We calculate the rapid proton ( rp) capture process of hydrogen burning on the surface of an accreting neutron star with an updated reaction network that extends up to Xe, far beyond previous work. In both steady-state nuclear burning appropriate for rapidly accreting neutron stars (such as the magnetic polar caps of accreting x-ray pulsars) and unstable burning of type I x-ray bursts, we find that the rp process ends in a closed SnSbTe cycle. This prevents the synthesis of elements heavier than Te and has important consequences for x-ray burst profiles, the composition of accreting neutron stars, and potentially galactic nucleosynthesis of light p nuclei.

The spectral energy distributions (SEDs) of dusty high‐redshift galaxies are poorly sampled in frequency and spatially unresolved. Their form is crucially important for estimating the large luminosities of these galaxies accurately, for providing circumstantial evidence concerning their power sources, and for estimating their redshifts in the absence of spectroscopic information. We discuss the suite of parameters necessary to describe their SEDs adequately without introducing unnecessary complexity. We compare directly four popular descriptions, explain the key degeneracies between the parameters in each when confronted with data, and highlight the differences in their best‐fitting values. Using one representative SED model, we show that fitting to even a large number of radio, submillimetre and far‐infrared (far‐IR) continuum colours provides almost no power to discriminate between the redshift and dust temperature of an observed galaxy, unless an accurate relationship with a tight scatter exists between luminosity and temperature for the whole galaxy population. We review our knowledge of this luminosity–dust temperature relation derived from three galaxy samples, to better understand the size of these uncertainties. Contrary to recent claims, we stress that far‐IR‐based photometric redshifts are unlikely to be sufficiently accurate to impose useful constraints on models of galaxy evolution: finding spectroscopic redshifts for distant dusty galaxies will remain essential.

We present observations of a remarkable submillimetre‐selected galaxy, SMM J16359+6612. This distant galaxy lies behind the core of a massive cluster of galaxies, A 2218, and is gravitationally lensed by the foreground cluster into three discrete images which were identified in deep submillimetre maps of the cluster core at both 450 and 850 μm. Subsequent follow‐up investigations using deep optical and near‐infrared (NIR) images identify a faint counterpart to each of the three images, with similar red optical–NIR colours and Hubble Space Telescope morphologies. By exploiting a detailed mass model for the cluster lens we estimate that the combined images of this galaxy are magnified by a factor of ∼45, implying that this galaxy would have unlensed magnitudes Ks= 22.9 and I= 26.1, and an unlensed 850‐μm flux density of only 0.8 mJy. Moreover, the highly constrained lens model predicted the redshift of SMM J16359+6612 to be z= 2.6 ± 0.4. We confirm this estimate using deep optical and NIR Keck spectroscopy, measuring a redshift of z= 2.516. SMM J16359+6612 is the faintest submillimetre (submm)‐selected galaxy so far identified with a precise redshift. Thanks to the large gravitational magnification of this source, we identify three sub‐components in this submm galaxy, which are also seen in the Near Infrared Spectrograph (NIRSPEC) data, arguing for either a strong dust (lane) absorption or a merger. Interestingly, there are two other highly amplified galaxies at almost identical redshifts in this field (although neither is a strong submm emitter). The three galaxies lie within a ∼100‐kpc region on the background sky, suggesting this submm galaxy is located in a dense high‐redshift group.

Long-duration gamma-ray bursts (GRBs) accompany the deaths of some massive stars and hence, because massive stars are short-lived, are a tracer of star formation activity. Given that GRBs are bright enough to be seen to very high redshifts and detected even in dusty environments, they should therefore provide a powerful probe of the global star formation history of the Universe. The potential of this approach can be investigated via submillimetre (submm) photometry of GRB host galaxies. Submm luminosity also correlates with star formation rate, so the distribution of host-galaxy submm fluxes should allow us to test the two methods for consistency. Here, we report new JCMT/SCUBA 850-µm measurements for 15 GRB hosts. Combining these data with results from previous studies, we construct a sample of 21 hosts with <1.4 mJy errors. We show that the distribution of apparent 850-µm flux densities of this sample is reasonably consistent with model predictions, but there is tentative evidence of a dearth of submm-bright (>4 mJy) galaxies. Furthermore, the optical/infrared properties of the submm-brightest GRB hosts are not typical of the galaxy population selected in submm surveys, although the sample size is still small. Possible selection effects and physical mechanisms which may explain these discrepancies are discussed.