JWST: Where Are New Stars Born?

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JWST: Where Are New Stars Born?

Post by bystander » Wed Aug 21, 2019 6:32 pm

Where Are New Stars Born? JWST Will Investigate
NASA | GSFC | STScI | JWST | 2019 Aug 21
STSCI-J-p1941a-z-1000x816[1].png
This is a Hubble Space Telescope image of galaxy SDSS J1226+2152, which is being
magnified and distorted by the immense gravity of a galaxy cluster in front of it.
It is one of four distant, star-forming galaxies the TEMPLATES team will study
with Webb. The team chose it as an example of a galaxy that is not very dusty.
Credits: NASA, ESA, STScI, and H. Ebeling (University of Hawaii)

When it comes to making new stars, the party is almost over in the present-day universe. In fact, it’s been nearly over for billions of years. Our Milky Way continues to form the equivalent of one Sun every year. But in the past, that rate was up to 100 times greater. So if we really want to understand how stars like our Sun formed in the universe, we need to look billions of years into the past.

Using NASA’s James Webb Space Telescope as a sort of time machine, a team of researchers intends to do just that. Led by principal investigator Jane Rigby of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and co-principal investigator Joaquin Vieira of the University of Illinois, Champaign, the team will take advantage of natural, cosmic telescopes called gravitational lenses. These large celestial objects will magnify the light from distant galaxies that are at or near the peak of star formation. ...

The program is called Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star Formation, or TEMPLATES. Although TEMPLATES is an acronym, its meaning goes deeper. The word “template” refers to something used as a pattern, mold, or guide for designing or constructing similar items. “We want to make these four targets incredibly well-studied, and to have really good data, so other Webb researchers can use them as templates, or good examples, when they are working to understand data for a large number of galaxies that are much fainter,” said Rigby. ...

The TEMPLATES team has four main goals:
  1. Measure how many new stars are forming, to determine how rapidly galaxies form stars. By making different kinds of measurements of star-formation rates for the four galaxies, the team plans to see how well they agree or disagree. Through cross-checks, the team will determine whether or not these galaxies are in the midst of vigorous star formation, or if they are just forming a star occasionally.
  2. Map the star-formation rate in these galaxies. Scientists don’t know much about where stars form in galaxies over most of cosmic time. Mapping star formation in galaxies in the nearby universe is relatively easy, but it’s much more difficult for distant galaxies. Looking across most of cosmic time, distant galaxies all appear very small in the sky and individual features cannot be resolved. So, scientists don’t have a good understanding of where stars formed in galaxies in the early universe.
  3. Compare the young and old stellar populations. Scientists will measure the older stars—stars that live for billions of years, like the Sun. They’ll determine where those stars reside within a galaxy, which will inform them about the past history of star formation. Then they can compare that data to where the new stars are forming. That will reveal how star formation has changed in galaxies over time, and answer some basic questions about how galaxies grow. For example, do they build up from the inside out, or from the outside in?
  4. Measure the conditions of the gas within these galaxies. Scientists will determine how much of the periodic table these galaxies have built up—for example, how much carbon, oxygen, and nitrogen they contain. They will also measure other physical conditions, such as how dense the gas is.
...
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