Within the Large Magellanic Cloud, a hot core is observed associated with the embedded high-mass YSO (IRAS 05195˗6911), known as ST16. Comparative observations with molecular abundances typical of Galactic hot cores are discussed, as is the evidence for a rotating protostellar envelope and outflow cavity. A second LMC source, the prominent star-formation region N113, shows centrally focused star formation with associated point-like mid-infrared emission, masers, and compact HII regions superimposed on extended emission. Gas and dust appear compressed by a complex structure of ionized gas bubbles (prominent in Hα detections) engendered by massive stars in several young clusters. In both ST16 and N113 low-metallicity sources, warm dust appears to inhibit COMs formation and survival, while reaction routes appear broadly comparable with Galactic models.

The opening chapter introduces the most significant areas of contemporary research in the molecular astronomy of star formation: prestellar cores, hot cores, hot corinos, accretion, protoplanetary disks, photodissociation regions (PDRs), HII regions, stellar jets, disk winds, outflows, and masers. These sit within the wider considerations of dense molecular clouds on many scales, from the giant molecular clouds (GMCs) to fragments, filaments, and clumps. Our understanding of these molecular cloud environments depends on our understanding of molecular excitation, energy balance, gas and grain surface reaction kinetics, cosmic ray ionization, and photochemistries. Chemical modelling involving both gas-phase and grain-surface reactions is described, as are the observational and analytical essentials of antenna temperature, optical depth, velocity distribution, column density, beam dilution, relative abundance, rotation diagrams, and radiative transfer modelling.

The chapter takes a detailed look at low-mass star formation towards IRAS 16293-2422, a warm core surrounding a binary source within the L1689 cloud of Ophiuchus. Prestellar cores are strung out in elongated filamentary structures of dense gas and dust. Sensitive temperature measurements distinguish prestellar cores from unbound starless cores. Towards the Class 0 protostar source in IRAS 16293 detailed views of the principal components associated with low-mass star formation are discussed, from dense cloud filaments to rotating accretion disk, bipolar outflows, and larger circumbinary envelopes. IRAS 16293 shows warm/hot corino chemistry (warm carbon chain chemistry, WCCC), illustrating the conditions in which the chemical signatures involving COMs help us to define the structure of disks and envelopes on scales of ~100-1,000 AU. Both COMs and deuterated species, particularly the ratios of deuterated species to their hydrgenated counterparts, trace gas and dust temperatures and densities, and compositionally dependent gas–grain interactions, through comparisons with chemical modelling.

The chapter presents two surveys of low-mass star formation regions (LMSFR). The first survey uses the IRAM (Institute for Radio Astronomy in the Millimeter Range) 30 metre telescope at Pico Veleta in Spain to identify 16 deeply embedded YSOs and the emission from eight complex organic molecules (COMs). The second survey uses ALMA (Atacama Large Millimetre Array) directed towards five low-mass candidates (all in the Serpens cluster at distances ~440 pc) and detected emission from five COMs species.