The JWST promises exceptional observations of stellar nurseries in the farthest reaches of the Milky Way galaxy never seen before by astronomers. In the latest research as part of the expert group, headed by Natsuko Izumi, Gifu University National Astronomical Observatory of Japan, the advanced capabilities of the JWST have been used to examine young star clusters over 50000 light years away from the galactic center.
The Extreme Halo: An Untapped Approach to Star Formation
These investigating regions also termed as Digel Clouds 1 and 2 fall into what is called the ‘extreme outer Galaxy’ or EOG which is a region further than 18 kiloparsecs which is about 59,000 light years from the center of the galaxy. This far-flung environment is quite different from the solar neighborhood which most of the nearby star formation research and studies have been carried out. Gas densities are about ten times lower than values encountered close to the Sun and metallicity is about one-third of solar metallicity level.
Thus, under such conditions, one can study the formation of stars in more protostellar like conditions. In particular, it is possible that the properties bear some resemblance to the properties in dwarf galaxies, or to early epochs of our Milky Way. Therefore, exploring star formation in these environments can provide the information as to how such proceedings were in the early universe.
New Levels of Sensitivity Showing Everything Hidden in a Freakish Way
The research team was able to image several young star clusters in Digel Clouds 1 and 2 utilizing the Near Infrared Camera (NIRCam) and Mid Infrared Instrument (MIRI) of the James Webb Space Telescope. It is worth noting that these instruments allowed them to image objects which are 10-80 more than the faintness level of the free ground based telescopes available today.
The latter advance implies that it has become possible with JWST to identify very young stars of 0.01-0.05 solar masses in these remote locations. The typical bulge of around 10 mass stars is limited in prior studies. Faint young stars in the first EOG were finally resolved thanks to protracted infrared wavelengths for each individuum using JWST.
New Structures Encountered
The greater resolution and sensitivity of JWST has revealed to us a number of interesting structures which were not noticed in previous observations. The following are
- Very Young Protostars: Additionally, the team discovered two very bright objects only at the longest infrared wavelengths while they were invisible at shorter wavelengths. These are probably very early protostars, probably submerged less than 100,000 years away in deep dusty clouds.
- Outflows and Jets: The images also revealed several typical structures of young stellar outflows, including bow shonks and knotlike structures. These features span tens of thousands of astronomical units (1 astronomical unit is the distance from the sun to the earth) outwards.
- Complex Nebulae: There were also discrete knots around the young star clusters where JWST detected complicated gas and dust around the star clusters. There was even one region with several pillar structures that were characteristic to the well known star forming regions such as the “Pillars of Creation” in the Eagle nebula.
Implications for Understanding Star Formation
This new perspective of star formation towards the extreme outer Galaxy also has several important implications as well.
- Initial Mass Hierarchy: More importantly, because they are now capable of detecting stars down to much lower masses, they can now examine how the initial mass function stellar mass distribution is likely to vary in this extreme location.
- Disk Lifetimes: Previous studies hinted that the disks of gas and dust around young stars in the EOG may actually disperse in a shorter period than their counterparts in the vicinity of the Sun. This will enable a much deeper analysis of this phenomenon.
- Triggered Star Formation: The observations support scenarios where in these areas, the formation of star took place due to outside force events like the supernova activity or the interaction between gas clouds.
- Early Universe Analogs: The processes of star formation observed here may have taken placed in the early universe so this provides a closer lab to understand the formation of first generation stars.
Future Work
This step and its findings is just the first step for the use of JWST towards such distant star forming regions in future studies. The research team intends to analyze these data and make a detailed census of the young stars as well as their distributions and corelate the observations with other wavelengths such as sub millimeter to give out a holistic approach to the dynamics of formation of stars in the extreme outer parts of the Galaxy.
With the impressive resources such as JWST at our disposal, we are able to work even beyond the observable limits of comprehension that our galaxy was created with and is still being shaped today. Over the last few years the extreme outer Galaxy, which was thought to be a rather placid backwater, is turning out to be an exciting laboratory for basic cosmic origins.
