We report calculations of rate coefficients for the rovibrational excitation of H2 and HD by H. The calculations relate explicitly to non‐reactive scattering, excluding the proton‐exchange channels. For vibrationally inelastic transitions, the new rate coefficients at T≈ 1000 K are larger than the results of earlier calculations in which the vibrational motion was treated approximately, by means of a simple harmonic oscillator model. As a result, much better agreement is obtained with the empirical estimates by Allers et al. of the rate coefficients for vibrational relaxation of the levels (v, j) = (1, 3) and (2, 3) of H2. However, the effects of the new data on the results of illustrative astrophysical models – of a C‐type shock wave and of the gravitational collapse of a condensation of the primordial gas – are less pronounced than the changes to the rate coefficients for vibrationally inelastic transitions might suggest; we explain why this is the case.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We consider the ground state of an attractively interacting atomic Bose-Einstein condensate in a prolate, cylindrically symmetric harmonic trap. If a true quasi-one-dimensional limit is realized, then for sufficiently weak axial trapping this ground state takes the form of a bright soliton solution of the nonlinear Schrödinger equation. Using analytic variational and highly accurate numerical solutions of the Gross-Pitaevskii equation, we systematically and quantitatively assess how solitonlike this ground state is, over a wide range of trap and interaction strengths. Our analysis reveals that the regime in which the ground state is highly solitonlike is significantly restricted and occurs only for experimentally challenging trap anisotropies. This result and our broader identification of regimes in which the ground state is well approximated by our simple analytic variational solution are relevant to a range of potential experiments involving attractively interacting Bose-Einstein condensates.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

Cross sections have been computed for rovibrational transitions of H2, induced by collisions with H atoms, using the H–H2 interaction potential calculated recently by Mielke et al and an earlier potential of Boothroyd et al. We compare cross sections derived using a simple harmonic oscillator approximation to the vibrational motion with results obtained using numerically ‘exact’ solutions of the rovibrational eigenvalue equation. We also investigate the convergence of the cross sections with respect to the size of the rovibrational basis set. Convergence is found to be slow, owing to the strength of the collisional coupling between vibrational manifolds.

The Solar Activity Magnetic Monitor (SAMM) Network (SAMNet) is a future UK-led international network of ground-based solar telescope stations. SAMNet, at its full capacity, will continuously monitor the Sun’s intensity, magnetic and Doppler velocity fields at multiple  heights in the solar atmosphere (from photosphere to upper chromosphere). Each SAMM sentinel will be equipped with a cluster of identical telescopes each with different magneto-optical filter (MOFs) to take observations in K~I, Na~D and Ca~I spectral bands. A subset of SAMM stations will have white-light coronagraphs and emission line coronal spectropolarimeters. The objectives of SAMNet are to provide observational data for the space weather research and forecast. The goal is to achieve an operationally sufficient lead time of e.g. flare warning of 2-8 hours, and provide much sought-after continuous synoptic maps (e.g., LoS magnetic and velocity fields, intensity) of the lower solar atmosphere with a spatial resolution limited only by seeing or diffraction limit, and with a cadence of 10 minutes. The individual SAMM sentinels will be connected into their master HQ hub where data received from all the slave stations will be automatically processed and flare warning issued up to 26 hrs in advance.