History of the solar-type protostar IRAS16293-2422 as told by the cyanopolyynes

Abstract

Cyanopolyynes are chains of carbon atoms with an atom of hydrogen and a CN group on either side. They are detected almost everywhere in the ISM, as well as in comets. In the past, they have been used to constrain the age of some molecular clouds, since their abundance is predicted to be a strong function of time. We present an extensive study of the cyanopolyynes distribution in the solar-type protostar IRAS16293-2422 based on TIMASSS IRAM-30m observations. The goals are (i) to obtain a census of the cyanopolyynes in this source and of their isotopologues; (ii) to derive how their abundance varies across the protostar envelope; and (iii) to obtain constraints on the history of IRAS16293-2422. We detect several lines from HC3N and HC5N, and report the first detection of DC3N, in a solar-type protostar. We found that the HC3N abundance is roughly constant (~1.3x10^(-11)) in the outer cold envelope of IRAS16293-2422, and it increases by about a factor 100 in the inner region where Tdust>80K. The HC5N has an abundance similar to HC3N in the outer envelope and about a factor of ten lower in the inner region. The HC3N abundance derived in the inner region, and where the increase occurs, also provide strong constraints on the time taken for the dust to warm up to 80K, which has to be shorter than ~10^3-10^4yr. Finally, the cyanoacetylene deuteration is about 50\% in the outer envelope and <5$\% in the warm inner region. The relatively low deuteration in the warm region suggests that we are witnessing a fossil of the HC3N abundantly formed in the tenuous phase of the pre-collapse and then frozen into the grain mantles at a later phase. The accurate analysis of the cyanopolyynes in IRAS16293-2422 unveils an important part of its past story. It tells us that IRAS16293-2422 underwent a relatively fast (<10^5yr) collapse and a very fast (<10^3-10^4yr) warming up of the cold material to 80K.

Accepted for publication in A&A

References in corpus (6)

• The 2014 KIDA network for interstellar chemistry
• First detection of triply-deuterated methanol
• On the abundance discrepancy problem in HII regions
• Rotational Excitation of HC_3N by H_2 and He at low temperatures
• The census of complex organic molecules in the solar type protostar IRAS16293-2422
• Non-Detection of HC${}_{11}$N toward TMC-1: Constraining the Chemistry of Large Carbon-Chain Molecules

Cited by in corpus (21)

• Seeds Of Life In Space (SOLIS): The organic composition diversity at 300--1000 au scale in Solar-type star forming regions
• The Perseus ALMA Chemistry Survey (PEACHES). I. The Complex Organic Molecules in Perseus Embedded Protostars
• Chemical modelling of complex organic molecules with peptide-like bonds in star-forming regions
• SOLIS II. Carbon-chain growth in the Solar-type protocluster OMC2-FIR4
• First detection of the pre-biotic molecule glycolonitrile (HOCH2CN) in the interstellar medium
• A cold accretion flow onto one component of a multiple protostellar system
• Chemical survey of Class I protostars with the IRAM-30m
• Successive deuteration in low-mass star-forming regions: the case of D${}_2$-methanol (CHD${}_2$OH) in IRAS 16293-2422
• A Detailed View of the Circumstellar Environment and Disk of the Forming O-star AFGL 4176
• Cyanopolyyne chemistry in the L1544 prestellar core: new insights from GBT observations
• Improved temperature dependence of rate coefficients for rotational state-to-state transitions in H${}_2$O + H${}_2$O collisions
• DC${}_3$N observations towards high-mass star-forming regions
• Neutral-Neutral Synthesis of Organic Molecules in Cometary Comae
• A Computational Study of the Reaction Cyanoacetylene and Cyano Radical leading to 2-Butynedinitrile and Hydrogen Radical
• Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC${}_3$N) from millimeter-wavelengths to the infrared domain
• Toward Unraveling Cyanopolyyne Surface Chemistry: A Preview on Isolated Systems From HC_{3}N to Ethyl Cyanide and Propylamine
• Identification of molecular line emission using Convolutional Neural Networks
• Long-Range Complex in the HC3N + CN Potential Energy Surface: Ab Initio Calculations and Intermolecular Potential
• Digging into the Massive Protostar S255IR NIRS3: A Study of Nitrogen-Bearing Molecules and Their Prebiotic Chemistry
• ATOMS: ALMA Three-millimeter Observations of Massive Star-forming regions -- X. Chemical differentiation among the massive cores in G9.62+0.19
• Carbon chain diversity in L1544 and IRAS 16293-2422: an astrochemical pathfinder study for the SKAO