博碩士論文 92229008 詳細資訊




以作者查詢圖書館館藏 以作者查詢臺灣博碩士 以作者查詢全國書目 勘誤回報 、線上人數:12 、訪客IP:3.235.172.213
姓名 蕭文珊(Wen-Shan Hsiao)  查詢紙本館藏   畢業系所 天文研究所
論文名稱
(Identification of Herbig Ae/Be Starsin Open Clusters)
相關論文
★ 金牛座分子雲外圍之年輕恆星★ 濃密分子雲核中的紅外源
★ 球狀星團NGC288的運動狀態★ 利用2微米巡天觀測(2MASS)資料庫分析疏散星團之空間結構
★ 中美掩星計畫的光度資料分析★ 薔薇星雲中的X射線源
★ 銀河系球狀星團 M13 之中頻寬 CCD 光度測量及其恆星組成★ 毫米與次毫米波段的大質量恆星形成
★ 中美掩星計劃的掩星偵測和星場選擇★ 晚期恆星之環星物質的結構研究
★ 豺狼三分子雲中的年輕星球★ 塵粒成長對原行星盤能譜分佈演化之作用
★ OB星協裡的中低質量星球的形成★ 船底座星雲之多波段研究
★ 從中美掩星計畫資料裡計算古伯帶遮掩背景星的機率以及尋找變星★ RCW57 之近紅外偏極化影像觀測
檔案 [Endnote RIS 格式]    [Bibtex 格式]    [相關文章]   [文章引用]   [完整記錄]   [館藏目錄]   [檢視]  [下載]
  1. 本電子論文使用權限為同意立即開放。
  2. 已達開放權限電子全文僅授權使用者為學術研究之目的,進行個人非營利性質之檢索、閱讀、列印。
  3. 請遵守中華民國著作權法之相關規定,切勿任意重製、散佈、改作、轉貼、播送,以免觸法。

摘要(中) Herbig Ae/Be星是中質量的年輕星球,它們在主序前的演化速度快,使得我們所觀測到的數量,以及對這一類星球的了解,遠少於低質量年輕星球。在觀測上,Herbig Ae/Be星除了發射譜線,多數還具有紅外超量的特性;我們利用2MASS資料庫在疏散星團中挑選具有紅外超量的星球,並使用低色散光譜儀驗證這些Herbig Ae/Be候選星的譜型以及它們是否具有發射線。在觀測的11個候選星中,我們在星團Dolidze 16裡辨認出一個Herbig Ae星球,另外在其它星團裡則辨識出5個具有極大紅外超量的低質量年輕星球。最特別的乃是星團NGC 1857當中一顆具有Herbig Be星的特徵的B型星VES 888。我們的光度觀測顯示NGC 1857是個108.35年的中年星團,遠老於具有Herbig Be星之星團的年齡,因此推論VES 888為典型Be (classical Be) 恆星。它們的自轉接近碎裂速度(break-up velocity),且其光譜具有發射線,然而這一類型星球多數沒有明顯的紅外超量,突顯了 VES 888的特殊性。在恆星的演化上,VES 888接近主序帶的轉折點;另外二個在NGC 1857裡的典型 Be 恆星僅有少量的紅外超量,位在相對於VES 888較遠離轉折點的主序帶上。典型Be恆星的紅外超量,在多數的例子中是來自於高溫的自由離子躍遷過程產生的輻射,似乎隨著恆星漸漸離開主序帶的過程中增加:恆星風將外殼層物質吹離表面,加以高速的自轉,使得物質堆積在盤狀結構上,吸收中心恆星的光線再往外輻射,造成明顯的紅外超量現象。
摘要(英) Herbig Ae/Be stars are intermediate-mass young stars. The fast evolution in the premain sequence phase causes a much less number of-and hence relatively poorer knowledge toward|Herbig Ae/Be stars than that of low-mass young stars. In addition to the emission lines in the spectra, the Herbig Ae/Be stars are characterized by infrared excess. We utilized the 2MASS database to identify Herbig Ae/Be candidates in open clusters, and carried out low-dispersed spectroscopic observations to study the nature of these candidate stars. Out of 11 observed sources, we have found 1 Herbig Ae star in the open cluster Dolidze 16, and in other clusters 5 extremely red low-mass young stars. Most notable is the star VES888 in NGC1857. Our optical photometry suggests that the age of the cluster is about 108:35 years, too old to host a Herbig Ae/Be star. It turns out that VES888 is a classical Be star, which as a group is characterized by rapid rotation close to break-up and emission lines in their spectra. Typically however the classical Be stars are lacking in infrared excess, hence making VES888 a rare case. VES888 is near the main sequence turn-off, whereas two other classical Be stars in the cluster, with much weaker IR excess, are both in earlier evolutionary stages. The infrared excess in classical Be stars, while in most cases arising from thermal free-free emission, seems to be escalated when the star is evolving off the main sequence to pu up the stellar envelope, in a disk-like geometry because of the rapid rotation, in which the dust grains condense to reprocess stellar light to be responsible for the strong circumstellar infrared emission.
關鍵字(中) ★ 紅外超量
★ 中質量年輕星球
關鍵字(英) ★ Herbig Ae/Be stars
★ NGC 1857
★ classical Be stars
★ open clusters
★ IR excess
論文目次 1 Introduction 1
1.1 Star Formation and the Herbig Ae/Be stars...............1
1.2 Herbig Ae/Be Stars in Open Clusters.....................4
2 Target Selection and Observations 5
2.1 Target Selection........................................5
2.2 Observations............................................6
2.2.1 Spectroscopy..........................................6
2.2.2 Photometry............................................9
3 NGC 1857 and the Be Phenomena 10
3.1 Age and Distance of NGC 1857...........................12
3.2 Classical Be Stars in NGC 1857.........................15
3.3 Classical Be Stars.....................................17
3.4 Evolution of IR Excess Emission of Classical Be Stars..17
4 Conclution 20
Bibliography 22
Appendix A 24
A.1 NGC 2175...............................................24
A.2 Pismis 27..............................................27
A.3 Ivanov 2...............................................29
A.4 L1641C.................................................31
A.5 van den Bergh 92.......................................32
A.6 Dolidze 16.............................................35
參考文獻 Acke,B., van den Ancker,M.E. 2004, A&A, 426, 151
Bessell,M.S., Brett,J.M. 1988, PASP, 100, 1134
Bica,E., Dutra,C.M., Barbuy,B. 2003, A&A, 397, 177
Bohm,T., Balona,L.A. 2000, ASPC, 214, 103
Colegrove,T., Rogers,P., Rodrigue,M., Thompson,J., Schultz,A., Fink,U. 1994,
A&AS, 18510304C
Colegrove,P.T. 1999, Ph. D. Thesis, 164
Cuffey,J. 1937, BHarO, 905, 12
Davies,J.K., Evans,A., Bode M.F., Whittet,D.C.B. 1990, MNRAS, 247, 517
Dias,W.S., Alessi,B.S., Moitinho,A., Lepine,J.R.D. 2002, A&A, 389, 871
Dougherty,S.M., Taylor,A.R., Clark,T.A. 1999, AJ, 102, 1753
Fabregat,J., Torrejon,J.M. 2000, A&A, 357, 451
Fukagawa,M., Hayashi,M., Tamura,M., Itoh,Y., Hayashi,S.S., Oasa,Y.,
Takeuchi,T., Morino,J.I., Murakawa,K., Oya,S., Yamashita,T., Suto,H.,
Mayama,S., Naoi,T., Ishii,M., Pyo,T.S., Nishikawa,T., Takato,N., Usuda,T.,
Ando,H., Iye,M., Miyama,S.M., Kaifu,N. 2004, ApJL, 605, 53
Girardi,L., Bressan,A., Bertelli,G., Chiosi,C. 2000, A&AS, 141, 371
Haikala,L.K. 1995, A&A, 294, 89
Herbig,G.H. 1960, ApJS, 4, 337
Humphreys,R.M. 1978, ApJS, 38, 309
Ivanov,V.D., Borissova,J., Pessev,P., Ivanov,G.R., Kurtev,R. 2002, A&A, 394L, 1
Jacoby,G.H., Hunter,D.A., Christian,C.A. 1984, ApJS, 56, 257
Kawamura,A., Onishi,T., Yonekura,Y., Dobashi,K., Mizuno,A., Ogawa,H., Fukui,Y.
1998, ApJS, 117, 387
Kohoutek,L., Wehmeyer,R. 1999, A&AS, 134, 255
Lada,C.J., Lada,E.A. 2003, ARA&A, 41. 57
Meyer,M.R., Calvet,N., Hillenbrand,L.A. 1997, AJ, 114, 288
Negueruela,I., Marco,A. 2003, A&A, 406, 119
Palla,F., Stahler,S.W. 1993, ApJ, 418, 414
Pickles,A.J. 1998, PASP, 110, 863
Porras,A., Christopher,M., Allen,L., Di Francesco,J., Megeath,S.T., Myers,P.
2003, AJ, 126, 1916
Porter,J.M., Rivinius,T. 2003, PASP, 115. 1153
Shevchenko,V.S., Ezhkova,O.V., Ibrahimov,M.A., van den Ancker,M.E., Tjin A
Djie,H.R.E. 1999, MNRAS, 310, 210
Slettebak,A. 1985, ApJS, 59, 769
Soares,J.B., Bica,E. 2002, A&A, 388, 172
Soares,J.B., Bica,E. 2003, A&A, 404, 217
Strom,S.E., Strom,K.M., Yost,J. 1972, ApJ, 173, 353
Testi,L., Palla,F., Natta,A. 1999, A&A, 342, 515
The,P.S., de Winter D., P erez,M.R. 1994, A&AS, 104, 315
Waters,L.B.F.M., Waelkens,C. 1998, ARA&A, 36, 233
Zhang,P., Chen,P.S., Yang,H.T. 2005, NewA, 10, 325
指導教授 陳文屏(Wen-Ping Chen) 審核日期 2006-7-17
推文 facebook   plurk   twitter   funp   google   live   udn   HD   myshare   reddit   netvibes   friend   youpush   delicious   baidu   
網路書籤 Google bookmarks   del.icio.us   hemidemi   myshare   

若有論文相關問題,請聯絡國立中央大學圖書館推廣服務組 TEL:(03)422-7151轉57407,或E-mail聯絡  - 隱私權政策聲明