• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 2
  • Tagged with
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

A Herschel/HIFI study of Water in Two Intermediate-Mass Star Forming Regions: Vela IRS 17 and Vela IRS 19

Tisi, Samuel January 2013 (has links)
While the single core accretion model for low mass star formation is well developed, it cannot simply be extended into the high mass star formation regime where clustered star formation dominates. The study of intermediate-mass star formation should provide us with insights into how the process of star formation changes for high mass stars. In this thesis observations of H2O line emission from two intermediate-mass candidate Young Stellar Objects (YSOs) made using the HIFI instrument aboard the Herschel Space Observatory are presented. Modelling of molecular line emission using the radiative transfer code RATRAN is used to put constraints on kinematics and the abundance of water throughout the region by modelling the observed water lines after decomposing them into separate Gaussian components. The medium component of the 752 GHz line from Vela IRS 17 was modelled by using a turbulent velocity of 1.7 km s^-1 and an outer abundance of 6x10^-8. The narrow component of the 752 GHz line from Vela IRS 19 could be modelled using a turbulent velocity of 0.6 km s^-1 and an outer abundance of 6x 10^-8, while the medium component required an outer abundance of 4 x 10^-7 with a turbulent velocity of 2.5 km s^-1. The constraints on water abundance in these star-forming regions are to be used along with studies of water in low and high mass star-forming regions in the effort to improve our understanding of star formation across the entire stellar mass spectrum.
2

A Herschel/HIFI study of Water in Two Intermediate-Mass Star Forming Regions: Vela IRS 17 and Vela IRS 19

Tisi, Samuel January 2013 (has links)
While the single core accretion model for low mass star formation is well developed, it cannot simply be extended into the high mass star formation regime where clustered star formation dominates. The study of intermediate-mass star formation should provide us with insights into how the process of star formation changes for high mass stars. In this thesis observations of H2O line emission from two intermediate-mass candidate Young Stellar Objects (YSOs) made using the HIFI instrument aboard the Herschel Space Observatory are presented. Modelling of molecular line emission using the radiative transfer code RATRAN is used to put constraints on kinematics and the abundance of water throughout the region by modelling the observed water lines after decomposing them into separate Gaussian components. The medium component of the 752 GHz line from Vela IRS 17 was modelled by using a turbulent velocity of 1.7 km s^-1 and an outer abundance of 6x10^-8. The narrow component of the 752 GHz line from Vela IRS 19 could be modelled using a turbulent velocity of 0.6 km s^-1 and an outer abundance of 6x 10^-8, while the medium component required an outer abundance of 4 x 10^-7 with a turbulent velocity of 2.5 km s^-1. The constraints on water abundance in these star-forming regions are to be used along with studies of water in low and high mass star-forming regions in the effort to improve our understanding of star formation across the entire stellar mass spectrum.

Page generated in 0.1816 seconds