The complex organic molecular content in the L1517B starless core

Abstract

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$5000 au from the core's centre). Our observations reveal that a lower number of COMs and COM precursors are detected in L1517B with respect to L1498 and L1544, and also show lower abundances. Besides methanol, we only detected CH${}_3$O, H${}_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.

17 pages, 13 figures

References in corpus (43)

• A computer program for fast non-LTE analysis of interstellar line spectra
• Complex Chemistry in Star-Forming Regions: An Expanded Gas-Grain Warm-up Chemical Model
• The Cologne Database for Molecular Spectroscopy, CDMS, in the Virtual Atomic and Molecular Data Centre, VAMDC
• Non-thermal desorption from interstellar dust grains via exothermic surface reactions
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• Probing the evolutionary status of starless cores through N2H+ and N2D+ observations
• Polycylcic Aromatic Hydrocarbons (PAH's) in dense cloud chemistry
• Formation of complex organic molecules in cold objects: the role of gas phase reactions
• Reactive Desorption and Radiative Association as Possible Drivers of Complex Molecule Formation in the Cold Interstellar Medium
• Reaction Networks For Interstellar Chemical Modelling: Improvements and Challenges
• The origin of complex organic molecules in prestellar cores
• Complex molecules in the hot core of the low mass protostar NGC1333-IRAS4A
• Formation of Complex Molecules in Prestellar Cores: a Multilayer Approach
• The Spatial Distribution of Complex Organic Molecules in the L1544 Pre-stellar Core
• On the internal structure of starless cores. II. A molecular survey of L1498 and L1517B
• A cold complex chemistry toward the low-mass protostar B1-b: evidence for complex molecule production in ices
• Molecular ions in L1544. I. Kinematics
• Discovery of Interstellar Propylene (CH_2CHCH_3): Missing Links in Interstellar Gas-Phase Chemistry
• Formation of Complex Organic Molecules in Cold Interstellar Environments through non-diffusive grain-surface and ice-mantle chemistry
• Structure and kinematics of the Taurus star-forming region from Gaia-DR2 and VLBI astrometry
• Spectral Line Identification and Modelling (SLIM) in the MAdrid Data CUBe Analysis (MADCUBA) package: An interactive software for data cube analysis
• A recent accretion burst in the low-mass protostar IRAS 15398-3359: ALMA imaging of its related chemistry
• Deuterated methanol in the pre-stellar core L1544
• Chemical differentiation in a prestellar core traces non-uniform illumination
• The Deuterium Fractionation Timescale in Dense Cloud Cores: A Parameter Space Exploration
• Prevalence of Complex Organic Molecules in Starless and Prestellar Cores within the Taurus Molecular Cloud
• Estimation and reduction of the uncertainties in chemical models: Application to hot core chemistry
• The Central 1000 au of a Pre-stellar Core Revealed with ALMA. II. Almost Complete Freeze-out
• High sensitivity maps of molecular ions in L1544: I. Deuteration of N2H+ and HCO+ and first evidence of N2D+ depletion
• L1521E: the first starless core with no molecular depletion
• Molecules with ALMA at Planet-forming Scales (MAPS). IX. Distribution and Properties of the Large Organic Molecules HC${}_3$N, CH${}_3$CN, and $c$-C${}_3$H${}_2$
• Complex Organic Molecules Towards Embedded Low-Mass Protostars
• Collisional excitation of HC3N by para- and ortho-H2
• On the Influence of Uncertainties in Chemical Reaction Rates on Results of the Astrochemical Modelling
• The cosmic-ray ionisation rate in the pre-stellar core L1544
• The complex organic molecular content in the L1498 starless core
• Detection of Complex Organic Molecules in Young Starless Core L1521E
• Molecular composition of comet 46P/Wirtanen from millimetre-wave spectroscopy
• The chemical structure of the very young starless core L1521E
• Observations of CH${}_3$OH and CH${}_3$CHO in a Sample of Protostellar Outflow Sources
• Methanol Mapping in Cold Cores: Testing Model Predictions
• A Revised Description of the Cosmic Ray-Induced Desorption of Interstellar Ices
• A radical route to interstellar propylene formation

Cited by in corpus (15)

• Discovery of the elusive carbonic acid (HOCOOH) in space
• Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
• Conformational isomerism of methyl formate: new detections of the higher-energy trans conformer and theoretical insights
• Interstellar Chemistry of CN Radicals on Ices: The formation of CH3CN and CH3NC and potential connection to acetamide
• Non-Equilibrium Abundances Treated Holistically (NEATH): the molecular composition of star-forming clouds
• Identification of hot gas around low-mass protostars
• Nascent chemical complexity in prestellar core IRAS 16293E: complex organics and deuterated methanol
• Hydrogenation of acetaldehyde on interstellar ice analogs reveals limited destruction
• First Detections of PN, PO, and PO+ toward a Shocked Low-mass Starless Core
• Hunting pre-stellar cores with APEX: overview
• Chemical complexity in star formation induced by stellar feedback: cores shock-formed by the supernova remnant W44
• A fast machine learning tool to predict the composition of astronomical ices from infrared absorption spectra
• Post-Outburst Chemistry in a Very Low-Luminosity Object: Peculiar High Abundance of Nitric Oxide
• Digging into the Massive Protostar S255IR NIRS3: A Study of Nitrogen-Bearing Molecules and Their Prebiotic Chemistry
• c-C3H2 deuteration towards prestellar and starless cores in the Perseus Molecular Cloud