The future of astrochemistry of star-forming regions and Hot topics for observers

Astrochemistry of star-forming regions Why is astrochemistry important in SFRs? 1.Molecules formed by the chemistry allow us to trace the gas in optically opaque regions 2.Astrochemistry is time-dependent, so the chemistry defines an evolutionary age; 3.In SFRs: t chem ~ t dyn so we also learn about dynamics

Astrochemistry of star-forming regions Why is astrochemistry important in SFRs? 4. Gas-dust interaction introduces ideas of freeze- out during the core collapse and desorption during the warm-up phase. 5. The ice is an integrated record of the chemistry – and hence the physical conditions during the collapse. 6. The desorption is a thermometer of gas during the warm-up.

Astrochemistry of star-forming regions Why is astrochemistry important in SFRs? Molecular observations + chemical modelling give information on physical state of gas in SFRs both before and after the birth of the star.

Astrochemistry of star-forming regions Conclusion: 1.We need astrochemical modelling to exploit the wealth of information contained in molecular observations of SFRs 2.This need will continue into the future as observations at higher spatial resolution and sensitivity call for more detailed models

Hot topics for observers of SFRs How can we study star formation observationally? By studying molecular clouds before stars form By studying the influence of new stars on their environments, and inferring the physical conditions at stellar birth

Hot topics for observers of SFRs Molecular clouds before star formation Aim is to study structure To distinguish between models of star formation To establish link with initial mass function We need high angular resolution

Hot topics for observers of SFRs Molecular clouds before star formation Very few detailed high resolution studies available (TMC-1 Core D:Peng et al. 1998; L673: Morata et al. 2003, 2005). These two examples show many cores of sub- stellar and near-stellar masses. Are these examples typical, or special? Are the cores transient? How do the cores arise? What determines their masses, etc.? Links to IMF, multiple stars? etc.

Hot topics for observers of SFRs Molecular clouds before star formation high angular resolution observations should soon become easier to make. Studies of molecular clouds in conventional tracers of high density gas (CS, NH 3, N 2 H +, etc.) should permit answers to these questions.

Hot topics for observers of SFRs Molecular clouds after star formation When new stars begin to warm up, they also warm up the gas nearby. Molecules in the ices evaporate and radiate. These regions are called hot cores (near massive stars) or warm cores (near intermediate mass stars)

Hot topics for observers of SFRs Molecular clouds after star formation We can use hot/warm cores: 1.To study the rise time to Main Sequence of stars of different mass 2.To infer from the chemistry in the core the nature of the pre-existing ice, and hence the physical conditions when the ice was deposited during the collapse

Hot topics for observers of SFRs Molecular clouds after star formation We can use hot/warm cores: 3.To infer the elemental abundances in the SFR before star formation and nuclear processing modified them 4.To use elemental abundances determined in this way to probe models of earliest stars in the Universe

Hot topics for observers of SFRs Conclusion Study hot and warm cores in lines of the conventional tracers (e.g. methanol; formic acid; formaldehyde; etc.) Study galactic objects to infer information on the SF process for both massive and intermediate mass stars Identify chemical differences that distinguish hot cores in their earliest phases

Hot topics for observers of SFRs Conclusion Use these early phase hot cores to determine the rise time to the MS, as a function of stellar mass For distant extragalactic objects, hot cores are unresolved, but can be used to determine elemental abundances of the earliest stars