HARPS-N, key to first insight into the chemical evolution of the Radcliffe wave

The Radcliffe wave is a recently discovered filamentary gas structure that encompasses most of the star-forming regions in the solar neighbourhood. Its spatial structure and kinematic properties have been studied in sufficient detail in the last years. However, no study has characterized it from a chemical point of view, to investigate its nature and the composition of the natal cloud that gave rise to it.

Now, for the first time since its discovery in 2020, a team of astronomers from INAF has conducted a pioneering chemical study of the Radcliffe wave. They used seven young open clusters, with ages between about 10 and 100 Myr and located at different positions along the wave, as tracers (ASCC 16, ASCC 19, NGC 2232, NGC 7058, Melotte 20, Pleiades and Roslund 6). After careful selection among the most likely members of each cluster, 53 stars, most of them slowly rotating FGK dwarfs, were observed with GIARPS@TNG (although in this research the authors only use HARPS-N spectra). Thanks to the high resolution and quality of the data, it was possible to first perform a detailed characterisation of each star individually and then that of the clusters that host them. The current study provides accurate stellar parameters, level of stellar activity, chemical abundances for 25 elements covering the main nucleosynthesis channels and cluster ages based on the lithium depletion. An eighth cluster, ASCC 123, previously studied by this team with the same instrument and methodology, was also included in the research to complete the sample.

With all these data in hand and others from the literature (age, XYZ Galactic coordinates, Galactocentric distance, etc), the authors investigated the existence of a possible link between the clusters and the Radcliffe Wave. They found moderate-to-strong correlations between the chemical composition of the clusters and their age or position along the wave, revealing a physical connection. One of the most important conclusions of this study is the existence of an age gradient across the Radcliffe wave, with older clusters closer to the Galactic centre, confirming the oscillating nature of the wave, which moves radially from the centre outwards. Furthermore, a positive trend was observed between age and metallicity, with younger clusters being metal-poorer respect to older ones. This fact would favour an inhomogeneous mixing or local chemical enrichment scenarios over the canonical triggered star formation within a large-star forming region.

"We are very pleased with the results obtained, they are very promising” explains Javier Alonso Santiago, the leading author of the paper, “but we are aware that our sample is small and more observations are still needed to confirm our findings. In any case, they are encouraging evidence to continue working in this direction."

Link to the paper

Distribution of the molecular clouds forming the Radcliffe Wave in the XY and ZY planes (grey circles). Rhe targets are represented with different colors depending on their age (left) and metallicity (right). See paper for more details.