English

Chemical differences among collapsing low-mass protostellar cores

Solar and Stellar Astrophysics 2023-12-13 v1 Astrophysics of Galaxies

Abstract

Organic features lead to two distinct types of Class 0/I low-mass protostars: hot corino sources, and warm carbon-chain chemistry (WCCC) sources. Some observations suggest that the chemical variations between WCCC sources and hot corino sources are associated with local environments, as well as the luminosity of protostars. We conducted gas-grain chemical simulation in collapsing protostellar cores, and found that the fiducial model predicts abundant carbon-chain molecules and COMs, and reproduces WCCC and hot corino chemistry in the hybrid source L483. By changing values of some physical parameters, including the visual extinction of ambient clouds (AVambA_{\rm V}^{\rm amb}), the cosmic-ray ionization rate (ζ\zeta), the maximum temperature during the warm-up phase (TmaxT_{\rm max}), and the contraction timescale of protostars (tcontt_{\rm cont}), we found that UV photons and cosmic rays can boost WCCC features by accelerating the dissociation of CO and CH4_4 molecules. On the other hand, UV photons can weaken the hot corino chemistry by photodissociation reactions, while the dependence of hot corino chemistry on cosmic rays is relatively complex. The TmaxT_{\rm max} does not affect WCCC features, while it can influence hot corino chemistry by changing the effective duration of two-body surface reactions for most COMs. The long tcontt_{\rm cont} can boost WCCC and hot corino chemistry, by prolonging the effective duration of WCCC reactions in the gas phase and surface formation reactions for COMs, respectively. Subsequently, we ran a model with different physical parameters to reproduce scarce COMs in prototypical WCCC sources. The scarcity of COMs in prototypical WCCC sources can be explained by insufficient dust temperature in the inner envelopes to activate hot corino chemistry. Meanwhile, the High ζ\zeta and the long tcontt_{\rm cont} favors the explanation for scarce COMs in these sources.

Keywords

Cite

@article{arxiv.2312.06959,
  title  = {Chemical differences among collapsing low-mass protostellar cores},
  author = {Jingfei Sun and Xiaohu Li and Fujun Du and Yao Wang and Juan Tuo and Yanan Feng},
  journal= {arXiv preprint arXiv:2312.06959},
  year   = {2023}
}

Comments

Accepted for publication in A&A, 18 pages, 10 figures

R2 v1 2026-06-28T13:47:56.813Z