Papers by Stan Grzedzielski
A cone-like enhancement of polar solar corona plasma and its influence on heliospheric particles
EGU General Assembly Conference Abstracts, Apr 1, 2017
One of the most popular models of the LISM suggests coexistence of warm partially ionized clouds ... more One of the most popular models of the LISM suggests coexistence of warm partially ionized clouds embedded in the fully ionized plasma of the bay of the Local Bubble. The two clouds closest to the Sun are probably the Local Interstellar Cloud (LIC) and Galactic (G) Cloud (Redfield & Linsky 2008, Linsky & Redfield 2014). The structure of the clouds could be resolved using atomic absorption lines in high-resolution spectra of the closest stars. This method requires the minimal thickness of the observed cloud of the order of 0.1 pc, and thus gives only an upper limit for the distance to the LIC boundary (Wood et al. 2000).
Helium binary interactions Hydrogen→ important charge-exchange with protons (H + H0→ H0 + H) → ot... more Helium binary interactions Hydrogen→ important charge-exchange with protons (H + H0→ H0 + H) → other: almost negligible if the energy is small . 100 keV Helium: I three charge-states He2+ (α-particles), He and He0 I a number of different reactions that change charge state of He ion or atom, including ionization (ion), charge-exchange (cx), double charge-exchange between He2+ and He0 (2cx) I contributions depends on assumed conditions in plasma (different in the inner heliosheath, interstellar medium, and hot interstellar bubbles) For energy . 10 keV the mean free path (m.f.p.) against He ENA ionization is up to one order of magnitude longer than the m.f.p. of H ENA. For assumed Local Interstellar Medium (LISM) conditions: nH = 0.194 cm−3, np = 0.056 cm−3, nHe = 0.0153 cm−3, nHe+ = 0.0096 cm −3, m.f.p. of He ENA: 7 800 AU; H ENA 870 AU at E = 5 keV.
The Astrophysical Journal, 2017
We provide observational evidence for the existence of large-scale cylindrical (or conic-like) cu... more We provide observational evidence for the existence of large-scale cylindrical (or conic-like) current sheets (CCSs) at high heliolatitudes. Long-lived CCSs were detected by Ulysses during its passages over the South Solar Pole in 1994 and 2007. The characteristic scale of these tornado-like structures is several times less than a typical width of coronal holes within which the CCSs are observed. CCS crossings are characterized by a dramatic decrease in the solar wind speed and plasma beta typical for predicted profiles of CCSs. Ulysses crossed the same CCS at different heliolatitudes at 2-3 au several times in 1994, as the CCS was declined from the rotation axis and corotated with the Sun. In 2007, a CCS was detected directly over the South Pole, and its structure was strongly highlighted by the interaction with comet McNaught. Restorations of solar coronal magnetic field lines reveal the occurrence of coniclike magnetic separators over the solar poles in both 1994 and 2007. Such separators exist only during solar minima. Interplanetary scintillation data analysis confirms the presence of long-lived low-speed regions surrounded by the typical polar high-speed solar wind in solar minima. Energetic particle flux enhancements up to several MeV/nuc are observed at edges of the CCSs. We built simple MHD models of a CCS to illustrate its key features. The CCSs may be formed as a result of nonaxiality of the solar rotation axis and magnetic axis, as predicted by the Fisk-Parker hybrid heliospheric magnetic field model in the modification of Burger and coworkers.
Trapped Radiation in the Outer Heliosphere
COSPAR Colloquia Series, 1990
ABSTRACT
Evolution of Trapped Radiation in a 3-DIMENSIONAL Heliosphere: A Computer Simulation
Solar Wind Seven, 1992
ABSTRACT
LIMF direction inferred from the mechanism for IBEX ribbon generation based on SW-LIC interaction vs 2-3 kHz radio emission
After the discovery of the heliospheric ribbon of energetic neutral atoms (ENAs) by the first ded... more After the discovery of the heliospheric ribbon of energetic neutral atoms (ENAs) by the first dedicated Energetic Neutral Atom spaceborn observatory IBEX, scientists have tried to explain the underlying physics of ribbon generation. Up to now two different mechanisms have been proposed: one based on the solar wind-local interstellar cloud (SW-LIC) interaction, the second on the LIC-LB (Local Bubble) interaction. An interpretation of the ribbon as coming up due to the production of the ENAs in locations in space ordered by the local interstellar magnetic field (LIMF) allows to constrain the spatial configuration (direction) of the LIMF near the Sun. However, the LIMF direction inferred from this mechanism (alpha ~ 45°) contradicts the result coming from the 2-3 kHz radio emission (alpha ~ 90°). The second mechanism based on the LIC-LB interaction does not involve directly the LIMF. Nevertheless it appears interesting to assume the LIMF direction as coming from the 2-3 kHz radio emiss...
Local Interstellar Cloud(s) Observations with the GHRS
Does the present state of the Local Interstellar Cloud result from an impulsive ionization event ?
The present state of the Local Interstellar Cloud (LIC) and adjacent cloud - ionization, metal-to... more The present state of the Local Interstellar Cloud (LIC) and adjacent cloud - ionization, metal-to-hydrogen abundances, local velocity differences, absorption lines widths - can not be explained within the frame of an equilibrium model. We argue that most of the presently available observables of the LIC and its surrounding can be understood if one assumes that our local galactic environment was subjected in the recent past (i.e. less than about 10^6 years ago) to a sudden strong burst of X- r a y s causing excess helium ionization, apparent Si II, Mg II and Fe II abundance variations relative to hydrogen, non-uniform heating and resulting large amplitude non-linear running waves affecting both average local interstellar Doppler velocities and line widths. We discuss several possible sources of such an event: single or multiple supernova(e), local magnetar, a gamma ray burst associated with a nearby star formation region, and follow the time-dependent consequences of various scenario...
Possible effects - of direct interstellar particles and interstellar grains interacting with the ... more Possible effects - of direct interstellar particles and interstellar grains interacting with the Oort cloud objects - on the outer solar system dust populations are analyzed. We estimate the influence of (i) fast, wave accelerated grains from the local interstellar medium, (ii) pick-up grains from the Oort cloud, (iii) grains diffusing from the hot Local Bubble, on dust production in the Edgeworth-Kuiper belt and in a (hypothetical) external disk of beta Pictoris type. Contributions of these sources to the statistics of Pioneer dust impact data collected beyond Saturn orbit are analyzed.
Fermi I electron acceleration by magnetic reconnection exhausts on closely stacked current sheets near the heliopause
AIP Conference Proceedings, 2010
ABSTRACT Recent observations (up to 32 AU) of solar wind reconnection exhausts suggest fairly fre... more ABSTRACT Recent observations (up to 32 AU) of solar wind reconnection exhausts suggest fairly frequent occurrence of such events on current sheets associated with the ICME fronts and on the heliospheric current sheet (HCS). Comparison of relevant plasma β values and magnetic field strengths with conditions in the heliosheath indicates that reconnection may also take place in the heliosheath, especially towards the heliopause where the folds of HCS are expected to be pressed together by the slowing of solar plasma flow. We propose a Fermi I type acceleration mechanism in which particles gain energy by random collisions reconnection exhausts expanding typically with local Alfven speed. The most probable place for this process is a (several wide) region of tightly folded HCS near the nose of heliopause. The process may in particular provide the mechanism of accelerating the electrons needed for generation of 2–3 kHz heliospheric emissions.
Organizational project of intensifying research in the field of space physics in Poland
Energetic Ions and the Observations of the Heliosheath by means of ENA
AIP Conference Proceedings, 2010
ABSTRACT Voyager observations show that the inner heliosheath is characterized by high intensity ... more ABSTRACT Voyager observations show that the inner heliosheath is characterized by high intensity of the energetic (E>28 keV) ions. Due to neutralization of these ions, the heliosheath is an important source of the energetic neutral atoms, which in turn can be observed in the inner solar system. The fluxes of the energetic hydrogen (58–88 keV) and helium (28–58 keV∕n) atoms from the heliosheath have been measured by the instrument HSTOF on board SOHO. By combining these observations with the Voyager post‐shock ion data it is possible to estimate the parameters of the inner heliosheath. We discuss recent developments related to this approach.
Further Estimation of the Thickness of the Heliosheath using Updated SOHO Data
Instrument HSTOF/CELIAS on SOHO continues to monitor the heliosphere in a 14° strip for ENA in th... more Instrument HSTOF/CELIAS on SOHO continues to monitor the heliosphere in a 14° strip for ENA in the energy interval, 58-88 keV for H and 28-58 keV/A for He. Here we update on the measured ENA flux and on the estimated thickness of the heliosheath in different directions normalized to the values based on the comparison between heliosheath ion fluxes measured by V1 and V2 and the ENA fluxes measured by SOHO in the frontal portion of the heliosphere, using specific models (Czechowski et al., Astron. & Astophys. 487, 329-335, 2008). We discuss the influence of energetic ion distribution in the heliosheath on the ENA production rate.
Ionization and neutralization processes in the heliosphere
Ionization and neutralization are key processes shaping the heliosphere and creating the plethora... more Ionization and neutralization are key processes shaping the heliosphere and creating the plethora of heliospheric charged and neutral populations The most important include charge exchange between solar wind ions and neutral interstellar gas atoms ionization by the solar EUV radiation and inside a few AU from the Sun and most probable within the inner heliosheath ionization by electron impact The newly ionized atoms are immediately picked up by the solar wind slowing it down by mass-loading and eventually transfer some of their quasi-thermal energy to the thermal energy of the solar wind Consequently ionization of interstellar gas atoms is a coupling process responsible for deposition of energy and momentum of interstellar gas in the solar wind The other charge exchange products -- Energetic Neutral Atoms being mainly the neutralized solar wind protons -- manage to escape from the heliosphere to the Local Interstellar Cloud in significant numbers where they again enter into charge e...
Global heliospheric model of ionization states of C, N, O, Mg, Si, S carried by the solar wind
A global heliospheric model of spatial distribution of multiply ionized C N O Mg Si S atoms carri... more A global heliospheric model of spatial distribution of multiply ionized C N O Mg Si S atoms carried by the solar wind is developed basing on observed inner heliosphere abundances and subsequent ionic charge evolution due to relevant atomic processes radiative and dielectronic recombination charge exchange with neutrals collisional and photonic ionizations Coulomb scattering The background distributions of the ion-electron
Solar ions in the heliosheath as a possible new source of heavy neutral atoms pickup ions and ACR seed populations
We show that multiply ionized C N O Mg Si S carried by the solar wind and neutralized by multiple... more We show that multiply ionized C N O Mg Si S carried by the solar wind and neutralized by multiple electron capture from neutral insterstellar atoms constitute an important source of Energetic Neutral Atoms in the inner heliosheath with energies up to 1 keV n In the model we developed the heavy ions are treated as test particles carried by
Neutralization of heavy solar wind ions as source of seed particles for the ACR populations
We analyze the production of pickup ions (PUI) of C, N, O, Mg, Si and S in the supersonic solar w... more We analyze the production of pickup ions (PUI) of C, N, O, Mg, Si and S in the supersonic solar wind out of fluxes of energetic neutral atoms (ENA) of these species originating in the heliosheath by successive electron capture deionization of highly-charged ions of coronal origin carried by the solar wind. ENA produced preferentially in the vicinity of heliopause
Heavy energetic neutral atoms (ENA) in the heliosphere produced by neutralization of the solar wind in the heliosheath
A model of ENA production in the heliosheath by electron capture neutralization of solar wind C, ... more A model of ENA production in the heliosheath by electron capture neutralization of solar wind C, N, O, Mg, Si, S ions is developed. The heavy ions are treated as test particles convected by a hydrodynamically calculated background plasma flow. They interact (radiative and dielectronic recombinations, charge exchanges, photoand electron impact ionizations) with plasma particles, interstellar neutral atoms (calculated on
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Papers by Stan Grzedzielski