Isotopic ratios as probes of star formation and the origin of molecular gas in the Central Molecular Zone
Abstract
The Central Molecular Zone (CMZ) contains most of the dense molecular gas in the Milky Way but forms stars at a surprisingly low rate. Isotopic ratios provide a unique tool to investigate both the local physical conditions and the nucleosynthetic history of this gas. I summarize recent isotopic studies toward the molecular cloud G+0.693−0.027. Deuterium fractionation (D/H ratios) reveals a cold (Tkin≲30 K), relatively quiescent gas component embedded within the otherwise warm and turbulent CMZ, indicating that the earliest stages of star formation can survive in this extreme environment. I also present new 12C/13C measurements from HC3N and HC5N, including the first constraints from doubly substituted 13C isotopologues. After accounting for isotopic fractionation with astrochemical models, the inferred elemental ratio (∼37--48) exceeds the canonical CMZ assumed value (∼20), supporting a scenario in which the Galactic center is replenished by less chemically processed gas flowing inward along the Galactic bar.
Related
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BibTeX
@misc{colzi2026isotopic,
title = {{Isotopic ratios as probes of star formation and the origin of molecular gas in the Central Molecular Zone}},
author = {Laura Colzi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.11541},
eprint = {2610.11541},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.11541},
}
RIS
TY - UNPB
TI - Isotopic ratios as probes of star formation and the origin of molecular gas in the Central Molecular Zone
AU - Laura Colzi
PY - 2026
DA - 2026/10/08
PB - arXiv
DO - 10.48550/arxiv.2610.11541
UR - https://arxiv.org/abs/2610.11541
AB - The Central Molecular Zone (CMZ) contains most of the dense molecular gas in the Milky Way but forms stars at a surprisingly low rate. Isotopic ratios provide a unique tool to investigate both the local physical conditions and the nucleosynthetic history of this gas. I summarize recent isotopic studies toward the molecular cloud G+0.693−0.027. Deuterium fractionation (D/H ratios) reveals a cold (T_kin≲30 K), relatively quiescent gas component embedded within the otherwise warm and turbulent CMZ, indicating that the earliest stages of star formation can survive in this extreme environment. I also present new ^12C/^13C measurements from HC_3N and HC_5N, including the first constraints from doubly substituted ^13C isotopologues. After accounting for isotopic fractionation with astrochemical models, the inferred elemental ratio (∼37--48) exceeds the canonical CMZ assumed value (∼20), supporting a scenario in which the Galactic center is replenished by less chemically processed gas flowing inward along the Galactic bar.
ER -