1 / 13

Understanding Star Formation in Molecular Clouds: Modes and Characteristics

Stars are birthed in the spiral arms of galaxies, predominantly within the dense and cold regions known as Molecular Clouds. Within these regions, star formation occurs in two primary modes: isolated mode in dark clouds and clustered mode in giant molecular clouds. The properties of dense cores vary significantly between regions of high and low mass star formation. This exploration delves into the mechanisms of star formation, highlighting the spectral energy distributions of protostars and the evolution through various stellar classes as they develop and emerge from their molecular natal environments.

sienna
Télécharger la présentation

Understanding Star Formation in Molecular Clouds: Modes and Characteristics

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. In previous episodes …..

  2. Stars are formed in the spiral arms of the Galaxy, in the densest and coldest regions of the interstellar medium, which are called Molecular Clouds. Image: portion of the galactic plane: darker colours indicate higher extinction regions (due to dust in MCs).

  3. 0.1 pc 0.1 pc Star Formation • Observationally, two modes of star formation in the Galaxy: • isolated mode, in dark clouds • clustered mode, in giant molecular clouds Taurus Perseus Orion isolated clustered Kandori 2007

  4. Dark clouds(103 Msun, 5 pc, 10 K) • Giant Molecular Clouds(105 Msun, 100 pc, 30 K) • Young stars are associated with the dense cores in molecular clouds • The properties of these dense cores differ for regions of high and low mass star formation Star Formation: must convert dense cores into stars: • temperature ~10—100 K to >107 K -> 6 o. m. • size ~0.5 pc to 2x10-8 (1 Rsun) -> 7 o.m. • density 103-4 cm-3 to ~1026 cm-3 -> 22 o.m.

  5. Low Mass Star Formation ...

  6. Blackbody Spectrum

  7. SPECTRAL ENERGY DISTRIBUTION

  8. Spectral Energy Distribution(SED) a > 0, peak ~100 mm, BB at 10-30 K, Lsmm/Lbol > 0.5%, faint IR cold envelope opt thick in free-fall. powerful and collimated outflows, protostar Class 0 a = d log l Fl / d log l , between 2 and 25 micron

  9. a >~ 0, flat SED, superposition of BB at different T,IR, faint optical envelope part. thick + disk. Moderate outflows, evolvedprotostar Class I

  10. Class II -1.5 <a < 0, mid-IR excess compared to BB, optical envelope being disrupted faint outflow, classical T Tauri, FU Ori

  11. a < -1.5, similar to BB, optical stellar photosphere reddened by circumstellar extinction debris disk, weak-line T Tauri, PMS Class III

  12. Spatial Distribution Class II ~ Class III spatial distribution. Class I: higher density regions Hartmann 2003

More Related