Hostname: page-component-78c5997874-mlc7c Total loading time: 0 Render date: 2024-11-19T22:42:56.408Z Has data issue: false hasContentIssue false
  • English
  • Français

Chemical Signatures of the Evolutionary State of Cores

Published online by Cambridge University Press:  23 September 2016

Yuri Aikawa
Yuri Aikawa*
Affiliation:
Department of Earth and Planetary Sciences, Kobe University, Kobe 657-8501, Japan

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Recent observations with high angular resolution revealed chemical differentiation in several prestellar cores; while N2H+ emission peaks at the core center, CO, CS and CCS emission peaks are offset from the center. Molecular abundances also vary among cores; some cores have high CCS abundance and low N2H+ abundance, but others have less CCS and more N2H+. Numerical calculations of a chemical-reaction network in contracting cores show that these differentiations and variations can be diagnostics of physical evolution of cores, because molecular abundances and distributions are determined by the balance between the dynamical and chemical time scales. In prestellar cores, low temperatures and high densities cause adsorption of molecules onto grains. Depletion time scale varies among species; early-phase species deplete first because of destruction via gas-phase reactions in addition to the adsorption. N2H+ is the last to deplete because of the low adsorption energy of its parent molecule N2 and depletion of main reactants such as CO. Molecular D/H ratio is another probe of core evolution, since it increases as the adsorption proceeds.

Type
Part 2: From Molecular Clouds to Protostellar Cores
Information
Symposium - International Astronomical Union , Volume 221: Star Formation at High Angular Resolution , 2004 , pp. 67 - 74
Copyright
Copyright © Astronomical Society of the Pacific 2004 

References

Aikawa, Y., Ohashi, N., Inutsuka, S., Herbst, E., & Takakuwa, S. 2001, ApJ, 552, 639 CrossRefGoogle Scholar
Aikawa, Y., Ohashi, N., & Herbst, E. 2003, ApJ, 593, 906 CrossRefGoogle Scholar
Alves, J. F., Lada, C. J., & Lada, E. A. 2001, Nature 409, 159 Google Scholar
Bergin, E. A., & Langer, W. D. 1997, ApJ, 486, 316 Google Scholar
Bergin, E. A., Alves, J., Huard, T., & Lada, C. J. 2002, ApJ, 570, L101 Google Scholar
Bacmann, A., Lefloch, B., Ceccarelli, C., Steinacker, J., Castets, A., & Loinard, L. 2003, ApJ, 585, L55 CrossRefGoogle Scholar
Caselli, P., Benson, P. J., Myers, P. C. & Tafalla, M. 2002, ApJ, 572, 238 Google Scholar
Caselli, P., van der Tak, F. F. S., Ceccarelli, C. & Bacmann, A. 2003, A&A, 403, L37 Google Scholar
Ceccarelli, C., Castets, A., Loinard, L., Caux, E., & Tielens, A. G. G. M. 1998, A&A 338, L43 Google Scholar
Hirahara, Y., Suzuki, H., Yamamoto, S., Kawaguchi, K., Kaifu, N., Ohishi, M., Takano, S., Ishikawa, S., Masuda, A. 1992. ApJ, 394, 539 Google Scholar
Hirota, T., Yamamoto, S., Mikami, H., & Ohishi, M. 1998, ApJ, 503, 717 Google Scholar
Hirota, T., Ikeda, M., & Yamamoto, S. 2003, ApJ, in press Google Scholar
Hirota, T., Ito, T., & Yamamoto, S. 2002, ApJ, 565, 359 Google Scholar
Larson, R. B. 1969, MNRAS, 145, 271 Google Scholar
Li, Z.-Y., Shematovich, V. I., Wiebe, D. S., & Shustov, B. M. 2002, ApJ, 569, 792 Google Scholar
Lis, D. C., Roueff, E., Gerin, M., Phillips, T. G., Coudert, L. H., van der Tak, F. F. S., & Schilke, P. 2002, ApJ, 571, L55 Google Scholar
Loinard, L., Castets, A., Ceccarelli, C., Tielans, A. G. G. M., Faure, A., Caux, E., & Duvert, G. 2000, A&A 359, 1169 Google Scholar
Ohashi, N. 2000, in Astrochemistry: From Molecular Clouds to Planetary Systems, IAU Symposium 197, ed. Minh, Y. C. & van Dishoeck, E. F. (Astronomical Society of the Pacific), 61 Google Scholar
Parise, B., Ceccarelli, C., Tielens, A. G. G. M., Herbst, E., Lefloch, B., Caux, E., Castets, A., Mukhopadhyay, I., Pagani, L., Loinard, L. 2002, A&A, 393, L49 Google Scholar
Penston, M. V. 1979, MNRAS, 144, 425 Google Scholar
Pratap, P., Dickens, J. E., Snell, R. L., Miralles, M. P., Bergin, E. A., Irvine, W. M., & Schloerb, F. P. 1997, ApJ 486, 862 CrossRefGoogle Scholar
Roberts, H., & Millar, T. J. 2000, A&A, 364, 780 Google Scholar
Roberts, H., Herbst, E., & Millar, T. J. 2003, ApJ, 591, L41 CrossRefGoogle Scholar
Roueff, E., Tiné, S., Coudert, L. H., Pineau des Forets, G., Falgarone, E., & Gerin, M. 2000, A&A, 354, L63 Google Scholar
Shematovich, V. I., Wiebe, D. S., Shustov, B. M., & Li, Z.-Y. 2003, ApJ, 588, 894 Google Scholar
Suzuki, H., Yamamoto, S., Ohishi, M., Kaifu, N., Ishikawa, S.-I., Hirahara, Y., & Takano, S. 1992, ApJ, 392, 551 Google Scholar
Tafalla, M., Myers, P. C., Caselli, P., Walmsley, C. M., & Comito, C. 2002, ApJ, 569, 815 Google Scholar
Tafalla, et al. 2003, submitted to ApJ Terzieva, R. & Herbst, E. 1998, ApJ, 501, 207 CrossRefGoogle Scholar
van der Tak, F. F. S., Schilke, P., Muller, H. S. P., Lis, D. C., Phillips, T. G., Gerin, M., & Roueff, E. 2002, A&A, 388, L53 Google Scholar
Ward-Thompson, D., Scott, P. F., Hills, R. E., & André, P. 1994, MNRAS, 268, 276 Google Scholar
Ward-Thompson, et al. in this volume Google Scholar
Willacy, K., Langer, W. D., & Velusamy, T. 1998, ApJ, 507, L171 Google Scholar