Suprathermal Ions in the Outer Heliosphere
Suprathermal Ions in the Outer Heliosphere
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DOI：
10.3847/1538-4357/ab125f
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发表时间：
2019-05
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通讯作者：
P. Kollmann;M. Hill;R. McNutt;L. Brown;R. Allen;G. Clark;B. Andrews;N. Salazar;J. Westlake;G. Romeo;J. Vandegriff;M. Kusterer;D. Smith;S. Jaskulek;R. Decker;A. Cheng;S. Krimigis;C. Lisse;D. Mitchell;H. Weaver;P. Delamere;H. Elliott;E. Fattig;G. Gladstone;P. Valek;S. Weidner;F. Bagenal;M. Horányi;J. Kammer;D. Kaufmann;C. Olkin;M. Piquette;J. Spencer;A. Steffl;S. Stern;L. Young;K. Ennico;I. Linscott;D. Strobel;M. Summers;J. Szalay
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文献类型：
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作者：
P. Kollmann;M. Hill;R. McNutt;L. Brown;R. Allen;G. Clark;B. Andrews;N. Salazar;J. Westlake;G. Romeo;J. Vandegriff;M. Kusterer;D. Smith;S. Jaskulek;R. Decker;A. Cheng;S. Krimigis;C. Lisse;D. Mitchell;H. Weaver;P. Delamere;H. Elliott;E. Fattig;G. Gladstone;P. Valek;S. Weidner;F. Bagenal;M. Horányi;J. Kammer;D. Kaufmann;C. Olkin;M. Piquette;J. Spencer;A. Steffl;S. Stern;L. Young;K. Ennico;I. Linscott;D. Strobel;M. Summers;J. Szalay
超热离子是由星际气体形成的，星际气体首先被电离成拾取离子，然后被加速到数十和数百keV的能量。由此产生的超热离子光谱与数百千电子伏以前已经观察到整个日光层，然而，在较低的能量，周围的皮卡离子截止能量，他们从加速，测量被限制为<10 Au。在这里，我们提出了一个统计研究的超热离子在千电子伏到百千电子伏的能量范围。我们使用冥王星高能粒子光谱仪科学调查（PEPSSI）仪器上的新视野号航天器，它记录了在广泛的日心距离的观测，并将这些测量结果与卡西尼号上的电荷能量质谱仪（CHEMS）观测结果进行比较，卡西尼号巡航并留在土星上。我们发现超热离子强度与能量的幂律指数在-1和-2之间，在接近可能是共转合并相互作用区域的不连续处突然变化，与太阳风的整体速度相关，并在太阳周期的时间尺度上显示出长期的演化。新视野号和卡西尼号的独立测量结果是一致的，证实了新视野号/PEPSSI仪器的首次完全校准测量结果。
Suprathermal ions form from interstellar gas that is first ionized into pickup ions and then accelerated to tens and hundreds of keV in energy. The resulting suprathermal ion spectra with hundreds of keV have been previously observed throughout the heliosphere; however, measurements at lower energies, around the pickup ion cutoff energy where they are accelerated from, were limited to <10 au. Here we present a statistical study of suprathermal ions in the keV to hundred keV energy range. We use the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument on the New Horizons spacecraft, which recorded observations at a wide range of heliocentric distances, and compare these measurements to charge energy mass spectrometer (CHEMS) observations on Cassini, which cruised to and remained at Saturn. We find that the power-law exponents of suprathermal ion intensity over energy are between −1 and −2, change abruptly close to discontinuities that are likely corotating merged interaction regions, correlate with the solar wind bulk speed, and show a long-term evolution on the timescale of the solar cycle. The independent measurements from New Horizons and Cassini are consistent, confirming the first fully calibrated measurements from the New Horizons/PEPSSI instrument.