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## ISAAC LW Telluric Line Atlas

### The 2007 ESO Instrument Calibration Workshop (2008-01-01): 149-152 , January 01, 2008

We present a status report on a project with the aim to enhance the wavelength calibration of ISAAC’s long wavelength spectroscopic mode. We measure telluric standard stars with high signal/noise and use the comparison with theoretical spectra of the telluric lines for the wavelength calibration. We show that calibrations done with arc-lines only can be wrong by up to 0.2 μm. The new atlas of telluric lines allows a spectral calibration with a precision of 0.003 μm.

## Regularization of the two body problem with variable mass

### Celestial Mechanics (1974-10-01) 10: 141-149 , October 01, 1974

Using Levi Civita's regularization, we put the two body problem with variable mass (x=−*M*x*r*^{−3}) into a form which can be solved analytically on computer. Two particular cases are discussed: 1.
$$\dot M$$
=*C*^{te}; 2.
$$\dot M$$
÷*M*^{α} (α unspecified).

## Temperature of Polar Corona of the Sun According to Kislovodsk Observations During 1957–2002

### Solar Physics (2006-08-01) 237: 201-210 , August 01, 2006

We continued a study of the long-term variations of temperature in the solar corona at all latitudes (Makarov, Tlatov, and Callebaut, 2002a). The series of the green (Fe xiv 530.3 nm; KI_{5303}) and red (Fe x 637.4 nm; KI_{6374}) coronal intensities for 1957–2002 has been obtained using the coronal observations at the Kislovodsk Solar Station. The mean monthly coronal intensities have been calculated at all latitudes (0–90^{˚}) and in the high latitude (45–90^{˚}) zones. It was found that the value of KI_{6374}/KI_{5303}increased about 2.0 times at the high latitudes during the last 45 years. This corresponds to a decrease of the average temperature by 0.1 ×10^{6}K of the polar corona. We suppose that a polar decrease of coronal temperature is connected with an increase of the area of polar zones *A*_{PZ}occupied by unipolar magnetic fields (Makarov *et al*., 2002) and, probably, with an increase of the area of polar coronal holes. The maximum ratio KI_{6374}/KI_{5303}is observed during the minimum sunspot activity.

## A combination of SPH andN-body 2 for gas dynamics in star clusters

### Astrophysics and Space Science (1990-08-01) 170: 221-224 , August 01, 1990

When stars are being formed in a region of a molecular cloud, the presence of the gas of this cloud will influence the dynamics of these newly formed stars. We discuss an implementation of SPH or Smooth Particle Hydrodynamics within the framework of*N*-body2, which will permit the study of this kind of mixed systems. It is our intention to include various gas removal processes, and to study their influence on the behaviour of stars and gas.

## Kinetic Models of Solar and Polar Winds

### Astrophysics and Space Science (2001-06-01) 277: 169-180 , June 01, 2001

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.

## Resonantly Damped Surface and Body MHD Waves in a Solar Coronal Slab with Oblique Propagation

### Solar Physics (2007-11-01) 246: 213-230 , November 01, 2007

The theory of magnetohydrodynamic (MHD) waves in solar coronal slabs in a zero-*β* configuration and for parallel propagation of waves does not allow the existence of surface waves. When oblique propagation of perturbations is considered, both surface and body waves are able to propagate. When the perpendicular wavenumber is larger than a certain value, the body kink mode becomes a surface wave. In addition, a sausage surface mode is found below the internal cutoff frequency. When nonuniformity in the equilibrium is included, surface and body modes are damped by resonant absorption. In this paper, first, a normal-mode analysis is performed and the period, the damping rate, and the spatial structure of the eigenfunctions are obtained. Then, the time-dependent problem is solved, and the conditions under which one or the other type of mode is excited are investigated.

## Planetary perturbations on the Libration of the Moon

### Celestial Mechanics (1984-09-01) 34: 263-273 , September 01, 1984

A theory of the libration of the Moon, completely analytical with respect to the harmonic coefficients of the lunar gravity field, was recently built (Moons, 1982). The Lie transforms method was used to reduce the Hamiltonian of the main problem of the libration of the Moon and to produce the usual libration series p_{1}, p_{2} and τ. This main problem takes into account the perturbations due to the Sun and the Earth on the rotation of a rigid Moon about its center of mass. In complement to this theory, we have now computed the planetary effects on the libration, the planetary terms being added to the mean Hamiltonian of the main problem before a last elimination of the angles. For the main problem, as well as for the planetary perturbations, the motion of the center of mass of the Moon is described by the ELP 2000 solution (Chapront and Chapront-Touze, 1983).

## The reducing transformation and Apocentric Librators

### Celestial Mechanics (1986-04-01) 38: 335-344 , April 01, 1986

We propose a canonical transformation reducing the averaged planar planetary problem near resonance to a one degree of freedom problem when the perturbation is truncated at the first order in the eccentricities.

This reducing transformation leads to a very simple explanation of the puzzling behaviour of the Apocentric Librators, a class of asteroids identified by Franklin*et al.* (1975).

An exploration of the phase space of the average problem with the use of the mapping technique shows that the alternation of two libration mechanism is a common feature for initial conditions near, but not inside, the deep resonance region.

## A semi-numerical perturbation method for separable hamiltonian systems

### Celestial Mechanics and Dynamical Astronomy (1990-03-01) 49: 43-67 , March 01, 1990

A detailed account is given of a semi-numerical perturbation method which has been proposed and improved upon in a succession of previous papers. The method analyses the first order effect of a small perturbation applied to a non-trivial two-degreeof-freedom separable Hamiltonian system (including the description of resonances) and construct approximate surfaces of section of the perturbed system. When the separable Hamiltonian system is already the description of a resonance, as it is the case in the problems we have investigated in the previous papers, these resonances are actually secondary resonances. The key role of the method is the numerical description of the angle-action variables of the separable system. The method is thus able to describe the perturbations of non-trivial separable systems and is not confined to the analysis of a small neigborhood of their periodic orbits.