SH34A-01  

Early Solar Wind Observations from the Plasma and Suprathermal Ion Composition (PLASTIC) Experiments on STEREO

* Galvin, A B (toni.galvin@unh.edu), Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Kistler, L A, Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Popecki, M A, Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Farrugia, C , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Moebius, E , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Lee, M , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Ellis, L , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Simunac, K , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Singer, K , Space Science Center, University of New Hampshire, EOS SSC Morse Hall, Durham, NH 03824, United States
Russell, C , Institute of Geophysics, University of California, Los Angeles, CA 90095, United States
Walker, C , Physikalisches Institut, University of Bern, Berne, Switzerland
Walker, C , Mount Holyoke College, 3030 Blanchard Student Center, South Hadley, MA 01075, United States
Blush, L , Physikalisches Institut, University of Bern, Berne, Switzerland
Klecker, B , Max-Planck Institut fuer extraterrestrische Physik, P.O. Box 1312, Garching, D 85741, Germany
Wimmer-Schweingruber, R F, Institute for Experimental and Applied Physics, University of Kiel, Kiel, D-24098, Germany
Thompson, B , NASA, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Bochsler, P , Physikalisches Institut, University of Bern, Berne, Switzerland
Wurz, P , Physikalisches Institut, University of Bern, Berne, Switzerland
Daoudi, H , Physikalisches Institut, University of Bern, Berne, Switzerland
Giammanco, C , Physikalisches Institut, University of Bern, Berne, Switzerland
Karrer, R , Physikalisches Institut, University of Bern, Berne, Switzerland
Opitz, A , Physikalisches Institut, University of Bern, Berne, Switzerland
Koeten, M , Institute for Experimental and Applied Physics, University of Kiel, Kiel, D-24098, Germany
Luhmann, J , Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
Howard, R , Solar Physics Branch, Naval Research Laboratory, Washington, DC , United States
Wuelser, J P, Lockheed Martin Solar and Astrophysics Laboratory, 3251 Hanover St., Org. ADBS, Bldg. 252, Palo Alto, CA 94304, United States
Acuna, M , NASA, Goddard Space Flight Center, Greenbelt, MD 20771, United States

Two identical Plasma and Suprathermal Ion Composition (PLASTIC) instruments are now flying on the STEREO A and B observatories, which launched in October 2006. The STEREO observatories are drifting away from the Earth and from each other, providing different longitudinal perspectives. PLASTIC together with the IMPACT suite provides the in-situ measurements for the STEREO mission, while SECCHI provides remote imaging of the solar corona. The PLASTIC solar wind sector measures solar wind proton bulk parameters and provides species identification and relative abundances for the more dominant solar wind minor (Z>2) ions. During this early part of the STEREO mission, as we approach solar minimum conditions, there have been a series of coronal- hole associated high speed streams and interstream sector boundaries. In this talk we will provide initial observations of the solar wind during selected time periods.

SH34A-02 INVITED  

On the Variability of Suprathermal He⁺: new Results From STEREO and SOHO

* Klecker, B (berndt.klecker@mpe.mpg.de), Max-Planck Institut fuer extraterrestrische Physik, Postfach 1312, Garching, 85741, Germany
Galvin, A B, EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Kistler, L M, EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Popecki, M A, EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Mouikis, C , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Farrugia, C , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Moebius, E , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Lee, M , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Ellis, L , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Simunac, K , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Singer, K , EOS Space Science Center, University of New Hampshire, Durham, NH 03824, United States
Blush, L M, Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Bochsler, P , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Wurz, P , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Daoudi, H , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Giammanco, C , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Karrer, R , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Opitz, A , Physikalisches Institut, University of Bern, Bern, 3012, Switzerland
Wimmer-Schweingruber, R F, Institute for Experimental and Applied Physics, University of Kiel, Kiel, 24098, Germany
Koeten, M , Institute for Experimental and Applied Physics, University of Kiel, Kiel, 24098, Germany
Hilchenbach, M , Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Strasse 2, Katlenburg- Lindau, 37191, Germany
Thompson, B , NASA, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Acuna, M , NASA, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Luhmann, J , Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States

The two Plasma and Suprathermal Ion Composition (PLASTIC) experiments onboard STEREO-A and STEREO-B and the CELIAS experiment onboard SOHO provide measurements of velocity, mass and ionic charge of solar wind ions and of suprathermal particles up to energies of 80 keV/e (PLASTIC) and 600 keV/e (CELIAS), respectively. The observations with SOHO showed a large variability of the He⁺/He²⁺ -ratio at suprathermal energies, with He⁺/He²⁺ > 1 in many interplanetary shock related solar energetic particle (SEP) events. This variability is much larger than the observed variations in the interstellar pickup He⁺ source and suggests that the different velocity distributions of the two sources, i.e. solar wind and pickup ions of interstellar origin, play an important role for the efficiency of injection and/or acceleration of these ions. Thus PLASTIC onboard STEREO, covering the energy range from solar wind to pickup ion and suprathermal energies, has the potential for resolving some of the questions related to the large variability of the He⁺/He²⁺-ratios. In this paper we will review the SOHO measurements of pickup and suprathermal He⁺ ions at 1 AU, show first results from PLASTIC onboard STEREO and discuss the perspective to tackle some of the open questions.

SH34A-03  

Observations of Energetic O+ in the Distant Tail Magnetosheath: Results from STEREO/PLASTIC

* Kistler, L M (Lynn.Kistler@unh.edu), University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Galvin, A B, University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Popecki, M A, University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Mouikis, C , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Farrugia, C , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Moebius, E , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Lee, M A, University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Ellis, L , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Simunac, K , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Singer, K , University of New Hampshire, Space Science Center, Morse Hall, Durham, NH 03824, United States
Blush, L M, University of Bern, Physikalisches Institute, Bern, 3012, Switzerland
Klecker, B , MPE, Giessenbachstrasse, Garching, 85748, Germany
Wimmer-Schweingruber, R F, University of Kiel, Institute for Experimental and Applied Physics, Kiel, 24098, Germany
Thompson, B , NASA GSFC, 8800 Greenbelt Rd, Greenbelt, MD 20771, United States
Bochsler, P , University of Bern, Physikalisches Institute, Bern, 3012, Switzerland
Wurz, P , University of Bern, Physikalisches Institute, Bern, 3012, Switzerland
Karrer, R , University of Bern, Physikalisches Institute, Bern, 3012, Switzerland
Opitz, A , University of Bern, Physikalisches Institute, Bern, 3012, Switzerland
Luhmann, J , University of California, Berkeley, Space Sciences Laboratory, Berkeley, CA 94720, United States
Acuna, M , NASA GSFC, 8800 Greenbelt Rd, Greenbelt, MD 20771, United States
Russell, C T, UCLA, Institute of Geophysics, Los Angeles, CA 90095, United States

Two identical Plasma and Suprathermal Ion Composition (PLASTIC) instruments are now flying on the STEREO A and B observatories, which launched in October 2006. PLASTIC is a solar wind and heliospheric ion mass spectrometer that utilizes electrostatic deflection, post-acceleration,time-of-flight, energy, and position measurements in the energy-per-charge range of 0.25-80 keV/e. During the month of February, 2007, as the spacecraft were approaching their final heliocentric orbits, STEREO B traversed the dusk-side magnetosheath and boundary layer from -100 Re to -300 Re down the tail. Throughout the month, bursts of energetic O+ were observed in the magnetosheath. The energy of the O+ extended to the upper range of the instrument, 80 keV. The occurrence of O+ correlated with periods of high solar wind velocity. We will compare these observations with observations of O+ in the near-earth magnetosheath, as observed by CLUSTER, and discuss the possible sources and transport paths for these ions.

SH34A-04  

STEREO's in-situ perspective on the solar minimum solar wind structure

* Luhmann, J G (jgluhman@ssl.berkeley.edu), Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
Larson, D (davin@ssl.berkeley.edu), Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
Schroeder, P (peters@ssl.berkeley.edu), Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
Lee, C O (clee@ssl.berkeley.edu), Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
Sauvaud, J (sauvaud@cesr.fr), CESR, CNRS, Toulouse, France
Acuna, M H (mha@lepmom.gsfc.nasa.gov), NASA, Goddard Space Flight Center, Greenbelt, MD 20771, United States
Galvin, A B (toni.galvin@unh.edu), SSC, University of New Hampshire, Durham, NH 03824, United States
Russell, C T (ctrussel@igpp.ucla.edu), IGPP, UCLA, Los Angeles, CA 90095, United States
Jian, L (jlan@igpp.ucla.edu), IGPP, UCLA, Los Angeles, CA 90095, United States
Arge, C N (nick.arge@hanscom.af.mil), AFRL, Hanscom AFB, MA 01731, United States
Odstrcil, D (dusan.odstrcil@noaa.gov), CIRES and, NOAA SEC, Boulder, CO 80303, United States
Riley, P (pete.riley@saic.com), SAIC, San Diego, CA 92121, United States
Howard, R A (russ.howard@nrl.navy.mil), Naval Research, Laboratory, Washington, DC 20375, United States
Aschwanden, M (aschwanden@lmsal.com), LMSAL, Lockheed, Palo Alto, CA 94304, United States
MacNeice, P (pmacneic@pop900.gsfc.nasa.gov), CCMC, GSFC, Greenbelt, MD 20771, United States
Chulaki, A (achulaki@nasa.gov), CCMC, GSFC, Greenbelt, MD 20771, United States

STEREO multipoint measurements of the solar wind structure with the IMPACT and PLASTIC investigations, near Earth but off the Sun-Earth line, allow its sources and structure to be examined at solar minimum when such studies are particularly straightforward. With the aid of 3D models of the heliosphere available at the CCMC, we map the in-situ observations to their solar sources using a combination of the open field regions inferred from the SECCHI EUVI imagers and SOHO EIT, and the magnetogram-based models of the corona and solar wind. Our ultimate goal is the continuous tracking of solar wind source regions as the STEREO mission progresses, as well as the use of the mappings to deduce the distinctive properties of solar wind from different types of sources

SH34A-05  

The High Energy Telescopes for the STEREO Mission

* von Rosenvinge, T (tycho@milkyway.gsfc.nasa.gov), NASA/Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, United States
Cummings, A (ace@srl.caltech.edu), California Institute of Technology, 220-47 Downs Laboratory, Pasadena, CA 91125, United States
Cohen, C (cohen@srl.caltech.edu), California Institute of Technology, 220-47 Downs Laboratory, Pasadena, CA 91125, United States
Leske, R (ral@srl.caltech.edu), California Institute of Technology, 220-47 Downs Laboratory, Pasadena, CA 91125, United States
Mewaldt, R (rmewaldt@srl.caltech.edu), California Institute of Technology, 220-47 Downs Laboratory, Pasadena, CA 91125, United States
Stone, E (ecs@srl.caltech.edu), California Institute of Technology, 220-47 Downs Laboratory, Pasadena, CA 91125, United States
Wiedenbeck, M (Mark.E.Wiedenbeck@jpl.nasa.gov), Jet Propulsion Laboratory, MS 169-327, Pasadena, CA 91109, United States

The High Energy Telescopes (HETs) described in this paper are part of the IMPACT investigation for the STEREO mission (Principal Investigator: Janet Luhmann, University of California at Berkeley). The two STEREO spacecraft were launched from Cape Canaveral, FL on October 25, 2006. High energy electrons (~ 0.7 -6 MeV) and nuclei from hydrogen to iron (~ 13 - 200 MeV/nucleon) are detected by the HETs, one on each spacecraft. The HET design, the associated electronics, and the on-board software are described in some detail. Observations from one pass through the Earth's magnetosphere and from four X-class solar events in December, 2006 are presented to illustrate the capabilities of the HETs. The event of December 13th was a Ground Level Event. We will compare the elemental composition of this event with that of a previous Ground Level Event on January 20, 2005. This work was supported by NASA (at Caltech and JPL under contract NAS5-00133).

SH34A-06  

Solar Energetic Particle Observations From the STEREO Low Energy Telescope (LET)

* Mewaldt, R A (RMewaldt@SRL.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Cohen, C S (Cohen@SRL.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Mason, G M (Glenn.Mason@jhuapl.edu), Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, United States
Cummings, A C (ace@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Davis, A J (ad@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Labrador, A W (Labrador@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Leske, R A (ral@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Miyasaka, H (Miyasaka@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
Stone, E C (ECS@srl.caltech.edu), Caltech, 220-47 Downs Lab, Pasadena, CA 91125, United States
von Rosenvinge, T T (tycho@milkyway.gsfc.nasa.gov), NASA/Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, United States
Wiedenbeck, M E (mark.e.wiedenbeck@jpl.nasa.gov), Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, United States

Each STEREO spacecraft includes a suite of four solar energetic particle (SEP) sensors (part of the IMPACT investigation) that measure the composition and energy spectra of SEP ions from H to Fe with energies from ~0.05 to ~100 MeV/nucleon, as well as electrons. The STEREO SEP sensors were first powered up in space in mid-November and were still being commissioned in early December when an X9 solar flare from active region 930 erupted at longitude E71. Several hours later real time data from STEREO and ACE signaled the start of a large SEP event. A subsequent X6.5 flare (at E57) apparently added to the SEP population, which peaked in intensity on December 7th. On December 13th and 14th this same active region released two more X-class flares and fast coronal mass ejections from W23 and W44, resulting in two additional large SEP events. We present observations of the December 2006 events from the Low Energy Telescope (LET) on STEREO, which measures SEP composition from ~3 to ~30 MeV/nucleon. Observations from the SIS and ULEIS instruments on ACE are used to extend the energy coverage. In addition, we present observations of impulsive SEP events observed by LET and by the Suprathermal Ion Telescope (SIT), which measures ion composition from ~0.05 to ~5 MeV/nuc. These new observations from STEREO are discussed in the context of SEP events observed earlier in solar cycle 23. This work was supported by NASA under NAG5-03131 and NAG5-12929.

SH34A-07  

STEREO, ACE and Wind Observations of Reconnection X-line Extents and Durations in the Solar Wind

* Gosling, J T (jgosling@lasp.colorado.edu), University of Colorado, 1234 Innovation Drive, Boulder, CO 80303, United States
Eriksson, S (stefan.eriksson@lasp.colorado.edu), University of Colorado, 1234 Innovation Drive, Boulder, CO 80303, United States
Blush, L M (lisa.blush@space.unibe.ch), University of Bern, Sidlerstrasse 5 3012, Bern, Switzerland
Phan, T D (phan@ssl.berkeley.edu), University of California, Grizzly Peak Drive, Berkeley, CA 94720, United States
Luhmann, J G (jgluhman@ssl.berkeley.edu), University of California, Grizzly Peak Drive, Berkeley, CA 94720, United States
McComas, D J (dmccomas@swri.edu), Southwest Research Institute, P.O. Drawer 28510, San Antonio, TX 78228-0510, United States
Acuna, M H (mario.acuna@nasa.gov), Goddard Space Flight Center, Code 673, Greenbelt, MD 20771, United States
Russell, C T (ctrussel@igpp.ucla.edu), University of California, 405 Hilgard Avenue, Los Angeles, CA 90095, United States
Galvin, A B (toni.galvin@unh.edu), University of New Hampshire, 39 College Road, Durham, NH 03824, United States

Multi-spacecraft observations of magnetic reconnection exhausts in the solar wind near Earth have provided direct evidence that the exhausts typically result from quasi-stationary reconnection at continuous and extended X- lines. Thus far reconnection events have been identified where the X-line extended at least 2.5 x 10⁶ km and where reconnection persisted for at least 5 hours. These are only lower limits to X-line extents and reconnection durations, limited by available spacecraft spatial separations in the near-Earth vicinity. Although spacecraft separations typically have been large compared to separations available for studying reconnection in the magnetosphere, they have been small compared to the scale sizes of some current sheets in the solar wind. In order to extend these reconnection exhaust measurements to larger scale sizes and longer times, larger spacecraft separations are required. With the launch of the twin STEREO A and B spacecraft, which now increasingly lead and trail Earth in its orbit about the Sun, respectively, a large and varying range of spacecraft separations has become available for study. We have begun to identify solar wind reconnection exhausts in solar wind data as STEREO A and B drift ever further from the Sun-Earth line. Preliminary analysis reveals that common reconnection exhausts were observed by STEREO A and B and by ACE and Wind (both near L1) in the early phases of the STEREO mission. Here we report initial results of a study of X-line extents and reconnection durations as inferred from measurements by these four spacecraft in the early months of 2007.

Authors (2007), Title, Eos Trans. AGU, 88(23), Jt. Assem. Suppl., Abstract xxxxx-xx