Astronomy

Composition and Proton Flux from the Solar Wind

Composition and Proton Flux from the Solar Wind


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I am taking a class on the space environment and I have a few questions about the solar wind. A number of sources list the composition as (approximately) 4% He$^{++}$ and 96% H$^{+}$. What exactly does this mean? Does it mean by mass or by number of ions?

Also, when discussing proton flux due to the solar wind at Earth: What exactly is included in the flux numbers quoted (e.g., one source I have says 2e12 m$^{-2}$s$^{-1}$). Is that the flux due to only the H$^{+}$ and excluding the He$^{++}$ and other minor constituents? Or, are they including all the protons from the other ions as well?


That's by number-- you get a lot more helium than that by mass. Also, when they talk about proton flux, they just count the bare protons, not protons embedded in larger ions like helium. Those are the kinds of things that should be made clear, but end up being common assumed conventions.


Real Time Solar Wind

20 years and displays with only Magnetometer, only Solar Wind Plasma, or a combination of both as well as other features described below.

Plotted on this page are data from the 'active' real-time solar wind spacecraft. Since July 27, 2016 NOAA's Deep Space Climate Observatory (DSCOVR (link is external)) has been the operational spacecraft. Only magnetometer and solar wind thermal plasma data are displayed.

The two DSCOVR instruments for which data are available:

An inverse chronological list of Real-Time Solar Wind Announcements

The Faraday Cup Data Processing Unit (IDPU) experienced two recent interrupts that resulted in data outages. These were the first times this occurred in the life of the mission.

==================================================================
October 10, 2017: Safe Hold #14
DSCOVR had its 14th safe hold event today. All of the safehold events so far are listed below.

Safehold # / Date
-----------------------
1 / Jun 23, 2015
2 / Jun 28, 2015
3 / Jul 15, 2015
4 / Aug 04, 2015
5 / Sep 29, 2015
6 / Oct 08, 2015
7 / Jan 06, 2016
8 / Jan 14, 2016
9 / May 24, 2016
10 / Sep 17, 2016
11 / Oct 11, 2016
12 / Oct 30, 2016
13 / Aug 24, 2017
14 / Oct 10, 2017

Changes were made to the Faraday Cup flight software to alter the behavior of the instrument. Essentially, the instrument now waits longer between scans to reduce the impact of spurious noise that was causing the instrument to lose the solar wind proton peak. This change may not eliminate the loss of peak tracking issue completely, but it is a significant step in the right direction.

A change was made to the Faraday Cup processing to remove some of the noise that was resulting in higher than expected densities and temperature. The change ignores high energy noise that was resulting in wider than expected velocity distributions.

NOAA's Deep Space Climate Observatory (DSCOVR) became the operational RTSW spacecraft. It replaced the NASA Advanced Composition Explorer (ACE) spacecraft, which has been in use since 1998.

Real-time Solar Wind and Magnetometer data is now available in JSON format for up to the past 7 days from the SWPC Data Service. These JSON files will automatically include the data from the active RTSW spacecraft. By default, that has been DSCOVR since July 27 at 1600 UT.

A complete DSCOVR data archive is available at the NOAA National Center for Environmental Information.

Anyone with questions about these data, the DSCOVR spacecraft, or tracking of DSCOVR should contact Douglas Biesecker (link sends e-mail).


Big Data for the Magnetic Field Variations in Solar-Terrestrial Physics and Their Wavelet Analysis

Bozhidar Srebrov Assoc Prof, Dr , . Georgi Simeonov Assistant , in Knowledge Discovery in Big Data from Astronomy and Earth Observation , 2020

19.2.6.1 The Storm in 2003

The data obtained from solar astronomy observations have provided the following report.

During the 23rd solar cycle in October and November 2003 there were two very strong storms. One started on October 29 and the other began on November 21. In the last 10 days of October 2003, the lean activity has gone to an extremely high level. On October 18, a large active region (AR), turning North of the solar equator, was designated by NOAA as AR 484. On October 28, AR 484 was located near the sub-Earth point of the solar disk 8 ∘ on the East of the central meridian and 16 ∘ North latitude. At 11:10 UTC AR 484 produced one of the largest solar flares for the current solar cycle. This flare was classified as X17 (peak X-ray flux 1.7 × 10 − 3 W/m 2 ).

An extreme CME with a radial plasma velocity of 2500 km/s was observed. The mass ejected from this CME was in the range of 1.4– 2.1 × 10 13 kg, and the kinetic energy released was 4.2– 6.4 × 10 25 J. The following day, 29 October, AR 484 again produced a large eruption. This peak was named X10 (X-ray flux 10 − 3 W/m 2 ) at 20:49 UTC. I was targeting the Earth halo at a speed of 2000 km/s and with a kinetic energy of 5.7 × 10 25 J. The IMF reached about −50 nT its normal value, in calm conditions, is 10 times lower. The shock wave of the event on 28 October was determined by the ACE satellite at 05:59 UTC. At 06:13 UTC an SSC pulse was registered, marking the beginning of the sixth storm by the registration stamp (since 1932). On 29 and 30 October the planetary index Kp reached a value of 9. The geomagnetic storm continued until 1 November and had a horizontal component down to around −400 nT. The highest value of the D s t index was registered on 30 October at 23:00 UT.


Apollo 11 Mission

The Sun continually emits a flux of electrically charged particles into space. This is termed the solar wind. The Earth's magnetic field prevents these charged particles from reaching the Earth's surface, although in the Earth's polar regions, these particles can reach the upper part of the atmosphere, causing auroras. The Moon is outside the Earth's magnetic field for most of each month and has a negligible atmosphere, allowing solar-wind particles to reach the Moon's surface. Two different experiments, the Solar Wind Composition Experiment and the Solar Wind Spectrometer, were deployed on the Moon to study the solar wind.

The Solar Wind Composition Experiment was performed on Apollo 11, 12, 14, 15, and 16. It consisted of an aluminum foil sheet, 1.4 meters by 0.3 meters, that was deployed on a pole facing the sun. On Apollo 16, a platinum sheet was also used. This foil was exposed to the sun for periods ranging from 77 minutes on Apollo 11 to 45 hours on Apollo 16, allowing solar-wind particles to embed themselves into the foil. The foil was then returned to Earth for laboratory analysis. This allowed the chemical composition of the embedded solar wind to be determined more accurately than would be possible if the measurement were made using remotely controlled instruments on the Moon, but limited the periods at which observations could be made. The isotopes of the light noble gases were measured, including helium-3, helium-4, neon-20, neon-21, neon-22, and argon-36. Some variation in the composition of the solar wind was observed in the measurements from the different mission. These variations were correlated with variations in the intensity of the solar wind as determined from magnetic field measurements.

The Solar Wind Spectrometer was deployed on Apollo 12 and 15. Although the solar wind contains ions of most chemical elements (including the noble gases measured by the Solar Wind Composition Experiment), over 95% of the particles in the solar wind are electrons and protons, in roughly equal numbers. The Solar Wind Spectrometer measured the flux of protons and electrons as a function of particle velocity. The measurements were made in a set of seven detector cups with different orientations in order to determine the direction of particle motion. Most of the measured flux was in the detector that was oriented most directly toward the Sun.

Because the Solar Wind Spectrometer made continuous measurements, it was possible to measure how the Earth's magnetic field affects arriving solar wind particles. For about two-thirds of each orbit, the Moon is outside of the Earth's magnetic field. At these times, a typical proton density was 10 to 20 per cubic centimeter,with most protons having velocities between 400 and 650 kilometers per second. For about five days of each month, the Moon is inside the Earth's geomagnetic tail, and typically no solar wind particles were detectable. For the remainder of each lunar orbit, the Moon is in a transitional region known as the magnetosheath, where the Earth's magnetic field affects the solar wind but does not completely exclude it. In this region, the particle flux is reduced, with typical proton velocities of 250 to 450 kilometers per second. During the lunar night, the spectrometer was shielded from the solar wind by the Moon and no solar wind particles were measured.


Solar Wind Speed

Solar Wind Parameters Used: Date: 25 06 2021 0604 UT Velocity: 382 km/sec Bz: 0.0 nT Density = 5.0 p/cc Calculated Information from Solar wind parameters: Magnetopause Stand Off Distance = 12.2Re Solar Wind Dynamic Pressure Dp = 0.61nPa

The above diagram indicates solar wind speed and strength of the interplanetary magnetic field (IMF) in a north/south direction. Higher solar wind speeds and strong south pointing (negative) IMF are associated with geomagnetic storms on earth. The red area on the image indicates an approximate region in which disturbed conditions might be expected.

The plots on this page were produced from data supplied by the US NOAA Space Weather Prediction Center (SWPC). This Real Time Solar Wind (RTSW) data set originates from NASA's Deep Space Climate Observatory (DSCOVR) satellite. The above image shows with a black square the value of the solar wind speed (horizontal) axis and the strength of the interplanetary magnetic field in a north/south direction (Bz - vertical axis). Higher solar wind speeds and strong south pointing (negative) interplanetary magnetic field are associated with geomagnetic disturbances on earth. The red area on the image indicates an approximate region in which disturbed conditions might be expected. The coloured dot within the black square, is an indicator of solar wind density, and is yellow when density exceeds 10 particles per cubic cm, red when density exceeds 15 particles per cubic cm, otherwise green.

The DSCOVR spacecraft is positioned at the L1 point between the Earth and the sun and gives approximately one hour advance notice of conditions on Earth. This typical lead time decreases with faster solar wind speeds associated with coronal mass ejections.

The solar wind magnetic field, can be measured in three compoenents, Bz, Bx, and By. Bx lies along the Sun-Earth line, with Bz and By defining a vertical plane (the clock "face"). The solar wind clock angle is the angle produced from the vector sum of By and Bz.

The image below shows recent trends in solar wind speed and interplanetary magnetic field north/south direction.


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Acceleration

While early models of the solar wind relied primarily on thermal energy to accelerate the material, by the 1960s it was clear that thermal acceleration alone cannot account for the high speed of solar wind. An additional unknown acceleration mechanism is required and likely relates to magnetic fields in the solar atmosphere. [ citation needed ]

The Sun's corona, or extended outer layer, is a region of plasma that is heated to over a megakelvin. As a result of thermal collisions, the particles within the inner corona have a range and distribution of speeds described by a Maxwellian distribution. The mean velocity of these particles is about 145 km/s , which is well below the solar escape velocity of 618 km/s . However, a few of the particles achieve energies sufficient to reach the terminal velocity of 400 km/s , which allows them to feed the solar wind. At the same temperature, electrons, due to their much smaller mass, reach escape velocity and build up an electric field that further accelerates ions away from the Sun. ⎥]

The total number of particles carried away from the Sun by the solar wind is about 1.3 × 10 36 per second. ⎦] Thus, the total mass loss each year is about (2–3) × 10 −14 solar masses, ⎧] or about 1.3–1.9 Million tonnes per second. This is equivalent to losing a mass equal to the Earth every 150 million years. ⎨] However, only about 0.01% of the Sun's total mass has been lost through the solar wind. ⎩] Other stars have much stronger stellar winds that result in significantly higher mass-loss rates.


Composition and Proton Flux from the Solar Wind - Astronomy

The solar wind is now know to be a mixture of materials found in the solar plasma, composed of ionized hydrogen (electrons and protons) with an 8% component of helium and trace amounts of heavy ions. The solar wind has been detected inward toward the sun to the orbit of Mercury, and outward past the orbits of Uranus and Neptune. The flux of particles is modulated by the pressure (both magnetic and thermal) at the base of the wind in the solar corona, and to a certain extent, some of the features of the solar wind, particularlly in the case of high speed streams, can be identified with specific large scale coronal features, the coronal hole structures.

At the orbit of the earth the average solar wind consists of a strongly ionized gas having a proton and electron density of about 3 - 10 particles per cubic centimeter, with an average flow velocity of approximately 400 km/s. Occasionally stream structures are detected in the steady solar wind, which have peak velocities which tend toward a mean of about 750 km/s near the earth. Occasionally impulsive events are detected with peak velocities in excess of 1000 km/s. Assuming a brief period of acceleration in the low corona, material in the normal solar wind near the equator reaches the earth about 4 days after departing from the Sun. Temperatures of the plasma at the earth are found to be about 150,000°K, approximately a factor of ten lower than the estimates for the temperatures of the bulk of the coronal plasma found in the upper atmosphere of the Sun.

The physical mechanism responsible for the solar wind is the difference in pressure between the corona and a point in space located (say) at the earth. Using average temperature and density values between the lower corona and the solar wind measured at the earth, the difference in pressure is of the order of a factor of a million, causing outward flow. Since the electrical conductivity of the wind material is very high, the plasma being nearly fully ionized, the solar magnetic field lines are frozen into the material, and since the material flows outward from a rotating star, the flow and field patterns take on the general form of a spiral. The solar wind, in fact, is the medium which connects the magnetic variation of the Sun out through the heliosphere, the volume of interplanetary space which is influenced by solar magnetic fields, to various bodies found in the solar system. The scientific interest in the solar wind stems from this fact, and has held the attention of researchers for two reasons: (1) To the extent that the physics of the solar wind is known, it is possible to establish causality, and establish predictive capability for solar-geophysical events. (2) The wide range of physical conditions found in the solar wind and its interactions with magnetized and non-magnetized planets, dust, cosmic rays, comets, and spacecraft allow the investigation of physical mechanisms not easily duplicated in the terrestrial laboratory. Many contributions to the basic understanding of plasma processes have been identified and understood in the context of the solar wind. Numerous problems await further investigation and resolution.

In the space between the orbits of Mercury and Jupiter, research in the solar wind was dominated by data obtained from instruments carried on spacecraft restricted to near the ecliptic plane. In 1990 the joint ESA-NASA Ulysses mission was launched with the intent of conducting a systematic experimental investigation of the solar wind as a function of solar latitude. The spacecraft was launched toward Jupiter and after a gravity assist around the planet, the resulting plane of the orbit is highly inclined allowing the spacecraft to pass over the polar regions of the Sun. The first polar passage occurred in 1994 during which time the Ulysses sampled the plasma originating from regions near the south solar pole. Since that time it has proceeded toward the solar equator and will have a second (north) polar passage in 1995 August-September.

Joint SPARTAN 201-Ulysses operations are aimed at the collection of a complete observational picture of the solar wind from the polar regions. The Ulysses spacecraft carries instruments which will sample the temperature, density, velocity, and magnetic field configuration in the location of the spacecraft which will be over the solar polar region and at a distance of about 2.2 times the distance from the earth to the Sun. The SPARTAN instruments, observing at the same time, will measure the density and temperature of the proton and electron components of the corona, attempting to establish boundary conditions for the initial state of the solar wind as it departs on its path out of the solar system.

Other resources for the solar wind:

    The Rice University Department of Space Physics and Astronomy Space Weather pages

It's still early days for this page, folks.

This is the access to this page since July 10, 1995. Return to the SPARTAN 201 home page.


Recent Geoeffective Space Weather Events and Technological System Impacts

Robert J. Redmon , . Dominic Fuller-Rowell , in Extreme Events in Geospace , 2018

4.1 Energetic Particles and Magnetic Field Observations at GEO

Observations of the GEO-charged particle and magnetic field environment from the GOES Space Environment Monitor (SEM) are shown in Fig. 2 . Proton fluxes in 7 integral energy ranges from > 1 to > 100 MeV as 5-min time averages from the west viewing telescopes of the SEM Energetic Proton, Electron, and Alpha Detector (EPEAD) instrument are shown in the top row. The westward viewing telescopes for EPEAD are shown here as they observe larger solar proton fluxes than the eastward view due to the former seeing particles whose gyro centers lie outside geosynchronous orbit and are hence less filtered by the geomagnetic field (e.g., Rodriguez et al., 2010 ). Similarly, averaged electron fluxes in the 3 integral energy ranges: > 0.8, > 2, and > 4 MeV are shown in the middle row. The vector magnetic field averaged to 1 min from the MAG instrument is shown in the bottom row. An SEM package has been included on all NOAA geostationary satellites, starting with the Synchronous Meteorological Satellite (SMS)-1 (launched on May 17, 1974). For a summary of the EPEAD instrument design, and derived products, see Hanser (2011) , Rodriguez et al. (2014, 2017) , Rodriguez (2014) and references therein. For a similar summary of the GOES MAG instrument see Singer et al. (1996) .

Fig. 2 . GOES SEM measurements of charged particles and the magnetic field for events E1 (left), E2 (middle) and E3 (right) from the western (E1, E2) and eastern (E3) longitude observing location. Proton fluxes are shown in the top row for the 7 integral MeV energy ranges: &gt 1 (black), &gt 5 (red), &gt 10 (green), &gt 30 (magenta), &gt 50 (blue), &gt 60 (purple), and &gt 100 (cyan). SEP event onsets (E1, E3) are indicated by blue arrows where &gt 10 MeV proton fluxes (green) exceed the dashed blue line (green curve, top row). Electron fluxes are shown in the middle row for the 3 integral MeV ranges: &gt 0.8 (black), &gt 2 (red), &gt 4 (green). The dashed blue line is the alert level for &gt 2 MeV electrons (red curve). Vector magnetic measurements are shown in the bottom row with the EPN orientation: northward (“P,” black), earthward (“E,” red), and eastward (“N,” green). Geostationary magnetopause crossings for all three events are annotated with blue arrows. The vertical trace in the MAG plot on the far right of E2 (middle row, bottom plot) is a calibration artifact. Events E1 and E2 show GOES-15, and E3 shows GOES-13, because GOES-15's magnetometer was in an anomalous state on June 25, 2015.

From NOAA, https://ngdc.noaa.gov/stp .


Description

Ring Current protons from the Fok Ring Current Model are computed using plasma a fourth state of matter where atoms are broken down into ions and separate electrons [[Glossary/plasma]] and magnetic field values from the SWMF magnetosphere The region of space dominated by the magnetic field of a star or planet. Earth’s magnetosphere takes on a tear-drop shape under the influence of the flowing solar wind. [[Glossary/magnetosphere]] simulation and real-time solar wind plasma flowing out from the sun [[Glossary/ solar wind]] measurements from the ACE the Advanced Composition Explorer (ACE) spacecraft is positioned on the Earth-Sun line and provides measurements of the solar wind plasma and radiation conditions that will impact Earth. [[Glossary/ACE]] spacecraft.

This plot shows the fluxes at the 2.8 keV energy level, the third lowest channel modeled.

The images specify the fluxes in the inner magnetosphere The region of space dominated by the magnetic field of a star or planet. Earth’s magnetosphere takes on a tear-drop shape under the influence of the flowing solar wind. [[Glossary/magnetosphere]] predicted by the model.


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