S. Koutchmy

French National Centre for Scientific Research | CNRS · Institut d'Astrophysique de Paris

The main observations of 1761 by M. Lomonossov and those that followed are recalled by extending the discussion to other remarkable visual observations of the passages, then with more and more powerful imagers producing images in profusion. The modern treatment of parasitic effects is briefly recalled by focusing on the expert observation of 1761 w...

In this work we performed a polarimetric study of a fast and wide coronal mass ejection (CME) observed on 12 July 2012 by the COR1 and COR2 instruments onboard the Solar TErrestrial RElations Observatory (STEREO) mission. The CME source region was an X1.4 flare located at approximately S15W01 on the solar disk, as observed from the Earth’s perspect...

In this work we performed a polarimetric study of a fast and wide coronal mass ejection (CME) observed on 12 July 2012 by the COR1 and COR2 instruments onboard Solar TErrestrial RElations Observatory (STEREO) mission. The CME source region was an X1.4 flare located at approximately S15W01 on the solar disk as observed from the Earth's perspective....

The forthcoming solar cycle (SC) 25 was beleived to be rather low when using the sunspot number (SN) as a measurement of the level of activity. The most popular prediction was made by the panel of NASA in 2019, including works based on extrapolations of dynamo-type models. We however discovered that using different observations to measure the level...

Total solar eclipse (TSE) coronal large- and small-scale events were reported in the historical literature but a definite synoptic coverage was missing for studying a relationship with the more general magnetic context of the solar-disk. We here analyze temporal changes in the solar corona before, during, and after the total solar eclipse on 21 Aug...

Total solar eclipse (TSE) coronal large and small scale events were reported in the historical literature but a definite synoptic coverage was missing for studying a relationship with the more general magnetic context of the solar-disk. We here analyze temporal changes in the solar corona before, during, and after the total solar eclipse on 21 Augu...

Context. The origin of the high temperature of the solar corona, in both the inner bright parts and the more outer parts showing flows toward the solar wind, is not understood well yet. Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum white-light (W-L) radiations from electrons (K-corona)...

Total eclipses permit a deep analysis of both the inner and the outer parts of the corona using the continuum White-Light (W-L) radiations from electrons (K-corona), the superposed spectrum of forbidden emission lines from ions (E-corona) and the dust component with F-lines (F-corona). By sufficiently dispersing the W-L spectrum, the Fraunhofer (F)...

To study motions and oscillations in the solar chromosphere and at the transition region (TR) level we analyze some extreme Doppler shifts observed off-limb with the Interface Region Imaging Spectrograph (IRIS). Raster scans and slit-jaw imaging observations performed in the near-ultraviolet (NUV) channels were used. Large transverse oscillations a...

Abstract : Total eclipses permit a deep analysis of both the inner and the outer parts of the solar corona using the continuum White- Light (W-L) radiations and the superposed spectrum of forbidden emission lines. After sufficiently dispersing the W-L corona, the Fraunhofer (F) spectrum of the dust corona appears and the continuum Thomson radiation...

Photographic and video observations made by astronaut Thomas Pesquet (European Space Agency) during the 51st expedition to the International Space Station (ISS) contain a series of color images of the emission and scattering layers of the Earth’s atmosphere under night and twilight conditions. The stars of various constellations can be clearly seen...

We examine the dynamical behavior of white-light polar-plume structures in the inner corona that are observed from the ground during total solar eclipses, based on their extreme ultraviolet (EUV) hot and cool emission line counterparts observed from space. EUV observations from Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) of a...

We examine the dynamical behavior of white light polar plume structures in the inner corona that are observed from the ground during total solar eclipses, based on their EUV hot and cool emission line counterparts observed from space. EUV observations from SDO/AIA of a sequence of rapidly varying coronal hole structures are analyzed. Evidence of ev...

A shower of secondary cosmic ray (CR) particles is produced at high altitudes in the Earth's atmosphere, so the primordial galactic cosmic rays (GCRs) are never directly measured outside the Earth magnetosphere and atmosphere. They approach the Earth and other planets in the complex pattern of rigidity's dependence, generally excluded by the magnet...

To deepen the analysis of the photometric properties of the umbra of a sunspot, we study proper motions of small features such as umbral dots (UDs) inside a single sunspot observed by the Solar Optical Telescope of Hinode close to the disk center. We consider horizontal flows with high precision and details to study the transient motion behavior of...

A shower of secondary Cosmic Ray (CR) particles is produced at high altitudes in the Earth's atmosphere, so the primordial Galactic Cosmic Rays (GCRs) are never directly measured outside the Earth magnetosphere and atmosphere. They approach the Earth and other planets in the complex pattern of rigidity's dependence, generally excluded by the magnet...

The photometry of eclipse white-light (W-L) images showing a moving blob is interpreted for the first time together with observations from space with the PRoject for On Board Autonomy (PROBA-2) mission (ESA). An off-limb event seen with great details in W-L was analyzed with the SWAP imager (Sun Watcher using Active pixel system detector and image...

Emission-line and K-coronal observations in the IR have the significant advantage of reduced sky brightness compared with the visible, while the effects of seeing are also reduced. Moreover, strong lines are available in the near-IR. Examples of the current capabilities of IR coronal observations using conventional Lyot coronagraphs are discussed b...

The origin and evolution of solar sunspots in deep photospheric layers are not yet well understood. The case of a quasi- symmetric single mature sunspot near the solar centre is selected for analysis. We use the best available observations of the partial Sun free of turbulent Earth atmospheric effects from the Solar Optical Telescope (SOT) onboard...

The origin and evolution of solar sunspots in deep photospheric layers are not yet well understood. The case of a quasi-symmetric single mature sunspot near the solar centre is selected for analysis. We use the best available observations of the partial Sun free of turbulent Earth atmospheric effects from the Solar Optical Telescope (SOT) onboard t...

This paper presents the design of an innovative solar spectrometer that will y on the NSF/NCAR Gulfstream V High-Performance Instrumented Airborne Platform for Environmental Research (GV HIAPER) during the 2017 solar eclipse. The airborne infrared spectrometer (AIR-Spec) is groundbreaking in two aspects: it will image infrared coronal emission line...

We present some new accurate CCD photometry analysis of the white light solar corona at the time of the last 20 March 2015 total eclipse (airborne observations on a Falcon 7X and at ground-based Svalbard). We measured coronal brightness profiles taken along radial directions from 1.001 to 3 solar radii in the northern, southern and equatorial regio...

The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA Small Explorer mission provides significantly more complete and higher resolution spectral coverage of the dynamical conditions inside the chromosphere and Transition Region (TR) than has heretofore been available. Near the solar limb high temporal, spatial (0''3) an...

We report on a novel technique for measuring the solar radius during total solar eclipses that exploits light curves recorded just before and after second and third contacts. The measurements are performed by pre-programmed photometers that are deployed over the eclipse paths and are operated without supervision. The recorded light curves are compa...

The “sonic region” of the Sun corona remains extremely difficult to observe with spatial resolution and sensitivity sufficient to understand the fine scale phenomena that govern the quiescent solar corona, as well as phenomena that lead to coronal mass ejections (CMEs), which influence space weather. Improvement on this front requires eclipse-like...

In the framework of development of ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun), the Centre Spatial de Liege is responsible of the optical design of the coronagraph and the optics will be manufactured by TOPTEC. The particularity of this coronagraph is to have an external occulter located 1...

We consider the best today available observations of the Sun free of turbulent Earth atmospheric effects, taken with the Solar Optical Telescope (SOT) onboard the Hinode spacecraft. Both the instrumental smearing and the observed stray light are analyzed in order to improve the resolution. The Point Spread Function (PSF) corresponding to the blue c...

Observations of the Sun's corona during the space era have led to a picture of relatively constant, but cyclically varying solar output and structure. Longer-term, more indirect measurements, such as from 10Be, coupled by other albeit less reliable contemporaneous reports, however, suggest periods of significant departure from this standard. The Ma...

Slitless consecutive spectra were obtained during the contacts of the last total solar eclipses (2008, 2009, 2010, 2012, et 2013). They allowed to show that the overabundance of low First Ionisation Potential (FIP) elements (Fe II, Ti II, Ba II) in the corona comes from the low layers of the solar atmosphere, just near and above the temperature min...

In the context of transiting exoplanets, the last June 6, 2012 Venus transit was a unique opportunity to address important questions regarding its atmosphere. The transit of Venus is indeed a particular case of an Earth-like planet transit, and the inference one can make about the upper layers of its atmosphere can be applied to other exoplanets. T...

Context. For investigating spicules from the photosphere to coronal heights, the new Hinode/SOT long series of high resolution observations from Space taken in CaII H line emission o_ers an improved way to look at their remarkable dynamical behavior using images free of seeing effects. They should be put in the context of the huge amount of already...

The Interface Region Imaging Spectrograph (IRIS) of the recently commissioned NASA Explorer mission provides a significantly more complete spectral coverage of the dynamical conditions inside the chromosphere and Transition Region (TR) than has heretofore been available. High temporal, spatial (0”.3) and spectral resolution observations of 1 kms-1...

In this work, we present digital and graphical atlases of spectra of both the solar disk-center and of the limb near the Solar poles using data taken at the UTS-IAP & RIAAM (the University of Tabriz Siderostat, telescope and spectrograph jointly developed with the Institut d'Astrophysique de Paris and Research Institute for Astronomy and Astrophysi...

Both the origin of the quiescent prominences and their eruption related to CMEs event are still a matter of extended studies. The case of high latitudes quiescent prominences producing slow CMEs can be considered as a potential component of the slow wind. A high latitude prominence was observed on November 13 - 14, 2011. A schematic representation...

Both the origin of the quiescent prominences and their eruption related to CMEs are still a matter of extended studies. The small scale dynamic aspects like vortex structures and counter- flows are now seriously taken into account having in mind that the flows are a good proxy of the line of force of the omnipresent but rather unknown in detail for...

We used total solar eclipse free of parasitic light for studying the prominence to corona interface, and the corresponding cavity in the context of the coronal physics. We analysed the visible continuum between the prominences to directly look at the electron density. We demonstrate some enhanced heating in the cavity region. Some similarities with...

Transverse oscillatory motions and recurrence behavior in the chromospheric jets observed by Hinode/SOT are studied. A comparison is considered with the behavior that was noticed in coronal X-ray jets observed by Hinode/XRT. A jet like bundle observed at the limb in Ca II H line appears to show a magnetic topology that is similar to X-ray jets (i.e...

At the beginning of the 1990s, it was found out that the strongest disturbances of space weather were associated with huge ejections of matter from the solar corona, which took the form of the magnetic clouds when moved from the Sun. It is the collisions of the magnetic clouds with the Earth's magnetosphere that lead to strong, sometimes to ca...

Aims. We report several Hinode/SOT long series observations in Ca H line and discuss a remarkable dynamical behavior which might be nothing else than Helical-Kink mode propagation or Alfvenic waves inside the multi-component spicules. Methods. Compute 2D velocity map using a technique base is using FFTs and cross-correlation function, and use a 2 n...

At the time of the two last solar total eclipses of August 1st, 2008 in Siberia and July 11th, 2010 in French Polynesia, high frame rate CCD flash spectra were obtained. These eclipses occurred in quiet Sun period and after. The slitless flash spectra show two helium shells, in the weak Paschen α 4686 Å line of the ionized helium HeII and in the ne...

Without spurious effects due to instrumental and/or Earth atmospheric parasitic light, the true solar edge can only be correctly analyzed at the time of solar total eclipses. We discuss the problems occurring when using solar diameter measurements made outside of solar total eclipses, including the possible limb effects related to different sources...

We consider the use of the commercially available Fabry-Perot etalons (FP) for the imaging of the solar chromosphere in the H alpha line of HI. Three etalons of 40, 60 and 90 mm diameter were accurately analysed. At normal incidence the maximum transmission wavelength as well as the finesse were evaluated. Polynomial curves precisely fitting the tr...

One of the important parameters of the ubiquitous spicules rising intermittently above the surface of the Sun is the variation of spicule spline orientation with respect to the solar coordinates, presumably reflecting the focusing of ejection by the coronal magnetic field. Here we first use a method of tracing limb spicules using a combination of s...

The variation of the solar diameter is the subject of hot debates due to the possible effect on Earth climate and also due to different interpretations of long period solar variabilities, including the total solar irradiance. We shortly review the topic and show that rather long term variations, corresponding to a length well over a a solar magneti...

SWAP images from PROBA2 taken at 174 {\AA} in the Fe IX/X lines are compared with simultaneous slitless flash spectra obtained during the solar total eclipse of 11 July, 2010. Myriads of faint low excitation emission lines together with the He I and He II Paschen {\alpha} chromospheric lines are recorded on eclipse spectra where regions of limb pro...

In order to clear up the origin and possibly explain some solar limb and disc spicule quasi-periodic recurrences produced by overlapping effects, we present a simulation model assuming quasi- random positions of spicules. We also allow a set number of spicules with different physical properties (such as: height, lifetime and tilt angle as shown by...

Images from the SWAP (Proba 2 mission) taken in the Fe IX/X coronal line emission are compared to simultaneous slitless flash spectra taken during the total solar eclipse of July, 11th 2010. Many faint low excitation emission lines together with the HeI and the HeII Paschen α (Pα) chromospheric lines are recorded in the regions of limb prominences...

The existence of coronal plasmoids has been postulated for many years in order to supply material to streamers and possibly to the solar wind (SW). The W-L SoHO C2 Lasco coronagraph observations were made under the 2.2 solar radii (R0) occulting disk to look at the ultimate sources of the SW; EUV imagers are preferably devoted to the analysis of th...

Observations of jet- like phenomena near the solar limb are reported for a long time, first in Hα (Secchi observations of spicules in the 1870 ies), and after, from eclipse high resolution coronal images taken in white-light (1920-1973) as spiky structures. EUV jets were reported in the 70 ies from rocket and space-borne CIV filtergrams and finally...

We focus our analysis on an event which occurred at the W-limb on May 30, 2003. The dynamical behavior of the filament, including damped oscillations, was investigated with the CDS and EIT (SoHO) experiments, as well as with Hα filtergrams (movies). The eruptive phase is analyzed taking into account the approximate phasing with other eruptive pheno...

Three-dimensional structures in the solar chromosphere and corona are considered. It is demonstrated that two photoheliograms separated by ∼1 day can be used (using computer-graphics methods) to construct a stereo image of the Sun. The algorithm for this is presented and carried out for Hα images of the total disk. A bulge in the equatorial region...

4th French-Chinese Meeting on Solar Physics Understanding Solar Activity: Advances and Challenges, 4th French-Chinese, Nice, France.

Flash spectra taken at high frame rate during the total solar eclipse of August 1st 2008 in Siberia and during the July 11th 2010 in French Polynesia are compared in the context of the quiet Sun near the minimum of activity. They both reveal the weak Paschen α 468.6 nm ionized helium line, seen as a helium shell in layers up to the 8 Mm heights. Th...

The variations in intensity and velocity inside an eruptive filament, observed on May 30, 2003 with CDS and EIT on-board SOHO, are analysed in the transition region He I line and the coronal Mg X line. Vertical oscillating motions of the filament with damped velocity oscillations before its disappearance are revealed. The link between theses oscill...

We analyze multi-wavelength and multi-viewpoint observations of a large-scale event viewed on 7 April 2011, originating from an active-region complex. The activity leads to a white-light jet being formed in the outer corona. The topology and evolution of the coronal structures were imaged in high resolution using the Atmospheric Imaging Assembly (A...