3I/ATLAS接近近日点前的快速变亮
Rapid Brightening of 3I/ATLAS Ahead of Perihelion
AI总结：
3I/ATLAS在接近近日点前亮度快速上升，日心距离与亮度呈r^(-7.5±1.0)关系，且其可见 coma 约4'直径，色测显示其比太阳更蓝。
摘要：
星际彗星3I/ATLAS在2025年10月29日近日点前接近时，由于地球位于太阳的另一侧，阻碍了地面光学观测的前一个月。然而，这种几何位置使彗星处于几个空间太阳日冕仪和日球成像仪的视野范围内，使其在接近近日点的最后阶段得以持续观测。我们报告了2025年9月至10月期间，STEREO-A的SECCHI HI1和COR2、SOHO的LASCO C3以及GOES-19的CCOR-1仪器的测光数据，显示彗星的亮度随着日心距离r呈r^(-7.5±1.0)的快速上升。CCOR-1还将彗星分辨为一个扩展源，其可见 coma 约为4'直径。此外，LASCO色测光显示彗星明显比太阳更蓝，这与近日点附近气体发射物对可见亮度的显著贡献一致。
英文摘要：
Interstellar comet 3I/ATLAS has been approaching its 2025 October 29 perihelion while opposite the Sun from Earth, hindering ground-based optical observations over the preceding month. However, this geometry placed the comet within the fields of view of several space-based solar coronagraphs and heliospheric imagers, enabling its continued observation during its final approach toward perihelion. We report photometry from STEREO-A's SECCHI HI1 and COR2, SOHO's LASCO C3, and GOES-19's CCOR-1 instruments in 2025 September--October, which show a rapid rise in the comet's brightness scaling with heliocentric distance r as r^(-7.5+/-1.0). CCOR-1 also resolves the comet as an extended source with an apparent coma ~4' in diameter. Furthermore, LASCO color photometry shows the comet to be distinctly bluer than the Sun, consistent with gas emission contributing a substantial fraction of the visible brightness near perihelion.
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