Search Publications
Electron density diagnostics for solar ultraviolet lines of O V
Doyle, J. G.; Keenan, F. P.; O'Shea, E. +1 more
We determine the electron densities for a range of solar features using new calculations for the O v line ratio, R=I(λ761.1)/I(λ760.4), in conjunction with observational data obtained with the Solar Ultraviolet Measurements of Emitted Radiation (SUMER) instrument on the Solar and Heliospheric Observatory (SOHO). The densities obtained from this di…
Quasi-stationary solar wind in ray structures of the streamer belt
Eselevich, M. V.; Eselevich, V. G.
It is shown on the basis of analyzing the LASCO/SOHO data that the main quasi-stationary solar wind (SW), with a typical lifetime of up to 10 days, flows in the rays of the streamer belt. Depending on R, its velocity increases gradually from V≈3 km s−1 at R≈1.3 R⊙ to V≈170 km s−1 at R≈15 R⊙. We have dete…
Response of the radial stratification at the base of the convection zone to the activity cycle
Eff-Darwich, Antonio; Korzennik, Sylvain G.
We have analyzed the differences in the oscillation eigenfrequencies measured over more than two years of GONG observations (December 1995-April 1998) and SOI/MDI observations (May 1996-July 1998). We have inverted these data to look for signatures of the solar activity cycle on the stratification. A one-dimensional (radial) structure inversion co…
Quiet-time periods observed by EPHIN/SOHO during the minimum of the 22nd solar cycle
Sierks, Holger; Gómez-Herrero, Raúl; Müller-Mellin, Reinhold +4 more
An analysis of the hydrogen and helium isotopic composition from EPHIN data, during the quiet-time period from January 1 to June 1, 1996, is presented. An isotopic discrimination and background rejection have been applied and relationships between the abundances of 2H/1H, 3He/4He, and 4He/
The Magnetic Connectivity of Moss Regions
Kosovichev, A. G.; Hoeksema, J. T.; Scherrer, P. H. +2 more
A novel emission feature resembling moss was first identified in high-resolution TRACE Fe ix/x 171 Å images by Berger et al. (1999). The moss emission is characterized by dynamic arc-second scale, bright elements surrounding dark inclusions in images of solar active regions. Patches of moss elements, called moss regions, have a scale of 20-30 Mm. …
The Energy Supply to X-ray Bright Points
Culhane, J. L.; Harra, L. K.; Matthews, S. A. +1 more
X-ray bright points (XBPs) are usually assumed to be isolated structures in the solar atmosphere that are powered exclusively by magnetic reconnection. We analyse a large XBP that does not satisfy this assumption. The XBP is observed to be connected to an active region approximately 280 000 km away by a magnetic loop. We find that the soft X-ray i…
Active region EUV transient brightenings - First Results by EIT of SOHO JOP 80
Berghmans, D.; Clette, F.
On 13 May 1998, the Extreme-Ultraviolet Imaging Telescope (EIT, on board SOHO) has produced a unique image sequence operating in 'shutterless mode' (SOHO JOP 80). In JOP 80, EIT is the lead instrument, followed by several space-born instruments (SXT, TRACE, MDI, CDS, SUMER), as well as two observatories on the ground (in La Palma and Sac Peak). Th…
Cme Associated with Transequatorial Loops and a Bald Patch Flare
Aulanier, G.; Delannée, C.
We study a flare which occurred on 3 November 1997 at 10:31 UT in the vicinity of a parasitic polarity of AR 8100. Using SOHO/EIT 195 Å observations, we identify the brightening of thin transequatorial loops connecting AR 8100 and AR 8102, and dimmings located between the two active regions. Difference images highlight the presence of a loop-like …
On the origin of solar metric type II bursts
Howard, Russell A.; Webb, David F.; Cliver, Edward W.
The vast majority of solar flares are not associated with metric Type II radio bursts. For example, for the period February 1980-July 1982, corresponding to the first two and one-half years of the Solar Maximum Mission, 95% of the ∼2500 flares with peak >25 keV count rates >100 c s−1lacked associated Type II emission. Even the ∼36…
Observations of a Propagating Disturbance in TRACE
Thompson, B. J.; Wills-Davey, M. J.
TRACE observations from 13 June 1998 in 171 and 195 Å wavelengths show a propagating disturbance, initiated near the origin of a C-class flare. The wave moves through and disrupts diffuse, overarching coronal loops. Only these overlying structures are affected by the wave; lower-lying coronal structures are unperturbed. The front does not appear i…