Context. M31N 2015-01a (or M31LRN 2015) is a red nova that erupted in January 2015 - the first event of this kind observed in M 31 since 1988. Very few similar events have been confirmed as of 2015. Most of them are considered to be products of stellar mergers. Aims: Results of an extensive optical monitoring of the transient in the period January

Aims: We observed the τ Boo system with the HARPS-N spectrograph to test a new observational strategy aimed at jointly studying asteroseismology, the planetary orbit, and star-planet magnetic interaction. Methods: We collected high-cadence observations on 11 nearly consecutive nights and for each night averaged the raw FITS files using a dedicated

We present results from 13 cosmological simulations that explore the parameter space of the `Evolution and Assembly of GaLaxies and their Environments' (EAGLE) simulation project. Four of the simulations follow the evolution of a periodic cube L = 50 cMpc on a side, and each employs a different subgrid model of the energetic feedback associated

Using the ARO KP 12 m telescope, we have carried out a CO(1–0) and 13CO(1–0) survey of the central regions of 113 “normal” spiral galaxies (i.e., unperturbed and with little or no nuclear activity). Our sample spans the whole range of morphological types (T = 1–7), with distances up to 75 Mpc. The detection rates for the observed objects are 99.1%

The fitting of radial velocity curves is a frequent procedure in binary star and exoplanet research. In the majority of cases, the fitting routines need to be fed with a set of initial parameter values and priors from which to begin the computations and their results can be affected by local minima. We present a new code, the rvfit code, for

Context. Massive stars burn hydrogen through the CNO cycle during most of their evolution. When mixing is efficient or when mass transfer in binary systems occurs, chemically processed material is observed at the surface of O and B stars. Aims: ON stars show stronger lines of nitrogen than morphologically normal counterparts. Whether this