One of the main tools to understand the origin of our Solar system, of the Milky Way and also of external galaxies is to study isotopic ratios of elements like hydrogen (D/H), carbon (12C/13C), nitrogen (14N/15N), and oxygen (16O/17O, 16O/18O). Isotopic ratios can be probed by millimeter wavelength observations of molecules and their isotopologues, and their abundance ratios are governed by two main processes: (i) chemical evolution of the galaxy due to stellar nucleosynthesis; (ii) local chemical fractionation effects that, from the initial nucleosynthesis driven ratios, favor the rarer isotopic substitution over the most abundant molecular isotopologue, depending on the local physical conditions.

In the last two decades the number of studies focused on isotopic ratios has grown thanks to the unprecedented capabilities of current astronomical facilities. This growth is mainly due to the improved sensitivity of the instrumentation of the single-dish

 IRAM 30m, GBT 100m, and Yebes 40m telescopes, and of the interferometers IRAM NOEMA and ALMA. Moreover, near IR observations obtained with the VLT and JWST have recently allowed the first detection of 13CO and 15NH3 in the atmosphere of a young exoplanet and a brown dwarf, opening new clues on local fractionation effects in exoplanetary objects. 

The second edition of this conference aims to bring a multidisciplinary community together, covering topics that range from astronomical observations in different Galactic environments, to the Solar System, exoplanetary systems, and (extra)galactic molecular clouds, as well as laboratory works and theoretical astrochemical and stellar Galactic chemical evolution models. The meeting will also discuss future projects related to the topic and what are the best facilities, including under construction or future, that are best suited for them.

Specific science topics include

• Theoretical and Laboratory chemical studies (spectroscopy, fractionation processes)

• Fractionation in the Milky Way: molecular clouds and star-forming regions

• Galactic chemical evolution of isotopes and isotopic ratios

• Fractionation in Solar System objects and exoplanets