Two dynamical models for solar spicules     

Paul Lorrain  Serge Koutchmy 《Solar physics》1996,165(1):115-137

Solar spicules are luminous jets that erupt up to 10 000 km from the surface of the Sun and have diameters, all along their length, of only about 150–200 km. We first review some recent observations made at the H wavelength. According to our models, a solar spicule is a self-channelled proton beam emitted by a magnetic element and surrounded by a cold sheath. The beam originates in a self-excited dynamo that exploits a v × B field and that could be situated either below or above the element, where v is the local plasma velocity and B is the local magnetic flux density. In falling back, the sheath provides a return current of protons that cancels the outgoing current. We discuss the channelling of charged-particle beams of very large cross-section and propose velocity channelling, which is apparently a new concept. We assume a steady state and a hydrogen plasma.  相似文献   

Study of the inner satellites of Saturn by photographic photometry     

S. Koutchmy  Ph.L. Lamy 《Icarus》1975,25(3):459-465

Good photographs of Saturn and its five inner satellites were obtained on January 2, 1974 with the 105 cm telescope at Pic du Midi Observatory with exposure times of 45 sec. The spread function is constant over the field, and isotropic. The true photometric profiles of the satellites are obtained after deriving a model for the stray light coming from the rings. The magnitudes, computed by integration, are in good agreement with published values except for Mimas, which is nearly one magnitude fainter then previously believed.  相似文献   

A Novel Technique for Measuring the Solar Radius from Eclipse Light Curves – Results for 2010, 2012, 2013, and 2015     

Philippe Lamy  Jean-Yves Prado  Olivier Floyd  Patrick Rocher  Guillaume Faury  Serge Koutchmy 《Solar physics》2015,290(10):2617-2648

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The three-dimensional structure of the solar corona     

S. L. Koutchmy  V. L. Merzlyakov  M. M. Molodenskii 《Astronomy Reports》2001,45(10):834-840

The surface where the radial component of the solar magnetic field changes sign is computed for a minimum corona. It is shown that (1) the projection of the folds of this surface onto the plane of the sky is consistent with the helmet structures observed during the eclipse of June 30, 1954; (2) there are type 1 and type 2 helmets, according to the well-known classification of coronal structures; (3) some elements of this sign-change surface of the radial field can be classified as so-called envelopes. The results obtained suggest that more complex coronal structures can be described in a similar way. An MHD model of polar plumes is considered.  相似文献   

Fine structure of the Solar Chromosphere: Arch-Shaped Mottles     

Zachariadis  Th.G.  Georgakilas  A.A.  Koutchmy  S.  Alissandrakis  C.E. 《Solar physics》1999,184(1):77-86

We analyze a time series of high resolution observations near the solar limb, obtained in H and the Mg b1 line. We identified arch-shaped dark mottles, which are thin, faint H structures observable under very good seeing conditions, best seen in H +0.75 Å. Their mean length is about 15, their mean height about 6 and indicative lifetimes is of the order of 5 min. They show negative (away from the observer) line-of-sight velocities. A possible interpretation is that material flows from the apex towards the feet of the arches.  相似文献   

Photometric study of chromospheric and coronal spikes observed during the total solar eclipse of 30 June, 1973     

S. Koutchmy  G. Stellmacher 《Solar physics》1976,49(2):253-265

A photometric and colorimetric analysis of a color picture of the very inner solar corona, near the South pole region, is performed. Dimensions and average electron densities of both chromospheric and very fine resolved coronal spikes are deduced. For the coronal spike a half width of 1.67 is measured, the estimate of electron density yields n _e = 10¹⁰ cm^–3. Some conclusions are attempted on the light of a simultaneously observed spectrum of the same region which appeared to be a disappearing coronal hole. The observations seem to support the concept of a striated corona.On leave from Institut d'Astrophysique, Paris as NRC Post-Doctoral Research Assistant.  相似文献   

Photometrie photographique de la couronne solaire     

Koutchmy  S.  Dzubenko  N. I.  Nesmjanovich  A. T.  Vsekhsvjatsky  S. K. 《Solar physics》1974,36(2):369-370

Solar Physics - A series of plates of the solar corona were obtained during the total solar eclipse of July 10th, 1972 near Anadyr (U.S.S.R.) using a standard eclipse coronagraph of Ø = 20 cm...  相似文献   

Magnetic configurations of streamer structures in the solar atmosphere     

S. L. Koutchmy  M. M. Molodensky 《Astronomy Letters》2005,31(6):398-405

We consider two types of streamer structures observed in the solar atmosphere. Structures of the first type are medium-scale configurations with scale lengths comparable to the scale height in the corona, kT/mg = 100 thousand km, which appear as characteristic plasma structures in the shape of a dome surrounding the active region with thin streamers emanating from its top. In configurations of this type, gravity plays no decisive role in the mass distribution. The plasma density is constant on magnetic surfaces. Accordingly, the structure of the configurations is defined by the condition ψ = const, where ψ is the flux function of the magnetic field. Structures of the second type are large-scale configurations (coronal helmets, loops, and streamers), which differ from the above structures in that their scale lengths exceed the scale height in the corona. For them, gravity plays a decisive role; as a result, instead of the magnetic surfaces, the determining surface is BgradΦ = 0. We constructed three-dimensional images of these structures. Some of the spatial curves called “visible contours” of the B_r = 0 surface are shown to be brightest in the corona. We assume that the helmet boundaries and polar plumes are such curves.  相似文献   

Analysis of the radiation of coronal suprathermal streams     

S. Koutchmy  A. G. Nikoghossian 《Astrophysics》2005,48(1):62-67

This paper reports on the first measurements of the color index of the coronal suprathermal streams. Observations performed during the total eclipse of 2001 in Angola imply that the color index of streams differs markedly from that for adjacent parts of the surrounding corona taken as reference. The registered drifts to the longwave and shortwave domains of the spectrum are in agreement with theoretical results obtained recently by the authors.Published in Astrofizika, Vol. 48, No. 1, pp. 79–85 (February 2005).  相似文献   

Fine Structure of the Quiet Solar Chromosphere: Limb-Crossing Features     

Zachariadis  Th.G.  Dara  H.C.  Alissandrakis  C.E.  Koutchmy  S.  Gontikakis  C. 《Solar physics》2001,202(1):41-52

In this article we study chromospheric structures (spicules) crossing the solar limb in H images corrected for limb darkening. This correction enabled us to view structures both on the disk and beyond the limb in the same image. The observations were obtained at the Sacramento Peak Observatory at H±0.75 Å. The processed images reveal both bright and dark (relative to the local background) features crossing the limb. We also observed bushes (rosettes) crossing the limb, as well as structures indicating probably arch-shaped mottles beyond the limb.  相似文献