Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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CHEMICAL EVOLUTION IN VeLLOs

  • Lee, Jeong-Eun (Department of Astronomy and Space Science, Sejong University)
  • Published : 2007.12.31
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Abstract

A new type of object called "Very Low Luminosity Objects (VeLLOs)" has been discovered by the Spitzer Space Telescope. VeLLOs might be substellar objects forming by accretion. However, some VeLLOs are associated with strong outflows, indicating the previous existence of massive accretion. The thermal history, which significantly affects the chemistry, between substellar objects with a continuous low accretion rate and objects in a quiescent phase after massive accretion (outburst) must be greatly different. In this study, the chemical evolution has been calculated in an episodic accretion model to show that CO and $N_2H^+$ have a relation different from starless cores or Class 0/I objects. Furthermore, the $CO_2$ ice feature at $15.2{\mu}m$ will be a good tracer of the thermal process in VeLLOs.

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References

  1. Aikawa, Y., Ohashi, N., Inutsuka, S.-I., Herbst, E., & Takakuwa, S., 2001, Molecular Evolution in Collapsing Prestellar Cores, ApJ, 552, 639
  2. Andre, P., Ward-Thompson, D., & Barsony, M., 1993, Submillimeter continuum observations of Rho Ophiuchi A - The candidate protostar VLA 1623 and prestellar clumps, ApJ, 406, 122
  3. Andre, P., Motte, F., & Bacmann, A., 1999., Discovery of an Extremely Young Accreting Protostar in Taurus, ApJ, 513, L57 https://doi.org/10.1086/311908
  4. Bergin, E. A., Langer, W. D., & Goldsmith, P. F., 1995, Gas-phase chemistry in dense interstellar clouds includ-ing grain surface molecular depletion and desorption, ApJ, 441, 222
  5. Bell, K. R., Lin, D. N. C., Hartmann, L. W., & Kenyon, S. J., 1995, The FU Orionis outburst as a thermal ac-cretion event: Observational constraints for protostellar disk models, ApJ, 444, 376
  6. Belloche, A., Andre, P., Despois, D., & Blinder, S., 2002, Molecular line study of the very young protostar IRAM 04191 in Taurus: infall, rotation, and outflow, A&A, 393, 927 https://doi.org/10.1051/0004-6361:20021054
  7. Belloche, A. & Andre, P., 2004, Disappearance of $N_2H^+$ from the gas phase in the class 0 protostar IRAM 04191, A&A, 419, L35 https://doi.org/10.1051/0004-6361:20040140
  8. Bergin, E. A. & Langer, W. D., 1997, Chemical Evolution in Preprotostellar and Protostellar Cores, ApJ, 486, 316 https://doi.org/10.1086/304510
  9. Bonnor, W. B., 1956, Boyle's Law and gravitational instability, MNRAS, 116, 351 https://doi.org/10.1093/mnras/116.3.351
  10. Boss, A. P., 1993, Collapse and fragmentation of molecular cloud cores. I - Moderately centrally condensed cores, ApJ, 410, 157
  11. Bourke, T. L., Crapsi, A., Myers, P. C., Evans, N. J. II, Wilner, D. J., Huard, T. L., Jorgensen, J. K., & Young, C. H., 2005, Discovery of a Low-Mass Bipolar Molecular Outflow from L1014-IRS with the Submillimeter Array, ApJ, 633, L129 https://doi.org/10.1086/498449
  12. Bourke, T. L., et al., 2006, The Spitzer c2d Survey of Nearby Dense Cores. II. Discovery of a Low-Luminosity Object in the 'Evolved Starless Core' L1521F, ApJ, 649, L37 https://doi.org/10.1086/508161
  13. Crapsi, A., Caselli, P., Walmsley, C. M., Tafalla, M., Lee, C. W., Bourke, T. L., & Myers, P. C., 2004, Observations of L1521F: A highly evolved starless core, A&A, 420, 957 https://doi.org/10.1051/0004-6361:20035915
  14. Crapsi, A., et al., 2005, Dynamical and chemical properties of the 'starless' core L1014, A&A, 439, 1023 https://doi.org/10.1051/0004-6361:20042411
  15. Di Francesco, J., Evans. N. J., II, Caselli, P., Myers, P. C., Shirley, Y., Aikawa, Y., & Tafalla, M., 2007, in Proto-stars and Planets V, ed. B. Reipurth, D. Jewitt, & K. Keil (Tucson: Univ. Arizona Press)
  16. Draine, B. T. & Anderson, N., 1985, Temperature fluctuations and infrared emission from interstellar grains, ApJ, 292, 494 https://doi.org/10.1086/163181
  17. Dunham, M. M., et al., 2006, The Spitzer c2d Survey of Nearby Dense Cores. I. First Direct Detection of the Embedded Source in IRAM 04191+1522, ApJ, 651, 945 https://doi.org/10.1086/508051
  18. Ebert, R., 1955, Uber die Verdichtung von H I-Gebieten. Mit 5 Textabbildungen, Z. Astrophys., 37, 217
  19. Evans, N. J. II, Rawlings, J. M. C., Shirley, Y., & Mundy, L. G., 2001, Tracing the Mass during Low-Mass Star Formation. II. Modeling the Submillimeter Emission from Preprotostellar Cores, ApJ, 557, 193
  20. Geppert, W. D., Thomas, R., Semaniak, J., Ehlerding, A., Millar, T., Osterdahl, F., af Ugglas, M., Djuric, N., Paaal, A., & Larsson, M., 2004, Dissociative Recombination of $N_2H^+$: Evidence for Fracture of the NN Bond, ApJ, 609, 459 https://doi.org/10.1086/420733
  21. Gerakines, P. A., Whittet, D. C. B., Ehrenfreund, P., Boogert, A. C. A., Tielens, A. G. G. M., Schutte, W. A., Chiar, J. E., v an Dishoeck, E. F., Prusti, T., Helmich, F. P., & de Graauw, T., 1999, Observations of Solid Carbon Dioxide in Molecular Clouds with the Infrared Space Observatory, ApJ, 522, 357 https://doi.org/10.1086/307611
  22. Huard, T. L., et al., 2006, Deep Near-Infrared Observations of L1014: Revealing the Nature of the Core and Its Embedded Source, ApJ, 640, 391 https://doi.org/10.1086/498742
  23. Ivezic, Z., Nenkova, M., & Elitzur, M., 1999, User Manual for DUSTY, astro-ph/9910475
  24. Knez, C., Boogert, A. C. A., Pontoppidan, K. M., Kessler-Silacci, J., van Dishoeck, E. F., Evans, N. J. II, Augereau, J.-C., Blake, G. A., & Lahuis, F., 2005, Spitzer Mid-Infrared Spectroscopy of Ices toward Extincted Background Stars, ApJ, 635, L145 https://doi.org/10.1086/499584
  25. Lee, J.-E., Evans, N. J., II, Shirley, Y. L., & Tatematsu, K., 2003, Chemistry and Dynamics in Pre-protostellar Cores, ApJ, 583, 789 https://doi.org/10.1086/345428
  26. Lee, J. -E., Bergin, E. A., & Evans, N. J. II, 2004, Evolution of Chemistry and Molecular Line Profiles during Protostellar Collapse, ApJ, 617, 360 https://doi.org/10.1086/425153
  27. Lin, D. N. C., Hayashi, M., Bell, K. R., & Ohashi, N., 1994, Is HL Tauri and FU Orionis system in quiescence?, ApJ, 435, 821 https://doi.org/10.1086/174861
  28. Masunaga, H., Miyama, S. M., & Inutsuka, S. -I., 1998, A Radiation Hydrodynamic Model for Protostellar Collapse. I. The First Collapse, ApJ, 495, 346
  29. Oberg K. I., van Broekhuizen, F., Fraser, H. J., Bisschop, S. E., van Dishoeck, E. F., & Schlemmer, S., 2005, Competition between CO and $N_2$ Desorption from Interstellar Ices, ApJ, 621, 33 https://doi.org/10.1086/428901
  30. Myers, P. C. & Ladd, E. F., 1993, Bolometric temperatures of young stellar objects, ApJ, 413, L47 https://doi.org/10.1086/186956
  31. Omukai, K., 2007, Observational Characteristics of the First Protostellar Cores, PASJ, 59, 589 https://doi.org/10.1002/(SICI)1097-4628(19960124)59:4<589::AID-APP4>3.0.CO;2-P
  32. Ossenkopf V. & Henning Th., 1994, Dust opacities for protostellar cores, A&A, 291, 943
  33. Pontoppidan, K. M, Boogert, A. C. A., Fraser, H. J., van Dishoeck, E. F., Blake, G. A., Lahuis, F., Oberg, K. I., Evans, N. J.,II, & Salyk, C., 2007, The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects II: CO2, ApJ, in press
  34. Shu, F. H., 1977, Self-similar collapse of isothermal spheres and star formation, ApJ, 214, 488
  35. Shu, F. H., Adams, F. C., & Lizano, S., 1987, Star formation in molecular clouds - Observation and theory, ARA&A, 25, 23
  36. Vorobyov, E. I. & Basu, S., 2005, The Origin of Episodic Accretion Bursts in the Early Stages of Star Formation, ApJL, 633, 137 https://doi.org/10.1086/498303
  37. Young, C. H., et al., 2004, Infrared Properties of Radio-selected Submillimeter Galaxies in the Spitzer First Look Survey Verification Field, ApJS, 154, 396 https://doi.org/10.1086/422818
  38. Young, C. H., & Evans, N. J., 2005, Evolutionary Signatures in the Formation of Low-Mass Protostars, ApJ, 627, 293 https://doi.org/10.1086/430436

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