1 / 10

B68 – The HERSCHEL view Dust temperatures and densities

B68 – The HERSCHEL view Dust temperatures and densities. Markus Nielbock ( MPIA ) (Herschel PACS ICC)

marius
Download Presentation

B68 – The HERSCHEL view Dust temperatures and densities

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. B68 – The HERSCHEL view Dust temperatures and densities Markus Nielbock (MPIA) (Herschel PACS ICC) Ralf Launhardt, Jürgen Steinacker, Amy Stutz, ZoltanBalog, HenrikBeuther, JeroenBouwman, Thomas Henning, Pierre Hily-Blant, JouniKainulainen, Oliver Krause, Hendrik Linz, Nils Lippok, Sarah Ragan, Christophe Risacher, AnikaSchmiedeke

  2. EPoS– The Earliest Phases of Star formation • Herschel guaranteed time key programme (PI: O. Krause, MPIA) • to investigate well studied cloud cores across the entire mass range • to determine the dust temperature and density distribution of 12 near and isolated • low-mass cores (Launhardt et al. 2012, in prep.; see also poster A05) • used PACS and SPIRE bolometers at 100, 160, 250, 350, and 500 µm • added ground-based (sub)mm and NIR extinction data • this talk: results of the starless core B68(Nielbock et al. 2012, in press; see poster A07)

  3. Barnard 68 B72 B68 B69 B70 B71 B74 B73

  4. Barnard 68 • starless core • distance:  150 pc • mass:  3 M • size:  0.2 pc (40 000 AU) • pre-stellar? • possibly on the verge of collapse Alves et al. (2001) Bonnor-Ebert fit NIR extinction

  5. Continuum data

  6. Ray-Tracing Modelling Results • simple SED fitting affected by LoS temperature averaging • employed 3D ray-tracing SED fitting (outside in) • assumed functional relationship for mean radial density profile (Plummer-like, • e.g. Whitworth & Ward-Thompson 2001) • externally heated • Tdust = 8 – 17 (20) K nH = (3.4 – 0.04) x 105 cm-3

  7. Ray-Tracing Modelling Results • radial distribution of temperature and densities • flat central distributions • steep slope in transition region • nH ~ r-3.5 • filamentary origin? (Ostriker 1964) • strong spatial variations r > 1’ • spheroid assumption invalid there • density drops to a flat distribution of the ambient tenous medium

  8. Core collision scenario Alves et al. (2001) B68 B69 B71 Burkert & Alves (2009)

  9. Summary and conclusions • observed the starless core B68 with the Herschel Space Telescope • resolved the distribution of the dust temperature and density • negative temperature gradient from up to 20 K at the outskirts to 8 K in the core centre • central density agrees with NIR extinction mapping results of Alves et al. (2001) • steep slope of mean radial density profile nH ~ r-3.5between r = 1’ and 3’ • contradicts SIS predictions, but agrees with filamentary origin or/and external pressure • peculiar FIR morphology consistent with anisotropic radiation field • ground-based CO observations are qualitatively consistent with core collision scenario • Next steps: • full 3Dradiative transfer modelling • exploit public Herschel data covering larger environment of B68

  10. Anisotropic irradiation • peculiar crescent-shaped morphology of FIR emission does not follow density • connected to (very uncertain) temperature gradient to SE? • can be explained withirradiation by anisotropic external irradiation field • 3D rad. transfer modelling • can reproduce shape • qualitatively • B68 40 pc above gal. plane • B2IV star  Ophnearby

More Related