Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/~astro/chicago2/talks/Sargent-Stars_Planets_Working_Group.pdf Дата изменения: Tue Aug 22 00:24:02 2006 Дата индексирования: Sun Dec 23 00:56:35 2007 Кодировка: Поисковые слова: п п п п п п п п п п п п п п п

Where we are from?
Interstellar medium Star and Planet Formation Astrobiology


Outstanding Questions
How stars? How How do molecular clouds collapse to form do very young stars evolve? do planets grow in circumstellar disks?

Are there observations unique to SKA that address these questions?


Major Challenges
How do planets grow in circumstellar disks? Dust to pebbles to boulders How do very young stars evolve? Let there be light How do molecular clouds collapse to form stars? Magnetic fields are to astronomers what sex is to psychologists (van de Hulst by way of Crutcher)


Growing planets in disks
cm-wave observations probe particle sizes larger than mm
distribution of particle sizes in "older" disks for comparison with models

cm-wave continuum: few x 1000 km baselines
detect concentrations > 2 mas, few M

cm-wave molecular lines ­ amino acids (life)
compact concentrations complex molecules

survey numerous disks
Consistent with suggestions by Wilner in SKA Science Upper frequency cut-off 22-24 GHZ


How do disks evolve?
Real-time protoplanetary/protostellar disk evolution - movies of disks in formation High sensitivity, 2 AU resolution cm-wave observations (100K, 0.2 mas, 8 GHz bandwidth, A/T 10,000)
proper motions (Reid ­ Bryden et al 1999) dynamical timescales months-years


How do very young stars evolve?
cm-waves probe inner few AU of accretion disks (optically thick at mm-wavelengths)
comparison with models (Hillenbrand ) detect gaps due to massive planet formation (seen in more evolved disks with HST/scattered light) binary star/disk relation detailed observations of outflows at origin in HI, recombination lines ( see Hoare SKA Science Book) movies of jets?


Molecular Clouds to Stars
Cloud collapse regulated by magnetic field or turbulence ­ fundamental question
high resolution, high sensitivity sources (extragalactic ) behind cloud cores magnetic fields measured in absorption pre-collapse, in early collapse magnetic support, ambipolar diffusion? Zeeman splitting OH, CCS


Structure of the Milky Way Galaxy
?? Compelling arguments for high priority ??