Hunting pre-stellar cores with APEX: overview
Abstract
[Abridged] Context. Pre-stellar cores are centrally concentrated starless cores on the verge of star formation and they represent the initial conditions for star and planet formation. Pre-stellar cores host an active organic chemistry and isotopic fractionation, kept stored into thick icy mantles, which can be inherited by the future protoplanetary disks and planetesimals. So far, only a few have been studied in detail, with special attention being paid to L1544 in the Taurus Molecular Cloud. Aims. The aim is to identify nearby (<200 pc) pre-stellar cores in an unbiased way, to build a sample that can then be studied in detail. Methods. We first used the Herschel Gould Belt Survey archival data, selecting all those starless cores with central H2 number densities higher than or equal to 3×105 cm-3, the density of L1544 within the Herschel beam. The selected 40 (out of 1746) cores have then been observed in N2H+(3-2) and N2D+(4-3) using the APEX antenna. Results. A total of 17 bona-fide (i.e., with a deuterium fraction larger than 10%) pre-stellar cores have been identified. Other 16 objects can also be considered pre-stellar, as they are dynamically evolved starless cores, but their deuterium fraction is relatively low (<10%). The remaining 7 objects have been found associated with very young stellar objects. Conclusions. Dust continuum emission, together with spectroscopic observations of N2H+(3-2) and N2D+(4-3), is a powerful tool to identify pre-stellar cores in molecular clouds. Detailed modeling of the physical structure of the objects is now required for reconstructing the chemical composition as a function of radius. This work has provided a statistically significant sample of 33 pre-stellar cores, a crucial step in the understanding of the process of star and planet formation.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.