Isolated Sunspot with a Dark Patch in the Coronal Emission

2012 ◽  
Vol 21 (4) ◽  
Author(s):  
D. A. Bezrukov ◽  
B. I. Ryabov ◽  
K. Shibasaki
Keyword(s):  
Active Region ◽  
Normal Mode ◽  
Plasma Density ◽  
Specific Region ◽  
The Sun ◽  
Coronal Emission ◽  
Plasma Parameters ◽  
X Ray ◽  
Dark Patch ◽  
Chromospheric Line

AbstractOn the base of the 17 GHz radio maps of the Sun taken with the Nobeyama Radio Heliograph we estimate plasma parameters in the specific region of the sunspot atmosphere in the active region AR 11312. This region of the sunspot atmosphere is characterized by the depletion in coronal emission (soft X-ray and EUV lines) and the reduced absorption in the a chromospheric line (He I 1.083 μm). In the ordinary normal mode of 17 GHz emission the corresponding dark patch has the largest visibility near the central solar meridian. We infer that the reduced coronal plasma density of about ~ 5 × 10

scholarly journals Is it possible to model observed active region coronal emission simultaneously in EUV and X-ray filters?

2011 ◽  
Vol 531 ◽  
pp. A115 ◽  
Author(s):  
J. Dudík ◽  
E. Dzifčáková ◽  
M. Karlický ◽  
A. Kulinová
Keyword(s):  
Active Region ◽  
Coronal Emission ◽  
X Ray

Slowly-Moving Disturbances in the X-Ray Corona

1979 ◽  
Vol 44 ◽  
pp. 276-277 ◽  
Author(s):  
D.M. Rust ◽  
Z. Švestka
Keyword(s):  
Active Region ◽  
Solar Radius ◽  
Central Point ◽  
The Sun ◽  
X Ray ◽  
Quiescent Filament ◽  
Coronal Structures

From 28 May through 27 November 1973, the S-054 X-ray telescope on Skylab took almost 1000 pictures of the Sun with exposure times (64 sec) long enough to show the faint structures of the inner corona. These pictures of the X-ray (≈ 2-54 Å) corona were made into a synoptic movie on which it is possible to see many variations in brightness and structure that escape notice in studies of individual images. In particular, the movie has led to the discovery of disturbances propagating with velocities under 100 km/sec and extending over distances of the order of one solar radius. The disturbances reveal themselves as brightened coronal structures at progressively greater distances from a central point, usually an active region with an activated or disappearing filament. In a number of cases these coronal brightenings were accompanied by quiescent filament disappearances.

scholarly journals Coronal Activity on Rapidly-Rotating Solar-Like Stars: Chandra Observations of ER Vul

2004 ◽  
Vol 215 ◽  
pp. 334-335
Author(s):  
Alexander Brown ◽  
Joanna M. Brown ◽  
Rachel A. Osten ◽  
Thomas R. Ayres ◽  
Edward Guinan
Keyword(s):  
Emission Measure ◽  
The Sun ◽  
Coronal Emission ◽  
Dwarf Stars ◽  
X Ray ◽  
Rotation Rates ◽  
Elemental Abundances ◽  
Long Duration ◽  
Short Period ◽  
Measure Distribution

We investigate the coronal structure of rapidly-rotating, solar-like stars using Chandra HETGS spectra of the short-period binary ER Vul, and by comparison with X-ray observations of the Sun and other dwarf stars. ER Vul consists of two solar-like (G0 + G5) dwarfs with rotation rates ~ 40 times that of the Sun. This binary is not interacting and these stars are the fastest rotating G dwarfs suitable for high resolution X-ray spectroscopy. X-ray (1.8-40 Å) spectra were obtained on 2001 March 29-30 along with 10.5 hours of simultaneous VLA monitoring at 3.6 and 20 cm. These spectra show hot, multi-temperature coronal emission with emission lines ranging in temperature from O VII (2 MK) to Fe XXIV (30 MK). ER Vul showed only low-level variability during the X-ray observation. Unlike the behaviour of longer period active binaries, no large, long-duration flares were detected, consistent with previous X-ray observations of this binary. No evidence for eclipses is seen in either the X-ray or radio emission. The coronal emission measure distribution and elemental abundances were derived for ER Vul.

scholarly journals Recent High Resolution X-Ray Spectra of the Sun

1972 ◽  
Vol 14 ◽  
pp. 740-741
Author(s):  
J. H. Parkinson ◽  
K. Evans ◽  
K. A. Pounds
Keyword(s):  
High Resolution ◽  
Active Region ◽  
Wavelength Range ◽  
South Australia ◽  
Active Regions ◽  
Effective Area ◽  
Field Of View ◽  
The Sun ◽  
X Ray

New results are presented from high resolution Bragg crystal spectrometers flown in late 1970 on two Skylark rockets. The first instrument, launched on 24 November 1970 at 22 13 UT from Woomera, South Australia, contained two crystal spectrometers, each with an effective area of 50 cm2 and field collimation to 3’ FWHM. This instrument obtained the X-ray spectrum of the quiet corona in the wavelength range 5–14 Å. The second instrument was launched on 6 December 1970 at 11 13 UT from Sardinia, Italy, and contained four crystals of 6 cm2, each collimated to 4’ FWHM. This instrument was pointed at a non-flaring active region near N20 W40(McMath region 11060), and obtained an X-ray spectrum between 5 and 23 Å. This first use of a collimator to limit the field of view has considerably increased the spectral clarity compared with earlier observations by excluding the contributions of other active regions.

scholarly journals X-Ray Structures Associated with Disappearing Hα Filaments in Active Regions

1980 ◽  
Vol 91 ◽  
pp. 61-65
Author(s):  
S. W. Kahler
Keyword(s):  
Active Region ◽  
Large Scale ◽  
Active Regions ◽  
Statistical Correlation ◽  
Coronal Emission ◽  
X Ray ◽  
Temporal Relationships ◽  
Using Data ◽  
Scale Length ◽  
Shape And Size

Several studies using data from Skylab instruments have been carried out to determine the spatial and temporal relationships between disappearing Hα filaments and the associated coronal emission features. Webb et al. (1976) studied 30 transient coronal X-ray enhancements which could be associated with the disappearances of Hα filaments outside active regions. They found that in the early phase of the transient X-ray brightening, emitting structures appeared at or near the filament location with shape and size resembling the filament. Sheeley et al. (1975) examined a long-lived X-ray enhancement of expanding loops associated with an active region filament which disappeared. Rust and Webb (1977) found a good statistical correlation in time and position between large scale (length > 60, 000 km) active region X-ray enhancements and Hα filament activity, in particular, events of an eruptive nature.

scholarly journals High Energy Exoplanet Transits

2016 ◽  
Vol 12 (S328) ◽  
pp. 356-362
Author(s):  
Joe Llama ◽  
Evgenya L. Shkolnik
Keyword(s):  
Active Region ◽  
Wavelength Range ◽  
Solar Disk ◽  
High Energy ◽  
Activity Levels ◽  
The Sun ◽  
X Rays ◽  
X Ray ◽  
High Energies ◽  
Wide Wavelength Range

AbstractX-ray and ultraviolet transits of exoplanets allow us to probe the atmospheres of these worlds. High energy transits have been shown to be deeper but also more variable than in the optical. By simulating exoplanet transits using high-energy observations of the Sun, we can test the limits of our ability to accurately measure the properties of these planets in the presence of stellar activity. We use both disk-resolved images of the Solar disk spanning soft X-rays, the ultraviolet, and the optical and also disk-integrated Sun-as-a-star observations of the Lyα irradiance to simulate transits over a wide wavelength range. We find that for stars with activity levels similar to the Sun, the planet-to-star radius ratio can be overestimated by up to 50% if the planet occults an active region at high energies. We also compare our simulations to high energy transits of WASP-12b, HD 189733, 55 Cnc b, and GJ 436b.

scholarly journals Plasma Parameters and Structures of the X4 Flare of 19 May 1984 as Observed by SMM-XRP

1989 ◽  
Vol 104 (2) ◽  
pp. 165-168
Author(s):  
J.T. Schmelz ◽  
J.L.R. Saba ◽  
K.T. Strong
Keyword(s):  
Solar Maximum ◽  
Coronal Plasma ◽  
The Sun ◽  
Plasma Parameters ◽  
Crystal Spectrometer ◽  
Solar Maximum Mission ◽  
X Ray ◽  
Bent Crystal ◽  
East Limb ◽  
Large Flare

AbstractThe eruption of a large flare on the east limb of the Sun was observed by the X-Ray Polychromator (XRP) on board the Solar Maximum Mission (SMM) on 19 May 1984. The XRP Flat Crystal Spectrometer (FCS) made polychromatic soft X-ray images during the preflare, flare and postflare phases. The XRP Bent Crystal Spectrometer (BCS) provided information on the temperature and dynamics of the hot (Te > 8 x 106K) coronal plasma from spectra integrated spatially over the whole region.

Characteristics of Soft X-Ray Radiation of the Solar Active Region NOAA 1024 Registered by the PINGVIN-M Device in July 2009

2020 ◽  
Vol 60 (7) ◽  
pp. 936-941
Author(s):  
M. I. Savchenko ◽  
P. V. Vatagin ◽  
P. B. Dmitriev ◽  
M. G. Ogurtsov ◽  
E. M. Kruglov ◽  
...  
Keyword(s):  
Active Region ◽  
Solar Active Region ◽  
Active Region Noaa ◽  
X Ray ◽  
Region Noaa

scholarly journals Energetics of magnetic transients in a solar active region plage

2019 ◽  
Vol 623 ◽  
pp. A176 ◽  
Author(s):  
L. P. Chitta ◽  
A. R. C. Sukarmadji ◽  
L. Rouppe van der Voort ◽  
H. Peter
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Flux ◽  
Numerical Simulations ◽  
Extreme Ultraviolet ◽  
Spatial Scales ◽  
Coronal Loops ◽  
The Sun ◽  
Flux Emergence ◽  
Transient Events

Context. Densely packed coronal loops are rooted in photospheric plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plage areas are patches of mostly unidirectional magnetic field extending several arcsec on the solar surface. Aims. We aim to explore the transient nature of the magnetic field, its mixed-polarity characteristics, and the associated energetics in the active region plage using high spatial resolution observations and numerical simulations. Methods. We used photospheric Fe I 6173 Å spectropolarimetric observations of a decaying active region obtained from the Swedish 1-m Solar Telescope (SST). These data were inverted to retrieve the photospheric magnetic field underlying the plage as identified in the extreme-ultraviolet emission maps obtained from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). To obtain better insight into the evolution of extended unidirectional magnetic field patches on the Sun, we performed 3D radiation magnetohydrodynamic simulations of magnetoconvection using the MURaM code. Results. The observations show transient magnetic flux emergence and cancellation events within the extended predominantly unipolar patch on timescales of a few 100 s and on spatial scales comparable to granules. These transient events occur at the footpoints of active region plage loops. In one case the coronal response at the footpoints of these loops is clearly associated with the underlying transient. The numerical simulations also reveal similar magnetic flux emergence and cancellation events that extend to even smaller spatial and temporal scales. Individual simulated transient events transfer an energy flux in excess of 1 MW m−2 through the photosphere. Conclusions. We suggest that the magnetic transients could play an important role in the energetics of active region plage. Both in observations and simulations, the opposite-polarity magnetic field brought up by transient flux emergence cancels with the surrounding plage field. Magnetic reconnection associated with such transient events likely conduits magnetic energy to power the overlying chromosphere and coronal loops.

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