Implementation of rare isotopologues into machine learning of the chemical inventory of the solar-type protostellar source IRAS 16293-2422

Fried, Zachary T. P.; Lee, Kelvin; Byrne, Alex; McGuire, Brett A.

doi:10.1039/d3dd00020f

“…Hence, quantum chemistry will long have a place in astrochemistry especially as the accuracy of the methods and sizes of the molecules studied to such accuracies increase. While modern techniques like machine learning may have impacts in various areas of astrochemistry, − the future of such methods remains to be seen. It will likely be utilized in conjunction with existing quantum chemical techniques to push the generation of astrochemical reference data in new and beneficial directions.…”

Section: Discussionmentioning

confidence: 99%

Quantum Chemistry and Astrochemistry: A Match Made in the Heavens

Fortenberry

2024

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Quantum chemistry can uniquely answer astrochemical questions that no other technique can provide. Computations can be parallelized, automated, and left to run continuously providing exceptional molecular throughput that cannot be done through experimentation. Additionally, the granularity of the individual computations that are required of potential energy surfaces, reaction mechanism pathways, or other quantum chemically derived observables produces a unique mosaic that make up the larger whole. These pieces can be dissected for their individual contributions or evaluated in an ad hoc fashion for each of their roles in generating the larger whole. No other scientific approach is capable of reporting such fine-grained insights. Quantum chemistry also works from a bottom-up approach in providing properties directly from the desired molecule instead of a top-down perspective as required of experiment where molecules have to be linked to observed phenomena. Furthermore, modern quantum chemistry is well within the range of "chemical accuracy" and is approaching "spectroscopic accuracy." As such, the seemingly difficult questions asked by astrochemistry that would not be asked initially for any other application require quantum chemical reference data. While the results of quantum chemical computations are needed to interpret astrochemical observation, modeling, or laboratory experimentation, such hard questions, regardless of the original need to answer them, produce unique solutions. While questions in astrochemistry often require novel developments in and implementations of quantum chemistry as outlined herein, the applications of these solutions will stretch beyond astrochemistry and may yet impact fields much closer to Earth.

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“…ML techniques have been brought to bear on modeling such environments in the case of protostars. Novel molecular targets have now been predicted in reaction networks providing impetus for subsequent observation . Additionally, ML has shown that it competes with traditional modeling needed to provide column densities (and, hence, emission peak heights) in the detection of C 10 H – , the first interstellar anion observed in more than a dozen years. , …”

Section: The 2050 Horizonmentioning

confidence: 99%

“…Novel molecular targets have now been predicted in reaction networks providing impetus for subsequent observation. 69 Additionally, ML has shown that it competes with traditional modeling needed to provide column densities (and, hence, emission peak heights) in the detection of C 10 H − , the first interstellar anion observed in more than a dozen years. 70,71 As such, the ML appears to be on the cusp of securing a place in how chemical reaction networks are processed.…”

Section: Modeling By 2050mentioning

confidence: 99%

A Vision for the Future of Astrochemistry in the Interstellar Medium by 2050

Fortenberry

2023

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By 2050, many, but not nearly all, unattributed astronomical spectral features will be conclusively linked to molecular carriers (as opposed to nearly none today in the visible and IR); amino acids will have been observed remotely beyond our solar system; the largest observatories ever constructed on the surface of the Earth or launched beyond it will be operational; high-throughput computation either from brute force or machine learning will provide unprecedented amounts of reference spectral and chemical reaction data; and the chemical fingerprints of the universe delivered by those of us who call ourselves astrochemists will provide astrophysicists with unprecedented resolution for determining how the stars evolve, planets form, and molecules that lead to life originate. Astrochemistry is a relatively young field, but with the entire universe as its playground, the discipline promises to persist as long as telescopic observations are made that require reference data and complementary chemical modeling. While the recent commissionings of the James Webb Space Telescope and Atacama Large Millimeter Array are ushering in the second "golden age" of astrochemistry (with the first being the radio telescopic boom period of the 1970s), this current period of discovery should facilitate unprecedented advances within the next 25 years. Astrochemistry forces the asking of hard questions beyond the physical conditions of our "pale blue dot", and such questions require creative solutions that are influential beyond astrophysics. By 2050, more creative solutions will have been provided, but even more will be needed to answer the continuing question of our astrochemical ignorance.

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“…Recently, as an attempt to predict strong molecular candidates for detection in the Class 0 protostellar source IRAS 16293 −2422B (hereafter referred to as IRAS 16293B), Fried et al (2023) trained a machine-learning model to map the molecular identities of the detected species to their observed column densities. The trained regressors could then be used to predict the column density of any other molecule in this region of interstellar space.…”

Section: Introductionmentioning

confidence: 99%

“…The rotational spectrum of this molecule has not been measured beyond ∼40 GHz. This, however, is necessary for observations in the star-forming regions, where Fried et al (2023) and others predict potential detection, as at the warmer excitation temperatures (ranging to several hundred kelvin in these sources) the strongest transitions of these species arise in the millimeter and submillimeter regimes.…”

Section: Introductionmentioning

confidence: 99%

Rotational Spectrum and First Interstellar Detection of 2-methoxyethanol Using ALMA Observations of NGC 6334I

Fried,

El-Abd,

Hays

et al. 2024

ApJL

Self Cite

2

0

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We use both chirped-pulse Fourier transform and frequency-modulated absorption spectroscopy to study the rotational spectrum of 2-methoxyethanol (CH3OCH2CH2OH) in several frequency regions ranging from 8.7 to 500 GHz. The resulting rotational parameters permitted a search for this molecule in Atacama Large Millimeter/submillimeter Array (ALMA) observations toward the massive protocluster NGC 6334I, as well as source B of the low-mass protostellar system IRAS 16293−2422. A total of 25 rotational transitions are observed in the ALMA Band 4 data toward NGC 6334I, resulting in the first interstellar detection of 2-methoxyethanol. A column density of 1.3 − 0.9 + 1.4 × 10 17 cm−2 is derived at an excitation temperature of 143 − 39 + 31 K. However, molecular signal is not observed in the Band 7 data toward IRAS 16293−2422B, and an upper-limit column density of 2.5 × 1015 cm−2 is determined. Various possible formation pathways—including radical recombination and insertion reactions—are discussed. We also investigate physical differences between the two interstellar sources that could result in the observed abundance variations.

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Implementation of rare isotopologues into machine learning of the chemical inventory of the solar-type protostellar source IRAS 16293-2422

Abstract: Machine learning techniques have been previously used to model and predict column densities in the TMC-1 dark molecular cloud. In interstellar sources further along the path of star formation, such...

Cited by 4 publications

References 78 publications

Quantum Chemistry and Astrochemistry: A Match Made in the Heavens

Quantum Chemistry and Astrochemistry: A Match Made in the Heavens

A Vision for the Future of Astrochemistry in the Interstellar Medium by 2050

Rotational Spectrum and First Interstellar Detection of 2-methoxyethanol Using ALMA Observations of NGC 6334I

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