Interview

"THERE IS LESS QUANTITY OF WATER IN THE CLOUDS THAN WE SUSPECT " Paul Goldsmith heads up the boards directive of astronomy, physic and space technology of the NASA. Their recent works have been centred on studying the process of formation of molecular clouds and also the creation of young stars. This includes the use of atomic hydrogen in molecular clouds. Paul Goldsmith is the responsible researcher of NASA “Herschel� Space Observatory, launched in May 2009.

What develops its research field?

My work has focused on determining the structure and physical conditions of dense molecular clouds where new stars are forming. Using the emission of different molecules, we can obtain information of temperature, density, and movements within the clouds, and their total size and mass. For this research I have been using ground-based telescopes and recent space mission called "Sub millimeter Wave Astronomy Satellite (Sub millimeter Wave Astronomy Satellite, SWAS).

Currently, the Herschel Space Observatory offers increased capabilities to investigate the molecular clouds and, in particular, to know how molecular clouds form new stars.

What do you think are the most important developments in their field in recent years?

In latest years, observations have revealed that one of the most important molecules, water is much less abundant in interstellar clouds of what was predicted. Water vapor in the atmosphere makes us go to space to study these molecular species, but the results of the ISO mission, SWAS, and Odin confirm that water has a presence of a factor 100 below predictions chemical models of the gas phase in cold molecular clouds. The best explanation is that it is frozen on the dust grains in the form of ice. On the other hand, recent results have confirmed that Herschel diatomic molecule hydride fluoride (HF) contains most of the fluoride of the interstellar clouds, and these species may be a good tracer for studying how much material is in diffuse interstellar medium. Herschel also is giving astronomers their first opportunity to accurately map the distribution of key species, the ionized carbon, found in significant quantities in the outer layers of molecular clouds, in regions that have been ignored by the difficulty involves observation by other means, and can have a significant effect on the structure of molecular clouds.

What is the importance of an international conference of this kind?

Many important issues in astrophysics depend on the composition and terms of molecular material. This field ranges from the formation of stars from dense molecular clouds, through the formation of planetary systems from disks of gas and dust that leaves the star formation to the study of how heavy elements are returned to interstellar space to be incorporated into future generations of stars, planets and even life itself.

Throughout the last 40 years, astronomers have only been able to confirm the fact that young stars are formed by cold molecular clouds (compared with the hot ionized gas or atomic). Some details about molecules are present are indispensable to determine how the gas itself is cooled to allow formation of new stars. The composition and behavior of dust grains that follow the molecular gas are also very important because the molecules can only be stick to the grains, creating reactions. In fact, the most important molecule, molecular hydrogen (H2) is formed by dust grains. Astronomers from around the world work on these issues, which are part of the central topics of this conference.

What do you think about the evolution and future of the Astrochemistry in Spain?

The Astrochemistry is a relatively new field and it's exciting that this pays special attention in Spain. There are many important centers that deal with this topic and relate it with other important astronomical matters as the origin of life. This combination is proposed, for example, is called the Center of Astrobiology. This type of work can offer valuable understand, for example, the connection between interstellar molecules and the origin of life in the Solar System.

What do you hope to discover your scientific community in the next decade?

Naturally, this is a difficult question to answer. I hope that we learn much more about the details of how new stars form in molecular clouds. ALMA instrument begins to operate soon in Chile, will give us an extremely detailed view of the surroundings of the new stars, the disks of gas and dust that often around them, and possibly the planets information with young stellar objects. The Stratospheric Observatory of Infrared Astronomy (Stratospheric Observatory for Infrared Astronomy, SOFIA) is a 747 airplane with a telescope almost as big as Herschel. Fly over almost all the water that contains the Earth's atmosphere and this will allow us to study many important species which signals are being blocked by the absorption of the atmosphere. This includes both the atoms and molecules, which may give clues of how they form their own molecular clouds.

This will provide important information about regulates the rhythm of star formation in the Milky Way and other galaxies throughout the universe.

Goldsmith has worked to determine the conditions of massive star formation using molecular lines and continuous emission of dust. He has also used specific chemical liners in the interstellar medium to evaluate the impact of star formation in the materials of the nearby molecular clouds by heating the dust, shock waves and other processes.