metallicity, and stellar population age. Among the three systems, only the VCC 1748 system provides spectra with sufficiently high signal-to-noise ratios (S/N) to reveal coherent velocity and metallicity structures extending between the companion spiral galaxy and its elliptical target. The velocity profile along the gas-bridge of the system is smooth and continuous from the companion spiral arm to the target galaxy, and the elliptical target, VCC 1748, exhibits younger stellar populations and a high star formation rate (SFR) in its newly formed disk regions compared to its central parts. These findings indicate in-situ star formation at the newly-formed spiral arm of the elliptical target, consistent with ongoing gas inflow from the spiral companion into the elliptical target. Altogether, the results capture an intermediate stage of morphological evolution in which an originally quiescent elliptical galaxy begins to assemble a rotationally supported disk through interaction-driven gas accretion.
