AI 中文总结
本研究利用IMAP-Lo的枢转平台交会不同延伸角的ISN参数管，精确测得本地星际流参数，发现其为介于本地星际云与G云之间的中间状态，为研究日球层演化奠定基础。
AI 中文摘要
太阳在星际介质中的运动形成了穿过日球层的星际中性（ISN）原子流。星际中性氦（ISN He）因宇宙丰度高、电离率相对较低，是1天文单位附近最丰富的星际物种，适合用于确定流参数。星际边界探测器（IBEX）对ISN He流参数（速度、温度、方向）的测量在4维参数空间中形成了一条管，其横截面狭窄但沿某一参数轴（如黄经方向）高度延伸。这种“4维参数管”会导致较大的系统不确定性，是IBEX-Lo在航天器上固定观测方向的直接结果。在星际测绘与加速探测器（IMAP）上，IMAP-Lo的视轴可通过其枢转平台进行转动，实现对ISN流的多种观测方向，从而显著降低系统不确定性。我们提供的首批结果明确交会了延伸角为79°、94°和109°的ISN参数管，得到了精确的星际参数：速度为26.37±0.82 km s⁻¹，黄经方向为74.85°±0.96°，黄纬方向为-5.212°±0.035°，温度为7740⁺⁷⁷⁰₋₇₃₀ K。推断出的甚本地星际介质流既与本地星际云不符，也与G云不符，而是处于中间状态。IMAP目前已具备研究这个复杂近邻星际区域详细物理过程的能力，通过解析和理解其物理特性，可确定日球层对本地星际流的响应方式及其随时间的演化情况。
英文摘要
The Sun's motion through the interstellar medium creates a flow of interstellar neutral (ISN) atoms through the heliosphere. ISN He, due to its high universal abundance and relatively low ionization rate, is the most abundant of the interstellar species near 1 au and ideal for flow parameter determination. The Interstellar Boundary Explorer (IBEX) measurements of ISN He flow parameters (speed, temperature, and direction) yielded a tube in 4D parameter space -- narrow in cross-section but highly extended along one parameter axis (e.g., ecliptic longitude direction). This ``4D parameter tube'' results in large systematic uncertainties, a direct consequence of IBEX-Lo's fixed viewing orientation on the spacecraft. On the Interstellar Mapping and Acceleration Probe (IMAP), the articulation of the IMAP-Lo boresight using its pivot platform enables multiple viewing orientations of the ISN flow for significant systematic uncertainty reduction. We provide first results that definitively intersect ISN parameter tubes for elongation angles $79^\circ$, 94$^\circ$, and 109$^\circ$, resulting in precise interstellar parameters: speed $26.37 \pm 0.82$ km s$^{-1}$, ecliptic longitude direction $74.85^\circ \pm 0.96^\circ$, ecliptic latitude direction $-5.212^\circ \pm 0.035^\circ$, and temperature $7740^{+770}_{-730}$ K. The inferred flow of the Very Local Interstellar Medium is not consistent with either the Local Interstellar Cloud or the G-Cloud, but rather an intermediate state. IMAP is now positioned to study the detailed physics of this complex, nearby interstellar region. By resolving and understanding its physics, we determine how the heliosphere responds to the local interstellar flow, and how it may evolve in time
Comments29 pages, 15 figures, 8 tables
