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Research Focus

  • Star formation in the Milky Way molecular clouds and other nearby galaxies
  • Fragmentation of molecular clouds over multiple scales of hierarchy
  • Connection between modes of cloud fragmentation and star formation
  • Role of turbulence, magnetic field and self-gravity of the gas for the support and collapse of a cloud structure

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Hierarchical Fragmentation

RESEARCH

In this paper I provide the first ever observational evidence of hierarchical fragmentation of a molecular cloud over five scales that are separated by five orders of magnitude. A molecular cloud of over 10 pc size does not collapse as a whole in a monolithic pattern to make a group of stars, rather a wave of supersonic turbulence sets density enhancements in certain regimes, and each over-dense region later contracts by gravitational instability. Turns out, each such region further produces other over-dense regions, and this process is repeated in a hierarchical fashion until stars are born in the densest regions. An outward pressure in clouds acts opposing the inward gravitational collapse of a cloud...

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Column density Probability Distribution Function

RESEARCH

Star formation is an end product of cloud fragmentation. The newly formed stars are called protostars and are found in the densest part of molecular clouds. Using the far-infrared dust emission, we can estimate the density of the clouds. Further, by studying the distribution of column density in such cloud, we can infer the conditions of star formation. Using this approach, I studied the column density probability distribution function (N-PDF in short) for Mon R2 giant molecular cloud and report a prominent powerlaw feature in denser parts of this molecular cloud...

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Star-gas correlations

RESEARCH

The star formation laws in molecular clouds have been studied for over half a century now. However, there is still no precise answer. The rate of star formation depends on the availability of dense gas in clouds. Thus, a relation is expected between natal gas and the rate of star formation. Studies in nearby galaxies report different values for this dependence. However, those galaxies are so far away that directly forming protostars can’t be probed and indirect measures are used to study star formation. The big advantage of studying this in nearby molecular clouds is that we can directly probe the forming protostars...

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Dense Gas Kinematics

RESEARCH

I use the spectroscopic information contained in quantum transition of rotational states of gas molecules to study the gas kinematics in the molecular clouds that are thousands of light years away. Different gas traces different regions of the molecular cloud. For e.g., I use ammonia transitions to trace the very dense central regions of a cloud, also known as cores and carbon monoxide transitions to study more diffuse regions of the cloud. These transitions contain kinematic information, such as velocity of clouds and dispersion velocity, which I decipher using different analyzing techniques...

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Protostellar Disk Fragmentation

RESEARCH

As a result of gravitational contraction, the cloud shrinks in size and the rotation of the cloud increases to conserve angular momentum of the system. Protostellar disks are produced as its direct consequence, and are expected to be ubiquitous in recently formed stars. The study of the formation and evolution of protostellar disks is vital for understanding both star and planet formation. These disks are predicted to form early in the protostellar stage by both analytic models and simulations...

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