An Investigation on the Morphological Evolution of Bright-Rimmed Clouds

Miao, Jingqi; White, G. J.; Thompson, M. A.; Nelson, Richard P.

doi:10.1088/0004-637x/692/1/382

Cited by 70 publications

(94 citation statements)

References 29 publications

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“…Some of these simulations (Sandford et al 1982;Bertoldi 1989;Lefloch & Lazareff 1994;Miao et al 2006;Henney et al 2008) concentrate on the morphology of the resulting bright-rimmed clouds. In contrast, Peters et al (2008) address the possibility that the flow of ionized gas off an irradiated cloud might be an important source of turbulence; and Kessel-Deynet & Burkert (2003), Gritschneder et al (2009), Dale et al (2005) and Miao et al (2009) explore the possibility that the collapse of a bright-rimmed cloud might sometimes lead to triggered star formation. These simulations show that it is possible to reproduce the observed morphologies of brightrimmed clouds (Lefloch & Lazareff 1995;Lefloch et al 1997;Morgan et al 2008).…”

Section: Introductionmentioning

confidence: 99%

Smoothed particle hydrodynamics simulations of expanding H II regions

Bisbas¹,

Wünsch²,

Whitworth³

et al. 2009

A&A

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Context. Ionizing radiation plays a crucial role in star formation at all epochs. In contemporary star formation, ionization abruptly raises the pressure by more than three orders of magnitude; the temperature increases from ∼10 K to ∼10 4 K, and the mean molecular weight decreases by a factor of more than 3. This may result in positive feedback, either by compressing pre-existing clouds and rendering them unstable, or by sweeping up gravitationally unstable shells. It may also result in negative feedback (by dispersing residual dense gas). Ionizing radiation from OB stars is also routinely invoked as a means of injecting kinetic energy into the interstellar medium and as a driver of sequential self-propagating star formation in galaxies. Aims. We describe a new algorithm for including the dynamical effects of ionizing radiation in SPH simulations, and we present several examples of how the algorithm can be applied to problems in star formation. Methods. We use the HEALPix software to tessellate the sky and to solve the equation of ionization equilibrium along a ray towards each of the resulting tesserae. We exploit the hierarchical nature of HEALPix to make the algorithm adaptive, so that fine angular resolution is invoked only where it is needed, and the computational cost is kept low. Results. We present simulations of (i) the spherically symmetric expansion of an Hii region inside a uniform-density, non-selfgravitating cloud; (ii) the spherically symmetric expansion of an Hii region inside a uniform-density, self-gravitating cloud; (iii) the expansion of an off-centre Hii region inside a uniform-density, non-self-gravitating cloud, resulting in rocket acceleration and dispersal of the cloud; and (iv) radiatively driven compression and ablation of a core overrun by an Hii region. Conclusions. The new algorithm provides the means to explore and evaluate the role of ionizing radiation in regulating the efficiency and statistics of star formation.

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Section: Introductionmentioning

confidence: 99%

Smoothed particle hydrodynamics simulations of expanding H II regions

Bisbas¹,

Wünsch²,

Whitworth³

et al. 2009

A&A

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“…Another possibility is the radiation-driven implosion (e.g. Bertoldi 1989, Lefloch & Lazareff 1994, Miao et al 2009) of preexisting dense cores. This scenario results in cometary-shaped structures.…”

Section: Gritschneder Et Almentioning

confidence: 99%

Pillars, Jets and Dynamical Features

et al. 2010

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Abstract. We present high resolution simulations on the impact of ionizing radiation on turbulent molecular clouds. The combination of hydrodynamics, gravitational forces and ionization in the tree-SPH code iVINE naturally leads to the formation of elongated filaments and clumps, which are in excellent agreement with the pillars observed around HII regions. Including gravity the formation of a second generation of low-mass stars with surrounding protostellar disks is triggered at the tips of the pillars, as also observed. A parameter study allows us to determine the physical conditions under which irregular structures form and whether they resemble large pillars or a system of small, isolated globules.

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“…Several theoretical models based on UV radiation of uniform spherical molecular clouds have successfully reproduced the formation of standard BRCs of different symmetrical morphologies (e.g., Lefloch & Lazareff 1994;Willams et al 2001;Kessel-Deynet & Burkert 2003;Miao et al 2006Miao et al , 2009Miao et al , 2010. Kessel-Deynet & Burkert (2003) and Miao et al (2009) have also revealed the importance of self-gravity of a molecular cloud in the evolution of a BRC.…”

Section: Introductionmentioning

confidence: 99%

“…Kessel-Deynet & Burkert (2003) and Miao et al (2009) have also revealed the importance of self-gravity of a molecular cloud in the evolution of a BRC. (02:28:58.8, +61:33:23) and the size of the image is 11.…”

Section: Introductionmentioning

confidence: 99%

Triggered Star Formation in a Bright-Rimmed Cloud (Brc 5) of Ic 1805

Fukuda

Miao

Sugitani

et al. 2013

ApJ

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We report recent optical, near-infrared (NIR), and millimeter observations which have revealed some new features of the bright-rimmed cloud BRC 5 associated with W4. With slitless spectroscopy, we detected 17 Hα emission stars around the cloud; 4 are near the surface of the cloud, and 1 is toward IRAS 02252+6120. NIR photometry shows that the central Hα emission star, together with one bright infrared source, has large NIR excesses and Class I spectral energy distributions. These two Class I objects are associated with the 2.9 mm continuum peaks and with a bipolar outflow, and are in between two separate, elongated C 18 O(J = 1-0) cores. The C 18 O cores and the two Class I sources are aligned along a line at position angle ∼240 • , somewhat less than perpendicular to the direction of UV radiation from the OB stars. Most of the detected Hα emission stars, all T Tauri candidates, are located within ∼3 of the cloud on the exciting star side. An estimate of the age of the stars based on a color-magnitude diagram suggests that these T Tauri candidates have ages of ∼1 Myr or less, but are more evolved objects than the central young stellar objects. This age sequence suggests sequential star formation within the BRC 5 cloud. The 13 CO(J = 1-0) emission shows three elongated structures, which indicates the asymmetric structure toward the UV incident axis. We present our exploratory simulation results by using a smoothed particle hydrodynamic code that suggests that the asymmetrical BRC 5 structure could possibly result from the evolution of a preexisting prolate molecular cloud subject to radiation-driven implosion (RDI). Our best-fit prolate cloud has an initial mass of ∼400 M , an axial ratio of ∼1.7, and a semi-major axis of ∼1.6 pc, pointing away from the ionization flux by an angle of 15 • . The simulated cloud structure not only closely matches the observed asymmetric morphological structure of BRC 5, but also reveals the possibility of the development of two major cores at the head of BRC 5. For the first time, the possibility of forming two stars by an RDI mechanism in a BRC is investigated.

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An Investigation on the Morphological Evolution of Bright-Rimmed Clouds

Cited by 70 publications

References 29 publications

Smoothed particle hydrodynamics simulations of expanding H II regions

Smoothed particle hydrodynamics simulations of expanding H II regions

Pillars, Jets and Dynamical Features

Triggered Star Formation in a Bright-Rimmed Cloud (Brc 5) of Ic 1805

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