Facts: Grains in turbulent medium should be moving through the gas, which could have astrochemical consequence. We tested the astrochemical effects of turbulent grain motion in dark cloud (DC), molecular cloud (MC) and cold neutral medium (CNM) models with a new gas-grain astrochemical code 'ggchem'. We have added new physics in the chemical model which played key roles in realing the grain motion effects: ion accretion, grain charging, photo electron ejection.  

Results: We found that the grain motion has profound astrochemical effects in both DC and CNM models, affecting the abundances of some gaseous and surface species by orders of magnitude. A comparison of the change of abundance relative to models without grain motion is given below.

Conclusions: The results confirm that the turbulent grain motion should be considered in routine astrochemical modeling practices.

(Ge, J.X.; He, J.H.; Yan, H.R., 2016MNRAS.455.3570G)

Chem in SFR

Facts: Among our millimeter line survey of Splitzer Glimpse Extended Green Objects (EGOs) , 29 of them show multiple transition lines from at least one of the four complex organic molecules (COMs): CH₃OH, CH₃OCH₃, HCOOCH₃ and CH₃CH₂CN. We determined their column density, excitation temperature and beam filling factor with the population diagram method and compared the results with that of other cloud cores from literature.

Results: Uniform properties are found for the EGOs: Tex ~ 44K, linear size ~ 0.036 pc, beam averaged Methanol abundance X(CH₃OH) ~ 10^9. Correlations of the abundance ratios are found among different kinds of cloud cores (see in the figures in the left).

Conclusions: The chemical properties of the EGO cloud cores lie between those of hot cores and
hot corinos. However, the abundances and abundance ratios of the four species cannot be
explained satisfactorily by recent chemical models, either among EGO cloud cores or among
the various types of cloud core from literature.

(Ge, J.X.,; He, J.H.; Chen, X.; Takahashi, S. 2014MNRAS.445.1170G)

Facts: Post-AGB is a brief transitional evolutionary stage of stars in the 2-8 Msun mass range. We study the coevolution of dust and gas in their circumstellar envelopes through comparing their CO 2-1 line strengths with dust IR fluxes

Results: We define a naval CO-IR diagram on which to reveal the relationship of dust and gas of different postAGB stars. We observed CO 2-1 line toward a sample of high Galactic latitude stars and collected literature CO 2-1 data.

Conclusions: The considered postAGB stars segregate into three groups (CO-IR groups): I, II and III, on the CO-IR diagrams. The distribution of postAGB stars and AGB and PNs agree well with the AGB-postAGB-PN evolutionary sequence. The three CO-IR groups of postAGB stars show distinct properties such as chemical types, spectral types, binarity, circumstellar expansion velocities, and SED types. The CO-IR diagram is proven to be a new useful tool analysing dust and gas coevolution during the fast postAGB evolutionary stage.

(He, J.H.; Szczerba, R.; Hasegawa, T. I.; Schmidt M.R. 2014ApJS..210...26H)

Facts: Splitzer Glimpse Extended Green Objects (EGOs) are a new sample of massive star formation regions. We surveyed millimeter molecular line emission toward 89 EGOs in two 1GHz wide bands around wavelengths of 1.1um, using the Arizona Radio Observatory 10m telescope. 

Results: We detected molecular lines from 8 species. The strongest line, the dense gas tracer H¹³CO⁺, is detected in 70 of the 89 EGOs. An example spectral plot is shown in the left top figure.

Conclusions: The results confirm that most of the EGOs are indeed associated with dense gas and many of them are experiencing active shocks (perhaps due to outflows). The line luminosities of the very different tracers (H¹³CO⁺, SO, CH₃OH for dense gas, SiO 6-5 for shocks, and CH₃OH, CH₃OCH₃, HCOOCH₃ and CH₃CH₂CN for oganics in hot gas) are all linear correlated. We explain this with such a physical picture:

1) All clouds have similar physical structures over many size scales;

2) Most of the outflow shocks are produced inside of the natal clouds of the forming massive stars.

(He, J.H.; Takahashi, S.; Chen, X., 2012ApJS..202....1H)

(He, J.H.; Imai, H.; Hasegawa, T.I.; Campbell, S.W.; Nakashima, J. A&A, 2008A&A...488L..21H)