Eric R. Willis's research while affiliated with University of Virginia and other places

... They are thought to form on dust grain surfaces during both the cold collapse and "warm-up" phases of massive star formation (e.g. Garrod & Herbst 2006;Garrod 2013;Öberg 2016;Garrod et al. 2022), with COMs forming earlier and at lower temperatures in models including non-diffusive chemistry (Garrod et al. 2022). In general, in gas-grain astrochemical models radiative heating from MYSOs ultimately heats the grains enough to sublimate their ice mantles, releasing both COMs and simpler molecules into the gas phase where they are observable via (sub)millimetre wavelength spectral line emission (e.g. ...

... The same applies to fused benzene rings such as naftalene and antracene. Among the possible substituents, the cyano (-CN) and ethynyl (-CCH) groups introduce good dipole moment and have led to the detection of benzonitrile , cyanonaphtalenes (McGuire et al., 2021), ethynyl cyclopropenylidene (Cernicharo et al., 2021a), ethynyl cyclopentadienes (Cernicharo et al., 2021b), and cyanoindenes (Sita et al., 2022). The limiting factor to further interstellar identifications is the availability of accurate line lists obtained from high-resolution laboratory investigations. ...

... As of GOTHAM DR4, no individual transitions of the cyano-butadiene isomers were bright enough for identification. In the absence of strong individual lines, we used the spectral stacking and matched-filtering procedure detailed in Loomis et al. (2021) to determine the statistical evidence for the presence of this molecule. In summary, a small spectral window is extracted for each of the top 5% strongest predicted transitions, provided that there is no interloping emission (>5σ) present in the spectrum. ...

... More recently, the discovery of benzonitrile (c-C 6 H 5 CN) by McGuire et al. (2018) added the first aromatic ring to this inventory. Following this detection, a number of additional aromatic and unsaturated cyclic molecules have been detected using our GBT Observations of TMC-1: Hunting for Aromatic Molecules (GOTHAM) line survey (Burkhardt et al. 2021b;Lee et al. 2021b;McCarthy et al. 2021;McGuire et al. 2021) and the Q-band Ultrasensitive Inspection Journey to the Obscure TMC-1 Environment (QUIJOTE) survey of Cernicharo and colleagues (Cernicharo et al. 2021a(Cernicharo et al. , 2021b(Cernicharo et al. , 2021c(Cernicharo et al. , 2022. ...

... Prior high-resolution observations of TMC-1 from both GOTHAM (Xue et al. 2020) and others (Dobashi et al. 2018(Dobashi et al. , 2019 have found that most emission seen at centimeter wavelengths can be separated into contributions from four distinct velocity components within the larger structure, at approximately 5.4, 5.6, 5.8, and 6.0 km s −1 ). In our model these are assigned to independent sets of SS, v lsr , and N T , while a uniform T ex and ΔV are adopted, resulting in a total of 14 modeling parameters. ...

... The GOTHAM program is a dedicated spectral-line observing program of TMC-1 covering almost 30 GHz of bandwidth at high sensitivity and spectral resolution. Details of the source, observations, and data-reduction methods can be found in McGuire et al. (2020) and McGuire et al. (2021). Briefly, the spectra in these data cover the entirety of the X-, K-, and Ka-receiver bands with nearly continuous coverage from 7.9 to 11.6 GHz, 12.7 to 15.6 GHz, and 18.0 to 36.4 GHz (24.9 GHz of total bandwidth). ...

... According to work by Martín-Doménech et al. (2016), sulfur is depleted in regions where it is expected to be abundant, especially around young stellar objects in which the S-bearing species detected already accounts for only 0.1% of its estimated cosmic abundance. It has recently been suggested that the as-yet undetected gas-phase sulfur-bearing molecules should play a key role in the observed sulfur depletion (McGuire et al., 2019) when one compares its cosmic values throughout the diffuse and translucent stages of an interstellar molecular cloud, and its atomic and molecular gas-phase constituents toward lines of sight containing higher-density environments . Therefore, as no S-substituted heterocyclic molecule has yet been detected in the ISM environment, these molecular species are likely interstellar targets. ...

... Even so, other gas phase molecular species containing element-16 are likely additional harbors for this material [13], especially if they play a role in the formation or destruction of known astrochemicals. Recent searches for H 2 CCS (thioketene) and HCCSH have returned with only possible upper bounds in regions searched [14], but further oxygen-analogue molecules like H 2 S + [15,16] and even unique sulfur compounds are likely still present in the ISM or in the atmospheres of carbon-rich stars. ...

... MM3 is known to be a UCHII region associated with free-free emission (Hunter et al. 2006). Many organic molecules have been reported in MM1 and MM2 (e.g., Walsh et al. 2010;Zernickel et al. 2012;El-Abd et al. 2019). ...

... 19,20 Later, it was detected in the hotcore source, 21 hot molecular clouds, 22 low-mass protostars, 23−25 nebula, 26 comet, 27,28 and massive star-forming regions. 30 The reported column densities of CH 3 C(O)OH range from 8 × 10 14 to 3 × 10 17 cm −2 . These column densities in the star-forming regions are well correlated with its isomer methyl formate with the ratio of the column densities for methyl formate to acetic acid mostly in the range 10 to 36. ...