A potential break through in Star formation?
In one of the recent observations made by JWST, astronomers probed the region of NGC 346, a nearby dwarf galaxy to our milky way. The reason behind this observation is the conditions and amount of metals within the SMC (Small Magellanic Cloud) that resemble those seen in galaxies billions of years ago, during an era known as "cosmic noon," when star formation was at its peak.
Using the JWST, scientists have been able to study the star clusters in NGC 346 with greater detail and have made the groundbreaking discovery of star formation in clusters' dusty ribbons.
Dusty ribbons are long, narrow gas and dust structures stretching through the cluster. These ribbons are the sites of active star formation. The JWST's observations have revealed that these ribbons contain dense concentrations of gas and dust collapsing under their gravity to form new stars.
The discovery of star formation in clusters' dusty ribbons has provided new insights into the processes that drive star formation in these clusters. Scientists have found that the movement of the stars within the cluster can create turbulent motions in the gas and dust, which can trigger the collapse of the ribbons and the formation of new stars. This discovery also provides a new understanding of the dynamics of the star formation process in the clusters, which have been previously not well understood.
More on NGC 346
NGC 346 is a region of active star formation located in the Small Magellanic Cloud (SMC), a small galaxy located approximately 200,000 light-years from Earth. The region is located just south of the main body of the SMC and is one of the most active and well-studied star-forming regions in our galaxy.
One of the most striking features of NGC 346 is the large number of young, massive stars formed in the region. These stars are several times more massive than the Sun. They are responsible for ionizing the surrounding gas and dust, creating the characteristic H II region that gives the region its name. The intense ultraviolet radiation and strong winds from these stars also help to shape the surrounding molecular cloud and trigger the formation of new stars.
In addition to the young massive stars, NGC 346 also contains many lower-mass stars in various stages of formation. These stars are thought to form through the collapse of dense cores within the molecular cloud. This process can be studied in detail using telescopes such as the Atacama Large Millimeter Array (ALMA) and the Hubble Space Telescope.
NGC 346 is also home to several interesting objects, including the massive binary star system HD 5980, the luminous blue variable RMC 136a, and the compact H II region NGC 346-11. The region is also rich in gas and dust, with molecular clouds and dense cores that are thought to be the sites of future star formation.
The study of NGC 346 has provided valuable insights into the star formation process and the early evolution of massive stars. The proximity of the SMC and the wealth of data available for this region have made it a popular target for observational studies and theoretical modeling.
In conclusion, NGC 346 is an active star formation region in the Small Magellanic Cloud. The region is home to many young, massive stars and is rich in gas and dust. The proximity of the SMC and the wealth of data available for this region have made it a popular target for observational studies and theoretical modeling. The study of NGC 346 has provided valuable insights into the star formation process and the early evolution of massive stars.
Spherical Collapse model (A peek into star formation)
The spherical collapse model is a mathematical model that describes the collapse of a spherical cloud of gas under the influence of gravity. The model is based on the equations of hydrodynamics and the Poisson equation for gravity. The basic equations for this model are
- the continuity equation, which describes the conservation of mass;
- the momentum equation, which describes the motion of the gas; and
- the energy equation, which describes the balance of energy within the cloud.
The continuity equation is given by:
∂ρ/∂t + ∇.(ρv) = 0
The momentum equation is given by:
∂(ρv)/∂t + ∇.(ρ$v *$v + P) = -ρ ∇Φ
The energy equation is given by:
∂E/∂t + ∇.(Ev + Pv) = -ρv. ∇Φ
The Poisson equation for gravity is given by:
$∇^2Φ$ = 4πGρ
Where ρ is the density of the gas, v is the velocity of the gas, P is the pressure of the gas, Φ is the gravitational potential, E is the internal energy of the gas, and G is the gravitational constant.
The mathematical solution of the spherical collapse model using the finite difference method involves discretizing the set of equations that describe the collapse of a spherical cloud of gas under the influence of gravity and approximating the values of the variables at discrete points in space and time.
The finite difference method involves the following steps:
Discretizing the equations: The equations are approximated at discrete points in space and time. The variables such as density, velocity, and temperature are represented by values at specific points in space and time.
Initial conditions: The initial conditions of the problem, such as the density, temperature, and velocity of the gas, are specified at the initial time step.
Time stepping: The equations are advanced using a time-stepping scheme, such as the Euler or the Runge-Kutta method.
Updating the variables: The values of the variables at each point in space and time are updated using the equations and the values of the variables at the previous time step.
Iteration: The process of time stepping and updating the variables is repeated until a steady state is reached or a predefined stopping criterion is met.
Solution: The final solution of the spherical collapse model is the set of values of the variables at each point in space and time.
For example, let's consider a spherical cloud of gas with radius R, discretized into N radial grid points, and let's assume that the cloud is isothermal. The density at each radial point i is denoted by ρi, and the velocity at each radial point i is denoted by vi.
The continuity equation becomes:
$ρ_i(n+1)$ = $ρ_i(n) - (4πR^2*v_i(n)Δt)/(iΔR)$
Where n is the current time step and n+1 is the next time step.
The momentum equation becomes:
$v_i(n+1) = v_i(n) - (4πG*ρ_i(n)iΔR)/(R^2)$
The Poisson equation for gravity becomes:
$Φ_i(n+1) = Φ_i(n) - (4πG*ρ_i(n)i^2ΔR^2)/(R^2)$
The energy equation is not needed as we assumed that the cloud is isothermal.
These equations are used to update the values of the variables at each point in space and time. The process of time stepping and updating the variables is repeated until a steady state is reached or a predefined stopping criterion is met. The final solution of the spherical collapse model is the set of values of the variables at each point in space and time.
It important to note here that this is a simplified example and the real implementation of the finite difference method for the spherical collapse model is much more complex and require computational resources. Also, the solution of the model depends on the accuracy of the numerical method used and the initial conditions.
For further reading:
A brief overview of star formation
Numerical Methods for Simulating Star Formation
https://www.frontiersin.org/articles/10.3389/fspas.2019.00051/full
https://www.stsci.edu/jwst/science-execution/program-information.html?id=1227
-Sanskar (MS21234)
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