scholarly journals Non-Equilibrium Excitation and Ionization of Be-Sequence Ions

1977 ◽  
Vol 43 ◽  
pp. 14-14
Author(s):  
J .C . Raymond ◽  
A.K. Dupree
Keyword(s):  
Solar Flares ◽  
Resonance Line ◽  
Coronal Holes ◽  
Detailed Comparison ◽  
Temporal Variations ◽  
Ionization State ◽  
Harvard College ◽  
Harvard College Observatory ◽  
Ultraviolet Observations ◽  
Non Equilibrium

Intensities of resonance and subordinate lines in C III and O V are calculated for several non-equilibrium states expected to occur in the solar atmosphere. In particular, cooling (recombination) phases of solar flares, and regions of mass flow such as coronal holes and the network offer conditions where non-equilibrium phenomena can be significant. In such situations, the ionization state may not be in equilibrium with the electron temperature. Detailed comparison is made with the ultraviolet observations from the Harvard College Observatory experiment on Skylab which show temporal variations as well as clear non-equilibrium enhancement of the ratio of the 2s2p 3P - 2p23P transition 2 1 1 to the resonance line 2s21S - 2s2p 1P in both C III and O V.

UV Emitting Spicules

1980 ◽  
Vol 91 ◽  
pp. 199-201
Author(s):  
Giannina Poletto
Keyword(s):  
Coronal Hole ◽  
Extreme Ultraviolet ◽  
Emission Measure ◽  
Harvard College ◽  
Chromospheric Network ◽  
Harvard College Observatory ◽  
Ultraviolet Observations ◽  
Lower Limits

Extreme ultraviolet observations of the chromospheric network in a coronal hole obtained in 1973 by the Harvard College Observatory experiment aboard Skylab are analyzed. Upper and lower limits to the actual emission measure in UV spicules have been obtained, and the consistency of the derived values with the hypothesis that UV spicules are Hα spicules falling back after being heated is discussed.

scholarly journals Density Sensitive Lines in the EUV Region

1977 ◽  
Vol 43 ◽  
pp. 15-15
Author(s):  
J. E. Vernazza ◽  
H.E. Mason
Keyword(s):  
Coronal Holes ◽  
Active Regions ◽  
Electron Densities ◽  
Harvard College ◽  
Sensitive Line ◽  
Harvard College Observatory ◽  
Solar Plasmas ◽  
Emergent Intensity ◽  
Made In

A search for density sensitive line ratios was made in the 1400 Å to 300 Å region of the solar spectra. The emergent intensity of resonance and subordinate lines from ions of the beryllium and boron isoelectrcnic sequence were calculated for typical solar plasmas. For individual ions, line, ratios which are sensitive to electron densities changes between 107 to 1013cm –3were selected. These line ratios were then compared to observations made by the Harvard College Observatory spectrometer aboard SKYLAB. From all the potential candidates only few are adequately observed to estimate electron densities. In particular the Mg VIII lines at 430 and 436 Å are good indicators of the coronal densities. Comparisons of the densities of coronal holes, flares, and active regions are made.

scholarly journals Dynamical Effects in the EUV Chromospheric Network

1977 ◽  
Vol 43 ◽  
pp. 10-10
Author(s):  
F.G. Chiuderi-Drago ◽  
G. Poletto
Keyword(s):  
Extreme Ultraviolet ◽  
Network Models ◽  
Average Intensity ◽  
The Sun ◽  
Harvard College ◽  
Spatial Intensity Distribution ◽  
Euv Emission ◽  
Chromospheric Network ◽  
Harvard College Observatory ◽  
Ultraviolet Observations

Extreme ultraviolet observations of the chromospheric network obtained by the Harvard College Observatory experiment aboard Skylab on May 31st, 1973, are analyzed.The data, which have a spatial resolution of 5“ x 5“, cover an area of 5‘ x 5‘ near the center of the sun, where a large coronal hole was present, and are recorded in several lines formed in a range of temperatures from 104 to 106 °K.By studying the EUV spatial intensity distribution, the average intensity in cell and network, the contrast, and the emission measures have been derived.The network distribution, highly asymmetrical and skewed to higher intensity, suggests an inhomogeneous network structure, probably associated with the presence of spicules, not resolved by the instrument.A dynamical model of the transition zone is therefore developed, and the resulting EUV emission in spicules is computed and compared with available observations, and with previous network models.

EUV Observations of the Active Sun from the Harvard Experiment on ATM

1975 ◽  
Vol 68 ◽  
pp. 3-17 ◽  
Author(s):  
R. W. Noyes ◽  
P. V. Foukal ◽  
M. C. E. Huber ◽  
E. M. Reeves ◽  
E. J. Schmahl ◽  
...  
Keyword(s):  
Solar Activity ◽  
Extreme Ultraviolet ◽  
Coronal Holes ◽  
Active Regions ◽  
Harvard College ◽  
Preliminary Results ◽  
Harvard College Observatory

In this paper we review some preliminary results from the Harvard College Observatory Extreme Ultraviolet Spectroheliometer on ATM that pertain to solar activity. The results reviewed here are described in more detail in other papers referred to in the text. In the following paragraphs we first describe the instrument and its capabilities, and then turn to results on active regions, sunspots, flares, EUV bright points, coronal holes, and prominences.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

scholarly journals Some kinematics of halo coronal mass ejections

2020 ◽  
Vol 29 (1) ◽  
pp. 81-88
Author(s):  
Virendra Kumar Verma ◽  
Nishant Mittal ◽  
Ramesh Chandra
Keyword(s):  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Coronal Holes ◽  
Geomagnetic Disturbances ◽  
Class A ◽  
Heliospheric Physics ◽  
Class B ◽  
The Mean ◽  
Class C

AbstractWe present an investigation of halo coronal mass ejections (HCMEs) kinematics and other facts about the HCMEs. The study of HCMEs is very important because HCMEs are regarded as the main causes of heliospheric and geomagnetic disturbances. In this study, we have investigated 313 HCMEs observed during 1996-2012 by LASCO, coronal holes, and solar flares. We find that HCMEs are of two types: accelerated HCMEs and decelerated HCMEs. The mean space speed of HCMEs is 1283 km/s while the mean speed of decelerated HCMEs and accelerated HCMEs is 1349 km/s and 1174 km/s, respectively. The investigation shows that 1 (0.3%) HCME was associated with class A SXR, 14 (4.7%) HCMEs were associated with class B SXR-flares, 87 (29.4%) HCMEs were associated with class C SXR-flares, 125 (42.2%) HCMEs were associated with class M SXR-flares and 69 (23.3%) HCMEs were associated with class X SXR-flares. The speed of HCMEs increases with the importance of solar SXR-flares. The various results obtained in the present analysis are discussed in the light of the existing scenario of heliospheric physics.

scholarly journals Simulating the interstellar medium of galaxies with radiative transfer, non-equilibrium thermochemistry, and dust

2020 ◽  
Vol 499 (4) ◽  
pp. 5732-5748 ◽  
Author(s):  
Rahul Kannan ◽  
Federico Marinacci ◽  
Mark Vogelsberger ◽  
Laura V Sales ◽  
Paul Torrey ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Galaxy Formation ◽  
State Of The Art ◽  
Complex Function ◽  
Ionization State ◽  
Radiation Fields ◽  
Stellar Feedback ◽  
Wide Range ◽  
Dust Distribution ◽  
Non Equilibrium

ABSTRACT We present a novel framework to self-consistently model the effects of radiation fields, dust physics, and molecular chemistry (H2) in the interstellar medium (ISM) of galaxies. The model combines a state-of-the-art radiation hydrodynamics module with a H  and He  non-equilibrium thermochemistry module that accounts for H2 coupled to an empirical dust formation and destruction model, all integrated into the new stellar feedback framework SMUGGLE. We test this model on high-resolution isolated Milky-Way (MW) simulations. We show that the effect of radiation feedback on galactic star formation rates is quite modest in low gas surface density galaxies like the MW. The multiphase structure of the ISM, however, is highly dependent on the strength of the interstellar radiation field. We are also able to predict the distribution of H2, that allow us to match the molecular Kennicutt–Schmidt (KS) relation, without calibrating for it. We show that the dust distribution is a complex function of density, temperature, and ionization state of the gas. Our model is also able to match the observed dust temperature distribution in the ISM. Our state-of-the-art model is well-suited for performing next-generation cosmological galaxy formation simulations, which will be able to predict a wide range of resolved (∼10 pc) properties of galaxies.

Strong earthquake activity influenced by solar flare intensity

2021 ◽  
Author(s):  
Gerald Duma
Keyword(s):  
Solar Flares ◽  
Strong Earthquake ◽  
Temporal Variations ◽  
Seasonal Effect ◽  
Earthquake Activity ◽  
Strong Earthquakes ◽  
International Service ◽  
Earthquake Frequency ◽  
Magnetic Index ◽  
Magnetic Disturbances

<p>Based on the comprehensive earthquake catalogue USGS ( HYPERLINK<span>  </span>https://earthquake.usgs.gov) the paper demonstrates that strong earthquake activity, seismic events with M≥6, exhibits a seasonal trend. This feature is the result of<span>  </span>analyses of earthquake data for the N- and S- Earth Hemisphere in period 2010-2019. It can be shown also for single earthquake prone regions as well, like Japan, Eurasia, S-America.</p><p>Any seasonal effect suggests an external influence. In that regard, one can think also of a solar-terrestrial effect, that is suggested already in several studies (e.g<span>  </span>M.Tavares, A.Azevedo, 2011; D.A.E. Vares, M.A.Persinger,2014; G.Duma, 2019). This assumption leads to the question: Which dynamic process can cause a trigger effect for strong earthquakes in the Earth's lithosphere.</p><p>In this study the intensity of solar flares and the resulting radiation, the solar wind, towards the Earth was taken into account. An appropriate parameter which has been regularity measured and reported for many decades and which reflects the intensity of solar radiation is the magnetic index Kp. It is measured at numerous geomagnetic observatories and describes the magnetic disturbances in nT within 3 hour intervals, respectively. Averages of all the measured 3-hour values are then published as Kp, therefore considered a planetary parameter (International Service of Geomagnetic Indices ISGI,France).</p><p>The temporal variations of strong earthquake activity over 10 years and their energy release was compared with the above mentioned index Kp. Actually, a distinct correlation between the two quantities, Kp and earthquake frequency, resulted in cases of different regions as well as globally. Another essential result of the study is that maxima of Kp preceed those of earthquake activity by about 60 to 80 days in most cases. The mechanism has not yet been modeled satisfactorily.</p>

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