FIRST RESULTS OF THE SUMER TELESCOPE AND SPECTROMETER ON SOHO – I. Spectra and Spectroradiometry     

Wilhelm  K.  Lemaire  P.  Curdt  W.  Schühle  U.  Marsch  E.  Poland  A. I.  Jordan  S. D.  Thomas  R. J.  Hassler  D. M.  Huber  M. C. E.  Vial  J.-C.  Kühne  M.  Siegmund  O. H. W.  Gabriel  A.  Timothy  J. G.  Grewing  M.  Feldman  U.  Hollandt  J.  Brekke  P. 《Solar physics》1997,170(1):75-104

SUMER – the Solar Ultraviolet Measurements of the Emitted Radiation instrument on the Solar and Heliospheric Observatory (SOHO) – observed its first light on January 24, 1996, and subsequently obtained a detailed spectrum with detector B in the wavelength range from 660 to 1490 Å (in first order) inside and above the limb in the north polar coronal hole. Using detector A of the instrument, this range was later extended to 1610 Å. The second-order spectra of detectors A and B cover 330 to 805 Å and are superimposed on the first-order spectra. Many more features and areas of the Sun and their spectra have been observed since, including coronal holes, polar plumes and active regions. The atoms and ions emitting this radiation exist at temperatures below 2 × 10⁶ K and are thus ideally suited to investigate the solar transition region where the temperature increases from chromospheric to coronal values. SUMER can also be operated in a manner such that it makes images or spectroheliograms of different sizes in selected spectral lines. A detailed line profile with spectral resolution elements between 22 and 45 mÅ is produced for each line at each spatial location along the slit. From the line width, intensity and wavelength position we are able to deduce temperature, density, and velocity of the emitting atoms and ions for each emission line and spatial element in the spectroheliogram. Because of the high spectral resolution and low noise of SUMER, we have been able to detect faint lines not previously observed and, in addition, to determine their spectral profiles. SUMER has already recorded over 2000 extreme ultraviolet emission lines and many identifications have been made on the disk and in the corona.  相似文献   

Electron Temperature in the Solar Wind From a Kinetic Collisionless Model: Application to High-Latitude Ulysses Observations     

Karine Issautier  Nicole Meyer-Vernet  Viviane Pierrard  Joseph Lemaire 《Astrophysics and Space Science》2001,277(1-2):189-193

We use a kinetic collisionless model of the solar wind to calculate the radial variation of the electron temperature and obtain analytical expressions at large radial distances. In order to be compared with Ulysses observations, the model, which initially assumed a radial magnetic field, has been generalized to a spiral magnetic field. We present a preliminary comparison with Ulysses observations in the fast solar wind at high heliospheric latitudes. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Prominence atlas in the SUMER range 800–1250 Å: I. Observations, data reduction and preliminary results     

S. Parenti  J.- C. Vial  P. Lemaire 《Solar physics》2004,220(1):61-80

The aim of this work is to build an EUV-UV spectral catalogue of a prominence. Here we focus on the preparatory work for the final result and we give an example of the results obtained. As a first step, we present the information needed for a full understanding of the results that will form the final entire catalogue. The data are composed of a full SUMER spectrum in the range 800–1250 Å of a prominence observed on 8 October 1999. A quiet-Sun area was also observed in the same spectral range in order to have a reference spectrum. Beside the standard corrections, we give details of the estimated stray light and the wavelength calibration of both datasets. We also present a short list of lines as an example of the results from the line-fitting procedure we applied to the data. For each line we give the measured position, the total intensity and the FWHM in the quiet Sun and at two different spatial positions in the prominence. With a final atlas of the prominence it will be possible to investigate several properties of the feature such as mass motion, differential emission measure, density, and elemental composition.  相似文献   

Theoretical plasma distributions consistent with Ulysses magnetic field observations in a solar wind tangential discontinuity     

J. De Keyser  M. Roth  J. Lemaire  B. T. Tsurutani  C. M. Ho  C. M. Hammond 《Solar physics》1996,166(2):415-422

The overall multi-layer structure of the magnetic field profile observed by Ulysses across a broad solar wind tangential discontinuity can be reproduced fairly well by means of a kinetic model. Such a simulation provides complementary information about the velocity distribution functions, which are not always available from the plasma experiment due to the low time resolution inherent in plasma measurements. The success of such a simulation proves that the kinetic model can be used as a realistic basis for further studies of the structure and stability of solar wind tangential discontinuities.  相似文献   

Kinetic Models of Solar and Polar Winds     

Joseph Lemaire  Viviane Pierrard 《Astrophysics and Space Science》2001,277(1-2):169-180

The study of the solar corona has been strewn with great discoveries, surprises and controversies. The major steps since van de Hulst's (1953)and Chapman's (1957) early hydrostatic models of the extended corona, until the most recent generations of kinetic models of the coronal expansion and of the supersonic solar wind flows, are presented. These models are compared to in-situ observations. Progress in polar wind models went through a somewhat similar evolution that is outlined also. The advantages and limitations of the successive brands of solar wind and polar wind models are considered. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

High-pressure behaviour of serpentine minerals: a Raman spectroscopic study   总被引：5，自引：2，他引：3  

A.-L.?Auzende  I.?DanielEmail author  B.?Reynard  C.?Lemaire  F.?Guyot 《Physics and Chemistry of Minerals》2004,31(5):269-277

Four main serpentine varieties can be distinguished on the basis of their microstructures, i.e. lizardite, antigorite, chrysotile and polygonal serpentine. Among these, antigorite is the variety stable under high pressure. In order to understand the structural response of these varieties to pressure, we studied well-characterized serpentine samples by in situ Raman spectroscopy up to 10 GPa, in a diamond-anvil cell. All serpentine varieties can be metastably compressed up to 10 GPa at room temperature without the occurrence of phase transition or amorphization. All spectroscopic pressure-induced changes are fully reversible upon decompression. The vibrational frequencies of antigorite have a slightly larger pressure dependence than those of the other varieties. The O–H-stretching modes of the four varieties have a positive pressure dependence, which indicates that there is no enhancement of hydrogen bonding in serpentine minerals at high pressure. Serpentine minerals display two types of hydroxyl groups in the structure: inner OH groups lie at the centre of each six-fold ring while outer OH groups are considered to link the octahedral sheet of a given 1:1 layer to the tetrahedral sheet of the adjacent 1:1 layer. On the basis of the contrasting behaviour of the Raman bands as a function of pressure, we propose a new assignment of the OH-stretching bands. The strongly pressure-dependent modes are assigned to the vibrations of the outer hydroxyl groups, the less pressure-sensitive peaks to the inner ones.  相似文献   

The ‘Roche-Limit’ of ionospheric plasma and the formation of the plasmapause     

J. Lemaire 《Planetary and Space Science》1974,22(5):757-766

The plasmapause position is determined by the innermost equipotential surface which is tangent to the ‘Roche-Limit’ surface of the ionospheric plasma filling the magnetosphere. When the thermal particles corotate with the Earth's angular velocity, the ‘Roche-Limit’ equatorial distance is L_c=5.78 [R_E]. When the angular convection velocity is evaluated from the quiet time electric field distribution E3 of McIIwain (1972), L_c depends on the local time. Its minimum value is then L_C=4.5Near 2400 LT, and the plasmapause shape and position satisfactorily fit the observations. The diffusive equilibrium dnesity distribution appropriated inside the plasmasphere, becomes convectively unstable beyond L = L_c, where the collisions type of model satisfactorily represents the observations. In the intermediate region between the plasmapause and the last closed magnetic field line, contimues ionization fluxes are expected to flow out of the midlatitude ionosphere  相似文献   

Partial purification and properties of cytochrome P450 from digestive gland microsomes of the common mussel, Mytilus edulis L.     

Cinta Porte  Philippe Lemaire  Laurence D. Peters  David R. Livingstone   《Marine environmental research》1995,39(1-4)

Cytochrome P450 from the digestive gland of M. edulis was partially purified by sodium cholate solubilization, 4–15% polyethylene glycol fractionation, and octyl-Sepharose affinity, DEAE-Sephacel ion-exchange and hydroxylapatite chromatography (yields of up to 7–10%). Three peaks were resolved by DEAE-Sephacel chromatography (termed peaks 1–3). P450 specific content was increased from 26 to 800 pmol per mg protein, and the ratio of P450 content to NADPH-cytochrome c (P450) reductase activity reduced by a factor of 250. Oxidised spectrum λmax of P450 was 410.5 ± 1.5 nm. Type II difference spectra were seen with both type II (clotrimazole, metyrapone) and type I (α-naphthoflavone, 7-ethoxycoumarin) compounds. Western blotting with polyclonal anti-P4501A from perch (Perca fluviatilis) gave a single band of approximately 54 kDa molecular weight. A reconstituted system containing peak 2 or 3, rat liver P450 reductase, lipid and NADPH metabolised benzo[a]pyrene to diones, diols, phenols and putative protein adducts. Peak 2 plus cumene hydroperoxide was indicated to produce diones and protein adducts only. Peak 2 alone was indicated to produce diones and phenols. The major free metabolites in all cases were diones (53–100%). The results indicate the existence of a P4501A-like enzyme in M. edulis, possibly with unusual properties as indicated by the difference spectra, metabolism in absence of NADPH and added P450 reductase, and predominance of diones.  相似文献   

Biochemical and histological responses in mussel (Mytilus edulis) exposed to North Sea oil and to a mixture of North Sea oil and alkylphenols     

N. Aarab  C. Minier  S. Lemaire  E. Unruh  P. -D. Hansen  B. K. Larsen  O. -K. Andersen  J. -F. Narbonne 《Marine environmental research》2004,58(2-5):437

Several environmental chemicals are suspected to be responsible for adverse health effects on the reproductive system in various organisms. During this work, environmentally relevant concentrations of North Sea oil were used alone or in combination with alkylphenols and additional PAH to study the effect on vitellogenin-like protein expression and gonadal development in mussels. North Sea oil (0.5 ppm) induced the expression of phospho-proteins in both sexes indicating that some compounds are oestrogen-mimics. This induction was not seen in samples dosed with the mixture but signs of toxic effects were observed in the gonads. Indeed, numerous degenerating ovarian follicles in females and foci, similar to vertebrate melanomacrophage centres, were observed in testes.  相似文献   

Impulsive penetration of filamentary plasma elements into the magnetospheres of the Earth and Jupiter     

J. Lemaire 《Planetary and Space Science》1977,25(9):887-890

Assuming that the solar wind plasma is usually non-uniform over distances of 10,000 km or less, it is shown that filamentary plasma elements stretched out from the Sun can penetrate impulsively and become engulfed into the magnetosphere.The diamagnetic effects associated with these plasma inhomogeneities are observed in outer magnetospheres and magnetosheaths as dips or directional discontinuities in the magnetic field measurements. From the mean penetration distances of these diamagnetic plasma elements one can deduce a mean deceleration time, as well as an approximate value of the integrated Pedersen conductivity in the polar cusp of the Earth and Jupiter.  相似文献