发表机构
Harvard & Smithsonian; NSF Institute for AI and Fundamental Interactions (IAIFI); California Institute of Technology; UCLA; University of Warwick; Columbia University; Kazan Federal University; Institute of Science and Technology Austria (ISTA)（哈佛与史密森尼学会; 美国国家科学基金会人工智能与基础相互作用研究所; 加州理工学院; 加州大学洛杉矶分校; 华威大学; 哥伦比亚大学; 喀山联邦大学; 奥地利科学技术研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究发现距地265秒差距的第三颗磁白矮星螺旋桨系统，通过多设备观测确定其参数，其诞生率与磁激变变星一致，揭示大量磁激变变星会经历螺旋桨阶段。
AI 中文摘要
最快的旋转白矮星（WD）接近瓦解速度，存在于密近双星系统中。在已知的两颗磁WD“螺旋桨”系统——AE Aqr和LAMOST J0240+1952中，磁WD旋转速度极快，会将其洛希瓣充满伴星转移的物质 ejected（此处保留原文术语，按规则处理）而非吸积。我们报告第三颗此类系统的发现：1eRASS J042633.5−250226（1eRASS J0426/Valeria），距离仅265秒差距（pc），通过结合SRG/eROSITA与Gaia数据，借助“X射线主序”识别得到。TESS测光显示其具有类似AE Aqr的耀发和轨道调制，轨道周期P_orb≈6.62小时；ZTF观测显示其存在长达数月的高低态变化。相位分辨的Palomar/DBSP光谱证实了轨道周期，并测得供体径向速度K₂=202±7 km s⁻¹。高速Palomar/CHIMERA测光在三个夜晚检测到光学脉冲，最强检测对应的旋转周期P_spin=26.8秒，但需进一步观测确认此为WD的自旋周期。低态下供体的光谱拟合显示其为晚型K型星，供体温度T_donor=4100±150 K。光学光谱中的塞曼分裂得出候选磁场强度B_WD=26±3 MG，意味着该系统将演化成极向星。与其他WD螺旋桨系统类似，该系统X射线辐射微弱（L_X≈7×10³⁰ erg s⁻¹），但未在射电波段被检测到，且SRG/eROSITA未在X射线波段检测到自旋周期。该系统的近距性及螺旋桨阶段时间框架的演化模型约束，得出其诞生率密度约为8×10⁻¹⁶ pc⁻³ yr⁻¹，与磁激变变星（CV）的诞生率密度一致，表明相当一部分磁CV会经历螺旋桨阶段。
英文摘要
The fastest spinning white dwarfs (WDs), which approach break-up speeds, are found in close binary systems. In the two known magnetic WD ``propellers'', AE~Aqr and LAMOST J0240+1952, the magnetic WD spins so rapidly that it ejects the material transferred by its Roche-lobe-filling companion rather than accreting it. We report the discovery of the third such system, 1eRASS J042633.5$-$250226 (1eRASS J0426/Valeria), at only 265 pc, identified by combining SRG/eROSITA and \textit{Gaia} data via the ``X-ray Main Sequence''. TESS photometry shows AE~Aqr-like flaring and orbital modulation with $P_{\mathrm{orb}} \approx 6.62$ hr, and ZTF shows month-long high/low state changes. Phase-resolved Palomar/DBSP spectroscopy confirms the orbital period and yields a donor radial velocity of $K_2 = 202\pm7$ km s$^{-1}$. High-speed Palomar/CHIMERA photometry detects optical pulsations on three nights with the strongest detection at $P_\textrm{spin} = 26.8$ sec, though further observations are needed to confirm this as the WD spin. Spectral fitting of the donor in the low state reveals a late K-type star with $T_{\mathrm{donor}} = 4100\pm150$ K. Zeeman splitting in the optical spectrum yields a candidate field strength of $B_{\mathrm{WD}} = 26 \pm 3$ MG, meaning the system will evolve into a polar. Like other WD propellers, the system is X-ray faint ($L_X \approx 7\times 10^{30}$ erg s$^{-1}$), but is not detected in the radio, and a spin period is not detected in X-rays by SRG/eROSITA. The proximity of this system and evolutionary model constraints on the timeframe of the propeller phase yield a birth rate density of $\sim8\times10^{-16} \textrm{pc}^{-3} \textrm{yr}^{-1}$, which agrees with that of magnetic CVs, suggesting that a substantial fraction of magnetic CVs pass through a propeller phase.
CommentsSubmitted to the Open Journal of Astrophsyics; comments welcome
