The Global Morphology of the Solar Wind Interaction With Comet Churyumov-Gerasimenko

Mendis, D. A.; Horányi, M.

doi:10.1088/0004-637x/794/1/14

Cited by 8 publications

(5 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in Fig. 9, in situ observations indicate that these structures include a bow shock, a "cometopause", and an ionopause (Mendis 1988;Flammer 1991;Mendis and Horányi 2014). The bow shock forms in response to mass loading.…”

Section: Cometsmentioning

confidence: 94%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

View full text Add to dashboard Cite

Both heliophysics and planetary physics seek to understand the complex nature of the solar wind's interaction with solar system obstacles like Earth's magnetosphere, the ionospheres of Venus and Mars, and comets. Studies with this objective are frequently conducted with the help of single or multipoint in situ electromagnetic field and particle observations, guided by the predictions of both local and global numerical simulations, and placed in con- text by observations from far and extreme ultraviolet (FUV, EUV), hard X-ray, and energetic neutral atom imagers (ENA). Each proposed interaction mechanism (e.g., steady or transient magnetic reconnection, local or global magnetic reconnection, ion pick-up, or the KelvinHelmholtz instability) generates diagnostic plasma density structures. The significance of each mechanism to the overall interaction (as measured in terms of atmospheric/ionospheric loss at comets, Venus, and Mars or global magnetospheric/ionospheric convection at Earth) remains to be determined but can be evaluated on the basis of how often the density signatures that it generates are observed as a function of solar wind conditions. This paper reviews efforts to image the diagnostic plasma density structures in the soft (low energy, 0.1-2.0 keV) X-rays produced when high charge state solar wind ions exchange electrons with the exospheric neutrals surrounding solar system obstacles. The introduction notes that theory, local, and global simulations predict the characteristics of plasma boundaries such the bow shock and magnetopause (including location, density gradient, and motion) and regions such as the magnetosheath (including density and width) as a function of location, solar wind conditions, and the particular mechanism operating. In situ measurements confirm the existence of time-and spatial-dependent plasma density structures like the bow shock, magnetosheath, and magnetopause/ionopause at Venus, Mars, comets, and the Earth. However, in situ measurements rarely suffice to determine the global extent of these density structures or their global variation as a function of solar wind conditions, except in the form of empirical studies based on observations from many different times and solar wind conditions. Remote sensing observations provide global information about auroral ovals (FUV and hard X-ray), the terrestrial plasmasphere (EUV), and the terrestrial ring current (ENA). ENA instruments with low energy thresholds (∼ 1 keV) have recently been used to obtain important information concerning the magnetosheaths of Venus, Mars, and the Earth. Recent technological developments make these magnetosheaths valuable potential targets for high-cadence wide-field-of-view soft X-ray imagers.Section 2 describes proposed dayside interaction mechanisms, including reconnection, the Kelvin-Helmholtz instability, and other processes in greater detail with an emphasis on the plasma density structures that they generate. It focuses upon the questions that remain as yet unanswered, such as the significanc...

show abstract

Section: Cometsmentioning

confidence: 94%

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

et al. 2018

View full text Add to dashboard Cite

show abstract

“…The basic feature of a comet-like solar wind interaction is the mass loading of the solar wind by ionizing the outflowing neutrals by UV and charge exchange, generating an upstream collisionless shock [Galeev et al, 1985;Ip and Axford, 1982;Mendis and Horanyi, 2014]. Ignoring kinetic effects and carrying out these fluid calculations, we find that the subsolar position of the shock at~4.5 R P is consistent with a neutral CH 4 production rate (escape rate from the atmosphere) Q = 5 × 10 25 s…”

Section: 1002/2016ja022599mentioning

confidence: 99%

Pluto's interaction with the solar wind

et al. 2016

View full text Add to dashboard Cite

This study provides the first observations of Plutogenic ions and their unique interaction with the solar wind. We find ~20% solar wind slowing that maps to a point only ~4.5 RP upstream of Pluto and a bow shock most likely produced by comet‐like mass loading. The Pluto obstacle is a region of dense heavy ions bounded by a “Plutopause” where the solar wind is largely excluded and which extends back >100 RP into a heavy ion tail. The upstream standoff distance is at only ~2.5 RP. The heavy ion tail contains considerable structure, may still be partially threaded by the interplanetary magnetic field (IMF), and is surrounded by a light ion sheath. The heavy ions (presumably CH4+) have average speed, density, and temperature of ~90 km s−1, ~0.009 cm−3, and ~7 × 105 K, with significant variability, slightly increasing speed/temperature with distance, and are N‐S asymmetric. Density and temperature are roughly anticorrelated yielding a pressure ~2 × 10−2 pPa, roughly in balance with the interstellar pickup ions at ~33 AU. We set an upper bound of <30 nT surface field at Pluto and argue that the obstacle is largely produced by atmospheric thermal pressure like Venus and Mars; we also show that the loss rate down the tail (~5 × 1023 s−1) is only ~1% of the expected total CH4 loss rate from Pluto. Finally, we observe a burst of heavy ions upstream from the bow shock as they are becoming picked up and tentatively identify an IMF outward sector at the time of the NH flyby.

show abstract

“…However, for the mirror mode waves the situation is different as they will develop outside the MPR but inside the bow shock, in the cometosheath. The expected global morphology of the interaction region of the solar wind with the outgassing 67P/CG has recently been discussed by Mendis and Horányi (2014). Figure 17 shows the time development of various parameters: the distance of the 67P/CG to the sun, the solar wind and pile-up magnetic field strength, the density, the distance of the bow shock and the ionopause and the pick-up ion cycloid at the pile-up boundary, as taken from the simulations by Koenders et al (2013).…”

Section: Implications For Rosettamentioning

confidence: 99%

A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta

et al. 2014

View full text Add to dashboard Cite

Abstract. Three flybys of comet 1P/Halley, by VEGA 1, 2 and Giotto, are investigated with respect to the occurrence of mirror mode waves in the cometosheath and field line draping in the magnetic pile-up region around the nucleus. The time interval covered by these flybys is approximately 8 days, which is also the approximate length of an orbit or flyby of Rosetta around comet 67P/Churyumov-Gerasimenko. Thus any significant changes observed around Halley are changes that might occur for Rosetta during one pass of 67P/CG. It is found that the occurrence of mirror mode waves in the cometosheath is strongly influenced by the dynamical pressure of the solar wind and the outgassing rate of the comet. Field line draping happens in the magnetic pile-up region. Changes in nested draping regions (i.e. regions with different B x directions) can occur within a few days, possibly influenced by changes in the outgassing rate of the comet and thereby the conductivity of the cometary ionosphere.

show abstract

The Global Morphology of the Solar Wind Interaction With Comet Churyumov-Gerasimenko

Cited by 8 publications

References 24 publications

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Imaging Plasma Density Structures in the Soft X-Rays Generated by Solar Wind Charge Exchange with Neutrals

Pluto's interaction with the solar wind

A comparison between VEGA 1, 2 and Giotto flybys of comet 1P/Halley: implications for Rosetta

Contact Info

Product

Resources

About