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

If the chemistry in the first phases of the collapse seems to reach a high level of complexity and sophistication,
much less is known about the chemistry in the proto-planetary disks. At present, only a very few and basic
molecules have been detected (CO, CN, HCO + ...) and in a very few objects. Whether new molecules form in
this phase, either in the gas phase or grain surfaces, is almost totally unknown. Chemistry in proto-planetary
disks is definitively a challenge for the incoming years, and we intend to take on this challenge.
Also, basic questions about the interaction between the forming star and the surrounding environments
remain open. What is the effect of the X-ray/UV irradiation on the circumstellar material? Are the outflows
from the central star only destructive? At what level do they contribute to the molecular complexity? What are
the basic physical processes occurring when the outflowing material encounter the surrounding parent cloud?
Answering all these very basic and important questions require:
i) acquiring new, more sensitive observational data;
ii) developing new, more sophisticated astrophysical models;
iii) carrying out new, more complex computations of basic molecular physics.
The next two subsections will describe in some detail the expected new directions and developments of
our research activity. The two subsections will address the “Star Formation” and “Molecular Physics” themes
respectively.
4.2.1 Star Formation
The overall goal is the study of the molecular complexity during the formation of solar type protostars. More
specifically, we plan to develop the following four major lines of research:
1. Molecular Deuteration in the ISM, pre-stellar cores, and protostars/ In the last few years our group has
had a leading role in the study of the molecular deuteration. Also thanks to our contribution, substantial
progresses have been achieved and the basics processes leading to the observed extreme deuterations is
now (probably) mastered. Therefore, the era of “using” this knowledge to study the relevant physical
processes during the star formation phase as well as in other astronomical sources, even to extra-galactic
in CO depleted
sources, is open. Notably examples are the diagnostic value of the deuterated forms of H + 3
regions, like the center of the pre-stellar cores or the midplane of the young proto-planetary disks. In the
formers, these molecules permit to study the motion, and whether, when and how the collapse sets in. In
the latter, H2D + and HD + 2 allow to measure the ionization degree and the dust to gas ratio (item 3).
2. Molecular Complexity in hot corinos. The existence of the hot corino has been demonstrated just in the
last two years, mostly by the works of our group, in collaboration with WAGOS (§2.7) and people of
IRAM (for the studies with the Plateau de Bure Interferometer). Very little is known so far, because
these objects are difficult to observe, being compact and faint in the lines. The incoming four years
will certainly see an explosion of these studies worldwide, both on observational and theoretical side, on
this subject. Our scope is to keep a prominent role in this field by expanding both our modeling and
observing capacities. It will be a challenge, because several groups have entered the race on this subject
(demonstrating its interest), but we have the right expertise to take this challenge. We are involved, and
often with a major role, in major projects worldwide to obtain the full census of the molecular lines in solar
type protostellar objects: the “Unbiased Spectral Survey of IRAS16293-2422” in the IRAM, JCMT and
APEX bands; the “Spectral Survey of Star Forming Regions Legacy Project” at JCMT; the Herschel-HIFI
Key Program “Spectral Surveys of Star Forming regions” (see details in §4.3). These surveys will allow
to have a complete view of the chemical composition of the solar type protostars and their surroundings
in some cases. In addition, they will allow studies of the kinematics and detailed physical structure across
the regions, thanks to the peculiarity of the chemical composition and line excitation, different in different
regions. In addition, we have embarked in the systematic study of the hot corino at high spatial resolution
with PdBI, to probe and measure their sizes and molecular content. In summary, the incoming years will
see likely a change of these studies from pioneer to fully established, and our group is in a good position
to be a major actor in this play.
3. Proto-planetary Disks. We plan to invest more and more in this field. In particular, we have new lines
of research that we intend to pursuit, as detailed in the following. i) We have shown that the deuterated
forms of H + 3 (notably the ground state transition of H2D + ) can be used to measure the ionization degree
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