scholarly journals Relationship between plasma flow Doppler velocities and magnetic field parameters during the appearance of active regions at the solar photospheric level

10.12737/7155 ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 75-84
Author(s):  
Анна Хлыстова ◽  
Anna Khlystova
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Spatial Scales ◽  
Vertical Component ◽  
Active Regions ◽  
Solar Disc ◽  
Doppler Imager ◽  
Photospheric Level ◽  
Using Data ◽  
The Magnetic Field

Using data obtained with the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO), we have conducted a statistical study of the relationship between plasma flow Doppler velocities and magnetic field parameters during the appearance of active regions at the solar photospheric level. We have examined 224 emerging active regions having different spatial scales and positions on the solar disc. The following relationships have been analysed: 1) those between the negative Doppler velocities and the position of active regions emerging on the solar disc; 2) those between the negative and positive Doppler velocities and the magnetic field parameters in the ac-tive regions emerging near the solar disc centre (the vertical component); 3) those between the negative and positive Doppler velocities and the magnetic field pa-rameters in the active regions emerging near the limb (the horizontal component); 4) those between the mag-netic flux growth rate and the strength of emerging magnetic fields; 5) those between the Doppler velocities and the magnetic field parameters during the first hours after the appearance of active regions with the total unsigned magnetic flux at the peak of their development.

scholarly journals EUV Line Intensities and the Magnetic Field in Solar Active Regions

2001 ◽  
Vol 203 ◽  
pp. 276-279
Author(s):  
J. Ireland ◽  
A. Fludra
Keyword(s):  
Magnetic Field ◽  
Extreme Ultraviolet ◽  
Active Regions ◽  
Central Meridian ◽  
Coronal Emission ◽  
Data Set ◽  
Line Intensities ◽  
Doppler Imager ◽  
Synoptic Observations ◽  
The Magnetic Field

The Coronal Diagnostic Spectrometer (CDS) on SOHO carries out daily synoptic observations of the Sun in four EUV (extreme ultraviolet) spectra: He I 584 Å, O V 630 Å, Mg IX 368 Å and Fe XVI 360 Å, over a 4 arcmin-wide strip along the solar central meridian. Using 53 active regions observed in this data set along with co-temporally observed SOHO-MDI (Michelson Doppler Imager) magnetograms we study the correlation of the chromospheric, transition region and coronal emission with the photospheric magnetic field for meridional active regions, probing the relation between the radiative output and magnetic observables. We also establish empirical, quantitative relations among intensities of different lines, and between intensities and the magnetic field flux.

scholarly journals Geomagnetic field influences upward movement of young Chinook salmon emerging from nests

2018 ◽  
Vol 14 (2) ◽  
pp. 20170752 ◽  
Author(s):  
Nathan F. Putman ◽  
Michelle M. Scanlan ◽  
Amanda M. Pollock ◽  
Joseph P. O'Neil ◽  
Ryan B. Couture ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chinook Salmon ◽  
Geomagnetic Field ◽  
Oncorhynchus Tshawytscha ◽  
Dimensional Space ◽  
Spatial Scales ◽  
Vertical Component ◽  
Life Cycles ◽  
Upward Movement ◽  
The Magnetic Field

Organisms use a variety of environmental cues to orient their movements in three-dimensional space. Here, we show that the upward movement of young Chinook salmon ( Oncorhynchus tshawytscha ) emerging from gravel nests is influenced by the geomagnetic field. Fish in the ambient geomagnetic field travelled farther upwards through substrate than did fish tested in a field with the vertical component inverted. This suggests that the magnetic field is one of several factors that influences emergence from the gravel, possibly by serving as an orientation cue that helps fish determine which way is up. Moreover, our work indicates that the Oncorhynchus species are sensitive to the magnetic field throughout their life cycles, and that it guides their movements across a range of spatial scales and habitats.

Active Phenomena in the Solar Atmosphere

1975 ◽  
Vol 2 (6) ◽  
pp. 316-317
Author(s):  
S.B. Pikel’ner
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Temperature Gradient ◽  
Active Regions ◽  
Convective Transport ◽  
Short Description ◽  
Photospheric Level ◽  
The Magnetic Field ◽  
Extended Review ◽  
Main Factor

This paper gives a short description and interpretation of some solar magneto-hydrodynamical and plasma phenomena, based mainly on work by the writer and his collaborators (for an extended review see Kaplan et al. 1974).The magnetic field is considered as the main factor responsible for a number of manifestations of solar activity. At the photospheric level active regions are displayed as plages, i.e., bright areas, seen near the limb. This means that the temperature gradient in plages is smaller than in the undisturbed photosphere. The decrease in gradient is a result of an increase of convective transport of energy.

Emergence of Twisted Magnetic Flux Related Sigmoidal Brightening

2000 ◽  
Vol 179 ◽  
pp. 263-264
Author(s):  
K. Sundara Raman ◽  
K. B. Ramesh ◽  
R. Selvendran ◽  
P. S. M. Aleem ◽  
K. M. Hiremath
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Ultra Violet ◽  
Active Regions ◽  
Morphological Properties ◽  
Energy Storage And Conversion ◽  
The Sun ◽  
X Rays ◽  
The Magnetic Field

Extended AbstractWe have examined the morphological properties of a sigmoid associated with an SXR (soft X-ray) flare. The sigmoid is cospatial with the EUV (extreme ultra violet) images and in the optical part lies along an S-shaped Hαfilament. The photoheliogram shows flux emergence within an existingδtype sunspot which has caused the rotation of the umbrae giving rise to the sigmoidal brightening.It is now widely accepted that flares derive their energy from the magnetic fields of the active regions and coronal levels are considered to be the flare sites. But still a satisfactory understanding of the flare processes has not been achieved because of the difficulties encountered to predict and estimate the probability of flare eruptions. The convection flows and vortices below the photosphere transport and concentrate magnetic field, which subsequently appear as active regions in the photosphere (Rust & Kumar 1994 and the references therein). Successive emergence of magnetic flux, twist the field, creating flare productive magnetic shear and has been studied by many authors (Sundara Ramanet al.1998 and the references therein). Hence, it is considered that the flare is powered by the energy stored in the twisted magnetic flux tubes (Kurokawa 1996 and the references therein). Rust & Kumar (1996) named the S-shaped bright coronal loops that appear in soft X-rays as ‘Sigmoids’ and concluded that this S-shaped distortion is due to the twist developed in the magnetic field lines. These transient sigmoidal features tell a great deal about unstable coronal magnetic fields, as these regions are more likely to be eruptive (Canfieldet al.1999). As the magnetic fields of the active regions are deep rooted in the Sun, the twist developed in the subphotospheric flux tube penetrates the photosphere and extends in to the corona. Thus, it is essentially favourable for the subphotospheric twist to unwind the twist and transmit it through the photosphere to the corona. Therefore, it becomes essential to make complete observational descriptions of a flare from the magnetic field changes that are taking place in different atmospheric levels of the Sun, to pin down the energy storage and conversion process that trigger the flare phenomena.

scholarly journals Nonlinear force-free modeling of magnetic fields in flare-productive active regions

2015 ◽  
Vol 11 (S320) ◽  
pp. 167-174
Author(s):  
M. S. Wheatland ◽  
S. A. Gilchrist
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Boundary Data ◽  
Numerical Solutions ◽  
Free Field ◽  
Active Regions ◽  
Coronal Magnetic Field ◽  
Nonlinear Force ◽  
The Magnetic Field ◽  
Force Free Field

AbstractWe review nonlinear force-free field (NLFFF) modeling of magnetic fields in active regions. The NLFFF model (in which the electric current density is parallel to the magnetic field) is often adopted to describe the coronal magnetic field, and numerical solutions to the model are constructed based on photospheric vector magnetogram boundary data. Comparative tests of NLFFF codes on sets of boundary data have revealed significant problems, in particular associated with the inconsistency of the model and the data. Nevertheless NLFFF modeling is often applied, in particular to flare-productive active regions. We examine the results, and discuss their reliability.

scholarly journals Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot

2018 ◽  
Vol 620 ◽  
pp. A191 ◽  
Author(s):  
M. Benko ◽  
S. J. González Manrique ◽  
H. Balthasar ◽  
P. Gömöry ◽  
C. Kuckein ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Temporal Evolution ◽  
Vertical Component ◽  
Field Vector ◽  
Linear Increase ◽  
Vertical Magnetic Field ◽  
Magnetic Diffusion ◽  
The Magnetic Field ◽  
Linear Decay

Context. It has been empirically determined that the umbra-penumbra boundaries of stable sunspots are characterized by a constant value of the vertical magnetic field. Aims. We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28–September 3, 2011. The observations were acquired with the spectropolarimeter on-board of the Hinode satellite. We aim to prove the validity of the constant vertical magnetic-field boundary between the umbra and penumbra in decaying sunspots. Methods. A spectral-line inversion technique was used to infer the magnetic field vector from the full-Stokes profiles. In total, eight maps were inverted and the variation of the magnetic properties in time were quantified using linear or quadratic fits. Results. We find a linear decay of the umbral vertical magnetic field, magnetic flux, and area. The penumbra showed a linear increase of the vertical magnetic field and a sharp decay of the magnetic flux. In addition, the penumbral area quadratically decayed. The vertical component of the magnetic field is weaker on the umbra-penumbra boundary of the studied decaying sunspot compared to stable sunspots. Its value seem to be steadily decreasing during the decay phase. Moreover, at any time of the sunspot decay shown, the inner penumbra boundary does not match with a constant value of the vertical magnetic field, contrary to what is seen in stable sunspots. Conclusions. During the decaying phase of the studied sunspot, the umbra does not have a sufficiently strong vertical component of the magnetic field and is thus unstable and prone to be disintegrated by convection or magnetic diffusion. No constant value of the vertical magnetic field is found for the inner penumbral boundary.

Localization of the magnetic field in a plasma flow in laboratory simulations of astrophysical jets at the KPF-4-PHOENIX installation

2017 ◽  
Vol 61 (9) ◽  
pp. 775-782 ◽  
Author(s):  
K. N. Mitrofanov ◽  
S. S. Anan’ev ◽  
D. A. Voitenko ◽  
V. I. Krauz ◽  
G. I. Astapenko ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Astrophysical Jets ◽  
Laboratory Simulations ◽  
The Magnetic Field

Influence of the magnetic field of stellar wind on hot jupiter’s envelopes

2019 ◽  
Vol 15 (S354) ◽  
pp. 268-279
Author(s):  
Dmitry V. Bisikalo ◽  
Andrey G. Zhilkin
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Coronal Mass Ejections ◽  
Stellar Wind ◽  
Roche Lobe ◽  
Bow Shock ◽  
Hot Jupiters ◽  
The Magnetic Field ◽  
Alfven Velocity ◽  
Hot Jupiter

AbstractHot Jupiters have extended gaseous (ionospheric) envelopes, which extend far beyond the Roche lobe. The envelopes are loosely bound to the planet and, therefore, are strongly influenced by fluctuations of the stellar wind. We show that, since hot Jupiters are close to the parent stars, magnetic field of the stellar wind is an important factor defining the structure of their magnetospheres. For a typical hot Jupiter, velocity of the stellar wind plasma flow around the atmosphere is close to the Alfvén velocity. As a result stellar wind fluctuations, such as coronal mass ejections, can affect the conditions for the formation of a bow shock around a hot Jupiter. This effect can affect observational manifestations of hot Jupiters.

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