She obtained her BSc (Physics) and MSc (Theoretical Physics) from Jiangxi Normal University in China, and PhD in Theoretical Physics from the University of Hull, England. She was a Postdoctoral Fellow at Queen Mary, University of London (QMUL) from November 1998 to October 2000 in the engineering department, and from November 2000-March 2001 in the physics department. She has been a Lecturer at the School of Physical Science at the University of Kent since April 2001.
back to top
Room 115, Ingram Building
Kinnear, T. et al. (2015). Evolution of prolate molecular clouds at HII boundaries - II. Formation of BRCs of asymmetrical morphology. Monthly Notices of the Royal Astronomical Society [Online] 450:1017-1031. Available at: http://dx.doi.org/10.1093/mnras/stv637.
Abstract | View in KAR | View Full Text
A systematic investigation on the evolution of a prolate cloud at an H II boundary is conducted using smoothed particle hydrodynamics in order to understand the mechanism for a variety of irregular morphological structures found at the boundaries of various H II regions. The prolate molecular clouds in this investigation are set with their semimajor axes at inclinations between 0 and 90 to a plane-parallel ionizing radiation flux. A set of four parameters, the number density n, the ratio of major to minor axis , the inclination angle and the incident flux FEUV, are used to define the initial state of the simulated clouds. The dependence of the evolution of a prolate cloud under radiation-driven implosion (RDI) on each of the four parameters is investigated. It is found that (i) in addition to the well-studied standard type A, B or C bright-rimmed clouds (BRCs), many other types such as asymmetrical BRCs, filamentary structures and irregular horse-head structures could also be developed at H II boundaries with only simple initial conditions; (ii) the final morphological structures are very sensitive to the four initial parameters, especially to the initial density and the inclination; (iii) the previously defined ionizing radiation penetration depth can still be used as a good indicator of the final morphology. Based on the simulation results, the formation time-scales and masses of the early RDI-triggered star formation from clouds of different initial conditions are also estimated. Finally a unified mechanism for the various morphological structures found in many different H II boundaries is suggested.
Kusune, T. et al. (2014). Near-IR imaging polarimetry toward a bright-rimmed cloud: Magnetic field in SFO 74. Astrophysical Journal [Online] 798:60-76. Available at: http://dx.doi.org/10.1088/0004-637X/798/1/60.
Abstract | View in KAR | View Full Text
We have made near-infrared (JHKs) imaging polarimetry of a bright-rimmed cloud (SFO 74). The polarization vector maps clearly show that the magnetic field in the layer just behind the bright rim is running along the rim, quite different from its ambient magnetic field. The direction of the magnetic field just behind the tip rim is almost perpendicular to that of the incident UV radiation, and the magnetic field configuration appears to be symmetric as a whole with respect to the cloud symmetry axis. We estimated the column and number densities in the two regions (just inside and far inside the tip rim) and then derived the magnetic field strength, applying the Chandrasekhar-Fermi method. The estimated magnetic field strength just inside the tip rim, ~90 G, is stronger than that far inside, ~30 G. This suggests that the magnetic field strength just inside the tip rim is enhanced by the UV-radiation-induced shock. The shock increases the density within the top layer around the tip and thus increases the strength of the magnetic field. The magnetic pressure seems to be comparable to the turbulent one just inside the tip rim, implying a significant contribution of the magnetic field to the total internal pressure. The mass-to-flux ratio was estimated to be close to the critical value just inside the tip rim. We speculate that the flat-topped bright rim of SFO 74 could be formed by the magnetic field effect.
Kinnear, T. et al. (2014). Evolution of prolate molecular clouds at HII boundaries - I. formation of fragment-core structures. Monthly Notices of the Royal Astronomical Society [Online] 444:1221-1235. Available at: http://dx.doi.org/10.1093/mnras/stu1510.
Abstract | View in KAR | View Full Text
The evolution of a prolate cloud at an HII boundary is investigated using smoothed particle hydrodynamics. The prolate molecular clouds in our investigation are setwith their semi-major axis perpendicular to the radiative direction of a plane-parallel ionizing extreme ultraviolet (EUV) flux. Simulations on three high-mass prolate clouds reveal that EUV radiation can trigger distinctive high-density core formation embedded in a final linear structure. This contrasts with results of the previous work in which only an isotropic far-ultraviolet interstellar background flux was applied. A systematic investigation on a group of prolate clouds of equal mass but different initial densities and geometric shapes finds that the distribution of the cores over the final linear structure changes with the initial conditions of the prolate cloud and the strength of the EUV radiation flux. These highly condensed cores may either scatter over the full length of the final linear structure or form two groups of high-density cores at two foci, depending on the value of the ionizing radiation penetration depth dEUV, the ratio of the physical ionizing radiation penetration depth to the minor axis of the cloud. Data analysis on the total mass of the high-density cores and the core formation time finds that the potential for EUV radiation triggered star formation efficiency is higher in prolate clouds with shallow ionization penetration depth and intermediate major-to-minor axial ratio, for the physical environments investigated. Finally, it is suggested that the various fragment-core structures observed at HII boundaries may result from the interaction between ionizing radiation and pre-existing prolate clouds of different initial geometrical and physical conditions.
Fukuda, N. et al. (2013). TRIGGERED STAR FORMATION IN A BRIGHT-RIMMED CLOUD (BRC 5) OF IC 1805. Astrophysical Journal [Online] 773:132. Available at: http://dx.doi.org/10.1088/0004-637X/773/2/132.
Abstract | View in KAR
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 H 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 H 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 C18O(J = 1-0) cores. The C18O 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 H 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 13CO(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.
Miao, J. et al. (2012). Filamentary structure formation in the Interstellar Radiation Field (ISRF) Wong, T. and Ott, J. eds. Proceedings of the International Astronomical Union [Online] 8:52-52. Available at: http://dx.doi.org/10.1017/S1743921313000331.
Abstract | View in KAR
A new mechanism is proposed for the formation of filament/core structure by ISRF and clumpy molecular cloud interaction. The derived characterizes of the filament/core network is consistent with that produced by the compressive forcing turbulence model.
An Investigation of the Type M Morphological Structure of IC59: A New Model for Bright Rim Clouds, Miao, Jingqi; Sugitani, Koji; White, Glenn J.; Nelson, Richard P., The Astrophysical Journal, Volume 717, Issue 2, pp. 658-665 (2010).
J. Miao, G.J.White, M. A. Thompson , R.Nelson , An Investigation on the Morphological Evolution of Bright-Rimmed Clouds, 2009, ApJ., 692, 382
R. Walker, P.Kenny, J.Miao, Exploratory Simulation for Astrophysics, The proceeding of the 2009, International Conference on Modeling, Simulation and Visualization Methods, Monte Carlo Resort, Las Vegas, Nevada, USA (July 13-16, 2009).
R.Walker, P.Kenny, J.Miao, Visualization and Data Analysis 2007. Edited by Erbacher, Robert F.; Roberts, Jonathan C.; Gröhn, Matti T.; Börner, Katy. Proceedings of the SPIE, Volume 6495, pp. 649509 (2007)
J. Miao*, G.J.White, M. A. Thompson , R.Nelson, L. Morgan, SPH simulation on the BRC: the Eagle Nebula revisit, 2006, MNRAS , 269,143.
M.A.Thompson, G.J.White, L. Morgan, J. Miao, C.V.M. Fridlund, M. Huldtgre-White, Searching for signs of triggered star formation toward IC 1848, Astronomy and Astrophysics, v.414, p.1017-1041 (2004 back to top
- SPH numerical simulation of stellar evolution
- Ionization effect from UV radiation of stars on the evolution of molecular cloud.
- The morphological evolution of molecular clouds in HII regions.
- Triggered formation of stars/small star clusters in HII regions.
I am currently particularly interested in the process of star formation through the compression of a molecular cloud via a photo-ionisation-induced shock, known as Radiatively-Driven Implosion (RDI).
Bright-rimmed clouds (BRCs) are isolated molecular clouds located on the edges of evolved HII regions. Their relative isolation and simple geometry make BRCs an ideal laboratory to explore the RDI mode of triggered star formation. Current observational investigations on triggered star formation in BRCs have raised a lot of unsolved questions, for which solutions may be found through theoretical simulations.
Some interesting results from our simulations on the morphological evolution of BRCs are shown in the four videos, which reveal that molecular clouds with different initial conditions evolves very differently under the effect of the UV radiation from nearby star(s).
back to top