Big data in star formation

Faculty Development Competitive Research Grant Program 2019-2021

The purpose of the proposed Project is to perform fundamental research on the formation and evolution of filamentary structures in the interstellar medium and determine their role in star formation process using big analysis data from space, stratospheric balloon and ground-based telescopes.

The role of filamentary structures in the evolution of the interstellar medium from the scales of molecular clouds down to the scales of pre-stellar cores is a critical question today. Several theories have been developed to connect the evolution of filaments and cores leading to the formation of stars through interplays between magnetic fields, turbulence and gravity. Theoretical scenarios are to be tested and improved using observational analysis. The advent of satellite telescopes and high-resolution balloon-borne and ground-based telescopes allows us to trace the formation and evolution of filamentary structures and to derive the counterparts of the main acting phenomena such as gravity, turbulence and magnetic fields in this process which is inherent for star formation. We propose to perform a multi-dimensional analysis of a combination of data from space (with Planck* and Herschel* space telescopes), balloon-borne (PILOT* telescope) and ground-based telescopes (TRAO*, JCMT*) at the forefront of computational techniques to trace the evolution of the filamentary structures and their role in star formation.
During the Project, new data processing techniques will be developed, in particular big data analysis and techniques for combining data from different instruments. Up to now, few Kazakhstani scientists had access to foreign high technology instruments. Bringing data and and developing techniques for data analysis will foster innovative technologies potential of Kazakhstani scientific society. Also, data analysis skills and expertise can be transferred to many fields. As an example, the image processing techniques applied to astronomical images can be used in remote sensing images analysis for agricultural purposes and natural resource management.
From theoretical point of view Miyama et al. (1987) considered fragmentational instability of molecular clouds having sheetlike form. He showed that the filamentary structures that form in the initial time of fragmentation tend to stay filamentary and become larger in mass and length. Pon et al. (2013) analytically showed that in a presence of small gravitational instability the filamentary structures are the most favorable form of matter condensation. From the other side, Pudritz & Kevlahan (2013) concluded that the dense filaments are caused by density fluctuations that arise from converging flow shocks. However, Smith et al. (2016) argued that it is the turbulence cascade which is in the origin of filaments. Moreover, Konyves et al. (2015) showed that filaments are more efficient to form stars than molecular clouds of other shapes. These theoretical works justify the studies of filamentary structures as being the most widespread and important structural form of matter in star formation process. By matching Planck and Herschel data in the core L1642 Malinen et al. (2016) showed that the magnetic field geometry is tightly connected to the filamentary cloud’s formation and evolution. Planck Collaboration Int. XXXII studied the relative orientation between the magnetic field and column density structures in Planck data at 15° resolution and found a preferential alignment in the diffuse ISM and a preferential perpendicular relative orientation in molecular clouds. Planck Collaboration Int. XXXV studied ten nearby molecular clouds in more details and showed that the relative orientation changes from mostly parallel to no preferred orientation with increasing column density. At higher angular resolution such a trend has also been observed using balloon-borne BLAST-POL instrument data (Soler & Hennebelle (2017)). These observational studies show the complexity of filaments formation and evolution with respect to the magnetic field. As a step forward, Alina et al. (2018) performed a statistical analysis of the relative orientation between the magnetic field direction and filamentary structures which are associated with the Cold Clumps (cold matter condensations where stars may form). Considering the variety of the filaments’ surroundings and the variations in the filaments’ evolution (by computing differential column densities), Alina et al. (2018) have shown that, first, the previously observed preferential perpendicular relative orientation for the high column density filaments in fact occurs in the cold clumps regions. Also, it strongly depends on the differential column density, as the analysis shows a possible decoupling of the magnetic field direction from the filaments direction for the filaments with higher column density contrast. Second, the cold clumps situated in highly contrasted filaments exhibit a significant trend for perpendicular relative orientation with respect to the derived inner magnetic field direction. This may be an indication of a certain evolutionary stage of the clumps in filaments and the role of the magnetic field in that process. In particular, the gravitational contraction along magnetic field could govern to the formation of cores with their main axis perpendicular to the field. These observational results are in agreement with the sub and trans-Alfvenic MHD simulations of turbulent ISM thus allowing us to make a first attempt for election among the whole range of theories. We estimate that further analysis of the data at different angular resolutions probing different evolutionary stages will bring insights on how the interplay between matter, magnetic fields, turbulence and gravity changes depending on the evolution of star forming regions.

*The Planck satellite telescope is a project of the European Space Agency (ESA) that was gathering data in a wide range of wavelengths (300 micrometers to 11 millimeters) to measure the Cosmic Microwave Background and the foregrounds (galaxies, interstellar medium) both in intensity and polarization with high sensitivity and a resolution of 5’ at higher frequency channel (353 GHz)
*Herschel space observatory is a project of ESA to measure infrared emission from the ISM that was operated from 2009 to 2013.
*PILOT (Polarized Instrument for Long wavelength Observation of the Tenuous interstellar medium) is a balloon-borne sub-millimeter telescope, operated by ESA, that have performed observations during two stratospheric flights from Canada and Australia that measures dust emission and polarization at close frequencies as Planck (125 THz and 545GHz) but at higher angular resolution (1.4’).
*JCMT (James Clerk Maxwell Telescope) operated by the East Asian Observatory has the ability to perform observations both in intensity and polarization at 850 micrometers with the Scuba-2 and Pol-2 instruments at the resolution of about 14’’.
*TRAO (Taeduk Radio Astronomy Observatory) is operated by the Korean Astronomy and Space Science Institute. This 14 meter radio telescope provides observations of spectral lines toward bright sources in molecular clouds.