Kinetic Properties of CMEs Corrected for the Projection Effect

Observations of coronal mass ejections (CMEs) with coronagraphs are subject to a projection effect, which results in statistical errors in many properties of CMEs, such as the eruption speed and the angular width. In this paper, we develop a method to obtain the velocity and angular width distributions of CMEs corrected for the projection effect, and then re-examine the relationship between CMEs and the associated flares. We find that (1) the mean eruption speed is 792 km s⁻¹ and the mean angular width is 59^∘, compared to the values of 549 km s⁻¹ and 77^∘, respectively before the correction; (2) after the correction, the weak correlation between CME speeds and the GOES X-ray peak flux of the flares gets unexpectedly poorer; and (3) before correction, there is a weak correlation between the angular width and the speed of CMEs, whereas the correlation is absent after the correction.     

Final analysis of ELAIS 15-μm observations: method, reduction and catalogue

We present the final analysis of the European Large Area Infrared Space Observatory ( ISO ) Survey (ELAIS) 15-μm observations, carried out with the ISO Camera (ISOCAM) instrument on board the ISO .
The data-reduction method, known as the Lari Method, is based on a mathematical model of the behaviour of the detector and was specifically designed for the detection of faint sources in ISOCAM/ISO Photopolarimeter (ISOPHOT) data. The method is fully interactive and leads to very reliable and complete source lists.
The resulting catalogue includes 1923 sources detected with signal-to-noise ratio of  > 5  in the 0.5–100 mJy flux range and over an area of 10.85 deg² split into four fields, making it the largest non-serendipitous extragalactic source catalogue obtained to date from the ISO data.
This paper presents the concepts underlying the data-reduction method together with its latest enhancements. The data-reduction process, the production and basic properties of the resulting catalogue are discussed. The catalogue quality is assessed by means of detailed simulations, optical identifications and comparison with previous analyses.     

An extension of Newton's apsidal precession theorem

Newton's apsidal precession theorem in Proposition 45 of Book I of the 'Principia' has great mathematical, physical, astronomical and historical interest. The lunar theory and the precession of the perihelion of the planet Mercury are but two examples of the applications of this theorem. We have examined the precession of orbits under varying force laws as measured by the apsidal angle θ( N , e ), where N is the index for the centripetal force law, for varying eccentricity e . The paper derives a general function for the apsidal angle, dependent only on e and N as the potential is spherically symmetric. Further, we explore approximate ways of the solution of this equation, in the neighbourhood of   N = 2  which happens to be the case of greatest historical interest. Exact solutions are derived where they are possible. The first derivatives  ∂θ/∂ N   and  ∂θ/∂ h   [where h ( N , e ) is the angular momentum] are analytically expressed in the neighbourhood of   N = 2  (case of the inverse square law). The value of  ∂θ/∂ N   is computed numerically as well for  1 ≤ N < 3  . The resulting integrals are interesting improper integrals with singularities at both limits. Some of the integrals, especially for   N = 2  , can be given in closed form in terms of generalized hypergeometric functions which are reducible in terms of algebraic and logarithmic functions. No evidence was found for isolated cases of zero precession as e was increased. The   N = 1  case of the logarithmic potential is also briefly discussed in view of its interest for the dynamics of eccentric orbits and its relevance to realistic galaxy models. The possibility of apsidal precession was also examined for a few cases of high-eccentricity asteroids and extrasolar planets. We find that these systems may provide interesting new laboratories for studies of gravity.     

Radial and rotational velocities of young brown dwarfs and very low-mass stars in the Upper Scorpius OB association and the ρ Ophiuchi cloud core

We present the results of a radial velocity (RV) survey of 14 brown dwarfs (BDs) and very low-mass (VLM) stars in the Upper Scorpius OB association (UScoOB) and three BD candidates in the ρ Ophiuchi dark cloud core. We obtained high-resolution echelle spectra at the Very Large Telescope using the Ultraviolet and Visual Echelle Spectrograph (UVES) at two different epochs for each object, and measured the shifts in their RVs to identify candidates for binary/multiple systems in the sample. The average time separation of the RV measurements is 21.6 d, and our survey is sensitive to the binaries with separation <0.1 au. We found that four out of 17 objects (or 24⁺¹⁶₋₁₃ per cent by fraction) show a significant RV change in 4–33 d time-scale, and are considered as binary/multiple 'candidates'. We found no double-lined spectroscopic binaries in our sample, based on the shape of cross-correlation curves. The RV dispersion of the objects in UScoOB is found to be very similar to that of the BD and VLM stars in Chamaeleon I (Cha I). We also found the distribution of the mean rotational velocities ( v   sin   i ) of the UScoOB objects is similar to that of the Cha I, but the dispersion of v   sin   i is much larger than that of the Cha I objects.     

XMM–Newton observations of bright ROSAT selected active galactic nuclei with low intrinsic absorption

We present a sample of 21 ROSAT bright active galactic nuclei (AGNs), representing a range of spectral classes, and selected for follow-up snapshot observations with XMM–Newton . The typical exposure was between 5 and 10 ks. The objects were primarily selected on the bases of X-ray brightness and not on hardness ratio; thus the sample cannot be strictly defined as a 'soft'sample. One of the main outcomes from the XMM–Newton observations was that all of the AGN, including 11 type 1.8–2 objects, required low levels of intrinsic absorption  ( N _H≲ 10²¹ cm⁻²)  . The low absorption in type 2 systems is a challenge to account for in the standard orientation-based unification model, and we discuss possible physical and geometrical models which could elucidate the problem. Moreover, there does not appear to be any relation between the strength and shape of the soft excess, and the spectral classification of the AGN in this sample. We further identify a number of AGN which deserve deeper observations or further analysis: for example, the low-ionization nuclear emission regions (LINERs) NGC 5005 and NGC 7331, where optically thin thermal and extended emission is detected, and the narrow-line Seyfert 1 II Zw 177, which shows a broad emission feature at ∼ 5.8 keV.     

On the sublimation of ice particles on the surface of Mars; with applications to the 2007/8 Phoenix Scout mission

Experimental studies related to the sublimation of ice, in bulk or as small particles, alone or mixed with dust similar to that expected on the surface of Mars, are reported. The experiments, a cloud physics particle sublimation model, and a convection model presented by Ingersoll, all indicate a strong dependence of sublimation rate on temperature, and this appears to be the dominant factor, assuming that the relative humidity of the air is fairly low. In addition the rate of loss of water vapour appears to depend primarily on exposed surface area and less on particle size and the total mass of the sample, or the mass of ice in the sample. The 2007/8 Phoenix Scout mission plans to obtain and analyse samples of sub-surface ice from about 70° N on Mars. A concern is that these samples, in the form of ice chips of size about 1 mm diameter, could be prone to sublimation when exposed for prolonged periods (many hours) to a relatively warm and dry atmosphere. Our laboratory simulations confirm that this could be a problem if particles are simply left lying on the surface, but also indicate that samples kept suitably cold and collected together in confined piles will survive long enough for the collection and delivery (to the analysis instruments) procedure to be completed.