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Are There Phases in the ISM?

Published online by Cambridge University Press:  17 September 2012

E. Vázquez-Semadeni
Affiliation:
Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, Campus Morelia, PO Box 3-72, Xangari, Morelia, Michoacán 58089, México
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Abstract

The interstellar medium (ISM) is subject, on one hand, to heating and cooling processes that tend to segregate it into distinct phases due to thermal instability (TI), and on the other, to turbulence-driving mechanisms that tend to produce strong nonlinear fluctuations in all the thermodynamic variables. In this regime, large-scale turbulent compressions in the stable warm neutral medium (WNM) dominate the clump-formation process rather than the linear developent of TI. Cold clumps formed by this mechanism are still often bounded by sharp density and temperature discontinuities, which however are not contact discontinuities as in the classical 2-phase model, but rather “phase transition fronts”, across which there is net mass and momentum flux from the WNM into the clumps. The clumps grow mainly by accretion through their boundaries, are in both thermal and ram pressure balance with their surroundings, and are internally turbulent as well, thus also having significant density fluctuations inside. The temperature and density of the cold and warm gas around the phase transition fronts fluctuate with time and location due to fluctuations in the turbulent pressure. Moreover, shock-compressed diffuse unstable gas can remain in the unstable regime for up to a few Myr before it undergoes a phase transition to the cold phase, and is furthermore constantly replenished by the turbulence. These processes populate the classically forbidden density and temperature ranges. Since gas at all temperatures appears to be present in bi- or tri-stable turbulence, we conclude that the word “phase” applies only locally, surrounding phase transition sites in the gas. Globally, the word “phase” must relax its meaning to simply denote a certain temperature or density range.

Type
Research Article
Copyright
© EAS, EDP Sciences, 2012

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References

Audit, E., & Hennebelle, P., 2004, A&A, 433, 1
Ballesteros-Paredes, J., Hartmann, L., & Vázquez-Semadeni, E., 1999b, ApJ, 527, 285CrossRef
Ballesteros-Paredes, J., Vázquez-Semadeni, E., & Scalo, J., 1999a, ApJ, 515, 286CrossRef
Banerjee, R., Vázquez-Semadeni, E., Hennebelle, P., & Klessen, R.S., 2009, MNRAS, submitted [arXiv:0808.0986]
Burgers, J.M., 1948, Adv. Appl. Mech., 1, 171CrossRef
Chiang, W.-H., & Bregman, J.N., 1988, ApJ, 328, 427CrossRef
de Avillez, M.A., & Breitschwerdt, D., 2005, A&A, 436, 585
Dickey, J.M., Salpeter, E.E., & Terzian, Y., 1977, ApJ, 211, L77CrossRef
Elmegreen, B.G., 1991, in The Physics of Star Formation and Early Stellar Evolution, ed. C.J. Lada & N.D. Kylafis (Dordrecht: Kluwer), 35CrossRefGoogle Scholar
Elmegreen, B.G., 1993, ApJ, 419, L29CrossRef
Field, G.B., 1965, ApJ, 142, 531CrossRef
Field, G.B., Goldsmith, D.W., & Habing, H.J., 1969, ApJ, 155, L149CrossRef
Field, G.B., & Saslaw, W.C., 1965, ApJ, 142, 568CrossRef
Fitzpatrick, E.L., & Spitzer, L., 1997, ApJ, 475, 623CrossRef
Fryxell, B., Olson, K., Ricker, P., et al., 2000, ApJS, 131, 273CrossRef
Gazol, A., Vázquez-Semadeni, E., Sánchez-Salcedo, F.J., & Scalo, J.M., 2001, ApJ, 557, 121CrossRef
Gazol, A., Vázquez-Semadeni, E., & Kim, J., 2005, ApJ, 630, 911CrossRef
Heiles, C., 2001, ApJ, 551, L105CrossRef
Heiles, C., 2001, in Galactic Structure, Stars and the Interstellar Medium, ASP Conference Series, 231, ed. C.E. Woodward, M.D. Bicay & J.M. Shull (San Francisco: Astronomical Society of the Pacific), 294Google Scholar
Heiles, C., & Troland, T., 2003, ApJ, 586, 1067CrossRef
Hennebelle, P., & Pérault, M., 1999, A&A, 351, 309
Hennebelle, P., & Audit, A&A, 465, 431
Kalberla, P.M.W., Schwarz, U.J., & Goss, W.M., 1985, A&A, 144, 27
Kanekar, N., Subrahmanyan, R., Chengalur, J.N., & Safouris, V., 2003, MNRAS, 346, L57CrossRef
Koyama, H., & Inutsuka, S.-I., 2000, ApJ, 532, 980CrossRef
Koyama, H., & Inutsuka, S.-I., 2002, ApJ, 564, L97CrossRef
Kritsuk, A., & Norman, M.L., 2002a, ApJ, 569, L127CrossRef
Kritsuk, A., & Norman, M.L., 2002b, ApJ, 580, L51CrossRef
Kwan, J., 1979, ApJ, 229, 567CrossRef
McKee, C.F., & Ostriker, J.P., 1977, ApJ, 218, 148CrossRef
Modell, M., & Reid, R.C., 1974, Thermodynamics and Its Applications (Englewood Cliffs, NJ: Prentice-Hall)Google Scholar
Nordlund, Å., & Padoan, P., 1999, in Interstellar Turbulence, ed. J. Franco & A. Carramiñana (Cambridge: Cambridge University Press), 218CrossRefGoogle Scholar
Norman, C.A., & Ferrara, A., 1996, ApJ, 467, 280CrossRef
Oort, J.H., 1954, Bull. Astr. Inst. Netherlands, 12, 177, 455
Passot, T., Vázquez-Semadeni, E., & Pouquet, A., 1995, ApJ, 455, 536CrossRef
Passot, T., & Vazquez-Semadeni, E., 1998, Phys. Rev. E, 1999, 58, 4501CrossRef
Pikel’ner, S.B., 1968, Sov. Astron. 11, 737
Piontek, R.A., & Ostriker, E.C., 2005, ApJ, 629, 849CrossRef
Rosen, A., & Bregman, J.N., 1995, ApJ, 440, 634CrossRef
Sánchez-Salcedo, F.J., Vázquez-Semadeni, E., & Gazol, A., 2002, ApJ, 577, 768CrossRef
Sasao, T., 1973, PASJ, 25, 1
Scalo, J., Vázquez-Semadeni, E., Chappell, D., & Passot, T., 1998, ApJ, 504, 835CrossRef
Smith, M.D., Mac Low, M.-M., & Zuev, J.M., 2000a, A&A, 356, 287PubMed
Smith, M.D., Mac Low, M.-M., & Heitsch, F., 2000b, A&A, 362, 333PubMed
Spitzer, L., & Fitzpatrick, E.L., 1995, ApJ, 445, 196CrossRef
Vázquez-Semadeni, E., Gazol, A., Sánchez-Salcedo, F.J., & Passot, T., 2003, in Turbulence and Magnetic Fields in Astrophysics, ed. T. Passot & E. Falgarone, Lecture Notes in Physics, 614, 213CrossRefGoogle Scholar
Vázquez-Semadeni, E., Gazol, A., & Scalo, J., 2000, ApJ, 540, 271CrossRef
Vázquez-Semadeni, E., Gómez, G.C., Jappsen, A.K., Ballesteros-Paredes, J., González, R.F., & Klessen, R.S., 2007, ApJ, 657, 870CrossRef
Vázquez-Semadeni, E., Passot, T., & Pouquet, A., 1995, ApJ, 441, 702CrossRef
Vázquez-Semadeni, E., Passot, T., & Pouquet, A., 1996, ApJ, 473, 881CrossRef
Vázquez-Semadeni, E., Ryu, D., Passot, T., González, R.F., & Gazol, A., 2006, ApJ, 643, 245CrossRef
von Weizsäcker, C.F., 1951, ApJ, 114, 165CrossRef
Wolfire, M.G., Hollenbach, D., McKee, C.F., Tielens, A.G.G.M., & Bakes, E.L.O., 1995, ApJ, 443, 152CrossRef
Wolfire, M.G., McKee, C.F., Hollenbach, D., & Tielens, A.G.G.M., 2003, 587, 278

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