User Manual
Doc. Number: ESO-323064
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Figure 3: Schematic diagram summarizing the differences between oCRIRES and CRIRES
after the upgrade
2.2 Science Drivers
A set of fundamental scientific goals were defined for CRIRES during the Phase A study:
2.2.1 Search for super-earth in habitable zone for low mass stars
A large fraction of all exoplanets has been discovered primarily through radial velocity (RV)
measurements. However, only 5% of the planets detected so far orbit stars with stellar
masses less than about 0.5 M
sun
. Thus, we lack key knowledge about the process of planet
formation around the most numerous stars in our galaxy
–
M dwarfs. Low mass stars are
especially interesting because these objects are cold, and the habitable zones are quite
close to the star. The reflex motion of an M star (0.15 M
sun
) with a 1 M
Earth
planet in its
habitable zone is about 1 m s
-1
. Since M dwarfs and brown dwarfs have low effective
temperatures, radiating most of their energy in the IR (1.0 -
2.5 μm), a high
-resolution IR
spectrograph is therefore ideal for searching for low mass planets around these objects. A
new gas absorption cell to provide a stable wavelength reference as well as the increase in
wavelength coverage by about a factor of ten should result in an attainable RV precision for
the upgraded CRIRES of 3 m s
-1
. This would enable the detection of super Earth-mass
planets in the habitable zone of an M-dwarf star in the solar neighbourhood.
2.2.2 Atmospheric characterization of exoplanets
High-resolution spectroscopy of exoplanets provides us with means of studying the physical
(e.g., winds) and chemical composition of exoplanetary atmospheres. CRIRES is well suited
for the observation of close-in, highly irradiated planets that radiate most of their light in the
IR. Furthermore, the IR is a spectral region where lines of molecular gases like CO, NH
3
,
CH
4
, etc. are expected to be present in exoplanetary atmospheres.
2.2.3 Origin and evolution of stellar magnetic field
Magnetic fields play a fundamental role in the life of all stars: they govern the emergence of
stars from proto-stellar clouds, control the in-fall of gas onto the surfaces of young stars and
