A-1 Exploring Chemical Diversity
● PEACHES (PErseus ALMA CHEmical Survey)
Aim:
Statistical study of the chemical diversity
Exploring Environmental Origin of the chemical diversity
A comprehensive understanding of chemical evolution from protostellar cores to protoplanetary disks is important in relation to the origin of the Solar-System environment, which can eventually be related to origin of life. So far, it has been established that chemical composition of the protostellar cores shows significant chemical diversity. One distinct case is the hot corino chemistry, which is characterized by rich existence of saturated organic molecules. The other distinct case is the warm carbon-chain chemistry (WCCC), which is characterized by rich existence of unsaturated organic molecules such as carbon-chain molecules. It is proposed that a duration time of the starless phase (i.e. shorter time after the UV shielding from outer part of the parent cloud) would cause this diversity. We have statistically studied the core scale (a few 1,000 au) diversity in Perseus Molecular cloud complex, and revealed the possible origin [1]. More interestingly, how is this chemical diversity brought into protoplanetary disks and planetary systems? With ALMA, we revealed that such diversity is certainly delivered to the disk forming region with size scale of 100 au [e.g. 2-5]. For comprehensive understandings, PEACHES aims to reveal the chemical diversity in disk formation scale (~100 au) in a statistical way.
A-2 Detailed View of the Chemical Diversity
● FAUST (Fifty AU STudy of the chemistry in the disk/envelop system of Solar-like protostars) (ALMA Large Project)
Exploring detailed Chemical Composition of Disk Forming Regions
● Individual Source Studies
- Class 0 Sources
- Class I Sources
- Massive
- Debris Disks
Faust is the ALMA large project approved in cycle 6 (2018). It consists of >60 international members with 5 co-PIs (Cecilia Ceccarelli, Claire Chandler, Claudio Codella, Nami Sakai, and Satoshi Yamamoto)
The huge variety of planetary systems discovered in recent decades likely depends on the early history of their formation. The FAUST Large Program forcuses specifically on the early history of Solar-like protostars and their chemical diversity at scales of ~50 au, where planets are expected to form. In particular, the goal of the project is to reveal and quantify the variety of chemical composition of the envelop/disk system at scale of 50 au in a sample of Class 0 and I protostars representative of the chemical diversity observed at larger scales. For each source, 50 au spatial resolution observations of a set of molecules able to:
(1) disentangle the components of the 50~2000 au envelope/disk sysmtems
(2) characterize the organic complexity in each of them
(3) probe their ionization structure
(4) measure their molecular deuteration
The output will be a homogeneous database of thousands of images from different lines and species, i.e., au unprecedented source-survey of the chemical diversity of Solar-like protostars at 50 au scales. FAUSt will provide the community with a legacy dataset that will be milestone for astrochemistry and star formation studies.