How Do We Observe Star Formation
Making sense out of what we see.
The emergent spectral energy distribution (SED) of young stars changes drastically as they evolve. We are starting to put together a detailed picture of the observed properties of the stars culled from both observations and advances in theory in the last few decades. The detailed SEDs help us decide which wavelength region, or combination of wavelength regions, is best suited for each phase. However, we have to be mindful of the role of environment, which can significantly affect the emergent light from the young stars or protostars.
Observational astronomers use various diagnostics -- metrics -- to help them disentangle and interpret the observations. For this project, we will rely mostly on photometry diagnostics. The idea is pretty simple. Saying that the SED of the protostar changes with time means simply that the emergent light at specific wavelength changes with time. So, we select (cleverly) the specific sections of the SED, and plot the relative strengths of these selections against each other. The measurements of the specific section is (usually) photometry.
External links:
A NITARP primer on color-magnitude plots
Learning points
- How does the emergent spectral energy distribution change for stars as they evolve in the earliest stages of their evolution?
- What is the advantage gained by near-infrared? sub-mm? radio?
- What do we observe in the optical with ground and space-based telescopes?
- "Short" vs "Long" lived stages (or phases) of evolution. How do we use number statistics to tell one? What are observational biases that could affect these number statistics.
