跳到主要內容

簡易檢索 / 詳目顯示

研究生: 蘇裕農
Yu-Nung Su
論文名稱: 毫米與次毫米波段的大質量恆星形成
Massive Star Formation at Millimeter and Submillimeter Wavelengths
指導教授: 陳文屏
Wen-Ping Chen
林仁良
Jeremy Lim
口試委員:
學位類別: 博士
Doctor
系所名稱: 理學院 - 天文研究所
Graduate Institute of Astronomy
畢業學年度: 92
語文別: 英文
論文頁數: 160
中文關鍵詞: 原恆星恆星形成氫離子區星際介質大質量恆星
外文關鍵詞: star formation, HII region, intestellar medium, high-mass star, protostar
相關次數: 點閱:17下載:0
分享至:
查詢本校圖書館目錄 查詢臺灣博碩士論文知識加值系統 勘誤回報
  • None


    Abstract
    This dissertation investigates massive star Formation in the Milky Way via millimeter and submillimeter observations of luminous young stellar objects.
    First, I describe a snapshot continuum and multi-molecular-line survey with the BIMA array aimed at characterizing very young high-mass stars. The target sample consists of eleven luminous IRAS sources associated with very young ultracompact (UC) HII regions, which have weak cm-wave flux densities and very compact angular sizes despite their small (kinematic) distances. In this
    way, I hope to preferentially select and study extremely young high-mass stars. Most of the 3 millimeter continuum emission shows multiple components, which is consistent with the picture of a clustered formation mode of massive stars. I identify five 3 mm dust sources as good candidates for high-mass protostars because
    they are coincident in position with their luminous IRAS counterparts and dense molecular gas as traced by H13CO+ emission, yet not detected at 3.6 cm. The typical dust and gas
    mass of the 3 mm components is a few tens M_sun, while the 3 mm components with centimeter counterparts are ~5 times less massive than those not associated with centimeter continuum, suggesting that some 3 mm sources with centimeter counterparts may relate to very young intermediate-mass stars. On the other hand,
    due to the relatively weak centimeter luminosity of a few mJy kpc^2, some target centimeter continuum sources could correspond to stellar winds/jets rather than real HII . Furthermore,
    I present near-IR photometry of the target compact centimeter sources obtained from the new released Two Micron All Sky Survey archival data.
    Second, I present millimeter observations with the BIMA array of the bipolar molecular outflows associated with the luminous far-IR sources IRAS
    21519+5613 and IRAS 22506+5944. Although outflows have been identified as a common occurrence in the formation of both high-and low-mass stars, only about ten molecular outflows associated
    with luminous young stellar objects have been studied in high angular resolutions (<10"). I find that the outflow associated with each IRAS source shows a clear bipolar morphology in 12CO, with properties (i.e., total mass of order 10-100
    M_sun, mass-outflow rate >10^-3 M_sun yr^-1, dynamical timescale 10^4-10^5 yrs, and
    energetics) comparable with those of other massive outflows associated with luminous young stellar objects. Each outflow appears to be centered on a dust and gas condensation with a mass of 200-300 M_sun, likely marking the location of the driving source. The mass-velocity diagrams of both outflows change in slope at a velocity of ~10 km s^-1, suggesting that
    the high-velocity component (HVC) may drive the low-velocity component (LVC). Neither HVC has a momentum supply rate sufficient to drive their corresponding LVCs, and as for other molecular
    outflows the primary driving agent cannot be ionized gas, leaving atomic gas as the other remaining candidate.
    Finally, I present a first glimpse at the small-scale distribution of dust around UC HII regions and high-mass protostellar objects (HMPOs) at 0.85 mm made with the Submillimeter Array (SMA), and investigate whether HMPOs and UC HII regions can serve as useful gain calibrators for the SMA. The SMA observations with an angular resolution of ~3" reveal that although a large fraction of the dust emission originates from an extended ``halo'' component, a compact unresolved component often remains that when sufficiently strong may serve as a useful calibrator. I discuss
    the origin of the core-halo structure seen in many sources and conclude with suggestions for future searches for calibrators with the SMA.

    Abstract iii List of Figures ix List of Tables xi 1 Background and Motivation 1 1.1 Models of High-Mass Star Formation . . . . . . . . . . . . . . . . . . 3 1.2 Observational Perspectives . . . . . . . . . . . . . . . . . . . . . . 5 1.2.1 Centimeter Free-Free Emission — Ultracompact HII Regions 7 1.2.2 Hot Molecular Cores . . . . . . . . . . . . . . . . . . . . . . . 10 1.2.3 Sub-Millimeter Continuum — Dust Cocoons . . . . . . . . . 10 1.2.4 Maser Phenomena . . . . . . . . . . . . . . . . . . . . . . . . 12 1.2.5 Molecular Outflows . . . . . . . . . . . . . . . . . . . . . . . 15 1.2.6 Mid-Infrared Emission . . . . . . . . . . . . . . . . . . . . . . 16 1.3 Motivation and Outline of this Thesis . . . . . . . . . . . . . . . . 17 2 Young Ultracompact HII Regions and High-Mass Protostars 21 2.1 ntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.1.1 Molinari et al. (1996, 1998a, 2000, 2002) . . . . . . . . . . . . 22 2.1.2 Sridharan et al. (2002) & Beuther et al. (2002a) . . . . . . . . 24 2.1.3 Overview of This Work . . . . . . . . . . . . . . . . . . . . . . 26 2.2 The Sample & Observations . . . . . . . . . . . . . . . . . . . . . . 27 2.2.1 The Sample . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.2.2 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . 32 2.3 3 Millimeter Continuum Emission . . . . . . . . . . . . . . . . . . . 34 2.3.1 Radiation Mechanisms — Free-Free or Dust Emission . . . . 37 2.3.2 Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 2.4 H13CO+ Emission . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 2.4.1 Structure & Kinematics . . . . . . . . . . . . . . . . . . . . . 42 2.4.2 Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48 2.5 Near-Infrared Emission — the 2MASS Data . . . . . . . . . . . . . . 48 2.6 The Nature of Centimeter Continuum Emission . . . . . . . . . . . . 50 2.6.1 Radio Jets associated with YSOs . . . . . . . . . . . . . . . . 54 2.6.2 Emission Mechanisms — UV Radiation or Jets/Winds . . . . 55 2.6.3 Radio Continuum Emission without 3 mm Dust Counterparts 57 2.6.4 Radio Continuum Emission with Near-IR Counterparts . . . . 58 2.7 Candidates of High-Mass Protostar . . . . . . . . . . . . . . . . . . 59 2.8 The Nature of 3 mm Sources . . . . . . . . . . . . . . . . . . . . . .62 2.9 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 3 Bipolar Molecular Outflows from High-Mass Protostars 65 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 3.2 Observations & Data Reduction . . . . . . . . . . . . . . . . . . . . 69 3.2.1 BIMA array and NRAO 12 m Telescope . . . . . . . . . . . . 69 3.2.2 Combining Single-dish and Interferometric Data . . . . . . . 70 3.3 Dust and Molecular Gas Condensation . . . . . . . . . . . . . . . . . 72 3.3.1 Structure and Kinematics . . . . . . . . . . . . . . . . . . . . 72 3.3.2 Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73 3.4 Bipolar Molecular Outflows . . . . . . . . . . . . . . . . . . . . . 74 3.4.1 Structure and Kinematics . . . . . . . . . . . . . . . . . . . . 74 3.4.2 Physical Properties . . . . . . . . . . . . . . . . . . . . . . . 81 3.4.3 Mass/Position vs Velocity . . . . . . . . . . . . . . . . . . . . 87 3.5 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 3.5.1 Outflow Properties . . . . . . . . . . . . . . . . . . . . . . . .90 3.5.2 Outflow Driving Sources . . . . . . . . . . . . . . . . . . . . . 92 3.5.3 Outflow Driving Agents . . . . . . . . . . . . . . . . . . . . . 95 3.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98 4 In Search of SMA Calibrators 101 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 4.2 Observations . . . . . . . . . . . . . . . . . . . . . . . . . . . .103 4.2.1 Sample Selection and Observational Strategy . . . . . . . . . 103 4.2.2 Observational Parameters . . . . . . . . . . . . . . . . . . . . 104 4.3 Structure of the 0.85 mm Continuum Emission . . . . . . . . . . . . .107 4.4 Suitability as Calibrators . . . . . . . . . . . . . . . . . . . . . 112 4.5 Dust Distribution of UC H.418ptII Regions and HMPOs . . . . . . . 115 4.6 Discussion of Individual Sources . . . . . . . . . . . . . . . . . . 116 4.6.1 G10.841–2.592 . . . . . . . . . . . . . . . . . . . . . . . . . 116 4.6.2 G45.07+0.13 . . . . . . . . . . . . . . . . . . . . . . . . . . .118 4.7 Future Directions . . . . . . . . . . . . . . . . . . . . . . . . . .119 5 Conclusion 121 Bibliography 125 Appendix Comments on Individual Candidate HMPO Sources 135 A.1 IRAS 02575+6017 . . . . . . . . . . . . . . . . . . . . . . . . . . .135 A.2 IRAS 06056+2131 . . . . . . . . . . . . . . . . . . . . . . . . . . .140 A.3 IRAS 06058+2138 . . . . . . . . . . . . . . . . . . . . . . . . . . .143 A.4 IRAS 20350+4126 . . . . . . . . . . . . . . . . . . . . . . . . . . .146 A.5 IRAS 22551+6221 . . . . . . . . . . . . . . . . . . . . . . . . . . .148

    Altenho®, W. J., Downes, D., Pauls, T., & Schraml, J. 1979, A&AS, 35, 23
    Andr´e, P., Montmerle, T., & Feigelson, E. D. 1987, AJ, 93, 1182
    Anglada, G. 1995, in Circumstellar Disks, Outflows and Star Formation, ed. S. Lizano & J. M. Torrelles (Rev. Mexicana Astron. Astrofis. Ser. Conf. 1) (Mexico, D.F.:Inst. Astron., Univ. Nac. Autonoma Mexico), 67
    Anglada, G., Estalella, R., Pastor, J., Rodriguez, L. F., & Haschick, A. D. 1996, ApJ, 463, 205
    Anglada, G. 1996, in ASP Conf. Ser. 93, Radio Emission from the Stars and the Sun, ed. A. R. Taylor & J. M. Paredes (San Francisco: ASP), 3
    Araya, E., Hofner, P., Churchwell, E., & Kurtz, S. 2002, ApJS, 138, 63
    Aso, Y., Tatematsu, K., Sekimoto, Y., Nakano, T., Umemoto, T., Koyama, K., &
    Yamamoto, S. 2000, ApJS, 131, 465
    Bachiller, R., Cernicharo, J., Mart´ın-Pintado, J., Tafalla, M., & Lazare®, B. 1990, A&A, 231, 174
    Bachiller, R., Mart´ın-Pintado, J., & Planesas, P. 1991, A&A, 251, 639
    Bachiller, R. & Tafalla M. 1999, in The Origin of Stars and Planetary Systems, ed. C. J. Lada & N. D. Kylafis (NATO ASI Ser. C, 540 Dordrecht: Kluwer), 227
    Barsony, M. 1989, ApJ, 345, 268
    Barsony, M., Scoville, N. Z., Bally, J., & Claussen, M. J. 1989, ApJ, 343, 212
    Baudry, A., Desmurs, J. F., Wilson, T. L., & Cohen, R. J. 1997, A&A, 325, 255
    Beichman, C. A., Myers, P. C., Emerson, J. P., Harris, S., Mathieu, R., Benson, P.J., & Jennings, R. E. 1986, ApJ, 307, 337
    Beichman, C. A., Neugebauer, G., Habing, H. J., Clegg, P. E., & Chester, T. J.,
    eds. 1988, IRAS Catalogs and AtlasesExplanatory Supplement (NASA RP-1190)
    (Washington, DC: GPO)
    Beuther, H., Kramer, C., Deiss, B., & Stutzk, J. 2000, A&A, 362, 1109
    Beuther, H., Schilke, P., Menten, K. M., Motte, F., Sridharan, T. K., & Wyrowski,F 2002a, ApJ, 566, 945
    Beuther, H., Schilke, P., Sridharan, T. K., Menten, K. M., Wamsley, C. M., &
    Wyrowski, F. 2002b, A&A, 383, 892
    Beuther, H., Schilke, P., Gueth, F., McCaughrean, M., Andersen, M., Sridharan, T.K., & Menten, K. M. 2002c, A&A, 387, 931
    Beuther, H., Schilke, P., & Stanke, T. 2003, A&A, 408, 601
    Beuther, H., Hunter, T., Zhang, Q., Sridharan, T. K., Zhao, J.-H., Sollins, P., Moran,J., Ho, P., Ohashi, N., Liu, S.-Y., Lim, J., & Su, Y.-N. 2004a, ApJ, in press
    Beuther, H., Schilke, P., & Wyrwoski, F., 2004b, ApJ, in press
    Bonnell, I. A., Bate, M. R., & Zinnecker, H. 1998, MNRAS, 298, 93
    Bonnell, I. A. 2002, in ASP Conf. Ser. 267, Hot Star Workshop III: The Earliest
    Stages of Massive Star Birth, ed. P. A. Crowther (San Francisco: ASP), 193
    Brand, J., Cesaroni, R., Palla, F., & Molinari, S. 2001, A&A, 370, 230
    Bridle, A. H. 1989, in ASP Conf. Proc. 6, Synthesis Imaging in Radio Astronomy, ed. R. A. Perley, F. R. Schwab, & A. H. Bridle (San Francisco: ASP), 443
    Bronfman, L., Nyman, L.-A., & May, J. 1996, A&AS, 115, 81
    Cabrit, S., & Bertout, C. 1992, A&A, 261, 274
    Carpenter, J. M., Snell, R. L., Schloerb, F. P., & Skrutskie, M. F. 1993, ApJ, 407,657
    Caswell, J. L.. Vaile, R. A., Ellingsen, S. P., Whiteoak, J. B., & Norris, R. P. 1995, MNRAS, 272, 96
    Cesaroni, R., Churchwell, E., Hofner, P., Walmsley, C. M., & Kurtz, S. 1994, A&A, 288, 903
    Cesaroni, R., Felli, M., Testi, L., Walmsley, C. M., & Olmi, L. 1997, A&A, 325, 725
    Cesaroni, R., Hofner, P., Walmsley, C. M., & Churchwell, E. 1998, A&A, 331, 709
    Churchwell, E., Walmsley, C. M., & Cesaroni, R. 1990, A&AS, 83, 119
    Churchwell, E. 1991, in The Physics of Star Formation and Early Stellar Evolution, ed. C. J. Lada & N. D. Kylafis (Dordrecht: Kluwer), 221
    Churchwell, E. 1997, ApJ, 479, L59
    Churchwell, E. 1999, in The Origin of Stars and Planetary Systems, ed. C. J. Lada & N. D. Kylafis (NATO ASI Ser. C, 540 Dordrecht: Kluwer), 515
    Churchwell, E. 2002, ARA&A, 40, 27
    Codella, C., Felli, M., & Natale, V. 1996, A&A, 311, 971
    Cohen, R. J., Baart, E. E., & Jonas, J. L. 1988, MNRAS, 231, 205
    Conti, P., & Blum, R. D. 2002, ApJ, 564, 827
    Davis, C. J., Moriarty-Schieven, G., Eisl¨o®el, J., Hoare, M. G., & Ray, T. P. 1998, AJ, 115, 1118
    De Buizer, J. M., Watson, A. M., Radomski, J. T., Pi˜na, R. K., & Telesco, C. M. 2002, ApJ, 564, L101
    De Buizer, J. M., Radomski, J. T., Telesco, C. M., & Pi˜na, R. K. 2003, ApJ, 598, 1127
    Deharveng, L., Zavagno, A., Cruz-Gonzalez, I., Salas, L., Caplan, J., & Carrasco, L. 1997, A&A, 317, 459
    De Pree, C. G., Rodr´ıuez, L. F., & Goss, W. M. 1995, Rev. Mexicana Astron. Astrofis.,31, 39
    Felli, M., Massi, M., Staude, H. J., Reddmann, T., Eiroa, C., Hefele, H., Neckel, T.,& Panagia, N. 1984, A&A, 135, 261
    Forster, J. R., & Caswell, J. L. 2000, ApJ, 530, 371
    Fuente, A., Martin-Pintado, J., Bachiller, R., Neri, R., & Palla, F. 1998, A&A, 334, 253
    Garay, G., Reid, M. J., & Moran, J. M. 1985, ApJ, 289, 681
    Garay, G., Rodr´ıguez, L. F., & van Gorkom, J. H. 1986, ApJ, 309, 553
    Garay, G., Lizano, S., & G´omez, Y. 1994, ApJ, 429, 268
    Garay, G., Ram´ırez, S., Rodr´ıguez, L. F., Curiel, S., & Torrelles, J. M. 1996, ApJ, 459, 193
    Garay, G., & Lizano, S. 1999, PASP, 111, 1049
    Giovanardi, C., Rodr´ıguez, L. F., Lizano, S., & Cant´o, J. 2000, ApJ, 538, 728
    G´omez, J. F., Torrelles, J. M., Estalella, R., Anglada, G., Verdes-Montenegro, L., & Ho, P. T. P. 1992, ApJ, 397, 492
    Gomez, Y., Garay, G., & Lizano, S. 1995a, ApJ, 453, 727
    G´omez, Y. Rodr´ıguez, & Mart´ı, J. 1995b, ApJ, 453, 268
    G´omez, J. F., Sargent, A. I., Torrelles, J. M., Ho, P. T. P., Rodr´ıguez, L. F., Cant´o, J., & Garay, G. 1999, ApJ, 514, 287
    G´omez, Y. Rodr´ıguez, L. F., Girart, J. M., Garay, G., & Mart´ı, J. 2003, ApJ, 597, 414
    Gregory, P. C., & Condon, J. J. 1991, ApJS, 75, 1011
    Gri±th, M. R., Wright, A. E., Burke, B. F., & Ekers, R. D. 1994, ApJS, 90, 179
    Han, F., Mao, R. Q., Lu, J., Wu, Y. F., Sun, J., Wang, J. S., Pei, C. C., Fan, Y., Tang, G. S., & Ji, H. R. 1998, A&AS, 127, 181
    Hanson, M. M., Luhman, K. L., & Rieke, G. H. 2002, ApJS, 138, 35
    Harvey, D. W. A., Wilner, D. J., Di Francesco, J., Lee, C. W., Myers, P. C., &
    Williams, Jonathan P. 2002, AJ, 123, 3325
    Hatchell, J. private communication
    Hatchell, J., Fuller, G. A., Millar, T. J., Thompson, M. A., & Macdonald, G. H. 2000, A&A, 357, 637
    Haynes, R. F., Caswell, J. L., & Simons, L. W. J. 1979, Australian J. Phys. Astrophys. Suppl., 48, 1
    Heathcote, S., Reipurth, B., & Raga, A. C. 1998, AJ, 116, 1940
    Heaton, B. D., Little, L. T., & Bishop, I. S. 1989, A&A, 213, 148
    Henkel, C., Guesten, R., & Haschick, A. D. 1986, A&A, 165, 197
    Hildebrand, R. H. 1983, QJRAS, 24, 267
    Hillenbrand, L. A. 1997, AJ, 113, 1733
    Hillenbrand, L. A. & Hartmann, L. W. 1998, ApJ, 492, 540
    Ho, P. T. P. & Haschick, A. D. 1981, ApJ, 248, 622
    Ho, P. T. P., Moran, J., Lo, K. Y. 2004, ApJ, in press
    Hodapp, K. W. 1994, ApJS, 94, 615
    Ho®mann, W. F., Hora, J. L., Fazio, G. G., Deutsch, L. K., & Dayal, A. 1998, Proc.SPIE, 3354, 647
    Hofner, P. & Churchwell, E. 1996, A&AS, 120, 283
    Hofner, P., Cesaroni, R., Rodr´ıguez, L. F., & Mart´ı, J. 1999 A&A, 345, L43
    Hogerheijde, M. R., van Dishoeck, E. F., Blake, G. A., & van Langevelde, H. J. 1998, ApJ, 502, 315
    Holland, W. S., Robson, E. I., Gear, W. K., Cunningham, C. R., Lightfoot, J. F.,
    Jenness, T., Ivison, R. J., Stevens, J. A., Ade, P. A. R., Gri±n, M. J., Duncan, W. D., Murphy, J. A., & Naylor, D. A. Holland W.S., Robson E.I., Gear W.K. 1999, MNRAS, 303, 659
    Hughes V. A. 1988, ApJ, 433, 788
    Hunter, T. R., Benford, D. J., & Serabyn, E. 1996, PASP, 108, 1042
    Hunter, T. 1997, Ph.D. Thesis, CalTech
    Hunter, T. R., Neugebauer, G., Benford, D. J., Matthews, K., Lis, D. C., Serabyn, E., & Phillips, T. G. 1998, ApJ, 493, 97
    Hunter, T. R., Churchwell, E., Watson, C., Cox, P., Benford, D. J., & Roelfsema, P. R. 2000, AJ, 119, 2711
    Hutawarakorn, B. & Cohen, R. J. 2003, MNRAS, 345, 175
    Jenness, T., Scott, P. F., & Padman, R. 1995, MNRAS, 276, 1024
    Jijina, J. & Adams, F. C. 1996, ApJ, 462, 874
    Keto, E. 2002a, ApJ, 580, 980
    Keto, E. 2002b, ApJ, 568, 754
    K¨ompe, C., Joncas, G., Baudry, A., & Wouteerloot, J. G. A. 1989, A&A, 221, 295
    Kraemer, K. E., Jackson, J. M., Deutsch, L. K., Hora, J. L., Fazio, G. G.,
    Ho®mann, W. F., & Dayal, A. 2001, ApJ, 561, 282
    Kraemer, K. E., Jackson, J. M., Kassis, M., Deutsch, L. K., Hora, J. L., Simon, R., Ho®mann, W. F., Fazio, G. G.; Dayal, A., Bania, T. M., Clemens, D. P., & Heyer, M. H. 2003, ApJ, 588, 918
    Kramer, C., Alves, J., Lada, C., Lada, E., Sievers, A., Ungerechts, H., & Walmsley, M. 1998, A&A, 329, L33
    Kreysa, E., Gemuend, H.-P., Gromke, J., Haslam, C. G., Reichertz, L., Haller, E. E., Beeman, J. W., Hansen, V., Sievers, A., & Zylka, R. 1998, Proc. SPIE, 3357, 319
    Kurtz, S., Churchwell, E., & Woods, D. O. S. 1994, ApJS, 91, 659
    Kurtz, S., Cesaroni, R., Churchwell, E., Hofner, P., & Walmsley, C. M. 2000, in
    Protostars and Planets IV, ed. V. Mannings, A. P. Boss, & S. S. Russell, S. S.
    (Tucson: Univ. Arizonia Press), 299
    Lada, C. J. & Fich M. 1996, ApJ, 459, 638
    Lada, C. J. 1999, in The Origin of Stars and Planetary Systems, ed. C. J. Lada & N. D. Kylafis (Dordrecht: Kluwer), 143
    Larson, R. B., & Starrfield, S. 1971, A&A, 13, 190
    MacLeod, G. C. 1991, MNRAS, 252, 36
    MacLeod, G. C., van der Walt, D. J, North, A., Gaylard, M. J., Galt, J. A., &
    Moriarty-Schieven, G. H. 1998, AJ, 116, 2936
    Mars´alkov´a, P. 1974, Ap&SS, 27, 3
    Mart´ı, J., Rodr´ıguez, L. F., & Reipurth, B. 1993, ApJ, 416, 208
    Mart´ı, J., Rodr´ıguez, L. F., & Reipurth, B. 1995, ApJ, 449, 184
    Mart´ı, J., Rodr´ıguez, L. F., & Reipurth, B. 1998, ApJ, 502, 337
    Mart´ı, J., Rodr´ıguez, L. F., & Torrelles, J. M. 1999, A&A, 345, L5
    Masson, C. R., & Chernin, L. M. 1993, ApJ, 414, 230
    Masson, C. R. 1994, in ASP Conf. Ser. 59, Astronomy with Millimeter and Submillimeter Wave Interferometry, ed. M. Ishiguro & W. J. Welch (San Francisco: ASP), 87
    McKee, C. F., & Tan, J. C. 2003, ApJ, 585, 850
    McLaughlin, D. E., & Pudritz, R. E. 1997, A&A, 476, 750
    Megeath, S. T., Herter, T., Beichman, C., Gautier, N., Hester, J. J., Rayner, J., & Shupe, D. 1996, A&A, 307, 775
    Meyers-Rice, B. A., & Lada, C. J. 1991, ApJ, 368, 445
    Migenes, V., Horiuchi, S., Slysh, V. I., Val’tts, I. E., Golubev, V. V., Edwards, P. G., Fomalont, E. B., Okayasu, R., Diamond, P. J., Umemoto, T., Shibata, K. M., & Inoue, M. 1999, ApJS, 123, 487
    Minier, V., Conway, J. E., & Booth, R. S. 2001, A&A, 369, 278
    Molinari, S., Brand, J., Cesaroni, R., & Palla, F. 1996, A&A, 308, 573
    Molinari, S., Brand, J., Cesaroni, R., Palla, F., & Palumbo, G. G. C. 1998a,
    A&A, 336, 339
    Molinari, S., Testi, L., Brand, J., Cesaroni, R., & Palla, F. 1998b, ApJ, 505, L39
    Molinari, S., Brand, J., Cesaroni, R., & Palla, F. 2000, A&A, 355, 617
    Molinari, S., Testi, L., Rodriguez, L. F., & Zhang, Q. 2002, ApJ, 570, 758
    Motte, F., & Andr´e, P. 2001, A&A, 365, 440
    Motte, F., Schilke, P., & Lis, D. C. 2003, ApJ, 582, 277
    Mueller, K. E., Shirley, Y. L., Evans, N. J., II, & Jacobson, H. R. 2002, ApJS, 143, 469
    Myers, P. 1995, in Molecular Clouds and Star Formation, ed. C. Yuan & J. You
    (Singapore: World Scientific), 47
    Olmi L. & Felli M., 1998, A&A, 339, 872
    Panagia, N. & Felli, M. 1975 A&A, 39, 1
    Palagi, F., Cesaroni, R., Comoretto, G., Felli, M., & Natale, V. 1993, A&AS, 101, 153
    Palla, F., Brand, J., Comoretto, G., Felli, M., & Cesaroni, R. 1991, A&A, 246, 249
    Palla, F., & Stahler, S.W. 1993, ApJ, 418, 414
    Plume, R., Ja®e, D. T., Evans, N. J., II, Martin-Pintado, J., & Gomez-Gonzalez, J. 1997, ApJ, 476, 730
    Raga, A. & Cabrit, S. 1993 A&A, 278, 267
    Reynolds, S. P. 1986, ApJ, 304, 713
    Richards, P. J., Little, L. T., Toriseva, M., & Heaton, B. D. 1987, MNRAS, 228, 43
    Richer, J. S., Padman, R., Ward-Thompson, D., Hills, R. E., & Harris, A. I. 1993, MNRAS, 262, 839
    Richer, J. S., Shepherd, D. S., Cabrit, S., Bachiller, R., & Churchwell, E. 2000, in Protostars and Planets IV, ed. V. Mannings, A. P. Boss, & S. S. Russell, (Tucson:Univ. Arizona Press), 867
    Rodr´ıguez, L. F., Garay, G., Curiel, S., Ram´ırez, S., Torrelles, J. M., G´omez, Y., & Vel´azquez, A. 1994 ApJ, 430, L65
    Saito, M., Kawabe, R., Kitamura, Y., & Sunada, K. 2001, ApJ, 547, 840
    Sandell, G. 1994 MNRAS, 271, 75
    Schmidt-Kaler, T. 1982, in Landolt-B¨ornstein, New Series, Group, VI, Vol. 2, ed. K. Schaifers & H. H. Voigt (Berlin:Springer-Verlag), 1
    Schreyer, K., Henning, Th., K¨ompe, C.,& Harjunp¨aa, P. 1996, A&A, 306, 267
    Scoville, N. Z., Sargent, A. I., Sanders, D. B., Claussen, M. J., Masson, C. R., Lo, K. Y., & Phillips, T. G. 1986, ApJ, 303, 416
    Scoville, N. Z., Carlstrom, J. E., Chandler, C. J., Phillips, J. A., Scott, S. L., Tilanus, R. P. J., & Wang, Z. 1993, PASP, 105, 1482
    Shepherd, D. S. & Churchwell, E. 1996a, ApJ, 457, 267
    Shepherd, D. S. & Churchwell, E. 1996b, ApJ, 472, 225
    Shepherd, D. S., Watson, A. M., Sargent, A. I., & Churchwell, E. 1998, ApJ, 507, 861
    Shepherd, D. S., & Kurtz, S. E. 1999 ApJ, 523, 690
    Shepherd, D. S., Claussen, M. J., & Kurtz, S. E. 2001, science, 292, 1513
    Shepherd, D. S., & Watson, A. M. 2002 ApJ, 566, 966
    Shepherd, D. S., Testi, L., & Stark, D. P. 2003 ApJ, 584, 882
    Shirley, Y. L., Evans, N. J., II & Rawlings, J. M. C. 2002, ApJ, 575, 337
    Shirley, Y. L., Evans, N. J., II, Young, K. E., Knez, C. & Ja®e, D. T. 2003,
    ApJS, 149, 375
    Shu, F. H. 1977, ApJ, 214, 488
    Shu, F. H., Adams, F. C., & Lizano, S. 1987, ARA&A, 25, 23
    Shu, F. H., Ruden, S. P., Lada, C. J., & Lizano, S. 1991, ApJ, 370, L31
    Shu, F. H., Najita, J. R., Shang, H., & Li, Z.-Y. 2000, in Protostars and Planets IV, ed. V. Mannings, A. P. Boss, & S. S. Russell, (Tucson: Univ. Arizona Press), 789
    Skinner, S. L., Brown, A., & Stewart, R. T. 1993, ApJS, 87, 217
    Skrutskie, M. F., et al. 1997, in The Impact of Large-Scale Near-IR Sky Surveys, ed. F. Garzon et al. (Dordrecht: Kluwer), 25
    Slysh, V. I., Val’tts, I. E., Kalenskii, S. V., Voronkov, M. A., Palagi, F., Tofani, G., & Catarzi, M. 1999, A&AS, 134, 115
    Snell, R. L., Huang, Y. L., Dickman, R. L., & Claussen, M. J. 1988, ApJ, 325, 853
    Stahler, S. W., Palla, F., & Ho, P. T. P. 2000, in Protostars and Planets IV, ed. V. Mannings, A. P. Boss, & S. S. Russell, (Tucson: Univ. Arizona Press), 327
    Sridharan, T. K., Beuther, H., Schilke, P., Menten, K. M., & Wyrowski, F. 2002,
    ApJ, 566, 931
    Stecklum, B., Brandl, B., Henning, Th., Pascucci, I., Hayward, T. L., & Wilson, J. C. 2002, A&A, 392, 1025
    Su, Y.-N., Zhang, Q., & Lim, J. 2004a, ApJ, 604, 258
    Su, Y.-N., Liu, S. -Y., Lim, J., Ohashi, N., Beuther, H., Zhang, Q., Sollins, P., Hunter, T., Sridharan, T. K., Zhao, J.-H., & Ho, P. T. P., 2004b, ApJ, in press
    Sugitani, K., Matsuo, H., Nakano, M., Tamura, M., & Ogura, K. 2000, AJ, 119, 323
    Szymczak, M., Hrynek, G., & Kus, A. J. 2000a, A&AS, 143, 269
    Szymczak, M., Kus, A. J., & Hrynek, G. 2000b, MNRAS, 312, 211
    Tamura, M., Gatley, I., Joyce, R. R., Ueno, M., Suto, H., & Sekiguchi, M. 1991, ApJ, 378, 611
    Testi L., Olmi L., Hunt L., Tofani, G., Felli, M., & Goldsmith, P. 1995, A&A, 303, 881
    Tofani, G., Felli, M., Taylor, G. B., & Hunter, T. R. 1995, A&AS, 112, 299
    Torrelles, J. M., G´omez, J. F., Anglada, G., Estalella, R., Mauersberger, R., & Eiroa, C. 1992, ApJ, 392, 616
    Torrelles, J. M., Verdes-Montenegro, L., Ho, P. T. P., Rodr´ıguez, L. F., & Cant´o, J. 1993, ApJ, 410, 202
    Torrelles, J. M., G´omez, J. F., Garay, G., Rodr´ıguez, L. F., Curiel, S., Cohen, R. J., & Ho, P. T. P. 1998, ApJ, 509, 262
    Turner, B. E. & Matthews, H. E. 1984, ApJ, 277, 164
    Van Buren, D., Mac Low, M.-M., Wood, D. O. S., & Churchwell, E. 1990, ApJ, 353,
    570
    Van der Tak, F. F. S., van Dishoeck, E. F., Evans, N. J., II, & Blake, G. A. 2000, ApJ, 537, 283
    Van Dishoeck, E. F., & Hogerheijde, M. R. 1999, in The Origin of Stars and Planetary Systems, ed. C. J. Lada & N. D. Kylafis (Dordrecht: Kluwer), 97
    Vogel, S. N., Wright, M. C. H., Plambeck, R. L., & Welch, W. J. 1984, ApJ, 283, 655
    Walmsley, M. 1995, Rev. Mexicana de Astron. Astrofis. Ser. de Conf., 1, 137
    Walsh, A. J., Macdonald, G. H., Alvey, N. D. S., Burton, M. G., & Lee, J.-K. 2003, A&A, 410, 597
    Wilson, T. L., & Rood, R. T. 1994, ARA&A, 32, 191
    Wink, J. E., Altenho®, W. J., & Mezger, P. G. 1982, A&A, 108, 227
    Wolfire, M. G., & Cassinelli, J. P. 1987, ApJ, 319, 850
    Wood, D. O. S., Churchwell, E., & Salter, C. J. 1988a, ApJ, 325, 694
    Wood, D. O. S., Handa, T., Fukui, Y., Churchwell, E., Sofue, Y., & Iwata, T. 1988b, ApJ, 326, 884
    Wood, D. O. S., & Churchwell, E. 1989a, ApJ, 340, 265
    Wood, D. O. S. & Churchwell, E. 1989b, ApJS, 69, 831
    Wouterloot, J. G. A., Brand, J., & Fiegle, K. 1993, A&AS, 98, 589
    Wright, A. E., Gri±th, M. R., Burke, B. F., & Ekers, R. D. 1994, ApJS, 91, 111
    Wyrowski, F. et al. 2004, in preparation
    Yao, Y., Ishii, M., Nagata, T., Nakaya, H., & Sato, S. 2000, ApJ, 542, 392
    Yorke, H. W., & Kr¨ugel, E. 1977, A&A, 54, 183
    Yorke, H. W. & Welz, A. 1996, A&A, 315, 555
    Yorke, H. W. 2002, ASP Conf. Ser. 267, Hot Star Workshop III: The Earliest
    Stages of Massive Star Birth, ed. P. A. Crowther (San Francisco: ASP), 165
    Zavagno, A., Deharveng, L., Nadeau, D., & Caplan, J. 2002, A&A, 394, 225
    Zhang, Q. & Ho, P. T. P. 1997, ApJ, 488, 241
    Zhang, Q., Hunter, T. R., & Sridharan, T. K. 1998, ApJ, 505, L151
    Zhang, Q., Hunter, T. R., Brand, J., Sridharan, T. K., Molinari, S., Kramer, M. A., & Cesaroni, R. 2001, ApJ, 552, L167

    QR CODE
    :::