Search Publications
Variations of Magnetic Bright Point Properties with Longitude and Latitude as Observed by Hinode/SOT G-band Data
Veronig, A.; Utz, D.; Hanslmeier, A. +4 more
Small-scale magnetic fields can be observed on the Sun in high-resolution G-band filtergrams as magnetic bright points (MBPs). We study Hinode/Solar Optical Telescope (SOT) longitude and latitude scans of the quiet solar surface taken in the G-band in order to characterise the centre-to-limb dependence of MBP properties (size and intensity). We fi…
Sunspot Bright Points
Choudhary, Debi Prasad; Shimizu, Toshifumi
We used the flux-calibrated images from the Broad-band Filter Imager and Stokes Polarimeter data obtained with the Solar Optical Telescope onboard the Hinode spacecraft to study the properties of bright points in and around sunspots. The selected bright points are smaller in diameter than 150 km with contrasts exceeding about 3 % in the ratio of s…
The Projects for Onboard Autonomy (PROBA2) Science Centre: Sun Watcher Using APS Detectors and Image Processing (SWAP) and Large-Yield Radiometer (LYRA) Science Operations and Data Products
Berghmans, D.; Seaton, D. B.; Nicula, B. +18 more
The PROBA2 Science Centre (P2SC) is a small-scale science operations centre supporting the Sun observation instruments onboard PROBA2: the EUV imager Sun Watcher using APS detectors and image Processing (SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA's small, low-cost Projects for Onboard Autonomy (PROBA) and part of ESA's In-Orbit …
Variation of Emission Line Width in Mid- and High-Latitude Corona
Banerjee, D.; Krishna Prasad, S.; Singh, Jagdev
Spectroscopic studies of the solar corona, using the high spatial and spectral resolution 25-cm coronagraph at the Norikura Solar Observatory for equatorial off-limb observations, indicated that the variation of radiance and line width with height is different for different temperature lines. The line width of the forbidden red emission line [Fe x…
Electric Current Equilibrium in the Corona
Filippov, Boris
A hyperbolic flux-tube configuration containing a null point below the flux rope is considered as a pre-eruptive state of coronal mass ejections that start simultaneously with flares. We demonstrate that this configuration is unstable and cannot exist for a long time in the solar corona. The inference follows from general equilibrium conditions an…
A Comparative Study of Clustering Methods for Active Region Detection in Solar EUV Images
Caballero, C.; Aranda, M. C.
The increase in the amount of solar data provided by new satellites makes it necessary to develop methods to automate the detection of solar features. Here we present a method for automatically detecting active regions in solar extreme ultraviolet (EUV) images using a series of steps. Initially, the bright regions in the image are segmented using …
Observational Evidence for a Double-Helix Structure in CMEs and Magnetic Clouds
Osherovich, Vladimir; Fainberg, Joseph; Webb, Alla
We compare recent observations of a solar eruptive prominence as seen in extreme-UV light on 30 March 2010 by the Solar Dynamics Observatory (SDO) with the multi-tube model for interplanetary magnetic clouds (Osherovich, Fainberg, Stone, Geophys. Res. Lett.26, 2597, 1999). Our model is based on an exact analytical solution of the plasma equilibriu…
Prominence Cavity Regions Observed Using SWAP 174 Å Filtergrams and Simultaneous Eclipse Flash Spectra
Koutchmy, S.; Tavabi, E.; Bazin, C.
SWAP images from PROBA2 taken at 174 Å in the Fe IX/X lines are compared with simultaneous slitless flash spectra obtained during the solar total eclipse of 11 July 2010. Myriad faint low-excitation emission lines together with the He I and He II Paschen α chromospheric lines are recorded on eclipse spectra where regions of limb prominences are ob…
Detection of Solar Rotational Variability in the Large Yield RAdiometer (LYRA) 190 - 222 nm Spectral Band
Schmutz, W.; Rozanov, E.; Shapiro, A. I. +4 more
We analyze the variability of the spectral solar irradiance during the period from 7 January 2010 until 20 January 2010 as measured by the Herzberg channel (190 - 222 nm) of the Large Yield RAdiometer (LYRA) onboard PROBA2. In this period of time, observations by the LYRA nominal unit experienced degradation and the signal produced by the Herzberg…
Solar Activity and Deep Convection Modeling
Khodachenko, M. L.; Arkhypov, O. V.; Antonov, O. V.
We suggest from synoptic charts of radial magnetic field and intensities of spectral lines (Fe I, He II, and Fe IX/X) over Carrington rotations 1942 - 2050 that deep convective layers control the pattern of large-scale solar activity. A new result is a Kolmogorov-type energy spectrum of the longitudinal variations of solar activity. This spectrum …