Structure and Properties of the Foreshock at Venus

Omidi, N.; Collinson, G.; Sibeck, D. G.

doi:10.1002/2017ja024180

Cited by 23 publications

(48 citation statements)

References 74 publications

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“…Given that the distinction between HFA and SHFA is entirely due to the presence or absence of such an associated IMF discontinuity, by definition, these HFA‐like events must be classified as SHFAs. This conclusion is further supported by our hybrid simulations [ Omidi et al , ] which predict that SHFAs can form in the foreshocks of unmagnetized planets through the same mechanism as at Earth (i.e., the interaction of foreshock cavitons with the bow shock), and our observations at Mars and Venus are consistent with that predicted by this simulation. Through first‐order estimation of the size of the events with respect to the local proton gyroradius, we find that the Venusian SHFA was effectively larger than the Martian event (≈19 gyroradii versus ≈7).…”

Section: Discussionsupporting

confidence: 91%

Spontaneous hot flow anomalies at Mars and Venus

Collinson

Sibeck

Omidi³

et al. 2017

JGR Space Physics

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We report the first observations of Spontaneous Hot Flow Anomalies (SHFAs) at Venus and Mars, demonstrating their existence in the foreshocks of other planets beyond Earth. Using data from the ESA Venus Express and the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we present magnetic and plasma observations from events at both planets, exhibiting properties similar to “classical” Hot Flow Anomalies, with bounding shock‐like compressive regions and a hot and diffuse core. However, these explosive foreshock transients were observed without any attendant interplanetary magnetic field discontinuity, consistent with SHFAs observed at Earth and our hybrid simulations.

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Section: Discussionsupporting

confidence: 91%

Spontaneous hot flow anomalies at Mars and Venus

Collinson

Sibeck

Omidi³

et al. 2017

JGR Space Physics

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“…In particular, SHFAs have recently been observed and modelled in the foreshock upstream of Venus and Mars Omidi et al, 2017). These works show that the size and properties of SHFAs, as well as their formation mechanism, are similar to that at Earth.…”

Section: Blanco-cano Et Al: Cavitons and Spontaneous Hot Flow Anomentioning

confidence: 78%

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

et al. 2018

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Abstract. In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the downstream region and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angle spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.

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“…In particular, SHFAs have recently been observed and modeled in the foreshock upstream of Venus and Mars Omidi et al, 2017). These works show that the size and properties of SHFAs, as well as their formation mechanism, are similar to that at Earth.…”

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confidence: 78%

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Blanco‐Cano¹,

Battarbee²,

Turc³

et al. 2018

Preprint

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Abstract. In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the downstream region, and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on 5 the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angles spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.

show abstract

Structure and Properties of the Foreshock at Venus

Cited by 23 publications

References 74 publications

Spontaneous hot flow anomalies at Mars and Venus

Spontaneous hot flow anomalies at Mars and Venus

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation

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