NEATH

• Verfasst von: Priestley, Felix [VerfasserIn]
• Verfasst von: Clark, P C [VerfasserIn]
• Verfasst von: Glover, Simon [VerfasserIn]
• Verfasst von: Ragan, S E [VerfasserIn]
• Verfasst von: Fehér, O [VerfasserIn]
• Verfasst von: Prole, L R [VerfasserIn]
• Verfasst von: Klessen, Ralf S. [VerfasserIn]
• Titel: NEATH
• Titelzusatz: II. N2H+ as a tracer of imminent star formation in quiescent high-density gas
• Verf.angabe: F.D. Priestley, P.C. Clark, S.C.O. Glover, S.E. Ragan, O. Fehér, L.R. Prole and R.S. Klessen
• E-Jahr: 2023
• Jahr: December 2023
• Umfang: 9 S.
• Illustrationen: Illustrationen
• Fussnoten: Im Text ist "2" tiefgestellt und "+" hochgestellt ; Gesehen am 09.02.2024 ; Veröffentlicht: 10. Oktober 2023
• Titel Quelle: Enthalten in: Royal Astronomical SocietyMonthly notices of the Royal Astronomical Society
• Ort Quelle: Oxford : Oxford Univ. Press, 1827
• Jahr Quelle: 2023
• Band/Heft Quelle: 526(2023), 4 vom: Dez., Seite 4952-4960
• ISSN Quelle: 1365-2966
• DOI: doi:10.1093/mnras/stad3089
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1880425114

Abstract

Star formation activity in molecular clouds is often found to be correlated with the amount of material above a column density threshold of ∼1022 cm−2⁠. Attempts to connect this column density threshold to a volume density above which star formation can occur are limited by the fact that the volume density of gas is difficult to reliably measure from observations. We post-process hydrodynamical simulations of molecular clouds with a time-dependent chemical network, and investigate the connection between commonly observed molecular species and star formation activity. We find that many molecules widely assumed to specifically trace the dense, star-forming component of molecular clouds (e.g. HCN, HCO+, CS) actually also exist in substantial quantities in material only transiently enhanced in density, which will eventually return to a more diffuse state without forming any stars. By contrast, N2H+ only exists in detectable quantities above a volume density of ⁠, the point at which CO, which reacts destructively with N2H+, begins to deplete out of the gas phase on to grain surfaces. This density threshold for detectable quantities of N2H+ corresponds very closely to the volume density at which gas becomes irreversibly gravitationally bound in the simulations: the material traced by N2H+ never reverts to lower densities, and quiescent regions of molecular clouds with visible N2H+ emission are destined to eventually form stars. The N2H+ line intensity is likely to directly correlate with the star formation rate averaged over time-scales of around a Myr.