Context: Recently, James Webb Space Telescope observed 19 nearby face-on spiral galaxies as part of its contributions to the PHANGS program. These images have provided several new puzzle pieces to the understanding of these galaxies.
About Physics at High Angular resolution in Nearby GalaxieS (PHANGS) Project:
- Physics at High Angular resolution in Nearby GalaxieS (PHANGS) project is a large, long-standing initiative supported by more than 150 astronomers worldwide.
- PHANGS aims to make high-resolution observations of nearby galaxies with several telescopes, including ALMA, HUBBLE, JWST and the VLT. The project aims to understand the interplay of the small-scale physics of gas and star formation.
- Observations of nearby galaxies will be utilised to understand how physics at or near the “cloud” scale are affected by galaxy-scale conditions, how they affect still smaller scale processes, and how these influence the evolution of whole galaxies.
- PHANGS makes high-resolution observations of nearby galaxies with several telescopes, including NASA’s James Webb Space Telescope, Hubble Space Telescope, Very Large Telescope’s Multi-Unit Spectroscopic Explorer, and Atacama Large Millimeter/submillimeter Array.
- These observations are taken in ultraviolet, visible, radio, near- and mid-infrared light.
PHANGS-ALMA survey
- This is a part of the PHANGS project, which focuses on the molecular gas disks in 90 nearby galaxies that are typical of star-forming massive galaxies in the nearby universe.
- The survey resolves the molecular gas reservoir into individual molecular clouds and star-forming complexes that are the engines of star formation and galaxy evolution.
Infrared Astronomy and James Webb Telescope:
- The rainbow of light that the human eye can see is a small portion of the total range of light, known in science as the visible part of the electromagnetic spectrum.
- Telescopes can be engineered to detect light outside the visible range to show us otherwise hidden regions of space.
- James Webb Space Telescope detects near-infrared and mid-infrared wavelengths, the light beyond the red end of the visible spectrum.
- Some objects are better observed in infrared wavelengths. Some bodies of matter that are cool and do not emit much energy or visible brightness, like people or a young planet, still radiate in the infrared. For example, a snake is able to see infrared energy, which humans perceive as heat.
- Visible light’s short, tight wavelengths are prone to bouncing off dust particles, making it hard for visible light to escape from a dense nebula or protoplanetary cloud of gas and dust.
- The longer wavelengths of infrared light slip past dust more easily, and therefore instruments that detect infrared light—like those on Webb—are able to see the objects that emitted that light inside a dusty cloud.
- Low-energy brown dwarfs and young protostars forming in the midst of a nebula are among the difficult-to-observe cosmic objects that Webb can study. In this way, Webb will reveal a “hidden” universe of star and planet formation that is literally not visible.
- Infrared light holds clues to many mysteries from the beginning of everything, the first stars and galaxies in the early universe, after the big bang. Through a process called cosmological red-shifting (Geometry of Spacetime - article link).
- In cosmological red-shifting light is stretched as the universe expands, so light from stars that is emitted in shorter ultraviolet and visible wavelengths is stretched to the longer wavelengths of infrared light.
Observation of these early days in the universe’s history will shed light on perplexing questions of dark matter and energy, black holes, galaxy evolution over time, the nature of the first stars, and the path that led to the formation of the universe we have today.