Prof. Paola Caselli

Nominated by

• European Research Council (ERC)
• AcademiaNet member since 22.10.2013
• AcademiaNet- Selection Criteria

Employed by

• Max-Planck-Institut für extraterrestrische Physik, Garching

Academic Discipline/Fields

• Natural sciences, mathematics and statistics

Field

Physical sciences

Area of specialisation

Star formation, Planet formation, Astrochemistry, Astrobiology, Molecular astrophysics, Interstellar dust, Radiative transfer, Millimeter and sub-millimeter observations

Research interests

• The earliest stages of star and planet formation

• Stars like our Sun form within dense and cold fragments of interstellar molecular clouds. These regions are called pre-stellar cores and they represent the initial conditions in the process of star formation. Pre-stellar cores are cold (~10 K), dense and quiescent. Dust grains are covered with thick icy mantles, a variety of molecules, including deuterated species and complex organic molecules form and thrive, as interstellar UV photons cannot penetrate the dark cores. I study the physical structure and kinematics of pre-stellar cores, using millimeter and sub-millimeter molecular lines and dust continuum emission. To understand which molecule and which line to observe, I study the chemical processes in the gas-phase and on the surface of dust grains. The comparison between observations and model predictions, with the help of radiative transfer codes, allows us to derive the phyical conditions (volume density and kinetic temperature) as well to measure the internal motions, which typically display gravitational contraction toward a well defined center, the future stellar cradle. I use ground based single-dish telescopes, interferometers and satellites to carry out my research and in the past years I have been granted time at the Herschel Space Observatory and the Atacama Large Millimeter Array.

• With Herschel, I recently detected for the first time water vapor toward a pre-stellar core. These observations allowed us to measure the amount of water present in the pre-stellar core, thus the initial reservoir of water, just before the formation of a Sun-like star and its future planetary system. We found 0.5 Earth masses of water vapor, which can be explained by current models if dust grains carry about 2.6 Jupiter masses of water ice.

• Pre-stellar cores are slowly rotating clouds threaded by magnetic fields. The fraction of ionized particles within them is thus crucial for their dynamical evolution, as ions are linked to the magnetic field lines and, via collisions, to the bulk of the cloud material, which is in neutral form. I have measured the degree of ionization in a large sample of dense cores and the specific angular momentum of a pre-stellar core at different scalies, finding results consistent with current predictions of collapsing magnetized clouds, where the specific angular momentum is lost by the breaking action of magnetic fields.

• The collapse of a rotating cloud naturally leads to the formation of a protostar surrounded by a flattened structure, the accretion disk. Material accretes from the envelope to the disk and then to the protostar, which also drives powerful jets and outflows in a direction perpendicular to the accretion disk. I study the effects of the passage of these outflows on the parent cloud with magnetohydrodynamic codes. I also study the chemical evolution of the accretion disks, with the use of gas-grain chemical codes of relatively massive young accretion disks, which will eventually host planet formation.

• One major goal is to connect the various phases in the process of star and planet formation (molecular cloud, pre-stellar core, accretion disk) with the help of detailed observations and comprehensive chemo-dynamical models. This is crucial to unveil our origins and to bridge the gap between interstellar clouds and our solar system.

Distinctions and Awards

• ERC Advanced Grant (2013)

• Courtesy Professor, Department of Astronomy, University of Florida, Gainesville, FL, USA

Interested in

• Trekking, Music, Painting

Languages

English, Italian

Doctorate

• 1994: Nonthermal broadening of molecular lines and chemical processes in star forming regions