The complex organic molecular content in the L1517B starless core by Andrés Megías et al. on Tuesday 29 November

Recent observations of the pre-stellar core L1544 and the younger starless

core L1498 have revealed that complex organic molecules (COMs) are enhanced in

the gas phase toward their outer and intermediate-density shells. Our goal is

to determine the level of chemical complexity toward the starless core L1517B,

which seems younger than L1498, and compare it with the other two previously

studied cores to see if there is a chemical evolution within the cores. We have

carried out 3 mm high-sensitivity observations toward two positions in the

L1517B starless core: the core's centre and the position where the methanol

emission peaks (at a distance of $\sim$5000 au from the core's centre). Our

observations reveal that a lower number of COMs and COM precursors are detected

in L1517B with respect to L1498 and L1544, and also show lower abundances.

Besides methanol, we only detected H$_2$CCO, CH$_3$CHO, CH$_3$CN, CH$_3$NC,

HCCCN, and HCCNC. Their measured abundances are $\sim$3 times larger toward the

methanol peak than toward the core's centre, mimicking the behaviour found

toward the more evolved cores L1544 and L1498. We propose that the differences

in the chemical complexity observed between the three studied starless cores

are a consequence of their evolution, with L1517B being the less evolved one,

followed by L1498 and L1544. Chemical complexity in these cores seems to

increase over time, with N-bearing molecules forming first and O-bearing COMs

forming at a later stage as a result of the catastrophic depletion of CO.

arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.16119v1