发表机构
Faculty of Mathematics and Physics, University of Ljubljana; INAF National Institute of Astrophysics, Astronomical Observatory of Padova; INAF – Osservatorio di Astrofisica e Scienza dello Spazio; Instituto de Astrofisica, Depto. de Ciencias Fisicas, Facultad de Ciencias Exactas, Universidad Andres Bello（卢布尔雅那大学数学与物理学院; 意大利国家天体物理研究所帕多瓦天文台; 意大利国家天体物理研究所天文与空间科学观测站; 安德烈斯贝略大学精确科学学院物理科学系天体物理研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过VLT/X-shooter及Swift/XRT+UVOT观测，表征V745 Sco与V3890 Sgr的宁静态，确定其供体星光谱型，估计质量转移率，表明其爆发可由长期吸积维持。
AI 中文摘要
共生 recurrent 新星是已观测到多次热核爆发的共生双星，目前银河系仅已知4个此类系统：T CrB、RS Oph、V745 Sco和V3890 Sgr，它们为研究共生新星宁静态下的吸积及双星相互作用提供了便利实验室。本文对研究较少的V745 Sco和V3890 Sgr系统的宁静态进行表征，并将其性质与T CrB和RS Oph的性质进行比较。我们分析VLT/X-shooter光谱，结合Swift/XRT和UVOT观测，辅以地面光学测光及存档数据，确定红巨星供体星的光谱型，并将这些系统的光谱能量分布与相同光谱型的银核单颗巨星的光谱能量分布进行比较，以研究吸积性质。我们将V745 Sco和V3890 Sgr的供体星分别归类为M7III型和M6.5III型，推导得出的红化值和距离与两个系统均属于银核的结论一致。两个天体均表现出相对于正常晚型巨星的显著紫外超量，表明宁静态下存在持续吸积，据此我们估计质量转移率约为~5×10⁻⁸ M☉ yr⁻¹，与观测到的爆发时标大致相符。这些结果表明，V745 Sco和V3890 Sgr的 recurrent 新星爆发可由当前速率的长期吸积维持，无需类似T CrB中观测到的增强吸积阶段。
英文摘要
Symbiotic recurrent novae are symbiotic binaries in which multiple thermonuclear outbursts have been observed. Only four such systems are currently known in the Galaxy: T CrB, RS Oph, V745 Sco, and V3890 Sgr. They provide convenient laboratories for studying accretion and binary interaction in symbiotic novae during quiescence. We characterise the quiescent states of the less-studied systems V745 Sco and V3890 Sgr and compare their properties with those of T CrB and RS Oph. We analyse VLT/X-shooter spectra together with Swift/XRT and UVOT observations, supplemented by ground-based optical photometry and archival data. We determine the spectral types of the red-giant donors and compare the spectral energy distributions of the systems with those of single bulge giants of the same spectral type to investigate the properties of the accretion. We classify the donor stars in V745 Sco and V3890 Sgr as M7III and M6.5III, respectively. We derive reddenings and distances consistent with both systems belonging to the Galactic bulge. Both objects exhibit a significant ultraviolet excess relative to normal late-type giants, indicating ongoing accretion during quiescence. From this excess we estimate mass transfer rates of the order of $\sim 5 \times 10^{-8}\ M_{\odot}\ \mathrm{yr}^{-1}$, broadly consistent with the observed recurrence timescales. These results suggest that recurrent nova eruptions in V745 Sco and V3890 Sgr can be sustained by long-term accretion at approximately the present rate, without requiring an episode of enhanced accretion similar to that observed in T CrB.
Comments20 pages, 19 figures, 7 tables. Submitted to A&A. Comments welcome
