Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs

被引：52

作者：

Badman, S. V. ^{[1
]}

Achilleos, N. ^{[2
,10
]}

Arridge, C. S. ^{[3
,10
]}

Baines, K. H. ^{[4
]}

Brown, R. H. ^{[5
]}

Bunce, E. J. ^{[6
]}

Coates, A. J. ^{[3
,10
]}

Cowley, S. W. H. ^{[6
]}

Dougherty, M. K. ^{[7
]}

Fujimoto, M. ^{[1
]}

Hospodarsky, G. ^{[8
]}

Kasahara, S. ^{[1
]}

Kimura, T. ^{[1
]}

Melin, H. ^{[6
]}

Mitchell, D. G. ^{[9
]}

Stallard, T. ^{[6
]}

Tao, C. ^{[1
]}

机构：

[1] JAXA Inst Space & Astronaut Sci, Chuo Ku, Sagamihara, Kanagawa 2525210, Japan

[2] UCL, Dept Phys & Astron, London WC1E 6BT, England

[3] Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England

[4] Univ Wisconsin, SSEC, Madison, WI 53706 USA

[5] Univ Arizona, LPL, Tucson, AZ 85721 USA

[6] Univ Leicester, Dept Phys & Astron, Leicester LE1 7RH, Leics, England

[7] Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London SW7 2BZ, England

[8] Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA

[9] Johns Hopkins Univ, APL, Laurel, MD 20723 USA

[10] UCL Birkbeck, Ctr Planetary Sci, London, England

来源：

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS | 2012年 / 117卷

关键词：

INTERPLANETARY MAGNETIC-FIELD; FLUX-TRANSFER EVENTS; CURRENT REGION; MAGNETOSPHERE; RECONNECTION; MAGNETOPAUSE; IONOSPHERE; DYNAMICS; MODEL; CUSP;

D O I：

10.1029/2011JA017222

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We present Cassini Visual and Infrared Mapping Spectrometer observations of infrared auroral emissions from the noon sector of Saturn's ionosphere revealing multiple intense auroral arcs separated by dark regions poleward of the main oval. The arcs are interpreted as the ionospheric signatures of bursts of reconnection occurring at the dayside magnetopause. The auroral arcs were associated with upward field-aligned currents, the magnetic signatures of which were detected by Cassini at high planetary latitudes. Magnetic field and particle observations in the adjacent downward current regions showed upward bursts of 100-360 keV light ions in addition to energetic (hundreds of keV) electrons, which may have been scattered from upward accelerated beams carrying the downward currents. Broadband, upward propagating whistler waves were detected simultaneously with the ion beams. The acceleration of the light ions from low altitudes is attributed to wave-particle interactions in the downward current regions. Energetic (600 keV) oxygen ions were also detected, suggesting the presence of ambient oxygen at altitudes within the acceleration region. These simultaneous in situ and remote observations reveal the highly energetic magnetospheric dynamics driving some of Saturn's unusual auroral features. This is the first in situ identification of transient reconnection events at regions magnetically conjugate to Saturn's magnetopause.

引用

页数：12

共 54 条

[1] Modeling the size and shape of Saturn's magnetopause with variable dynamic pressure [J].

Arridge, C. S. ;

Achilleos, N. ;

Dougherty, M. K. ;

Khurana, K. K. ;

Russell, C. T. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2006, 111 (A11)

[2] A statistical analysis of the location and width of Saturn's southern auroras [J].

Badman, S. V. ;

Cowley, S. W. H. ;

Gerard, J-C ;

Grodent, D. .

ANNALES GEOPHYSICAE, 2006, 24 (12) :3533-3545

[3] Location of Saturn's northern infrared aurora determined from Cassini VIMS images [J].

Badman, S. V. ;

Achilleos, N. ;

Baines, K. H. ;

Brown, R. H. ;

Bunce, E. J. ;

Dougherty, M. K. ;

Melin, H. ;

Nichols, J. D. ;

Stallard, T. .

GEOPHYSICAL RESEARCH LETTERS, 2011, 38

[4] Cassini VIMS observations of latitudinal and hemispheric variations in Saturn's infrared auroral intensity [J].

Badman, Sarah V. ;

Tao, Chihiro ;

Grocott, Adrian ;

Kasahara, Satoshi ;

Melin, Henrik ;

Brown, Robert H. ;

Baines, Kevin H. ;

Fujimoto, Masaki ;

Stallard, Tom .

ICARUS, 2011, 216 (02) :367-375

[5] Open flux estimates in Saturn's magnetosphere during the January 2004 Cassini-HST campaign, and implications for reconnection rates -: art. no. A11216 [J].

Badman, SV ;

Bunce, EJ ;

Clarke, JT ;

Cowley, SWH ;

Gérard, JC ;

Grodent, D ;

Milan, SE .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2005, 110 (A11)

[6] IMF dependence of the open-closed field line boundary in Saturn's ionosphere, and its relation to the UV auroral oval observed by the Hubble Space Telescope [J].

Belenkaya, E. S. ;

Alexeev, I. I. ;

Blokhina, M. S. ;

Cowley, S. W. H. ;

Badman, S. V. ;

Kalegaev, V. V. ;

Grigoryan, M. S. .

ANNALES GEOPHYSICAE, 2007, 25 (05) :1215-1226

[7] EXTREME ULTRAVIOLET OBSERVATIONS FROM VOYAGER-1 ENCOUNTER WITH SATURN [J].

BROADFOOT, AL ;

SANDEL, BR ;

SHEMANSKY, DE ;

HOLBERG, JB ;

SMITH, GR ;

STROBEL, DF ;

MCCONNELL, JC ;

KUMAR, S ;

HUNTEN, DM ;

ATREYA, SK ;

DONAHUE, TM ;

MOOS, HW ;

BERTAUX, JL ;

BLAMONT, JE ;

POMPHREY, RB ;

LINICK, S .

SCIENCE, 1981, 212 (4491) :206-211

[8] The Cassini visual and infrared mapping spectrometer (VIMS) investigation [J].

Brown, RH ;

Baines, KH ;

Bellucci, G ;

Bibring, JP ;

Buratti, BJ ;

Capaccioni, F ;

Cerroni, P ;

Clark, RN ;

Coradini, A ;

Cruikshank, DP ;

Drossart, P ;

Formisano, V ;

Jaumann, R ;

Langevin, Y ;

Matson, DL ;

Mccord, TB ;

Mennella, V ;

Miller, E ;

Nelson, RM ;

Nicholson, PD ;

Sicardy, B ;

Sotin, C .

SPACE SCIENCE REVIEWS, 2004, 115 (1-4) :111-168

[9] Magnetic field structure of Saturn's dayside magnetosphere and its mapping to the ionosphere: Results from ring current modeling [J].

Bunce, E. J. ;

Arridge, C. S. ;

Cowley, S. W. H. ;

Dougherty, M. K. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2008, 113 (A2)

[10] Origin of Saturn's aurora:: Simultaneous observations by Cassini and the Hubble Space Telescope [J].

Bunce, E. J. ;

Arridge, C. S. ;

Clarke, J. T. ;

Coates, A. J. ;

Cowley, S. W. H. ;

Dougherty, M. K. ;

Gerard, J. -C. ;

Grodent, D. ;

Hansen, K. C. ;

Nichols, J. D. ;

Southwood, D. J. ;

Talboys, D. L. .

JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, 2008, 113 (A9)

← 1 2 3 4 5 6 →