Formation and evolution of giant molecular clouds in a barred spiral galaxy

• Material Type: 博士論文
• Title: Formation and evolution of giant molecular clouds in a barred spiral galaxy
• Author/Editor: 藤本, 裕輔
• Author Heading: 藤本, 裕輔
• Publication, Distribution, etc.: Hokkaido University
• Publication Date: 2016-03-24
• Publication Date (W3CDTF): 2016-03-24
• Alternative Title: 棒渦巻銀河における巨大分子雲の形成と進化
• Contributor: 羽部, 朝男; 小笹, 隆司; 倉本, 圭; 小林, 達夫; Tasker, Elizabeth; 岡本, 崇
• Degree grantor/type: 北海道大学
• Date Granted: 2016-03-24
• Date Granted (W3CDTF): 2016-03-24
• Dissertation Number: 甲第12238号
• Degree Type: 博士(理学)
• Conferring No. (Dissertation): 甲第12238号
• Text Language Code: eng
• NDC: 400
• Target Audience: 一般
• Note (General): Understanding where and how gas is converted into stars in a galaxy is important for under-standing a galaxy's formation and evolution through each epoch of the universe. Which physicalprocesses control the star formation in a galaxy is heavily debated.We are now at a stage where it is possible to investigate the giant molecular clouds (GMC)and star formation, while also taking global galactic dynamics into account. Thanks to highresolution and sensitive observations from sources such as the millimeter/submillimeter obser-vations by ALMA and infrared observations by Spitzer and Herschel, it is becoming possible tostatistically explore GMC and star forming regions through observations in nearby galaxies. Intheoretical works, we can also now investigate the formation and evolution of individual GMCsusing hydrodynamical isolated galaxy simulations with a self-consistent multiphase interstellarmedium (ISM) thanks to developments of super-computer and effective algorithms.Recent observations (high resolution, but not enough to resolve down to GMC scale yet)have shown the star formation activity changing between galactic-scale environments. The starformation efficiencies (SFEs) have systematic variations larger than one order of magnitudebetween different galaxy types and between different regions within a galaxy. This means thatthe gas density is not the only factor that determines the star formation activity in a galaxy.In particular, observations of barred galaxies showed that a central bar region has a lower SFEthan that in the spiral arm regions even when the gas surface densities are almost the same.Why does the star formation activity differ depending on the galactic structure's differentenvironments? This question is key to understanding the galactic-scale star formation and hasbeen the focus of my doctoral research. To understand this, it is important to investigate howthe formation and evolution of GMCs is affected by the galactic structures. This is becausethe GMCs are the star formation spots in a galaxy; they are formed from the cold phase of theISM, and their densest pockets are the birth place of stars.We performed three-dimensional hydrodynamical simulations of a barred spiral galaxy. Weclari ed that galactic environments and stellar feedbacks affect GMC formation and evolution,and that could explain the different star formation activities in a barred spiral galaxy. Theseworks consists of three parts. They are summarised below.; (主査) 教授 羽部 朝男, 教授 小笹 隆司, 教授 倉本 圭, 教授 小林 達夫, 助教 Elizabeth Tasker, 助教 岡本 崇; 理学院（宇宙理学専攻）
• DOI: 10.14943/doctoral.k12238; https://doi.org/10.14943/doctoral.k12238
• Persistent ID (NDL): info:ndljp/pid/9984752; https://dl.ndl.go.jp/pid/9984752
• Collection: 障害者向け資料
• Collection (Materials For Handicapped People:1): テキストデータ
• Collection (particular): 国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文; https://dl.ndl.go.jp/collections/A00014
• Acquisition Basis: 博士論文（自動収集）
• Date Accepted (W3CDTF): 2016-06-03T01:05:16+09:00
• Date Created (W3CDTF): 2016-03
• Format (IMT): PDF
• Access Restrictions: 国立国会図書館内限定公開
• Service for the Digitized Contents Transmission Service: 図書館・個人送信対象外
• Availability of remote photoduplication service: 可
• Periodical Title (URI): http://dx.doi.org/10.14943/doctoral.k12238; http://hdl.handle.net/2115/61705
• Is Referenced By (URI): http://hdl.handle.net/2115/61706
• Data Provider (Database): 国立国会図書館 : 国立国会図書館デジタルコレクション; https://dl.ndl.go.jp

• Summary, etc.: Understanding where and how gas is converted into stars in a galaxy is important for under-standing a galaxy's formation and evolution through each ep...