THz time-domain spectroscopy of mixed CO2–CH3OH interstellar ice analogs

The icy mantles of interstellar dust grains are the birthplaces of the primordial prebiotic molecular inventory that may eventually seed nascent solar systems and the planets and planetesimals that form therein. Here, we present a study of two of the most abundant species in these ices after water: carbon dioxide (CO2) and methanol (CH3OH), using TeraHertz (THz) time-domain spectroscopy and mid-infrared spectroscopy. We study pure and mixed-ices of these species, and demonstrate the power of the THz region of the spectrum to elucidate the long-range structure (i.e. crystalline versus amorphous) of the ice, the degree of segregation of these species within the ice, and the thermal history of the species within the ice. Finally, we comment on the utility of the THz transitions arising from these ices for use in astronomical observations of interstellar ices

Mirror asymmetry in life and in space

All life on Earth is based on amino acids that don’t align with their mirror images. Telescopes looking near the center of our galaxy may reveal the source of that asymmetry

MOLECULAR DISCOVERY ACROSS THE ALMA BANDS: FROM SALTY DISKS TO COMPLEX MOLECULES AT 900 GHz

The Atacama Large Millimeter/sub-millimeter Array (ALMA) provides a view of our molecular universe with unprecedented sensitivity and resolution over more than 850 GHz in bandwidth from 84 -- 950 GHz. In this talk, I will cover three recent results that showcase not only ALMA's power to probe interstellar chemical evolution, but also the critical role of laboratory molecular spectroscopy efforts in interpreting ALMA observations. At lower frequencies, I will discuss our recent detections of the extraordinarily vibrationally excited inorganic salts NaCl and KCl in the disk of Orion Src I, which may prove to be a unique, and much needed, probe of embedded disks around high-mass protostars. Moving up both in frequency and complexity, I will highlight our detection of methoxymethanol (\chem{CH_3OCH_2OH}) in the high-mass star-forming region NGC 6334I in very high abundance that was directly enabled by complementary laboratory spectroscopy work. Finally, I will discuss the first broadband line survey conducted with ALMA at Bands 9 and 10, again toward NGC 6334I. I will comment on not only the power and quality of high-frequency observations with ALMA but also the need for renewed laboratory efforts at these frequencies, as highlighted by glycolaldehyde (\chem{HC(O)CH_2OH}) and ethylene glycol (\chem{(CH_2OH)_2})

Microwave spectral taxonomy and astronomical searches for vibrationally-excited c2s and c3s

C$_2$S and C$_3$S are common interstellar species, and have relatively simple reaction chemistries. For these reasons, they frequently serve as probes of chemical evolution and physical conditions in rich astronomical sources. Because their rotational lines are often conspicuous there, detection of C$_2$S and C$_3$S in vibrationally-excited states might provide additional insight into formation pathways and excitation conditions. However, knowledge of the vibrational satellite transitions of both species is incomplete. Here, we report laboratory measurements of rotational spectra of vibrationally-excited C$_2$S and C$_3$S obtained from two microwave spectral taxonomy studies, in which CS$_2$ alone or in combination with a hydrocarbon precursor (acetylene or diacetylene), were produced using an electrical discharge. For C$_3$S, these studies, in combination with high-level quantum chemical calculations, greatly extend previous microwave measurements, while for C$_2$S, satellite transitions from several vibrational states have been observed for the first time. On the basis of precise laboratory rest frequencies, renewed searches for these transitions can be undertaken with confidence in publicly-available astronomical line surveys

THE 2020 CENSUS OF INTERSTELLAR, CIRCUMSTELLAR, EXTRAGALACTIC, PROTOPLANETARY DISK, AND EXOPLANETARY MOLECULES: WHAT ARE THE PRESSING SPECTROSCOPIC NEEDS FROM THE LABORATORY?

To date, nearly 220 individual molecular species, comprised of 19 different elements, have been detected in the interstellar and circumstellar medium by astronomical observations. In this talk, I will provide a 30,000 foot view of the demographics of this inventory, the history and lessons learned from where these molecules were first detected, and discuss interesting trends that may help guide future observations. Most importantly, I will identify critical gaps in our knowledge of this inventory, and the areas in which spectroscopic investigations in the laboratory might be most efficiently used to continue driving the ever increasing pace of molecular discovery in the ISM

THE CURIOUS CASE OF NH2OH: HUNTING A DIRECT AMINO ACID PRECURSOR SPECIES IN THE INTERSTELLAR MEDIUM

Despite the detection of amino acids, the building blocks of the proteins that support life, in cometary and meteoritic samples, we do not yet understand the conditions under which these life-essential species have formed. Hydroxylamine (NH$_2$OH) is potentially a direct precursor to the formation of the amino acids glycine and alanine in the ISM, through reaction with acetic and propionic acids. Recent laboratory and modeling work has shown that there are a variety of pathways to the formation of NH$_2$OH in interstellar ices both efficiently and in high abundance. Here, we present the result of a deep, multi-telescope search for NH$_2$OH in the shocked, complex molecular source L1157. We find no evidence suggesting the presence of this important precursor, and discuss the implications of this non-detection on the reactivity of NH$_2$OH both within the ices, and in the gas-phase ISM. We will also discuss how these observations should inform the direction of future studies, both in the laboratory and with state-of-the-art telescopes such as ALMA