A survey of HDCO and D2CO towards Class 0/I proto-brown dwarfs
نویسندگان
چکیده
ABSTRACT Deuterium fractionation can constrain the physical and chemical conditions at early stage of brown dwarf formation. We present IRAM 30-m observations over a wide frequency range 213–279 GHz singly doubly deuterated species formaldehyde (HDCO D2CO) towards Class 0/I proto-brown dwarfs (proto-BDs). Multiple low-excitation HDCO D2CO transition lines with upper energy level ?40 K are detected. The D2CO/HDCO, HDCO/H2CO, D2CO/H2CO abundance ratios between 0.01 2.5 for proto-BDs, similar to seen in low-mass protostars. highest D2CO/HDCO ?1.3–2.5 measured two Stage 0 proto-BDs. These objects could possess warm corino, few hot corino cases reported among mean D2CO/H2CO, HDCO/H2CO proto-BDs comparatively higher than predicted by current gas-grain models, indicating that formed via grain surface reactions dense cold interiors an formation stage.
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2022
ISSN: ['0035-8711', '1365-8711', '1365-2966']
DOI: https://doi.org/10.1093/mnras/stac1573