Evolution of anomalous cosmic-ray oxygen and helium energy spectra during the solar cycle 22 recovery phase in the outer heliosphere

被引:14
作者
Hill, ME [1 ]
Hamilton, DC
Krimigis, SM
机构
[1] Univ Maryland, Dept Phys, College Pk, MD 20742 USA
[2] Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA
基金
美国国家航空航天局;
关键词
convection; cosmic rays; diffusion; interplanetary medium; Sun : activity;
D O I
10.1086/341668
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We present annual 0.3-40 MeV nucleon(-1) anomalous cosmic-ray (ACR) oxygen and helium energy spectra from the 1991-1999 cosmic-ray recovery phase of solar cycle 22. These observations were made with the Low Energy Charged Particle instruments aboard the Voyager 1 and Voyager 2 spacecraft while at helioradial positions ranging from 34 to 76 AU. The peak intensities of both species increased by 2 orders of magnitude during this period, while the energies of peak O and He intensity decreased from similar to9 to 1.3 MeV nucleon(-1) and from similar to35 to 6 MeV nucleon(-1), respectively. Using these observations along with published O measurements from the Solar Anomalous Magnetospheric Particle Explorer at 1 AU, we investigate ACR transport phenomena. We make estimates related to transport parameters such as the relative change in the scattering mean free path over time, the rigidity dependence of the mean free path, and the distance between the Sun and the solar wind termination shock.
引用
收藏
页码:L169 / L172
页数:4
相关论文
共 21 条
[11]   An evaluation of perpendicular diffusion models regarding cosmic ray modulation on the basis of a hydromagnetic description for solar wind turbulence [J].
le Roux, JA ;
Zank, GP ;
Ptuskin, VS .
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 1999, 104 (A11) :24845-24862
[12]   Anomalous cosmic ray argon and other rare elements at 1-4 MeV/nucleon trapped within the Earth's magnetosphere [J].
Mazur, JE ;
Mason, GM ;
Blake, JB ;
Klecker, B ;
Leske, RA ;
Looper, MD ;
Mewaldt, RA .
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2000, 105 (A9) :21015-21023
[13]  
MORAAL H, 1999, P 26 INT COSM RAY C, V7, P543
[14]   PASSAGE OF ENERGETIC CHARGED PARTICLES THROUGH INTERPLANETARY SPACE [J].
PARKER, EN .
PLANETARY AND SPACE SCIENCE, 1965, 13 (01) :9-&
[15]   COSMIC-RAY DRIFT, SHOCK-WAVE ACCELERATION, AND THE ANOMALOUS COMPONENT OF COSMIC-RAYS [J].
PESSES, ME ;
JOKIPII, JR ;
EICHLER, D .
ASTROPHYSICAL JOURNAL, 1981, 246 (02) :L85-L88
[16]  
STEENBERG CD, 1998, THESIS POTCHEFSTROOM
[17]   Perspectives: Planetary science - News from the edge of interstellar space [J].
Stone, EC .
SCIENCE, 2001, 293 (5527) :55-56
[18]   The distance to the solar wind termination shock in 1993 and 1994 from observations of anomalous cosmic rays [J].
Stone, EC ;
Cummings, AC ;
Webber, WR .
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 1996, 101 (A5) :11017-11025
[19]  
STONE EC, 1999, P 26 INT COSM RAY C, V7, P551
[20]   The radial and latitudinal dependence of the cosmic ray diffusion tensor in the heliosphere [J].
Zank, GP ;
Matthaeus, WH ;
Bieber, JW ;
Moraal, H .
JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 1998, 103 (A2) :2085-2097