The process of star formation provides a rich environment for complex interstellar chemistry to occur. We are able to probe the physical and chemical processes of star and planet forming regions in detail using high resolution millimeter wave interferometry. We have used the Northern Extended Millimeter Array (NOEMA) to conduct observations of complex organic molecules (COMs) within the W3 star forming region at selected frequencies in the λ=2 mm band. W3 is a binary system with two high-mass hot cores centered on masers, W3(OH) and W3(H2O). The two cores display different chemistry despite being formed from the same interstellar cloud. This difference in chemistry may arise either because of a difference in source age, or because of different physical conditions within the sources. Interferometric observations of molecules in this region allow us to disentangle the spatial distribution of COMs and investigate the drivers of chemical differentiation between the two star-forming cores. Our results show the chemical morphology of prebiotically relevant molecules such as methanol, methyl formate, methyl cyanide, and formaldehyde, as well as kinematics and temperature distributions within the W3 complex. We will report on these findings and discuss the results in the context of interstellar prebiotic chemistry.

The chemistry of Class 0/I protostars have become increasingly important due to the mounting evidence of their impact on the chemical composition of future nascent planetary systems. Prior observations of molecular outflows, which are an energetic mass-ejection phenomenon associated with early stages of stellar evolution, have revealed that not only do these harsh environments contain a surprising array of complex molecules, but they also show highly-localized spatio-chemical differentiation. Because the velocities of these jets are relatively well-constrained based on mm-wave observations, it is possible to associate distance within the outflow with temporal evolution of chemistry. As well, the collimated nature of the outflows provides a relatively compact region in which comparisons can be made between outflow, shocked walls, and background ambient gas in a variety of density and temperature conditions as the chemistry evolves. We use Atacama Large Millimeter Array (ALMA) spectral line observations in the range of 300-360 GHz of HCO⁺ line and its isomers in five outflows in the southern hemisphere of widely-varying ages, velocities, and chemical conditions to elucidate the underlying links between physical conditions, outflow properties, and chemical evolution in these important pre-stellar environments.

Magnetic fields likely play a critical role in the accretion of material from protoplanetary disks onto protostars by providing a mechanism of angular momentum transport, particularly through magnetic disk winds. Constraining magnetic field strengths in protoplanetary disks is therefore necessary to test theories of magnetically-driven accretion. Zeeman splitting observations offer a way to directly measure or set upper limits on magnetic field strengths. We present the results of Zeeman splitting observations of several hyperfine lines of the CN(2-1) and CN(1-0) transitions in the Class II protoplanetary disk V4046 Sgr. We also present observations of the linear continuum dust polarization in this source and discuss their implications for the disk’s dust population.

In previous studies, we detected methanol in molecular clouds towards the edge of the Milky Way galaxy using the Arizona Radio Observatory (ARO) 12m. These observations implied that the Galactic Habitable Zone (GHZ) may extend beyond 20 kpc from the Galactic Center. As a continuation of this study, we have searched for other organic molecules towards these same edge clouds. We have current detections of c−C₃H₂, NO, and CH₃CN towards WB89-640, WB89-380, and 19423+2541, among other sources. These molecules appear to show no decrease in abundance with respect to galactic radius despite the decrease in metallicity. Clearly organic chemistry is active towards the edge of our galaxy. The detection of these organic molecules show that the universe is far more molecular in nature than previously thought.

SPT0311-58 is a pair of dusty star-forming galaxies (West and East) at z=6.9, less than 800 Myr after the Big Bang. It is the most massive infrared luminous galaxy pair discovered in the Epoch of Reionization (EoR). In this talk, I will present the analysis of the molecular emission lines in this source, observed with ALMA at 0.3” - 0.5” corresponding to  1.6 - 2.7 kpc. We analyzed CO(6-5), CO(7-6), CO(10-9), [CI](2-1), and H2O(211-202) molecular lines and dust continuum emission using non-local thermodynamic equilibrium (non-LTE) radiative transfer models. We find that the CO spectral line energy distribution and brightness temperature ratios in West and East are typical of high-redshift sub-millimeter galaxies (SMGs). The CO-to-H2 conversion factor and the gas depletion time scales estimated from the model are consistent with the other high-redshift SMGs within the uncertainties. Based on the energy budget calculations, we find that turbulence driven mechanical heating and energy from stellar winds and supernovae contribute significantly to the overall CO line excitation in the dense molecular region. This is the most detailed study of molecular gas content of a galaxy in the EoR to-date, with the most distant detection of H2O in the literature.

The Mira-type variable χ Cyg is an old S-type asymptotic giant branch (AGB) star that expels large amounts of material into space. This material forms dust and small to intermediate sized molecules - especially molecules composed of refractory materials. It is assumed that molecules like TiO and other small metall oxides that are formed in the expanding stellar envelope play a key role in the darkening process during the stellar pulsation. At temperatures around 1000 K the maximum radiation is shifted to the mid-infrared region, where laboratory spectroscopic data of small metal oxide molecules are sparse. To overcome the lack of data we have recently studied the molecules TiO, Al₂O and VO in the Kassel laboratory for astrophysics at high spectral resolution in the mid-infrared (IR) region. In addition, new observations using the TEXES spectrograph on the NASA Infrared Telescope Facility (IRTF) have been performed to investigate this star at high spectral resolution around 8.3 and 10 μm, i.e., at wavelengths were SiO, TiO, and VO have strong vibrational bands. We performed spectral and line shape analysis of SiO to study the dynamical behavior of the molecular layer surrounding the star. Preliminary results concerning TiO in χ Cyg will be presented.

In recent years, many questions have arisen regarding the chemistry of CN-bearing molecules in the carbon-rich winds of evolved stars. To address them, it is imperative to constrain the distributions of such species through high angular resolution interferometric observations of multiple rotational transitions. To that end, we used several archival ALMA observations to image high energy rotational transitions of cyanide-bearing molecules in the inner envelope ( < 8”) of the carbon star IRC+10216. The observed lines include the J = 38 - 37 and J = 28 - 27 transitions of cyanoacetylene (HC₃N), and the J = 18 - 17 (K = 0 - 9) transition of methyl cyanide (CH₃CN). In contrast to previous observations of photochemical products in the same source, the maps of these molecular lines show spatially coincident, compact morphologies comprising various arcs and loops, with significant enhancement in dense clumps at an angular distance of  ∼ 3” (350 AU) from the central AGB star. Considering the known gas phase formation mechanisms of these molecules, our results are consistent with photochemistry occurring in warm ( ∼ 200 K) knots present in the inner regions of this circumstellar envelope. Using visibility sampled LIME radiative transfer models accompanied by the results of a specialized photochemical model, we explore the possibility that the enhanced HC₃N abundances in the inner wind are due to a binary companion supplying UV photons to this region. In this talk, I will discuss the results of this analysis, and demonstrate how they may impact our understanding of circumstellar carbon chemistry at the final stages of stellar evolution.

Extreme supergiant stars, or hypergiants, are thought to undergo extensive, chaotic mass loss events in their later stages, with complex envelope structures composed of arcs, clumps, and knots. The red hypergiant VY CMa is one of the best examples of these types of stars. Previous studies in the infrared of VY CMa of dust emission have shown the presence of distinct arcs to the southwest (Arc 1, Arc 2), a NW arc, and another clumps and knots, many extending several arcseconds from the central star. Using ALMA, we imaged the envelope of VY CMa in multiple molecular lines at Band 6 (1 mm) with 0.25 arcsecond resolution and with the sensitivity to structures as large as 3-4 arcseconds. While some observations are still in progress, preliminary maps of SO₂, H¹³CN, and PO have been produced. From SO₂ emission, a map of the global molecular outflow structure of VY CMa has been obtained for the first time on scales of 6-8 arcseconds. These molecular data show the striking morphology seen in dust emission in VY CMa, including Arc 1, Arc 2, and the NW Arc, among other features. These new images will be presented, as well as other new data, and the implications for the evolution of massive stars will be discussed.

Protoplanetary nebulae (PPNe) are an important step in stellar evolution as they bridge the asymptotic giant branch (AGB) and planetary nebulae phases. Observations have demonstrated that planetary nebulae are rich in molecular content which varies considerably from the AGB phase; therefore, significant chemical changes must occur in the PPNe stage. To examine this issue, we have conducted observations of M1-92, the Cotton Candy Nebula, and IRAS22036+5306, all PPN sources in which CO had previously been detected. Measurements were conducted with the 12-meter antenna and the Sub-millimeter Telescope (SMT) of the Arizona Radio Observatory at 3, 2, and 1 mm. Towards M1-92 we have thus far detected CN, HCO⁺, H¹³CO⁺, HCN, and HNC. Towards the Cotton Candy Nebula, we have identified CN, HCN, and HNC. In IRAS22036+5306, H₂S and SO have been observed. Abundances in these PPNe appear to vary from those in circumstellar AGB envelopes. The detailed chemistry in these sources will be discussed.

Observations of the diffuse interstellar gas over the past few decades have revealed a surprisingly rich molecular inventory comprising over 25% of all known interstellar molecules. While the molecules observed in diffuse clouds are small relative to ones found in dark clouds, considerable progress has been made in recent years towards detecting larger, more complex molecules.Liszt, H. S., Gerin, M., Beasley, A., & Pety, J., 2018, Astrophysical Journal, 856, 151; and references therein.^,^b Gerin, M., Liszt, H., Neufeld, D., et al. 2019, Astronomy Astrophysics, 622, A26; and references therein.TMaier, J.P. Campbell, E.K. 2016, Phil. Trans. R. Soc. A, 374, (issue 2076), 1UOur sample includes two sightlines where millimeter-wave absorption from has previously been detected.BMolecular ions such as are far more challenging to produce in the laboratory than carbon chain radicals, and might first be found in space.b