Аннотация
The authors propose that the formation of low mass stars in molecular
clouds takes place in four stages. The first stage is the
formation of slowly rotating cloud cores through the slow
leakage of magnetic (and turbulent) support by ambipolar
diffusion. The second phase begins when a condensing cloud core
passes the brink of instability and collapses dynamically from
''inside-out'', building up a central protostar and nebular
disk. The emergent spectral energy distributions of theoretical
models in the infall stage are in close agreement with those of
recently found infrared sources with steep spectra. As the
rotating protostar gains mass, deuterium will eventually ignite
in the central regions and drive the star nearly completely
convective if its mass is less than about 2 M\_sun;. This
initiates the next step of evolution - the bipolar outflow phase
- in which a stellar wind pushes outward and breaks through the
infalling envelope. The initial breakout is likely to occur
along the rotational poles, leading to collimated jets and
bipolar outflows. The intense stellar wind eventually widens to
sweep out gas in nearly all 4\pi steradian,
revealing the fourth stage - a T Tauri star with a surrounding
remnant nebular disk. Radiation from a disk adds an infrared
excess to the expected spectral energy distribution of the
revealed source.
- 14mast
- astronomía
- astrophysics,
- bipolar
- circumstellar
- clouds,
- clouds:star
- collapse,
- ejection,
- emission
- envelopes,
- evolution,
- formation,
- formation:bipolar
- formation:molecular
- formation:t
- gravitational
- infrared
- mass
- matter
- matter:young
- models,
- molecular
- outflows,
- outflows:star
- protostars,
- spectra,
- star
- stars,
- stars:circumstellar
- stars:star
- stellar
- t
- tauri
- young
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