Persistent Link:
http://hdl.handle.net/10150/196018
Title:
Exploring Life-Cycles of the ISM at Submillimeter Wavelengths
Author:
Hedden, Abigail S
Issue Date:
2007
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This thesis focuses on addressing some important aspects of the life cycle of interstellar clouds through observational submillimeter and millimeter-wave studies of star formation and molecular cloud environments and the development of instrumentation to enable these studies.We examine the influence of star formation on parent molecular clouds through a case study of protostellar sources in the Mon OB1 northern cloud complex. An energetics analysis of these star forming regions and associated molecular outflows was carried out, suggesting that the cloud complex maintains its overall integrity, except along outflow axes and that the coupling between outflow kinetic energy and cloud turbulent energy is weak, < ~0.5%. In order to study the larger picture of cloud formation and disruption, this work was expanded to explore the molecular environment at cloud boundaries. To this end, acloud edge survey was undertaken consisting of multi-transition strip scan observations of CO and 13CO toward molecular clouds with a broad range of stellar and star forming characteristics. Our work supports the interpretation that cloud formation is taking place along the southeastern edge of Heiles Cloud 2, and the results will be used as a framework for guiding the analysis of other surveyed cloud edges.Achieving observational capabilities enabling effective studies of life cycles of the ISM is becoming possible through a new generation of heterodyne spectroscopic instruments. Here, we report on characterization measurements of a prototype mixer unit for the 64-pixel SuperCam array, an instrument commissioned to mapover 500 square degrees of the Galactic Plane with very high resolution at 345 GHz. These measurements were crucial to verifying the overall array design and anticipating its performance. Spectroscopic capabilities at THz (< 300 microns) frequencies permits access to a host of diagnostic tools (e.g., high-J CO, CI, NII, & CII) uniquely suited to probe crucial properties of the ISM. The development of heterodynetechnology at these frequencies is largely limited by availability of compact, powerful sources of local oscillator power. We explore the use of waveguide spatial filters in conjunction with Quantum Cascade Lasers, a promising power source at frequenciesabove ~ 2 THz.
Type:
text; Electronic Dissertation
Keywords:
molecular outflows; submillimeter spectroscopic arrays; spatial filters; Quantum Cascade Lasers
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Astronomy; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Walker, Christopher K.
Committee Chair:
Walker, Christopher K.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleExploring Life-Cycles of the ISM at Submillimeter Wavelengthsen_US
dc.creatorHedden, Abigail Sen_US
dc.contributor.authorHedden, Abigail Sen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis thesis focuses on addressing some important aspects of the life cycle of interstellar clouds through observational submillimeter and millimeter-wave studies of star formation and molecular cloud environments and the development of instrumentation to enable these studies.We examine the influence of star formation on parent molecular clouds through a case study of protostellar sources in the Mon OB1 northern cloud complex. An energetics analysis of these star forming regions and associated molecular outflows was carried out, suggesting that the cloud complex maintains its overall integrity, except along outflow axes and that the coupling between outflow kinetic energy and cloud turbulent energy is weak, < ~0.5%. In order to study the larger picture of cloud formation and disruption, this work was expanded to explore the molecular environment at cloud boundaries. To this end, acloud edge survey was undertaken consisting of multi-transition strip scan observations of CO and 13CO toward molecular clouds with a broad range of stellar and star forming characteristics. Our work supports the interpretation that cloud formation is taking place along the southeastern edge of Heiles Cloud 2, and the results will be used as a framework for guiding the analysis of other surveyed cloud edges.Achieving observational capabilities enabling effective studies of life cycles of the ISM is becoming possible through a new generation of heterodyne spectroscopic instruments. Here, we report on characterization measurements of a prototype mixer unit for the 64-pixel SuperCam array, an instrument commissioned to mapover 500 square degrees of the Galactic Plane with very high resolution at 345 GHz. These measurements were crucial to verifying the overall array design and anticipating its performance. Spectroscopic capabilities at THz (< 300 microns) frequencies permits access to a host of diagnostic tools (e.g., high-J CO, CI, NII, & CII) uniquely suited to probe crucial properties of the ISM. The development of heterodynetechnology at these frequencies is largely limited by availability of compact, powerful sources of local oscillator power. We explore the use of waveguide spatial filters in conjunction with Quantum Cascade Lasers, a promising power source at frequenciesabove ~ 2 THz.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectmolecular outflowsen_US
dc.subjectsubmillimeter spectroscopic arraysen_US
dc.subjectspatial filtersen_US
dc.subjectQuantum Cascade Lasersen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineAstronomyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWalker, Christopher K.en_US
dc.contributor.chairWalker, Christopher K.en_US
dc.contributor.committeememberBieging, Johnen_US
dc.contributor.committeememberKulesa, Craigen_US
dc.contributor.committeememberRieke, Georgeen_US
dc.contributor.committeememberShirley, Yancyen_US
dc.contributor.committeememberYoung, Ericken_US
dc.identifier.proquest2398en_US
dc.identifier.oclc659748289en_US
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