Search Publications
Polar Plumes and Inter-plume regions as observed by SUMER on SOHO
Doyle, J. G.; Teriaca, L.; Banerjee, D. +1 more
We present observations of O vi 1032 Å line profiles obtained with the SUMER instrument on SOHO extending from the solar disk to 1.5 R⊙ above the limb in the north polar coronal hole. Variations of the intensity and linewidth in the polar plume and inter-plume regions are investigated. We find an anti-correlation between the intensity a…
A Kinetic Model of Coronal Heating and Acceleration by Ion-Cyclotron Waves: Preliminary Results
Isenberg, Philip A.; Lee, Martin A.; Hollweg, Joseph V.
We present a kinetic model of the heating and acceleration of coronal protons by outward-propagating ion-cyclotron waves on open, radial magnetic flux tubes. In contrast to fluid models which typically insist on bi-Maxwellian distributions and which spread the wave energy and momentum over the entire proton population, this model follows the kinet…
Magnetic Activity Associated With Radio Noise Storms
van Driel-Gesztelyi, L.; Bentley, R. D.; Klein, K. -L. +4 more
As it crossed the solar disk in May and June 1998, AR 8227 was tracked by TRACE, Yohkoh, SOHO, and many ground-based observatories. We have studied how the evolution of the magnetic field resulted in changes in activity in the corona. In particular, we examine how the evolving field may have led to the acceleration of electrons which emit noise st…
Supergranulation rotation
Schou, Jesper; Beck, John G.
Simple convection models estimate the depth of supergranulation at approximately 7500 km which suggests that supergranules would rotate at the rate of the plasma in the outer 1% of the solar radius. The supergranulation rotation obtained from MDI dopplergrams shows that supergranules rotate faster than the outer 5% of the convection zone and show …
Acoustic Imaging of Solar Active Regions - (Invited Review)
Chou, Dean-Yi
Acoustic imaging is a new method to construct the acoustic signal at a point on the solar surface or in the solar interior with the signals measured at the solar surface. The constructed signals contain both intensity information and phase information. The intensity is computed by summing the squared amplitude of the constructed signal over time. …
The Preflight Photometric Calibration of the Extreme-Ultraviolet Imaging Telescope EIT
Delaboudinière, J. -P.; Dere, K. P.; Moses, J. D. +7 more
This paper presents the preflight photometric calibration of the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SOHO). The EIT consists of a Ritchey-Chrétien telescope with multilayer coatings applied to four quadrants of the primary and secondary mirrors, several filters and a backside-thinned CCD detec…
Structure of a Large low-Latitude Coronal Hole
Dobrzycka, D.; Del Zanna, G.; Gopalswamy, N. +7 more
Coronal holes on the Sun are the source of high-speed solar wind streams that produce magnetic disturbances at the Earth. A series of multi-wavelength, multi-instrument observations obtained during the 1996 `Whole Sun Month' campaign examined a large coronal hole in greater detail than ever before. It appeared on the Sun in August, and extended fr…
Solar Cycle Variation in Solar f-Mode Frequencies and Radius
Basu, Sarbani; Antia, H. M.; Pintar, J. +1 more
Using data from the Global Oscillation Network Group (GONG) covering the period from 1995 to 1998, we study the change with solar activity in solar f-mode frequencies. The results are compared with similar changes detected from the Michelson Doppler Imager (MDI) data. We find variations in f-mode frequencies which are correlated with solar activit…
EUV Full-Sun Imaged Spectral Atlas Using the SOHO Coronal Diagnostic Spectrometer
Brekke, Pål; Thompson, William T.
The Coronal Diagnostic Spectrometer (CDS) aboard the Solar and Heliospheric Observatory (SOHO) carries out a regular program of measuring the full-disk irradiance using the Normal Incidence Spectrograph (NIS). The full-disk solar spectrum is returned in the wavelength bands 308-379 Å and 513-633 Å, with a spectral resolution between 0.3 and 0.6 Å.…
NOAA AR 8210: Evolution and Flares from Multiband Diagnostics
Warmuth, Alexander; Hanslmeier, Arnold; Messerotti, Mauro +3 more
NOAA 8210 has been a region showing a remarkable level of activity well before solar maximum. Dominated by a large, rapidly rotating δ spot, it produced several intense flares during its disk passage at the end of April-beginning of May 1998. We examine the development of AR 8210 in Hα and white light (WL) and study the evolution of its complex ma…