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Cam OB1 Region Is Investigated NOTE TO USERS The original manuscript received by UMI contains pages with indistinct print. Pages were microfilmed as received. This reproduction is the best copy available UMI National Library Bibliothèque nationale du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. nie Weilington OttawaON K1AW OttawaON K1AW canada canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microfom, vendre des copies de cette thèse sous paper or electronic formats. la fome de microfiche/nlm, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts 6-om it Ni la thèse ni des extraits substantiels may be printed or othenivise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Supervisors: Drs. .A. C. Gower and C. R. Purton Star formation in the Cam OB1 region is investigated. Star formation. in general. is considered in terms of three elements: a) the structural relationship between the parent molecular clouds and newly formed stars. b) the temporal evolution of the parent molecular clouds, and c) the probability of the occurrence of star formation. Star formation in Cam OBI. over the range in 1 and b considered in this work. is concentrated in the vicinity of Cam RI and appears to have led to the formation of t hree distinct stellar groups: a) Group 1. formed .- 1 - 50 x 106 yr ago. and located spatially and kinematically between ttvo CO compleses. b) Group II. formed - 1 - 3 x 10" yr ago. and coincident with one of the previously mentioned complexes. and c) Group III. the youngest group. formed - 1 - 20 x IOJ yr ago. and located at the current point of intersection between the two complexes in (a). The mass function (MF) for Groups 1 and II is similar to the cloud mass function of the parent molecular clouds. i.e.. a power-law with exponent a - 2. .A similar analysis for the Group III stars and associated molecular clouds cannot be performed due to the relatively small numbers in both samples. The star forming efficiency (SFE) in al1 cases is .- 1%. It is proposed that cloud-cioud collisions between the CO complexes in the region triggered the formation of Groups 1 and III. while Group II was produced by a shock induced by the radiation pressure and stellar winds frorn the stars in Group 1. An analysis of the molecular cloud structure in Cam OB1 and the background Perseus arm also shows t hat the clouds in bot h regions are turbulent . and typical of clouds seen elseshere in the Galauy. However. the clouds in Cam OB 1 show a large dispersion in the degree with which they are self-gravitating, wit h the Üi larger. warmer clouds being gravitat ionally bound. The principal data set for this work comprises full? sarnpled "CO (J=1-0) ob- servat ions of the western half of Cam OB 1, which were obtained at the Center for .\strophysics during the winter of 1992- 1993. These data have an effective resolu- tion of 10'. a velocity resolution of 0.65 km s-'. and a sensitivity of 0.115 K. High resoiution (20") observations of the '*CO (J=Z-1) transition of the most active star iorming region were obtained wit h the James Clerk 'ulaxwell Telescope during the winter of 1994-1995. These observations led to the discovery of a second outflow. XFGL 490 - iki. associated with IR-AS 03234+58453. in the immediate vicinity of the very well-st udied molecular out floa AFGL 490. Addit ional observations of the CH30H maser - 60.\f ). taken ivith the 26m telescope at the Dominion Radio .Astrophysical Observatory during the fa11 of 1994. did not reveal any such maser- ing activity in the Cam OB1 region. but did lead to the discovery of a new maser. associated \vit h IR.-\S 024.55+60:34. in the background Perseus arm. Table of Contents Title Page ................................ .. ...............*................*.i .. Abstract ...................................................................... 11 Table of Contents .............................................................v List of Tables ................................................................. ?c .. List of Figures ............................................................... ?cil .-\cknowLedgements .......................................................... ni Dedicat ion ..................................................................xix vi C hap ter ................................................................... Page Introduction .............................................................. 1 Chapter 1 General Overview of CO Observing ........................... 15 1. I Introduction .............................................1.5 1.2 Physical Principles ....................................... 16 1.3 Physical Quantities of Interest ........................... 25 1.3.1 Measured Physical Quantities ......................... -26 1.3.2 Derived Physical Quant it ies ........................... -29 1.4 Summary of Assumpt ions and Const raints ...............:32 Chapter 2 The Present Survey .......................................... 33 '1.1 Introduction ............................................. :33 2.2 The Cf.-\ Telescope ...................................... 34 2 .:3 The Observations ........................................39 2.3.1 Observing Procedure ...................................40 2.4 The Data ...............................................-43 2.4.1 6 rs . L' ................................................. 46 2.4.2 1 L'S . L' .................................................4s 2.4.3 1 rs . 6: Local Emission (+IO to - 5 km s-') ...........-50 2.4. 1 rs. 6: Cam OB1 Ernission (-5 to - 22 km s-' ) ........53 4 1 t*s. 6: Interarm Emission ( -22 to - 30 km s-' ) ........ar- - 2.4.6 1 rs . 6: Perseus Emission (-30 to - 70 km s-') .........59 2.4.7 1 as. 6: Outer Galaq- (-70 to - 130 km s-l) ........... 62 2.3 Conclusions ............................................. 64 Chapter 3 Why the New Survey? ....................................... 65 3.1 Introduction ............................................. 65 3.2 Cornparison of Original and Present Surveys ............. 65 vii 3.1 Qualitative Cornparison ................................ 67 3-22 A Quantitative Analyses ................... .. ......... .;I 5.2.2.1 -4 FFT Analysis of the CO Emission Structure ............................................-71 3.2.2.2 Structure Tree Statistics ............................. -79 13.3 Discussion ...............................................$4 .3.4 Conclusions ............................................. 87 Chapter 4 Population 1 Objects ......................................... as7 3 4.1 Introduction .............................................a3 1 -l 4.2 Population 1 Objects .....................................90 4-21 The Distance to the Local Emission .................... 90 4.2.2 The Distance to the Perseus Emission ..................9.3 4.2.3 The Distance to the Cam OB1 Emission ................96 4.3. 1 The Observer's HR Diagram for Cam OB 1 ............ 100 4.3.2 The Theoretician's HR Diagram for Cam OB1 ........ -107 4.4 Conclusions ............................................11:3 Chapter 5 Extrerne Population l Objects ............................... 115 3.1 lnt roduct ion ............................................115 5.2 Infrared Objects in Cam OBI ...........................117 .i 2.I Selection of Candidate Infrared Objects in Cam OB1 . 1i 7 5.2.2 The Sature of the Infrared Objects in Cam OBI ...... 125 5.3 ePIo Identified by their Optical or Radio Ernission ...... 134 5.4 Methanol 'LIasers ....................................... 110 5.4.1 Introduction .......................................... 140 5.4.2 Observations ..........................................14 1 .5. 4..3 Discussion ............................................144 viii 5.4.4 Conclusions Regarding Methanol !thsers .............. 147 5.5 1Iolecular Outflows ..................................... 148 5 ..5 .1 Introduction ..........................................148 .3 ..5 2 Observations ......................................... .lSO 3 ..5 ..3 Discussion ............................................ 15.3 5.5.3.1 General Properties of the CO Spectra ............... 153 S.5.3.2 AFGLJSO-iki ....................................... .l.54 5.5.4 Conclusion Regarding Outflows ....................... 1.3 5.6 Conclusions Regarding ePIo in Cam OB1 ............... 1-39 Chapter 6 On the Association of Cam OB1 Stars with Cam 081 !vIolecular Gas ...................................... 160 6.1 Introduction ........................................... -160 6.2 ~IorphologicalArguments .............................. -161 6.3 Physical Interaction between the Cam OB1 CO Emission - and Population I Objects ........................... 142 6.3.1 HII Regions ........................................... 172 6.3.2 Dust Warmed by the Cam OB1 Stan ................. 177 6.4 Conclusions ............................................ 1S.5 Chapter T Star Formation in Cam OB1 ................................ 186 7.1 Introduction ........................................... -186 7.2 The 'vIolecular Clouds and Cloud
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