We use a sample of 154 observations of 124 H II regions that have measurements of both T e[O III] and T e[N II], compiled from the literature, to explore the behaviour of the T e[O III]-T e[N II] temperature relation. We confirm that the relation depends on the degree of ionization and present a new set of relations for two different ranges of this

We present the final Sloan Digital Sky Survey IV (SDSS-IV) quasar catalog from Data Release 16 of the extended Baryon Oscillation Spectroscopic Survey (eBOSS). This catalog comprises the largest selection of spectroscopically confirmed quasars to date. The full catalog includes two subcatalogs (the current versions are DR16Q_v4 and DR16Q_Superset

We present an optical analysis of 55 members of R136, the central cluster in the Tarantula Nebula of the Large Magellanic Cloud. Our sample was observed with STIS aboard the Hubble Space Telescope, is complete down to about 40 M ☉, and includes seven very massive stars with masses over 100 M ☉. We performed a spectroscopic analysis to derive their

We present a detailed study of the binary central star of the planetary nebula ETHOS 1 (PN G068.1+11.0). Simultaneous modelling of light and radial velocity curves reveals the binary to comprise a hot and massive pre-white dwarf with an M-type main-sequence companion. A good fit to the observations was found with a companion that follows expected

Introduction: The Solar System group of the Instituto de Astrofisica de Canarias (IAC) is member of a consortium of astronomical observatories leaded by Deimos Space S.L.U, that presented a proposal to the ESA ITT no. AO/1-9591/18/D/MR "P3-NEO-I - Observational support from collaborating observatories". The objective of this project is to provide

We report the discovery of a warm Neptune and a hot sub-Neptune transiting TOI-421 (BD-14 1137, TIC 94986319), a bright (V = 9.9) G9 dwarf star in a visual binary system observed by the Transiting Exoplanet Survey Satellite (TESS) space mission in Sectors 5 and 6. We performed ground-based follow-up observations—comprised of Las Cumbres Observatory