Vladimir A. Slemzin

The TESIS experiment on the CORONAS-PHOTON spacecraft

On February 26, 2009, the first data was obtained in the TESIS experiment on the research of the solar corona using imaging spectroscopy. The TESIS is a part of the scientific equipment of the CORONAS-PHO-TON spacecraft and is designed for imaging the solar corona in soft X-ray and extreme ultraviolet regions of the spectrum with high spatial, spectral, and temporal resolutions at altitudes from the transition region to three solar radii. The article describes the main characteristics of the instrumentation, management features, and operation modes.

Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models (e.g., the Wang–Sheeley–Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS-Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

XUV observations of solar corona in the spirit experiment on board the coronas-F satellite

The images of the solar corona from the limb out to the distance of about 5 solar radii have been obtained for the firs time in the XUV narrow spectral bands and monochromatic lines in the current experiment SPIRIT (SPectroheliographIc soft X-Ray Imaging Telescope). This paper presents the examples of images for the Suns “quiet” atmosphere as well as for some transient and eruptive events in the corona to illustrate the performance of the instrumentation and to point out the way for future studies. The data obtained will be used for diagnostic purposes and modeling of solar wind acceleration, coronal plasma structures and various active phenomena in the solar corona.

Analysis and interpretation of a fast limb CME with eruptive prominence, C-flare, and EUV dimming

Aims. Coronal mass ejections or CMEs are large dynamical solar-corona events. The mass balance and kinematics of a fast limb CME, including its prominence progenitor and the associated flare, will be compared with computed magnetic structures to look for their origin and effect. Methods: Multi-wavelength ground-based and spaceborne observations are used to study a fast W-limb CME event of December 2, 2003, taking into account both on and off disk observations. Its erupting prominence is measured at high cadence with the Pic du Midi full H? line-flux imaging coronagraph. EUV images from SOHO/EIT and CORONAS-F/SPIRIT space instruments are processed including difference imaging. SOHO/LASCO images are used to study the mass excess and motions. Computed coronal structures from extrapolated surface magnetic fields are compared to observations. Results: A fast bright expanding coronal loop is identified in the region recorded slightly later by GOES as a C7.2 flare, followed by a brightening and an acceleration phase of the erupting material with both cool and hot components. The total coronal radiative flux dropped by ~7% in the 19.5 nm channel and by 4% in the 17.5 nm channel, revealing a large dimming effect at and above the limb over a 2 h interval. The typical 3-part structure observed 1 h later by the Lasco C2 and C3 coronagraphs shows a core shaped similarly to the eruptive filament/prominence. The total measured mass of the escaping CME (~1.5×1016 g from C2 LASCO observations) definitely exceeds the estimated mass of the escaping cool prominence material although assumptions made to analyze the H? erupting prominence, as well as the corresponding EUV darkening of the filament observed several days before, made this evaluation uncertain by a factor of 2. This mass budget suggests that the event is not confined to the eruption region alone. From the current free extrapolation we discuss the shape of the magnetic neutral surface and a possible scenario leading to an instability, including the small scale dynamics inside and around the filament.

The Space Weather and Ultraviolet Solar Variability (SWUSV) Microsatellite Mission

We present the ambitions of the SWUSV (Space Weather and Ultraviolet Solar Variability) Microsatellite Mission that encompasses three major scientific objectives: (1) Space Weather including the prediction and detection of major eruptions and coronal mass ejections (Lyman-Alpha and Herzberg continuum imaging); (2) solar forcing on the climate through radiation and their interactions with the local stratosphere (UV spectral irradiance from 180 to 400 nm by bands of 20 nm, plus Lyman-Alpha and the CN bandhead); (3) simultaneous radiative budget of the Earth, UV to IR, with an accuracy better than 1% in differential. The paper briefly outlines the mission and describes the five proposed instruments of the model payload: SUAVE (Solar Ultraviolet Advanced Variability Experiment), an optimized telescope for FUV (Lyman-Alpha) and MUV (200–220 nm Herzberg continuum) imaging (sources of variability); UPR (Ultraviolet Passband Radiometers), with 64 UV filter radiometers; a vector magnetometer; thermal plasma measurements and Langmuir probes; and a total and spectral solar irradiance and Earth radiative budget ensemble (SERB, Solar irradiance & Earth Radiative Budget). SWUSV is proposed as a small mission to CNES and to ESA for a possible flight as early as 2017–2018.

Diagnostics of the inner corona by XUV-imaging of the sun

Results of solar observations in the XUV-region by means of the telescope TEREK aboard the “Phobos-1” spacecraft are presented. Images of the Sun in the HeII 30,4 nm and FeIX-FeXI 17–18 nm lines were obtained with new types of optical elements — multilayer normal incidence XUV-mirrors and CCD-detectors. About 140 images were obtained with an angular resolution up to 15″ and with exposure times 0.1 to 40 s. In the images one sees the structures in the transition layer from corona to chromosphere which has temperatures in the range 5×104 – 1×106 K as well as in the polar and equatorial coronal holes. Besides, a unique phenomenon — a “blob” in outer corona at a distance about 2 solar radii has been observed. Processing of the data revealed a complex correlation between the XUV-images and the magnetic field structure in the photosphere.

Multi-wavelength observations of CME-associated structures on the Sun with the CORONAS-F/SPIRIT EUV telescope

Multi-wavelength imaging of the solar corona is a powerful observational method to study CME-related dynamics of structures in spectral bands related to the solar corona and transition region. We analyze large-scale eruptive events caused by halo-type CMEs observed at the solar disk with the CORONAS-F/SPIRIT (175, 304, and 284 Å) and SOHO/EIT telescopes on November 4, 2001 and October–November, 2003. For most events, CME-associated dimmings coincide in different bands, but the 304 Å dimming in November 4, 2001 event was delayed by > 1/2 hours. In October–November events, coronal waves were observed in 195 Å and some in 175 Å channel. In a CME event associated with a filament eruption on November 18, the SPIRIT images display a propagating disturbance seen as a darkening in 304 Å channel only. This phenomenon was not described earlier.

Characterization of imaging normal-incidence multilayer mirrors for the 40- to 300-A range by spectroscopic techniques using a laser-plasma radiation source

A number of high-performance normal-incidence multilayer mirrors (MMs) have been fabricated on concave (r equals 1.6 - 2.0 m) fused silica substrates using laser deposition and a magnetron ion sputtering source. The resonance wavelengths (lambda) 0 equals 2nd of the MMs synthesized are proximate to 45, 130, 175, 190, and 304 angstroms. The MMs have been subjected to scrutiny by a spectroscopic technique employing a laser-plasma broadband XUV radiation source. The spectral shapes of the resonance reflection curves, the (lambda) 0 values, and the aperture uniformity (topography) of the mirrors have been determined spectroscopically. Normal-incidence reflection maxima, which correspond to higher-order reflection (k(lambda) equals 2n(lambda )d, k > 1), have been observed for all of the Mo-Si MMs with (lambda) >= 175 angstroms.

Manufacture and testing of x-ray optical elements for the TEREK-C and RES-C instruments on the CORONAS-I mission

The paper describes the main characteristics of the X-ray optical elements (multilayer spherical and aspherical mirrors and diffraction gratings for the 13-30 nm XUV spectral region, Bragg crystal spherical mirrors for the 0.18 and 0.84 m soft X-ray spectral regions) manufactured for the TEREK-C solar XUV telescope array and the RES-C solar spectroheliograph. The TEREK-C and RES-C instruments were placed aboard the CORONAS-I satellite which was launched on March 2, 1994. The testing procedures and results of laboratory tests in X-ray spectral range are also presented.

Normal-incidence multilayer mirrors for the 120-450 å wavelength region.

An electron-beam deposition method is used to fabricate spherical and flat mirrors with a peak reflectivity of 20% for wavelengths between 120 and 450 A. It is experimentally shown that the fabricated mirrors can be employed to form an image with a resolution of 1 μm for ultrasoft x rays. The possibility of producing intense directional high-temperature plasma radiation by spherical multilayer mirrors is demonstrated. A radiation intensity of 107 W/cm2 around 182 A has been experimentally obtained in the laser plasma image plane.