scholarly journals The impact of a stealth CME on the Martian topside ionosphere

2021 ◽  
Vol 503 (1) ◽  
pp. 625-632
Author(s):  
Smitha V Thampi ◽  
C Krishnaprasad ◽  
Govind G Nampoothiri ◽  
Tarun K Pant
Keyword(s):  
Field Measurements ◽  
Topside Ionosphere ◽  
The Sun ◽  
Solar Cycles ◽  
Solar Dynamics Observatory ◽  
Mars Atmosphere ◽  
Phase Measurements ◽  
Ion Escape ◽  
Solar Dynamics ◽  
The Impact

ABSTRACT Solar cycle 24 is one of the weakest solar cycles recorded, but surprisingly the declining phase of it had a slow coronal mass ejection (CME) that evolved without any low coronal signature and is classified as a stealth CME that was responsible for an intense geomagnetic storm at Earth (Dst = −176 nT). The impact of this space weather event on the terrestrial ionosphere has been reported. However, the propagation of this CME beyond 1 au and the impact of this CME on other planetary environments have not been studied so far. In this paper, we analyse the data from the Sun–Earth L1 point and from the Martian orbit (near 1.5 au) to understand the characteristics of the stealth CME as observed beyond 1 au. The observations near Earth are using data from the Solar Dynamics Observatory (SDO) and the Advanced Composition Explorer (ACE) satellite located at L1 point, whereas those near Mars are from the instruments for plasma and magnetic field measurements onboard Mars Atmosphere and Volatile EvolutioN (MAVEN) mission. The observations show that the stealth CME has reached 1.5 au after 7 d of its initial observations at the Sun and caused depletion in the nightside topside ionosphere of Mars, as observed during the inbound phase measurements of the Langmuir Probe and Waves (LPW) instrument onboard MAVEN. These observations have implications on the ion escape rates from the Martian upper atmosphere.

scholarly journals The Solar and Heliospheric Observatory

1984 ◽  
Vol 86 ◽  
pp. 155-158 ◽  
Author(s):  
Giancarlo Noci
Keyword(s):  
Solar Physics ◽  
Grazing Incidence ◽  
Spectral Irradiance ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Constant ◽  
Heliospheric Observatory ◽  
Explorer Mission ◽  
Solar Dynamics ◽  
Euv Spectrum

In the past years several space missions have been proposed for the study of the Sun and of the Heliosphere. These missions were intended to clarify various different aspects of solar physics. For example, the GRIST (Grazing Incidence Solar Telescope) mission was intended as a means to improve our knowledge of the upper transition region and low corona through the detection of the solar EUV spectrum with a spatial resolution larger than in previous missions; the DISCO (Dual Spectral Irradiance and Solar Constant Orbiter) and SDO (Solar Dynamics Observatory) missions were proposed to gat observational data about the solar oscillations better than those obtained from ground based instruments; the SOHO (Solar and Heliospheric Observatory) mission was initially proposed to combine the properties of GRIST with the study of the extended corona (up to several radii of heliocentric distance) by observing the scattered Ly-alpha and OVI radiation, which was also the basis of the SCE (Solar Corona Explorer) mission proposal; the development of the interest about the variability of the Sun, both in itself and for its consequences in the history of the Earth, led to propose observations of the solar constant (included in DISCO).

scholarly journals Hot prominence spicules launched from turbulent cool solar prominences

2019 ◽  
Vol 627 ◽  
pp. L5 ◽  
Author(s):  
L. P. Chitta ◽  
H. Peter ◽  
L. Li
Keyword(s):  
Transition Region ◽  
Extreme Ultraviolet ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Prominences ◽  
Solar Filament ◽  
Solar Dynamics ◽  
Ultraviolet Observations ◽  
Hot Corona ◽  
Shed Light

A solar filament is a dense cool condensation that is supported and thermally insulated by magnetic fields in the rarefied hot corona. Its evolution and stability, leading to either an eruption or disappearance, depend on its coupling with the surrounding hot corona through a thin transition region, where the temperature steeply rises. However, the heating and dynamics of this transition region remain elusive. We report extreme-ultraviolet observations of quiescent filaments from the Solar Dynamics Observatory that reveal prominence spicules propagating through the transition region of the filament-corona system. These thin needle-like jet features are generated and heated to at least 0.7 MK by turbulent motions of the material in the filament. We suggest that the prominence spicules continuously channel the heated mass into the corona and aid in the filament evaporation and decay. Our results shed light on the turbulence-driven heating in magnetized condensations that are commonly observed on the Sun and in the interstellar medium.

scholarly journals Enormous Eruption of 2.2 X-Class Solar Flares on 10th June 2014

2014 ◽  
Vol 36 ◽  
pp. 249-257 ◽  
Author(s):  
Zety Sharizat Hamidi ◽  
N.N.M. Shariff
Keyword(s):  
Active Region ◽  
Solar Flare ◽  
The Sun ◽  
X Rays ◽  
Solar Dynamics Observatory ◽  
Time Data ◽  
High Frequencies ◽  
The North ◽  
Solar Dynamics ◽  
Radio Blackout

The observational of active region emission of the Sun contain an critical answer of the time-dependence of the underlying heating mechanism. In this case, we investigate an X2.2 solar flare from a new Active Region AR2087 on the southeast limb of the Sun. The solar flare peaked in the X-rays is around 11:42 UT. It was found that the snapshot of this event from the Solar Dynamics Observatory (SDO) channel with the GOES X-ray plot overlayed. The flare is very bright causes by a diffraction pattern. We explore a parameter space of heating and coronal loop properties. Based on the wavelength, it shows plasma around 6 million Kelvin. At the same time, data from the NOAA issued an R3 level radio blackout, which is centered on Earth where the Sun is currently overhead at the North Africa region. This temporary blackout is caused by the heating of the upper atmosphere from the flare. The blackout level is now at an R1 and this will soon pass. Other than the temporary radio blackout for high frequencies centered over Africa this event will not have a direct impact on us. Until now, we await more data concerning a possible Coronal Mass Ejections (CMEs) but anything would more than likely not head directly towards Earth. An active region AR2087 just let out an X1.5 flare peaking at 12:52 UT. This shows plasmas with temperatures up to about 10 Million Kelvin. This event is considered one of the massive eruption of the Sun this year.

scholarly journals Photospheric downflows observed with SDO/HMI, HINODE, and an MHD simulation

2021 ◽  
Vol 647 ◽  
pp. A178
Author(s):  
T. Roudier ◽  
M. Švanda ◽  
J. M. Malherbe ◽  
J. Ballot ◽  
D. Korda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Surface ◽  
Outer Part ◽  
Data Cube ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Mhd Simulation ◽  
Quiet Sun ◽  
Solar Dynamics ◽  
The Magnetic Field

Downflows on the solar surface are suspected to play a major role in the dynamics of the convection zone, at least in its outer part. We investigate the existence of the long-lasting downflows whose effects influence the interior of the Sun but also the outer layers. We study the sets of Dopplergrams and magnetograms observed with Solar Dynamics Observatory and Hinode spacecrafts and an magnetohydrodynamic (MHD) simulation. All of the aligned sequences, which were corrected from the satellite motions and tracked with the differential rotation, were used to detect the long-lasting downflows in the quiet-Sun at the disc centre. To learn about the structure of the flows below the solar surface, the time-distance local helioseismology was used. The inspection of the 3D data cube (x, y, t) of the 24 h Doppler sequence allowed us to detect 13 persistent downflows. Their lifetimes lie in the range between 3.5 and 20 h with a sizes between 2″ and 3″ and speeds between −0.25 and −0.72 km s−1. These persistent downflows are always filled with the magnetic field with an amplitude of up to 600 Gauss. The helioseismic inversion allows us to describe the persistent downflows and compare them to the other (non-persistent) downflows in the field of view. The persistent downflows seem to penetrate much deeper and, in the case of a well-formed vortex, the vorticity keeps its integrity to the depth of about 5 Mm. In the MHD simulation, only sub-arcsecond downflows are detected with no evidence of a vortex comparable in size to observations at the surface of the Sun. The long temporal sequences from the space-borne allows us to show the existence of long-persistent downflows together with the magnetic field. They penetrate inside the Sun but are also connected with the anchoring of coronal loops in the photosphere, indicating a link between downflows and the coronal activity. A links suggests that EUV cyclones over the quiet Sun could be an effective way to heat the corona.

scholarly journals Investigations of solar plasma in the interior and corona from Solar Dynamics Observatory

2010 ◽  
Vol 6 (S274) ◽  
pp. 287-290
Author(s):  
A. G. Kosovichev
Keyword(s):  
Large Scale ◽  
Magnetic Activity ◽  
Solar Interior ◽  
Magnetized Plasma ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Magnetic Field Generation ◽  
Multi Wavelength ◽  
Solar Dynamics ◽  
Oscillations And Waves

AbstractThe Sun is a plasma laboratory for astrophysics, which allows us to investigate many important phenomena in turbulent magnetized plasma in detail. Solar Dynamics Observatory (SDO) launched in February 2010 provides unique information about plasma processes from the interior to the corona. The primary processes of magnetic field generation and formation of magnetic structures are hidden beneath the visible surface. Helioseismic diagnostics, based on observations and analysis of solar oscillations and waves, give insights into the physical processes in the solar interior and mechanisms of solar magnetic activity. In addition, simultaneous high-resolution multi-wavelength observations of the solar corona provide opportunity to investigate in unprecedented detail the coronal dynamics and links to the interior processes. These capabilities are illustrated by initial results on the large-scale dynamics of the Sun, the subsurface structure and dynamics of a sunspot and observations of a X-class solar flare.

scholarly journals Average motion of emerging solar active region polarities

2020 ◽  
Vol 640 ◽  
pp. A116 ◽  
Author(s):  
H. Schunker ◽  
C. Baumgartner ◽  
A. C. Birch ◽  
R. H. Cameron ◽  
D. C. Braun ◽  
...  
Keyword(s):  
Active Region ◽  
Flux Tube ◽  
Tilt Angle ◽  
Active Regions ◽  
Field Measurements ◽  
Solar Dynamics Observatory ◽  
Flux Tubes ◽  
Average Motion ◽  
Solar Dynamics ◽  
East West

Context. The tilt of solar active regions described by Joy’s law is essential for converting a toroidal field to a poloidal field in Babcock-Leighton dynamo models. In thin flux tube models the Coriolis force causes what we observe as Joy’s law, acting on east-west flows as they rise towards the surface. Aims. Our goal is to measure the evolution of the average tilt angle of hundreds of active regions as they emerge, so that we can constrain the origins of Joy’s law. Methods. We measured the tilt angle of the primary bipoles in 153 emerging active regions (EARs) in the Solar Dynamics Observatory Helioseismic Emerging Active Region survey. We used line-of-sight magnetic field measurements averaged over 6 h to define the polarities and measure the tilt angle up to four days after emergence. Results. We find that at the time of emergence the polarities are on average aligned east-west, and that neither the separation nor the tilt depends on latitude. We do find, however, that EARs at higher latitudes have a faster north-south separation speed than those closer to the equator at the emergence time. After emergence, the tilt angle increases and Joy’s law is evident about two days later. The scatter in the tilt angle is independent of flux until about one day after emergence, when we find that higher-flux regions have a smaller scatter in tilt angle than lower-flux regions. Conclusions. Our finding that active regions emerge with an east-west alignment is consistent with earlier observations, but is still surprising since thin flux tube models predict that tilt angles of rising flux tubes are generated below the surface. Previously reported tilt angle relaxation of deeply anchored flux tubes can be largely explained by the change in east-west separation. We conclude that Joy’s law is caused by an inherent north-south separation speed present when the flux first reaches the surface, and that the scatter in the tilt angle is consistent with buffeting of the polarities by supergranulation.

scholarly journals The stellar variability noise floor for transiting exoplanet photometry with PLATO

2020 ◽  
Vol 493 (4) ◽  
pp. 5489-5498 ◽  
Author(s):  
Brett M Morris ◽  
Monica G Bobra ◽  
Eric Agol ◽  
Yu Jin Lee ◽  
Suzanne L Hawley
Keyword(s):  
Impact Parameter ◽  
Solar Dynamics Observatory ◽  
Depth Measurement ◽  
Stellar Oscillations ◽  
Mission Duration ◽  
Intensity Images ◽  
Solar Dynamics ◽  
In Transit ◽  
Limb Darkening ◽  
The Impact

ABSTRACT One of the main science motivations for the ESA PLAnetary Transit and Oscillations (PLATO) mission is to measure exoplanet transit radii with 3 per cent precision. In addition to flares and starspots, stellar oscillations and granulation will enforce fundamental noise floors for transiting exoplanet radius measurements. We simulate light curves of Earth-sized exoplanets transiting continuum intensity images of the Sun taken by the Helioseismic and Magnetic Imager (HMI) instrument aboard the Solar Dynamics Observatory (SDO) to investigate the uncertainties introduced on the exoplanet radius measurements by stellar granulation and oscillations. After modelling the solar variability with a Gaussian process, we find that the amplitude of solar oscillations and granulation is of order 100 ppm – similar to the depth of an Earth transit – and introduces a fractional uncertainty on the depth of transit of 0.73 per cent assuming four transits are observed over the mission duration. However, when we translate the depth measurement into a radius measurement of the planet, we find a much larger radius uncertainty of 3.6 per cent. This is due to a degeneracy between the transit radius ratio, the limb darkening, and the impact parameter caused by the inability to constrain the transit impact parameter in the presence of stellar variability. We find that surface brightness inhomogeneity due to photospheric granulation contributes a lower limit of only 2 ppm to the photometry in-transit. The radius uncertainty due to granulation and oscillations, combined with the degeneracy with the transit impact parameter, accounts for a significant fraction of the error budget of the PLATO mission, before detector or observational noise is introduced to the light curve. If it is possible to constrain the impact parameter or to obtain follow-up observations at longer wavelengths where limb darkening is less significant, this may enable higher precision radius measurements.

scholarly journals Solar extreme ultraviolet (EUV) flare observations and findings from the Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE)

2015 ◽  
Vol 11 (S320) ◽  
pp. 27-40
Author(s):  
Thomas N. Woods ◽  
Francis G. Eparvier ◽  
James P. Mason
Keyword(s):  
Extreme Ultraviolet ◽  
Late Phase ◽  
Impulsive Phase ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
X Ray ◽  
Gradual Phase ◽  
Stellar Flares ◽  
Solar Dynamics ◽  
Coronal Dimming

AbstractNew solar soft X-ray (SXR) and extreme ultraviolet (EUV) irradiance observations from NASA Solar Dynamics Observatory (SDO) EUV Variability Experiment (EVE) provide full coverage from 0.1 to 106 nm and continuously at a cadence of 10 seconds for spectra at 0.1 nm resolution. These observations during flares can usually be decomposed into four distinct characteristics: impulsive phase, gradual phase, coronal dimming, and EUV late phase. Over 6000 flares have been observed during the SDO mission; some flares show all four phases, and some only show the gradual phase. The focus is on the newer results about the EUV late phase and coronal dimming and its relationship to coronal mass ejections (CMEs). These EVE flare measurements are based on observing the sun-as-a-star, so these results could exemplify stellar flares. Of particular interest is that new coronal dimming measurements of stars could be used to estimate mass and velocity of stellar CMEs.

scholarly journals The spectral impact of magnetic activity on disc-integrated HARPS-N solar observations: exploring new activity indicators

2020 ◽  
Vol 494 (3) ◽  
pp. 4279-4290
Author(s):  
A P G Thompson ◽  
C A Watson ◽  
R D Haywood ◽  
J C Costes ◽  
E de Mooij ◽  
...  
Keyword(s):  
Filling Factor ◽  
Active Regions ◽  
Magnetic Activity ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Radial Velocity Component ◽  
Solar Observations ◽  
Solar Dynamics ◽  
Absorption Features ◽  
Low Activity

ABSTRACT Stellar activity is the major roadblock on the path to finding true Earth-analogue planets with the Doppler technique. Thus, identifying new indicators that better trace magnetic activity (i.e. faculae and spots) is crucial to aid in disentangling these signals from that of a planet’s Doppler wobble. In this work, we investigate activity related features as seen in disc-integrated spectra from the HARPS-N solar telescope. We divide high-activity spectral echelle orders by low-activity master templates (as defined using both $\log {R^{\prime }_{HK}}$ and images from the Solar Dynamics Observatory, SDO), creating ‘relative spectra’. With resolved images of the surface of the Sun (via SDO), the faculae and spot filling factors can be calculated, giving a measure of activity independent of, and in addition to, $\log {R^{\prime }_{HK}}$. We find pseudo-emission (and pseudo-absorption) features in the relative spectra that are similar to those reported in our previous work on α Cen B. In α Cen B, the features are shown to correlate better to changes in faculae filling factor than spot filling factor. In this work, we more confidently identify changes in faculae coverage of the visible hemisphere of the Sun as the source of features produced in the relative spectra. Finally, we produce trailed spectra to observe the radial velocity component of the features, which show that the features move in a redward direction as one would expect when tracking active regions rotating on the surface of a star.

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