Using a Heliospheric Upwinding eXtrapolation Technique to Magnetically Connect Different Regions of the Heliosphere

Understanding how coronal structure propagates and evolves from the Sun and into the heliosphere has been thoroughly explored using sophisticated MHD models. From these, we have a reasonably good working understanding of the dynamical processes that shape the formation and evolution of stream interaction regions and rarefactions, including their locations, orientations, and structure. However, given the technical expertize required to produce, maintain, and run global MHD models, their use has been relatively restricted. In this study, we refine a simple Heliospheric eXtrapolation Technique (HUX) to include not only forward mapping from the Sun to 1 AU (or elsewhere), but backward mapping toward the Sun. We demonstrate that this technique can provide substantially more accurate mappings than the standard, and often applied “ballistic” approximation. We also use machine learning (ML) methods to explore whether the HUX approximation to the momentum equation can be refined without loss of simplicity, finding that it likely provides the optimum balance. We suggest that HUX can be used, in conjunction with coronal models (PFSS or MHD) to more accurately connect measurements made at 1 AU, Stereo-A, Parker Solar Probe, and Solar Orbiter with their solar sources. In particular, the HUX technique: 1) provides a substantial improvement over the “ballistic” approximation for connecting to the source longitude of streams; 2) is almost as accurate, but considerably easier to implement than MHD models; and 3) can be applied as a general tool to magnetically connect different regions of the inner heliosphere together, as well as providing a simple 3-D reconstruction.

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Characterisation of exoplanet host stars: A window into planet formation

Proceedings of the International Astronomical Union ◽

10.1017/s1743921317006421 ◽

2017 ◽

Vol 12 (S330) ◽

pp. 369-376 ◽

Cited By ~ 1

Author(s):

Nuno C. Santos

Keyword(s):

Planet Formation ◽

The Sun ◽

The Future ◽

The Galaxy ◽

Crucial Information ◽

Formation And Evolution ◽

Host Stars

AbstractThe detection of thousands of planets orbiting stars other than the Sun has shown that planets are common throughout the Galaxy. However, the diversity of systems found has also raised many questions regarding the process of planet formation and evolution. Interestingly, but perhaps not unexpectedly, crucial information to constraint the planet formation models comes from the analysis of the planet-host stars. In this talk I will review why it is so important to study and understand the stars when finding and characterising exoplanets. I will then present some of the most relevant star-planet relations found to date, and how they are helping us to understand planet formation and evolution. I will end with a presentation of the future steps in this field, including what Gaia will bring to help constrain the properties of planet-host stars, as well as to the star-planet connection.

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Large-Scale Internal Magnetic Field of the Sun

Symposium - International Astronomical Union ◽

10.1017/s0074180900044399 ◽

1990 ◽

Vol 138 ◽

pp. 391-394

Author(s):

A.E. Dudorov ◽

V.N. Krivodubskij ◽

A.A. Ruzmaikin ◽

T.V. Ruzmaikina

Keyword(s):

Magnetic Field ◽

Differential Rotation ◽

Large Scale ◽

The Sun ◽

Poloidal Magnetic Field ◽

The Core ◽

Torsional Waves ◽

Formation And Evolution ◽

Field Lines ◽

The Magnetic Field

The behaviour of the magnetic field during the formation and evolution of the Sun is investigated. It is shown that an internal poloidal magnetic field of the order of 104 − 105 G near the core of the Sun may be compatible with differential rotation and with torsional waves, travelling along the magnetic field lines (Dudorov et al., 1989).

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EISCAT measurements of the solar wind

Annales Geophysicae ◽

10.1007/s00585-996-1235-8 ◽

1996 ◽

Vol 14 (12) ◽

pp. 1235-1245 ◽

Cited By ~ 20

Author(s):

A. R. Breen ◽

W. A. Coles ◽

R. R. Grall ◽

M. T. Klinglesmith ◽

J. Markkanen ◽

...

Keyword(s):

Solar Wind ◽

Slow Solar Wind ◽

The Sun ◽

Interplanetary Scintillation ◽

Final Velocity ◽

Flow Vector ◽

Fast Wind ◽

Interaction Regions ◽

Slow Wind ◽

Eiscat Measurements

Abstract. EISCAT observations of interplanetary scintillation have been used to measure the velocity of the solar wind at distances between 15 and 130 R⊙ (solar radii) from the Sun. The results show that the solar wind consists of two distinct components, a fast stream with a velocity of ~800 km s–1 and a slow stream at ~400 km s–1. The fast stream appears to reach its final velocity much closer to the Sun than expected. The results presented here suggest that this is also true for the slow solar wind. Away from interaction regions the flow vector of the solar wind is purely radial to the Sun. Observations have been made of fast wind/slow wind interactions which show enhanced levels of scintillation in compression regions.

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Formation of current sheets and plasmoids within corotating/stream interaction regions

10.5194/egusphere-egu2020-2102 ◽

2020 ◽

Author(s):

Timofey Sagitov ◽

Roman Kislov

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Coronal Hole ◽

High Speed ◽

Solar Rotation ◽

Coronal Holes ◽

Rotation Period ◽

The Sun ◽

Current Sheets ◽

Interaction Regions

High speed streams originating from coronal holes are long-lived plasma structures that form corotating interaction regions (CIRs) or stream interface regions (SIRs) in the solar wind. The term CIR is used for streams existing for at least one solar rotation period, and the SIR stands for streams with a shorter lifetime. Since the plasma flows from coronal holes quasi-continuously, CIRs/SIRs simultaneously expand and rotate around the Sun, approximately following the Parker spiral shape up to the Earth&#8217;s orbit.Coronal hole streams rotate not only around the Sun but also around their own axis of simmetry, resembling a screw. This effect may occur because of the following mechanisms: (1) the existence of a difference between the solar wind speed at different sides of the stream, (2) twisting of the magnetic field frozen into the plasma, and&#160; (3) a vortex-like motion of the edge of the mothering coronal hole at the Sun. The screw type of the rotation of a CIR/SIR can lead to centrifugal instability if CIR/SIR inner layers have a larger angular velocity than the outer. Furthermore, the rotational plasma movement and the stream distortion can twist magnetic field lines. The latter contributes to the pinch effect in accordance with a well-known criterion of Suydam instability (Newcomb, 1960, doi: 10.1016/0003-4916(60)90023-3). Owing to the presence of a cylindrical current sheet at the boundary of a coronal hole, conditions for tearing instability can also appear at the CIR/SIR boundary. Regardless of their geometry, large scale current sheets are subject to various instabilities generating plasmoids. Altogether, these effects can lead to the formation of a turbulent region within CIRs/SIRs, making them filled with current sheets and plasmoids.&#160;We study a substructure of CIRs/SIRs, characteristics of their rotation in the solar wind, and give qualitative estimations of possible mechanisms which lead to splitting of the leading edge a coronal hole flow and consequent formation of current sheets within CIRs/SIRs.

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Energetic Particle Environment near the Sun from Parker Solar Probe

10.5194/egusphere-egu2020-6063 ◽

2020 ◽

Author(s):

Nathan Schwadron ◽

Keyword(s):

Energetic Particle ◽

Energetic Particles ◽

Solar Energetic Particles ◽

Radiation Environment ◽

The Sun ◽

Particle Radiation ◽

Integrated Science ◽

Direct Observations ◽

Interaction Regions ◽

Inner Heliosphere

NASA&#8217;s Parker Solar Probe (PSP) mission recently plunged through the inner heliosphere to perihelia at ~24 million km (~35 solar radii), much closer to the Sun than any prior human made object. Onboard PSP, the Integrated Science Investigation of the Sun (IS&#664;IS) instrument suite made groundbreaking measurements of solar energetic particles (SEPs). Here we discuss the near-Sun energetic particle radiation environment over PSP&#8217;s first two orbits, which reveal where and how energetic particles are energized and transported. We find a great variety of energetic particle events accelerated both locally and remotely. These include co-rotating interaction regions (CIRs), &#8220;impulsive&#8221; SEP events driven by acceleration near the Sun, and events related to Coronal Mass Ejections (CMEs). These IS&#664;IS observations made so close to the Sun provide critical information for investigating the near-Sun transport and energization of solar energetic particles that was difficult to resolve from prior observations. We discuss the physics of particle acceleration and transport in the context of various theories and models that have been developed over the past decades. This study marks a major milestone with humanity&#8217;s reconnaissance of the near-Sun environment and provides the first direct observations of the energetic particle radiation environment in the region just above the corona.

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Properties of Suprathermal-through-Energetic He Ions Associated with Stream Interaction Regions Observed over Parker Solar Probe’s First Two Orb¬¬its

10.5194/egusphere-egu2020-1901 ◽

2020 ◽

Author(s):

Mihir Desai ◽

Keyword(s):

High Speed ◽

Power Laws ◽

Low Energy ◽

Energy Spectra ◽

The Sun ◽

Integrated Science ◽

Time Histories ◽

Interaction Regions ◽

Low Energy Ions ◽

Inner Heliosphere

The Integrated Science Investigation of the Sun (IS&#9737;IS) suite on board NASA&#8217;s Parker Solar Probe (PSP) observed six distinct enhancements in the intensities of suprathermal-through-energetic (~0.03-3 MeV nucleon-1) He ions associated with corotating or stream interaction regions during its first two orbits. Our results from a survey of the time-histories of the He intensities, spectral slopes, and anisotropies, and the event-averaged energy spectra during these events show: 1) In the two strongest enhancements, seen at 0.35 au and 0.85 au, the higher energy ions arrive and maximize later than those at lower energies. In the event seen at 0.35 au, the He ions arrive when PSP was away from the SIR trailing edge and entered the rarefaction region in the high-speed stream; 2) The He intensities are either isotropic or show sunward anisotropies in the spacecraft frame; and 3) In all events, the energy spectra between ~0.2&#8211;1 MeV nucleon-1are power-laws of the form &#8733;E-2. In the two strongest events, the energy spectra are well represented by flat power-laws between ~0.03&#8211;0.4 MeV nucleon-1modulated by exponential roll-overs between ~0.4&#8211;3 MeV nucleon-1. We conclude that the SIR-associated He ions originate from sources or shocks beyond PSP&#8217;s location rather than from acceleration processes occurring atnearby portions of local compression regions. Our results also suggest that rarefaction regions that typically follow the SIRs facilitate easier particle transport throughout the inner heliosphere such that low energy ions do not undergo significant energy loss due to adiabatic deceleration, contrary to predictions of existing models.

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A Speckle Duplicity Survey of the Hyades Cluster

International Astronomical Union Colloquium ◽

10.1017/s0252921100007156 ◽

1992 ◽

Vol 135 ◽

pp. 561-563

Author(s):

B.D. Mason ◽

H.A. McAlister ◽

W.I. Hartkopf

Keyword(s):

Critical Role ◽

Speckle Interferometry ◽

The Sun ◽

Hyades Cluster ◽

Multiple Stars ◽

Cluster Distance ◽

Cluster Environment ◽

Formation And Evolution ◽

Binary And Multiple Stars

Due to its proximity to the Sun, the Hyades serves the critical role of luminosity calibration of all cluster main sequences, and hence is one of the lower rungs in the cosmic distance ladder. We attempt here to use the enhanced capabilities of speckle interferometry, in comparison with classical techniques, to add to the list of binary and multiple stars in the Hyades. New systems will not only eventually help to improve our knowledge of the cluster distance, but they will also help further our understanding of the formation and evolution of binary and multiple stars in the cluster environment.

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Interplanetary scintillation observations of interaction regions in the solar wind

Annales Geophysicae ◽

10.1007/s00585-998-1265-5 ◽

1998 ◽

Vol 16 (10) ◽

pp. 1265-1282 ◽

Cited By ~ 11

Author(s):

A. R. Breen ◽

P. J. Moran ◽

C. A. Varley ◽

W. P. Wilkinson ◽

P. J. S. Williams ◽

...

Keyword(s):

Solar Wind ◽

Key Words ◽

Theoretical Modelling ◽

The Sun ◽

Interplanetary Scintillation ◽

Prominent Feature ◽

Wind Measurements ◽

Leading Edges ◽

Interaction Regions

Abstract. Co-rotating interaction regions (CIRs) between fast and slow streams of plasma are a prominent feature of the solar wind. Measurements of interplanetary scintillation (IPS) using the three widely separated antennas of the EISCAT facility have been used to detect the compression regions at the leading edges of interaction regions and to determine the location and velocity of the structure. Observations show that interaction regions have developed as close to the Sun as 25–30 solar radii, a result supported by theoretical modelling which shows that the conditions needed for CIRs to develop exist inside 30 solar radii. Key words. EISCAT · Interplanetary scintillation · Solar Wind

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Preliminary results of Space Weather conditions encountered by BepiColombo during the first phase of its cruise

10.5194/epsc2020-689 ◽

2020 ◽

Author(s):

Beatriz Sanchez-Cano ◽

Richard Moissl ◽

Daniel Heyner ◽

Juhani Huovelin ◽

M. Leila Mays ◽

...

Keyword(s):

Solar Wind ◽

Space Weather ◽

High Speed ◽

Weather Conditions ◽

Slow Solar Wind ◽

Astronomical Unit ◽

The Sun ◽

Preliminary Results ◽

Outer Planets ◽

Interaction Regions

Planetary Space Weather is the discipline that studies the state of the Sun and how it interacts with the interplanetary and planetary environments. It is driven by the Sun&#8217;s activity, particularly through large eruptions of plasma (known as coronal mass ejections, CMEs), solar wind stream interaction regions (SIR) formed by the interaction of high-speed solar wind streams with the preceding slower solar wind, and bursts of solar energetic particles (SEPs) that form radiation storms. This is an emerging topic, whose real-time forecast is very challenging because among other factors, it needs a continuous coverage of its variability within the whole heliosphere as well as of the Sun&#8217;s activity to improve forecasting. The long cruise of BepiColombo constitutes an exceptional opportunity for studying the Space Weather evolution within half-astronomical unit (AU), as well as in certain parts of its journey, can be used as an upstream solar wind monitor for Venus, Mars and even the outer planets. This work will present preliminary results of the Space Weather conditions encountered by BepiColombo since its launch until mid-2020, which includes data from the solar minimum of activity and few slow solar wind structures. Data come from three of its instruments that are operational for most of the cruise phase, i.e., the BepiColombo Radiation Monitor (BERM), the Mercury Planetary Orbiter Magnetometer (MPO-MAG), and the Solar Intensity X-ray and particle Spectrometer (SIXS). Modelling support for the data observations will be also presented with the so-called solar wind ENLIL simulations.

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Self-Organization Processes on the Sun: The Heliosynergetics

Symposium - International Astronomical Union ◽

10.1017/s0074180900087854 ◽

1990 ◽

Vol 142 ◽

pp. 125-133 ◽

Cited By ~ 1

Author(s):

V. Krishan ◽

E.I. Mogilevskij

Keyword(s):

Nonlinear System ◽

Active Regions ◽

Turbulent Medium ◽

Self Organization ◽

The Sun ◽

Solar Granulation ◽

Non Linear ◽

Formation And Evolution ◽

Linear Interactions ◽

Stable Structures

Abstract Non-linear interactions between small fluid elements, magnetized or otherwise, in an energetically open nonlinear system facilitate the formation of large coherent stable structures. This is knwon as self-organization. We interpret solar granulation on all scales and the formation and evolution of some structures in solar active regions to be the result of self-organization processes occuring in a turbulent medium.

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