scholarly journals In Situ Demonstration of a Passive Radio Sounding Approach Using the Sun for Echo Detection

2018 ◽  
Vol 56 (12) ◽  
pp. 7338-7349 ◽  
Author(s):  
Sean T. Peters ◽  
Dustin M. Schroeder ◽  
Davide Castelletti ◽  
Mark Haynes ◽  
Andrew Romero-Wolf
Keyword(s):  
The Sun ◽  
Radio Sounding ◽  
Echo Detection

Notes from the Polar Night

2020 ◽  
Vol 9 (4) ◽  
pp. 35-43
Author(s):  
Chris Ingraham
Keyword(s):  
Global Warming ◽  
The Sun ◽  
Polar Night ◽  
Academic Scholarship

Drawing from in situ fieldwork in Longyearbyen, Svalbard, the northernmost settlement on Earth, these notes bring out the affective, ambient, and atmospheric power of extended darkness during the polar night, when the sun does not appear above the horizon for several months at a time. Each entry is composed of 113 words to reflect the number of days without light in Longyearbyen during the winter of my visit. Through a mixture of ethnographic observations, researched academic scholarship, and some endeavors of poetic worldmaking, these notes attempt to evoke the ineffable force of global warming by performing the sort of acutely observed and felt attentiveness to planetary being that is needed for our time.

scholarly journals Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

2017 ◽  
Vol 12 (S330) ◽  
pp. 148-151 ◽  
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Sun ◽  
Thick Disc ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

scholarly journals Transforming in-situ observations of CME-driven shock accelerated protons into the shock's reference frame.

2005 ◽  
Vol 23 (5) ◽  
pp. 1931-1941 ◽  
Author(s):  
I. M. Robinson ◽  
G. M. Simnett
Keyword(s):  
Solar Physics ◽  
Solar Energetic Particle ◽  
Transport Processes ◽  
Solar Energetic Particle Event ◽  
The Sun ◽  
Proton Acceleration ◽  
Angle Scattering ◽  
Peak Energy ◽  
In Situ Observations

Abstract. We examine the solar energetic particle event following solar activity from 14, 15 April 2001 which includes a "bump-on-the-tail" in the proton energy spectra at 0.99 AU from the Sun. We find this population was generated by a CME-driven shock which arrived at 0.99 AU around midnight 18 April. As such this population represents an excellent opportunity to study in isolation, the effects of proton acceleration by the shock. The peak energy of the bump-on-the-tail evolves to progressively lower energies as the shock approaches the observing spacecraft at the inner Lagrange point. Focusing on the evolution of this peak energy we demonstrate a technique which transforms these in-situ spectral observations into a frame of reference co-moving with the shock whilst making allowance for the effects of pitch angle scattering and focusing. The results of this transform suggest the bump-on-the-tail population was not driven by the 15 April activity but was generated or at least modulated by a CME-driven shock which left the Sun on 14 April. The existence of a bump-on-the-tail population is predicted by models in Rice et al. (2003) and Li et al. (2003) which we compare with observations and the results of our analysis in the context of both the 14 April and 15 April CMEs. We find an origin of the bump-on-the-tail at the 14 April CME-driven shock provides better agreement with these modelled predictions although some discrepancy exists as to the shock's ability to accelerate 100 MeV protons. Keywords. Solar physics, astrophysics and astronomy (Energetic particles; Flares and mass ejections) – Space plasma physics (Transport processes)

scholarly journals The Solar Orbiter Science Activity Plan

2020 ◽  
Vol 642 ◽  
pp. A3 ◽  
Author(s):  
I. Zouganelis ◽  
A. De Groof ◽  
A. P. Walsh ◽  
D. R. Williams ◽  
D. Müller ◽  
...  
Keyword(s):  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Coronal Magnetic Field ◽  
Space Mission ◽  
The Sun ◽  
Particle Radiation ◽  
Science Activity ◽  
Science Operations ◽  
Solar Eruptions

Solar Orbiter is the first space mission observing the solar plasma both in situ and remotely, from a close distance, in and out of the ecliptic. The ultimate goal is to understand how the Sun produces and controls the heliosphere, filling the Solar System and driving the planetary environments. With six remote-sensing and four in-situ instrument suites, the coordination and planning of the operations are essential to address the following four top-level science questions: (1) What drives the solar wind and where does the coronal magnetic field originate?; (2) How do solar transients drive heliospheric variability?; (3) How do solar eruptions produce energetic particle radiation that fills the heliosphere?; (4) How does the solar dynamo work and drive connections between the Sun and the heliosphere? Maximising the mission’s science return requires considering the characteristics of each orbit, including the relative position of the spacecraft to Earth (affecting downlink rates), trajectory events (such as gravitational assist manoeuvres), and the phase of the solar activity cycle. Furthermore, since each orbit’s science telemetry will be downloaded over the course of the following orbit, science operations must be planned at mission level, rather than at the level of individual orbits. It is important to explore the way in which those science questions are translated into an actual plan of observations that fits into the mission, thus ensuring that no opportunities are missed. First, the overarching goals are broken down into specific, answerable questions along with the required observations and the so-called Science Activity Plan (SAP) is developed to achieve this. The SAP groups objectives that require similar observations into Solar Orbiter Observing Plans, resulting in a strategic, top-level view of the optimal opportunities for science observations during the mission lifetime. This allows for all four mission goals to be addressed. In this paper, we introduce Solar Orbiter’s SAP through a series of examples and the strategy being followed.

First Results from Solar Orbiter’s Energetic Particle Detector

2021 ◽  
Author(s):  
Javier Rodriguez-Pacheco ◽  
Keyword(s):  
Energetic Particle ◽  
Wide Energy Range ◽  
High Temporal Resolution ◽  
The Sun ◽  
Particle Detector ◽  
First Results ◽  
Wide Energy ◽  
Spatio Temporal ◽  
Inner Heliosphere

<p>In this presentation, we will show the first measurements performed by EPD since the end of the commissioning phase until the latest results obtained. During these months EPD has been scanning the inner heliosphere at different heliocentric distances and heliolongitues allowing - together with other spacecraft - to investigate the spatio-temporal behavior of the particle populations in the inner heliosphere during solar minimum conditions. Solar Orbiter was launched from Cape Canaveral on February 10th, 2020, thus beginning the journey to its encounter with the Sun. Solar Orbiter carries ten scientific instruments, six remote sensing and four in situ, that will allow the mission main goal: how the Sun creates and controls the heliosphere. Among the in situ instruments, the Energetic Particle Detector (EPD) measures electrons, protons and heavy ions with high temporal resolution over a wide energy range, from suprathermal energies up to several hundreds of MeV/nucleon.</p>

scholarly journals A numerical study of the interaction between two ejecta in the interplanetary medium: one- and two-dimensional hydrodynamic simulations

2004 ◽  
Vol 22 (10) ◽  
pp. 3741-3749 ◽  
Author(s):  
A. Gonzalez-Esparza ◽  
A. Santillán ◽  
J. Ferrer
Keyword(s):  
Hydrodynamic Model ◽  
Physical Mechanism ◽  
Interplanetary Medium ◽  
Numerical Study ◽  
Two Dimensions ◽  
Magnetic Clouds ◽  
The Sun ◽  
Two Dimensional ◽  
Hydrodynamic Simulations

Abstract. We studied the heliospheric evolution in one and two dimensions of the interaction between two ejecta-like disturbances beyond the critical point: a faster ejecta 2 overtaking a previously launched slower ejecta 1. The study is based on a hydrodynamic model using the ZEUS-3-D code. This model can be applied to those cases where the interaction occurs far away from the Sun and there is no merging (magnetic reconnection) between the two ejecta. The simulation shows that when the faster ejecta 2 overtakes ejecta 1 there is an interchange of momentum between the two ejecta, where the leading ejecta 1 accelerates and the tracking ejecta 2 decelerates. Both ejecta tend to arrive at 1AU having similar speeds, but with the front of ejecta 1 propagating faster than the front of ejecta 2. The momentum is transferred from ejecta 2 to ejecta 1 when the shock initially driven by ejecta 2 passes through ejecta 1. Eventually the two shock waves driven by the two ejecta merge together into a single stronger shock. The 2-D simulation shows that the evolution of the interaction can be very complex and there are very different signatures of the same event at different viewing angles; however, the transferring of momentum between the two ejecta follows the same physical mechanism described above. These results are in qualitative agreement with in-situ plasma observations of "multiple magnetic clouds" detected at 1AU.

scholarly journals Dust Measurements in the Outer Solar System

1994 ◽  
Vol 160 ◽  
pp. 367-380
Author(s):  
Eberhard Grün
Keyword(s):  
Solar System ◽  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Spatial Density ◽  
Outer Solar System ◽  
The Sun

In-situ measurements of micrometeoroids provide information on the spatial distribution of interplanetary dust and its dynamical properties. Pioneers 10 and 11, Galileo and Ulysses spaceprobes took measurements of interplanetary dust from 0.7 to 18 AU distance from the sun. Distinctly different populations of dust particles exist in the inner and outer solar system. In the inner solar system, out to about 3 AU, zodiacal dust particles are recognized by their scattered light, their thermal emission and by in-situ detection from spaceprobes. These particles orbit the sun on low inclination (i ≤ 30°) and moderate eccentricity (e ≤ 0.6) orbits. Their spatial density falls off with approximately the inverse of the solar distance. Dust particles on high inclination or even retrograde trajectories dominate the dust population outside about 3 AU. The dust detector on board the Ulysses spaceprobe identified interstellar dust sweeping through the outer solar system on hyperbolic trajectories. Within about 2 AU from Jupiter Ulysses discovered periodic streams of dust particles originating from within the jovian system.

scholarly journals The Nasa Solar Probe Mission: In Situ Determination of Interplanetary Out-of-The Ecliptic and Near-Solar Dust Environments

1991 ◽  
Vol 126 ◽  
pp. 29-32
Author(s):  
Bruce T. Tsurutani ◽  
James E. Randolph
Keyword(s):  
Solar Cycle ◽  
Solar System ◽  
Solar Eclipse ◽  
Orbital Period ◽  
High Velocity ◽  
Scientific Community ◽  
The Sun ◽  
Probe Mission

AbstractThe NASA Solar Probe mission will be one of the most exciting dust missions ever flown and will lead to a revolutionary advance in our understanding of dust within our solar system. Solar Probe will map the dust environment from the orbit of Jupiter (5 AU), to within 4 solar radii of the sun’s center. The region between 0.3 AU and 4 Rshas never been visited before, so the 10 days that the spacecraft spends during each (of the two) orbit is purely exploratory in nature. Solar Probe will also reach heliographic latitudes as high as ~ 15 to 28 above (below) the ecliptic on its trajectory inbound (outbound) to (from) the sun. This, in addition to the ESA/NASA Ulysses mission, will help determine the out-of-the-ecliptic dust environment. A post-perihelion burn will reduce the satellite orbital period to 2.5 years about the sun. A possible extended mission would allow data reception for 2 more revolutions, mapping out a complete solar cycle. Because the near-solar dust environment is not well understood (or is controversial at best), and it is very important to have better knowledge of the dust environment to protect Solar Probe from high velocity dust hits, we urgently request the scientific community to obtain further measurements of the near-solar dust properties. One prime opportunity is the July 1991 solar eclipse.

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