Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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MOLECULAR CLOUDS WITH PECULIAR VELOCITY IN THE OUTER LOCAL ARM

  • Kang, Mi-Ju (Department of Astronomy & Space Science, Chungnam National University) ;
  • Lee, Young-Ung (Korea Astronomy and Space Science Institute, International Center for Astrophysics)
  • Published : 2006.12.31
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Abstract

We conducted an analysis of a selected region from the FCRAO $^{12}CO$ Outer Galaxy Survey. The selected region is located between galactic longitude $117^{\circ}$ and $124^{\circ}$ with the velocity of -23 km $s^{-1}. Molecular clouds in this region show a peculiar velocity field, protruding from the Local Arm population. The selected region is divided into 7 clouds by spatial location. Though we were not able to identify the direct driving source for peculiar velocity of our target region, we find that there are several internal YSOs or star forming activities; there are many associated sources like an outflows, a high-mass protostellar candidate and $H_2O$ maser sources. We attribute the driving energy source to older generation of episodic star formation. Masses of main clouds(cloud 1-4) estimated using a conversion factor from $^{12}CO$ luminosity are larger than $10^4M_{\odot}$. Other components have a small mass as about $10^3M_{\odot}$. Among main clouds, cloud 2 and 4 seem to be marginally gravitational bound systems as their ratio of $M_{CO}$ to $M_{VIR}$ is about $2{\sim}3$, and the internal velocity dispersion is larger than the centroid velocity dispersion. Total mass estimated using a conversion factor from $^{12}CO$ luminosity is $7.9{\times}10^4M_{\odot}$.

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References

  1. Avedisova, V. S., 2002, A Catalog of Star-Forming Regions in the Galaxy, Astronomy Reports, 46, 193 https://doi.org/10.1134/1.1463097
  2. Blitz, L., Fich, M., & Stark, A. A., 1982, Catalog of CO radial velocities toward galactic H II regions, ApJS, 49, 183 https://doi.org/10.1086/190795
  3. Brunt, C., Kerton, C. R., & Pomerleau, C., 2003, An Outer Galaxy Molecular Cloud Catalog, ApJS, 144, 47 https://doi.org/10.1086/344245
  4. Carey, S. J. 1995, Ph.D. thesis, Rensselaer Polytechnic Institute
  5. Cazzolato, F., & Pineault, S., 2003, Large-Scale Structure and Dynamics of Cassiopeia OB7, AJ, 125, 2050 https://doi.org/10.1086/368242
  6. Cohen, R. S., Cong, H., Dame, T. M., & Thaddeus, P., 1980, Molecular clouds and galactic spiral structure, ApJ, 239, 53 https://doi.org/10.1086/183290
  7. Emerson, J.P., 1988 in Formation and Evolution of Low Mass Stars, edited by A.K. Dupree and M.T.V.T. Lago (Kluwer Academic, Dordrecht), Vol. 241, p. 193
  8. Gottlieb, S., 1999, Cassiopeia recur 29 Jan 1999 Observing Report
  9. Heyer, Mark H., Brunt, C., Snell, R. L., Howe, J. E., Schloerb, F. P., & Carpenter, J. M., 1998, The Five College Radio Astronomy Observatory CO Survey of the Outer Galaxy, ApJS, 115, 241 https://doi.org/10.1086/313086
  10. Heyer, M. H., Carpenter, J. M., & Snell, R. L., 2001, The Equilibrium State of Molecular Regions in the Outer Galaxy, ApJ, 551, 852 https://doi.org/10.1086/320218
  11. Hodapp, K-W., 1994. A K' imaging survey of molecular out flow sources, ApJS, 94, 615 https://doi.org/10.1086/192084
  12. Kharchenko, N. V., Piskunov, A. E., Roser, S., Schilbach, E., & Scholz, R.-D., 2005, 109 new Galactic open clusters, A&A, 440, 403 https://doi.org/10.1051/0004-6361:20052740
  13. Kim, W-T., & Ostriker, E. C., 2006, Formation of Spiral-Arm Spurs and Bound Clouds in Vertically Stratified Galactic Gas Disks, ApJ, 646, 213 https://doi.org/10.1086/504677
  14. Lee, Y., Snell, R. L., & Dickman, R. L., 1990, Analysis of $^{12}CO\;and\;^{13}CO$ emission in a 3 square degree region of the Galactic plane between L = 23 deg and 25 deg, ApJ, 355, 536 https://doi.org/10.1086/168786
  15. Lee, Y., 1994, A Study of LYNDS 1251 Dark Cloud: I. Structure and Kinematics, JKAS, 27, 159
  16. Scoville, N. Z., Yun, M. S., Sanders, D. B., Clemens, D. P., & Waller, W. H., 1987, Molecular clouds and cloud cores in the inner Galaxy, 63, 821 https://doi.org/10.1086/191185
  17. Strong, A. W., & Mattox, J. R., 1996, Gradient model analysis of EGRET diffuse Galactic ${\gamma}-ray$ emission, A&A, 308, 21
  18. Valdettaro, R., Palla, F., Brand, J., Cesaroni, R., Comoretto, G., Di Franco, S., Felli, M., Natale, E., Palagi, F., Panella, D., & Tofani, G., 2001, The Arcetri Catalog of $H_2O$ maser sources: Update 2000, A&A, 368, 845 https://doi.org/10.1051/0004-6361:20000526
  19. Williams, S. J., Fuller, G. A., & Sridharan, T. K., 2004, The circumstellar environments of high¡mass protostellar objects. I. Submillimetre continuum emission, A&A, 417, 115 https://doi.org/10.1051/0004-6361:20031733
  20. Wu, Y., Wei, Y., Zhao, M., Shi, Y., Yu, W., Qin, S., & Huang, M., 2004, A study of high velocity molecular outflows with an up¡to¡date sample, A&A, 426, 503 https://doi.org/10.1051/0004-6361:20035767