Astrochemistry as a Tool To Follow Protostellar Evolution: The Class I Stage

Bianchi, E.; Ceccarelli, C.; Codella, C.; Enrique-Romero, Joan; Favre, Cécile; Leflóch, B.

doi:10.1021/acsearthspacechem.9b00158

Cited by 23 publications

(40 citation statements)

References 169 publications

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“…Recently, DC 3 N has been detected in some low-mass cores (see e.g., Refs. [9], [15]) and in a sample of 15 highmass star-forming cores [16]. The latter work, based on the spectroscopic results presented in this paper, suggests that DC 3 N is enhanced in the cold and outer regions of star-forming regions, likely indicating the initial deuteration level of the large-scale molecular cloud within which star formation takes place.…”

Section: Introductionmentioning

confidence: 56%

Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC3N) from millimeter-wavelengths to the infrared domain

Melosso

Bizzocchi

Adamczyk

et al. 2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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Cyanoacetylene, the simplest cyanopolyyne, is an abundant interstellar molecule commonly observed in a vast variety of astronomical sources. Despite its importance as a potential tracer of the evolution of starforming processes, the deuterated form of cyanoacetylene is less observed and less studied in the laboratory than the main isotopologue. Here, we report the most extensive spectroscopic characterization of DC 3 N to date, from the millimeter domain to the infrared region. Rotational and ro-vibrational spectra have been recorded using millimeter-wave frequency-modulation and Fourier-transform infrared spectrometers, respectively. All the vibrational states with energy up to 1015 cm −1 have been analyzed in a combined fit, where the effects due to anharmonic resonances have been adequately accounted for. The analysis contains over 6500 distinct transition frequencies, from which all the vibrational energies have been determined with good precision for many fundamental, overtone, and combination states. This work provides a comprehensive line catalog for astronomical observations of DC 3 N.

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Section: Introductionmentioning

confidence: 56%

Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC3N) from millimeter-wavelengths to the infrared domain

Melosso

Bizzocchi

Adamczyk

et al. 2020

Journal of Quantitative Spectroscopy and Radiative Transfer

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“…By studying the prototypical Class I protostars, SVS13-A, Bianchi et al (2017aBianchi et al ( , 2019a reported a decrease of deuteration of methanol, thioformaldehyde, and formaldehyde with respect to what is found towards Class 0 objects. With the results obtained for the four Class I sources in our sample, we can verify what is found in SVS13-A.…”

Section: Deuterium Fractionationmentioning

confidence: 95%

“…Class I protostars, with a typical age of 10 5 yr are a bridge between Class 0 protostars (∼10 4 yr), where the bulk of the material that forms the protostar is still in the envelope and the Class II protoplanetary disks (10 6 yr). Class I sources have recently begun to be chemically characterized through spectral surveys at millimeter wavelengths to search for interstellar complex organic molecules, small organics and deuterated species (Öberg et al 2014;Bergner et al 2017;Bianchi et al 2017a;Bergner et al 2019;Bianchi et al 2019aBianchi et al , 2020Le Gal et al 2020). Therefore, we are still far from concluding whether Class I protostars are also a bridge from a chemical point of view.…”

Section: Introductionmentioning

confidence: 99%

“…In this perspective, several prestellar cores and Class 0 protostars are studied by focusing on deuterium fractionations of H 2 CO, H 2 CS, and CH 3 OH (e.g., Bacmann et al 2003;Marcelino et al 2005;Bizzocchi et al 2014;Vastel et al 2018;Parise et al 2006;Bianchi et al 2017b;Drozdovskaya et al 2018;Manigand et al 2020, and references therein). On the other hand, there is only one Class I protostar for which the deuterium fractionation of these species was measured, SVS13-A (Bianchi et al 2017a(Bianchi et al , 2019a.…”

Section: Introductionmentioning

confidence: 99%

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Chemical survey of Class I protostars with the IRAM-30m

Mercimek,

Codella,

Podio

et al. 2021

Preprint

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Context. Class I protostars are a bridge between Class 0 protostars (≤ 10 5 yr old), and Class II (≥ 10 6 yr) protoplanetary disks. Recent studies show gaps and rings in the dust distribution of disks younger than 1 Myr, suggesting that planet formation may start already at the Class I stage. To understand what chemistry planets will inherit, it is crucial to characterize the chemistry of Class I sources and to investigate how chemical complexity evolves from Class 0 protostars to protoplanetary disks. Aims. The goal is twofold: (i) to obtain a census of the molecular complexity in a sample of four Class I protostars, and (ii) to compare it with the chemical compositions of earlier and later phases of the Sun-like star formation process. Methods. We performed IRAM-30 m observations at 1.3 mm towards 4 Class I objects (L1489-IRS, B5-IRS1, L1455-IRS1, and L1551-IRS5). The column densities of the detected species are derived assuming Local Thermodynamic Equilibrium (LTE) or Large Velocity Gradient (LVG). Results. We detected 27 species: C-chains, N-bearing species, S-bearing species, Si-bearing species, deuterated molecules, and interstellar Complex Organic Molecules (iCOMs; CH 3 OH, CH 3 CN, CH 3 CHO, and HCOOCH 3 ). Among the observed sample, L1551-IRS5 is the most chemically rich source. Different spectral profiles are observed: (i) narrow (∼1 km s −1 ) lines towards all the sources, (ii) broader (∼4 km s −1 ) lines towards L1551-IRS5, and (iii) line wings due to outflows (in B5-IRS1, L1455-IRS1, and L1551-IRS5). Narrow c-C 3 H 2 emission originates from the envelope with temperatures of 5 -25 K and sizes of ∼ 2 − 10 . The iCOMs in L1551-IRS5 reveal the occurrence of hot corino chemistry, with CH 3 OH and CH 3 CN lines originating from a compact (∼ 0 . 15) and warm (T > 50 K) region. Finally, OCS and H 2 S seem to probe the circumbinary disks in the L1455-IRS1 and L1551-IRS5 binary systems. The deuteration in terms of elemental D/H in the molecular envelopes is: ∼ 10 − 70% (D 2 CO/H 2 CO), ∼ 5 − 15% (HDCS/H 2 CS), and ∼ 1 − 23% (CH 2 DOH/CH 3 OH). For the L1551-IRS5 hot corino, we derive D/H ∼ 2% (CH 2 DOH/CH 3 OH). Conclusions. Carbon chain chemistry in extended envelopes is revealed towards all the sources. In addition, B5-IRS1, L1455-IRS1 and L1551-IRS5 show a low excitation methanol line which is narrow and centered at systemic velocity, suggesting an origin from an extended structure, plausibly UV illuminated. The abundance ratios of CH 3 CN, CH 3 CHO, and HCOOCH 3 with respect CH 3 OH measured towards the L1551-IRS5 hot corino are comparable to that estimated at earlier stages (prestellar cores, Class 0 protostars), as well as to that found in comets. The deuteration in our sample is also consistent with the values estimated for sources at earlier stages. These findings support the inheritance scenario from prestellar cores to the Class I phase when planets start forming.

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“…This in turn stresses the importance of investigating Class I objects, a sort of bridge between the prototellar phase and the protoplanetary disks around Class II young objects. Several projects focused on the chemical complexity of Class I objects have been recently performed, mainly focusing the attention on interstellar small or complex (with at least 6 atom) organic molecules and/or deuteration using both singledishes and interferometer (see e.g., Öberg et al 2014;Bianchi et al 2017;Bergner et al 2017Bergner et al , 2019Bianchi et al 2019aBianchi et al ,b, 2020Le Gal et al 2020;Yang et al 2021).…”

Section: Introductionmentioning

confidence: 99%

The SVS13-A Class I chemical complexity as revealed by S-bearing species. SOLIS XIII

Codella,

Bianchi,

Podio

et al. 2021

Preprint

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Context. Recent results in astrochemistry revealed that some molecules such as interstellar complex organic species and deuterated species represent precious tools to investigate star forming regions. Sulphuretted species can also be used to follow the chemical evolution of the early stages of the Sun-like star forming process. Aims. The goal is to obtain a census of S-bearing species using interferometric images, towards SVS13-A, a Class I object associated with a hot corino rich in interstellar complex organic molecules. Methods. To this end, we used the NGC1333 SVS13-A data at3mm and 1.4mm obtained with the IRAM-NOEMA interferometer in the framework of the Large Program SOLIS. The line emission of S-bearing species has been imaged and analysed using LTE and LVG approaches. Results. We imaged the spatial distribution on ≤ 300 au scale of the line emission of 32 SO, 34 SO, C 32 S, C 34 S, C 33 S, OCS, H 2 C 32 S, H 2 C 34 S, and NS. The low excitation (9 K) 32 SO line is tracing (i) the low-velocity SVS13-A outflow and (ii) the fast (up to 100 km s −1 away from the systemic velocity) collimated jet driven by the nearby SVS13-B Class 0 object. Conversely, the rest of the lines are confined in the inner SVS13-A region, where complex organics have been previously imaged. More specifically the non-LTE LVG analysis of SO, SO 2 , and H 2 CS indicates a hot corino origin (size in the 60-120 au range). Temperatures between 50 K and 300 K, and volume densities larger than 10 5 cm −3 have been derived. The abundances of the sulphuretted are in the following ranges: 0.3-6 × 10 −6 (CS), 7 × 10 −9 -1 × 10 −7 (SO), 1-10 × 10 −7 (SO 2 ), a few 10 −10 (H 2 CS and OCS), and 10 −10 -10 −9 (NS). The N(NS)/N(NS + ) ratio is larger than 10, supporting that the NS + ion is mainly formed in the extended envelope. Conclusions. The [H 2 CS]/[H 2 CO] ratio, once measured at high-spatial resolutions, increases with time (from Class 0 to Class II objects) by more than one order of magnitude (from ≤ 10 −2 to a few 10 −1 ). This suggests that [S]/[O] changes along the Sun-like star forming process. Finally, the estimate of the [S]/[H] budget in SVS13-A is 2%-17% of the Solar System value (1.8 × 10 −5 ), being consistent with what was previously measured towards Class 0 objects (1%-8%). This supports that the enrichment of the sulphuretted species with respect to dark clouds keeps constant from the Class 0 to the Class I stages of low-mass star formation. The present findings stress the importance of investigating the chemistry of star forming regions using large observational surveys as well as sampling regions on a Solar System scale.

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Astrochemistry as a Tool To Follow Protostellar Evolution: The Class I Stage

Cited by 23 publications

References 169 publications

Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC3N) from millimeter-wavelengths to the infrared domain

Extensive ro-vibrational analysis of deuterated-cyanoacetylene (DC3N) from millimeter-wavelengths to the infrared domain

Chemical survey of Class I protostars with the IRAM-30m

The SVS13-A Class I chemical complexity as revealed by S-bearing species. SOLIS XIII

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