Speaker
Description
The ingredients for the recipe to make a “habitable” planet like our own Earth are: a relatively small rocky planet at the right distance from the host star for water to be in the liquid state, and with a not-too-thick atmosphere organic-rich in volatiles and capable of developing organic molecules chemistry. Searches for exoplanets have shown a large degree of diversity in the planetary systems, and as yet it is unclear how common a System like our own is. Understanding the formation of planetary systems and the chemical processing of the volatiles that will form their atmospheres is key to understanding the origins of the Solar System. More specifically, key questions still to be addressed are: how chemically organic complex are the volatiles delivered to the pristine planetary atmospheres? What molecules are passed from the large-scale envelope to the disk in which planets, comets, and asteroids form? Where do organic complex species form? These are also key questions in the context of the SKA WG Cradle of Life.
Class 0 (10^4-10^5 yr) protostars are becoming more important in the study of planet formation because evidence is mounting that the chemical composition of the final planetary system objects is highly influenced by the chemical composition during the earliest phases. An example is provided by the Solar System comets, whose ices have a chemical composition similar to that found in the inner (< 100 au), hot (> 100 K) region around the protostar. In addition, ALMA observations of gaps/rings in disks around <1 Myr protostars provide direct clues of planet formation at an earlier stage than previously thought. However, ALMA is unable to survey the chemistry of the protostellar disk midplane where planets will eventually form, because the line emission is absorbed by the optically thick continuum at (sub)mm-wavelengths. An instructive example is provided by the protostellar disk around HH212-mm as observed by ALMA down to 10 au scales: the continuum shows a dark equatorial lane due to high dust opacity, plus an interstellar complex organic molecules (iCOMs) gas. These molecules are associated with the rotating disk on a Solar System scale, but they are tracing only the outer upper and lower surface disk layers. Either (i) the iCOMs gas abundance dramatically decreases in the equatorial disk, or (ii) the iCOMs detection is hampered by the high-opacity continuum. This is a limit of the ALMA datasets that further sub-mm observations will never overcome. Only high spatial resolution (< 10 au) observations at much lower frequencies, at cm wavelengths, where the dust continuum is more likely to be optically thin, will be able to provide the answer. We will discuss how the HH212 case is driving the SKA Band 6 science goals to observe at unprecedented sensitivity the midplanes of protostellar disks, and consequently to derive their chemical content.
| Reasearch area | Cradle of Life |
|---|
