Yang Gao

• Sun Yat-sen University

Stars form through the gravitational collapse of molecular cloud cores. Before collapsing, the cores are supported by thermal pressure and turbulent motions. A question of critical importance for the understanding of star formation is how to observationally discern whether a core has already initiated gravitational collapse or is still in hydrostat...

Stars form through the gravitational collapse of molecular cloud cores. Before collapsing, the cores are supported by thermal pressure and turbulent motions. A question of critical importance for the understanding of star formation is how to observationally discern whether a core has already initiated gravitational collapse or is still in hydrostat...

The magnetic fields of exoplanets shield the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both cyclotron and synchrotron radio emissions, neither of which have been definitively identified in observations. As the coherent cy...

Magnetic fields of exoplanets are important in shielding the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both cyclotron and synchrotron radio emissions, of which neither has been definitely identified in observations yet. A...

The mechanism of type Ia supernova explosions is still unsolved due to the uncertainties in the processes of flame acceleration and the associated deflagration to detonation transition. In carbon–oxygen (C–O) white dwarfs, due to the well known Rayleigh–Taylor (R-T) instability and turbulent vortices in the R-T fingers, there exist unburned islands...

Aims. We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation. Methods. We made a high-resolution column density map (18.2′′) with Herschel data, and extracted a complete sample of the cores in the CMC with the fellwal...

We aim to reveal the physical properties and the chemical composition of the cores in the California Molecular Cloud (CMC), so as to better understand the initial conditions of star formation. We made a high-resolution column density map (18.2") with Herschel data, and extracted a complete sample of the cores in the CMC with the fellwalker algorith...

As a key process that refreshes the interstellar medium (ISM), the dynamics and radiative properties of the supernova remnant (SNR) expansion front not only reflect the physical environment of the old ISM surrounding the supernova, but they also provide information about the refreshed ISM. However the expansion dynamics of SNRs cannot be simply exp...

Turbulence dissipation is an important process affecting the energy balance in molecular clouds, the birth place of stars. Previously, the rate of turbulence dissipation is often estimated with semi-analytic formulae from simulation. Recently, we developed a data analysis technique called core velocity dispersion, which, for the first time, provide...

Turbulence dissipation is an important process affecting the energy balance in molecular clouds, the birth place of stars. Previously, the rate of turbulence dissipation is often estimated with semi-analytic formulae from simulation. Recently we developed a data analysis technique called core-velocity-dispersion (CVD), which, for the first time, pr...

As a key process that refreshes the interstellar medium, the dynamics and radiative properties of the supernova remnant (SNR) expansion front not only reflect the physical environment of the old interstellar medium (ISM) surrounding the supernova, but they also provide information about the refreshed ISM. However the expansion dynamics of SNRs cann...

Spherical hydrodynamic models with a polytropic equation of state (EoS) for forming protostars are revisited in order to investigate the so-called luminosity conundrum highlighted by observations. For a molecular cloud (MC) core with such an EoS with polytropic index γ > 1, the central mass accretion rate (MAR) decreases with increasing time as a p...

Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in white...

Thermal-diffusional pulsation behaviors in planar as well as outwardly and inwardly propagating white dwarf (WD) carbon flames are systematically studied. In the 1D numerical simulation, the asymptotic degenerate equation of state and simplified one-step reaction rates for nuclear reactions are used to study the flame propagation and pulsation in W...

The integrated processes of flame acceleration, deflagration-to-detonation transition (DDT), and the resulting detonation propagation in micro- and macro-scale channels are simulated. It is found that the modes of flame acceleration and DDT in these two channels are different, being primarily controlled by viscosity and turbulent flame development,...

The role of the global curvature on the structure and propagation of cylindrical detonations is studied allowing and without allowing the development of cellular structures through two-dimensional (2-D) and 1-D simulations, respectively. It is shown that as the detonation transitions from being overdriven to the Chapman–Jouguet (CJ) state, its stru...

The globally planar detonation in free space is numerically simulated, with particular interest to understand and quantify the emergence and evolution of the onedimensional pulsating instability and the two-dimensional cellular structure which is inherently also affected by pulsating instability. It is found that the pulsation includes three stages...

The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the...

As a foundational element describing relativistic reacting waves of relevance to astrophysical phenomena, the Rankine-Hugoniot relations classifying the various propagation modes of detonation and deflagration are analyzed in the relativistic regime, with the results properly degenerating to the non-relativistic and highlyrelativistic limits. The e...

The accelerative expansion of the Crab Nebula's outer envelope is a mystery in dynamics, as a conventional expanding blast wave decelerates when bumping into the surrounding interstellar medium. Here we show that the strong relativistic pulsar wind bumping into its surrounding nebula induces energy-generating processes and initiates a detonation wa...

Various spectral emission lines from star-forming molecular cloud core L1517B manifest red asymmetric double-peaked profiles with stronger red peaks and weaker blue peaks, in contrast to the oft-observed blue-skewed molecular spectral line profiles with blue peaks stronger than red peaks. Invoking a spherically symmetric general polytropic hydrodyn...

Spectral observations of molecular line profiles reveal the so-called `blue profiles' for double-peaked molecular lines with stronger blue and weaker red peaks as notable features for star-forming cloud core collapses under the self-gravity. In contrast, 25-30 per cent of observed molecular spectral line profiles in star-forming clouds or cores als...

Spectral molecular line profile observations of star-forming molecular clouds sometimes show distinct red asymmetric double-peaked molecular line profiles with weaker blue peaks and stronger red peaks. For some star-forming molecular clouds, such molecular transitions with red asymmetric line profiles and blue asymmetric line profiles (i.e. blue as...

Emission line profiles of tracer molecule H$_2$CO 140 GHz transition from gravitational core collapsing clouds in the dynamic process of forming protostars are calculated, using a simple ray-tracing radiative transfer model. Three self-similar dynamic inside-out core collapse models -- the conventional polytropic model, the empirical hybrid model a...

Self-similar shock solutions in spherically symmetric polytropic gas flows are constructed and analyzed in contexts of proto-star formation processes. Among other possible solutions, we model a similarity shock across the sonic critical curve with an inner free-fall core collapse and a simultaneous outer expansion of the extended envelope; the sepa...