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Since its discovery by E. Salpeter in 1955, the high-mass end of the Initial
Mass Function (IMF) has been continuously tested, and its slope has not
changed from the value -2.35 originally calculated by Salpeter, the Salpeter
value. Furthermore, it is found that this value is universal. It not only
describes the mass distribution of stellar masses in the Milky Way but also in
other galaxies.
Stars form individually or in systems within molecular clouds, from local
condensations of sizes on the order of ~0.01 pc, the so-called dense
cores. In the case of low-mass star-forming regions, it is found that the Core
Mass Function (CMF) resembles the Salpeter IMF. However, in the case of massive
star-forming (MSF) regions, the answer is not that clear.
The first CMF for a MSF region was derived
for the MSF IRAS 19410+2336 in 2004. It was found that this CMF also resembled
the Salpeter IMF. Since then, a few more CMFs for MSF regions have been derived,
always with exponents comparable to Salpeter. This suggested that the CMF and
the IMF are related in a one-to-one or nearly one-to-one relationship, and
that the fragmentation processes within a molecular cloud would set the shape
of the IMF at an early evolutionary stage.
Attempting to test that scenario, I present and analyse
high angular resolution interferometric observations of several MSF regions at
millimeter wavelengths, describing their protostellar content and deriving
their CMF whenever is possible. We obtain a
CMF with a power-law slope similar to the Salpeter IMF, however for other MSF
regions we obtain a CMF with a power-law slope flatter than Salpeter.
This difference suggests that the IMF might not be set at the moment of the
fragmentation of the cloud, but insted would be a result of the evolution of the
cloud, starting with a flatter mass distribution that becomes steeper at
laterevolutionary stages. This result is not conclusive yet, and we suggest a
series of observations that would be needed to fully test it.
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