Can we observe the ion-neutral drift velocity in prestellar cores?

Aris Tritsis*, Shantanu Basu, Christoph Federrath

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    7 Citations (Scopus)

    Abstract

    Given the low-ionization fraction of molecular clouds, ambipolar diffusion is thought to be an integral process in star formation. However, chemical and radiative-transfer effects, observational challenges, and the fact that the ion-neutral drift velocity is inherently very small render a definite detection of ambipolar diffusion extremely non-trivial. Here, we study the ion-neutral drift velocity in a suite of chemodynamical, non-ideal magnetohydrodynamic (MHD), two-dimensional axisymmetric simulations of prestellar cores where we alter the temperature, cosmic-ray ionization rate, visual extinction, mass-to-flux ratio, and chemical evolution. Subsequently, we perform a number of non-local thermodynamic equilibrium (non-LTE) radiative-transfer calculations considering various idealized and non-idealized scenarios in order to assess which factor (chemistry, radiative transfer, and/or observational difficulties) is the most challenging to overcome in our efforts to detect the ion-neutral drift velocity. We find that temperature has a significant effect in the amplitude of the drift velocity with the coldest modelled cores (T = 6 K) exhibiting drift velocities comparable to the sound speed. Against expectations, we find that in idealized scenarios (where two species are perfectly chemically co-evolving) the drift velocity 'survives' radiative-transfer effects and can in principle be observed. However, we find that observational challenges and chemical effects can significantly hinder our view of the ion-neutral drift velocity. Finally, we propose that $rm HCN$ and $rm HCNH^+$, being chemically co-evolving, could be used in future observational studies aiming to measure the ion-neutral drift velocity.

    Original languageEnglish
    Pages (from-to)5087-5099
    Number of pages13
    JournalMonthly Notices of the Royal Astronomical Society
    Volume521
    Issue number4
    DOIs
    Publication statusPublished - 1 Jun 2023

    Fingerprint

    Dive into the research topics of 'Can we observe the ion-neutral drift velocity in prestellar cores?'. Together they form a unique fingerprint.

    Cite this