Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

• we develop quantum and classical formalisms in molecular physics, relevant to the understanding of the
physics and the spectra that we observe;
• we compute theoretical molecular physics data, developing and using state of the art ab initio quantum
chemistry codes as well as dynamical calculations.
Astromol is, therefore, composed of people having very different skills and backgrounds: astrophysical observations,
astrophysical modeling, ab initio molecular calculations, and theoretical molecular physics. In the
following we will refer to the two major activities of Astromol as the Star Formation and Molecular Physics
respectively. Figure 2.1 shows the logical scheme of the interaction between the astrophysical and the molecular
Figure 2.1: The activities of Astromol and the synergy of the different components. The logical sequence
is as follows: 1- we select the target of our study; 2- we do observations of the target object; 3- by using
the collisional coefficients relevant to the observed molecule, we interpret the observations deriving the temperature,
density and chemical composition of the studied object, by means of theoretical radiative transfer
models; 4- by using the rates of the chemical reactions we build a chemical model; 5- finally, we reconstruct the
physics/dynamics/chemistry of the target of our study.
physics expertise of Astromol members, taking the example of the study of a solar type forming star. In order to
understand the star formation process one needs to reconstruct the physical, dynamical and chemical structure
of the matter, as function of time, namely as this structure evolves during the formation process. One of the
best tools for this study are the lines emitted and/or absorbed by the gas, because:
i) lines intensities (either in emission or in absorption) depend on the gas temperature and density, and, for this
reason, multi-frequency line observations allow to reconstruct the density and temperature profile of the gas;
ii) lines from different chemical species allow to reconstruct the chemical composition of the gas;
iii) lines profiles provide information on the kinematics of the studied region.
Given the involved temperatures (between 10 and few hundreds Kelvin) and densities (between 10 4 and 10 9
cm −3 ), molecular lines are the privileged tool for studying forming solar type stars. The sequence in Fig. 2.1
illustrates, in practice, the synergy between the astrophysical observations and modeling, and the theoretical
molecular computations. Astrophysical observations and modeling motivate theoretical molecular computations;
in turn, theoretical molecular computations feed the astrophysical modeling, and allow the correct interpretation
of the data. In synthesis, the research activity of Astromol may be summarized into a few major axes:
observations at telescopes (§2.2), development of astrophysical models (§2.3), development of molecular physics
theories and codes, plus computation of molecular and intermolecular properties (§2.4). Our research leads
to several publications in international specialized journals, as well as to communications to congresses, both
invited or not (§2.5).
Another important aspect for Astromol is represented by the teaching and student formation, an activity
which absorbs a substantial fraction of the team energy and time, and which is vital for the life of the team
itself (§2.6).
Finally, Astromol is actively involved in national and international activities and collaborations. It is worth
here to mention three large national and international projects, where Astromol is a major actor (see §2.7
for a detailed description): “WAGOS”, “FP6 - THE MOLECULAR UNIVERSE”, and “HERSCHEL SPACE
OBSERVATORY - HIFI”. Regarding the interaction with the “Programmes Nationaux” Astromol is financially
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