Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Photo-evaporation of Globulettes: Numerical hydrodynamic studies of photo-evaporating low-mass globules in the Rosette Nebula
Stockholm University, Faculty of Science, Department of Astronomy.
2007 (English)Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

In this work, the long-term evolution of globulettes, low-mass globules found in H II regions, is studied through numerical hydrodynamic simulations. It has been proposed by Gahm et al. (2007) that these clouds may form free-floating planetary mass objects due to shock compression, caused by heating from the intense UV radiation of the central OB star cluster. To address this possibility, lifetimes are calculated for three different 3D simulated cases, similar to globulettes found in the Rosette Nebula. A plane-parallel approximation of the radiation field is used, as well as an inhomogeneous initial density distribution. The ionizing radiation will cause the globulettes to photo-evaporate, creating a rocket acceleration effect from the mass ejected on the heated side of the cloud. For a typical globulette with an initial mass of 29.5 Jupiter masses a lifetime of 50 000 yrs is estimated. This estimate is compared to the analytical models of Mellema et al. (1998) and Bertoldi and McKee (1990) which suggest longer lifetimes; the discrepancy is attributed to fragmentation of the clouds in the numerical simulation, which is not adequately described by the models. Synthesized H-alpha images and lightcurves are presented, indicating that the bright rims of small clouds are only likely to be visible in dim parts of the Rosette Nebula. The morphology of simulated clouds generally agrees with observations. While the code does not include self-gravity, the gravitational stability of the clouds is studied indirectly. It is concluded that clouds in the planetary mass range are stable against gravitational collapse, from supporting thermal pressure alone, when in pressure equilibrium with the heated ionization front. However, gravity may play a significant role during the initial shock compression.

Place, publisher, year, edition, pages
2007. , 41 p.
Keyword [en]
astronomi, astronomy, astrophysics
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:su:diva-8354OAI: oai:DiVA.org:su-8354DiVA: diva2:200148
Presentation
2007-10-17
Uppsok
fysik/kemi/matematik
Supervisors
Examiners
Available from: 2008-11-26 Created: 2008-11-26Bibliographically approved

Open Access in DiVA

fulltext(923 kB)242 downloads
File information
File name FULLTEXT01.pdfFile size 923 kBChecksum MD5
e97a3fbcefda965372a0f226e8f4bfec6f1cc465cf7f2888e65e809001aa20b1b5060155
Type fulltextMimetype application/pdf

By organisation
Department of Astronomy
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
Total: 242 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 283 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf