We present optical and infrared observations of the unusual Type Ia supernova (SN) 2004eo. The light curves and spectra closely resemble those of the prototypical SN 1992A, and the luminosity at maximum (MB=−19.08) is close to the average for a Type Ia supernova (SN Ia). However, the ejected 56Ni mass derived by modelling the bolometric light curve (about 0.45 M⊙) lies near the lower limit of the 56Ni mass distribution observed in normal SNe Ia. Accordingly, SN 2004eo shows a relatively rapid post‐maximum decline in the light curve [Δm15(B)true= 1.46], small expansion velocities in the ejecta and a depth ratio Si iiλ5972/Si iiλ6355 similar to that of SN 1992A. The physical properties of SN 2004eo cause it to fall very close to the boundary between the faint, low‐velocity gradient and high‐velocity gradient subgroups proposed by Benetti et al. Similar behaviour is seen in a few other SNe Ia. Thus, there may in fact exist a few SNe Ia with intermediate physical properties.

We present extensive optical (UBV RI, ¢ ¢ ¢ ¢ g r i z , and open CCD) and near-infrared (ZY JH) photometry for the very nearby Type IIP SN 2013ej extending from +1 to +461 days after shock breakout, estimated to be MJD 56496.9±0.3. Substantial time series ultraviolet and optical spectroscopy obtained from +8 to +135 days are also presented. Considering well-observed SNe IIP from the literature, we derive UBV RIJHK bolometric calibrations from UBV RI and unfiltered measurements that potentially reach 2% precision with a B−V colordependent correction. We observe moderately strong Si II l6355 as early as +8 days. The photospheric velocity (v ph ) is determined by modeling the spectra in the vicinity of Fe II l5169 whenever observed, and interpolating at photometric epochs based on a semianalytic method. This gives =  v 4500 500 ph km s −1 at +50 days. We also observe spectral homogeneity of ultraviolet spectra at +10-12 days for SNe IIP, while variations are evident a week after explosion. Using the expanding photosphere method, from combined analysis of SN 2013ej and SN 2002ap, we estimate the distance to the host galaxy to be -+ 9.0 0.6 0.4 Mpc, consistent with distance estimates from other methods. Photometric and spectroscopic analysis during the plateau phase, which we estimated to be 94±7 days long, yields an explosion energy of 0.9 0.3 10 51 erg, a final pre-explosion progenitor mass of 15.2±4.2  M and a radius of 250±70  R . We observe a broken exponential profile beyond +120 days, with a break point at +183±16 days. Measurements beyond this break time yield a 56 Ni mass of 0.013±0.001M  .

Globular clusters (GCs) have proven to be essential to our understanding of many important astrophysical phenomena. Here, we analyse spectroscopic observations of 10 halo GCs to determine their dark matter (DM) content, their tidal heating by the Galactic disc and halo, describe their metallicities and the likelihood that Newtonian dynamics explains their kinematics. We analyse a large number of members in all clusters, allowing us to address all these issues together, and we have included NGC 288 and M30 to overlap with previous studies. We find that any flattening of the velocity dispersion profiles in the outer regions of our clusters can be explained by tidal heating. We also find that all our GCs have M/LV≲ 5, therefore, we infer the observed dynamics do not require DM, or a modification of gravity. We suggest that the lack of tidal heating signatures in distant clusters indicates the halo is not triaxial. The isothermal rotations of each cluster are measured, with M4 and NGC 288 exhibiting rotation at a level of 0.9 ± 0.1 km s−1 and 0.25 ± 0.15 km s−1, respectively. We also indirectly measure the tidal radius of NGC 6752, determining a more realistic figure for this cluster than current literature values. Lastly, an unresolved and intriguing puzzle is uncovered with regard to the cooling of the outer regions of all ten clusters.

We studied the brightness and spectral evolution of the young eruptive star V1647 Ori during its recent outburst in the period 2004 FebruaryY2006 September. We performed a photometric follow-up in the bands V, R C , I C , J, H, and K s , as well as visible and near-IR spectroscopy. The main results derived from combining our data with those published by other authors are as follows: the brightness of V1647 Ori stayed more than 4 mag above the preoutburst level until 2005 October, when it started a rapid fading. In the high state we found a periodic component in the optical light curves with a period of 56 days. The delay between variations of the star and variations in the brightness of clumps of nearby nebulosity corresponds to an angle of 61 AE 14 between the axis of the nebula and the line of sight. The overall appearance of the infrared and optical spectra did not change in the period 2004 MarchY2005 March, although a steady decrease of H i emission-line fluxes could be observed. In 2006 May, in the quiescent phase, the He i 1.083 m line was observed in emission, contrary to its deep blueshifted absorption observed during the outburst. The J À H and H À K s color maps of the infrared nebula reveal an envelope around the star whose largest extension is about 18 00 (0.03 pc). The color distribution of the infrared nebula suggests reddening of the scattered light inside a thick circumstellar disk. Comparison of the K s and H images of McNeil's Nebula, the conical nebulosity illuminated by V1647 Ori, shows that HH 22A, the Spitzer infrared source, and the bright clump C of the nebula may be unrelated objects. We show that the observed properties of V1647 Ori could be interpreted in the framework of the thermal instability models of Bell and coworkers. V1647 Ori might belong to a new class of young eruptive stars, defined by relatively short timescales, recurrent outbursts, a modest increase in bolometric luminosity and accretion rate, and an evolutionary state earlier than that of typical EXors.

Globular clusters (GCs) are an important test bed for Newtonian gravity in the weak‐acceleration regime, which is vital to our understanding of the nature of the gravitational interaction. Recent claims have been made that the velocity dispersion profiles of GCs flatten out at large radii, despite an apparent paucity of dark matter (DM) in such objects, indicating the need for a modification of gravitational theories. We continue our investigation of this claim, with the largest spectral samples ever obtained of 47 Tucanae (47 Tuc) and M55. Furthermore, this large sample allows for an accurate metallicity calibration based on the equivalent widths of the calcium triplet lines and K‐band magnitude of the Tip of the Red Giant Branch. Assuming an isothermal distribution, the rotations of each cluster are also measured with both clusters exhibiting clear rotation signatures. The global velocity dispersions of NGC 121 and Kron 3, two GCs in the Small Magellanic Cloud, are also calculated. By applying a simple dynamical model to the velocity dispersion profiles of 47 Tuc and M55, we calculate their mass‐to‐light profiles, total masses and central velocity dispersions. We find no statistically significant flattening of the velocity dispersion at large radii for M55, and a marked increase in the profile of 47 Tuc for radii greater than approximately half the tidal radius. We interpret this increase as an evaporation signature, indicating that 47 Tuc is undergoing, or has undergone, core‐collapse, but find no requirement for DM or a modification of gravitational theories in either cluster.