Readers discuss JWST’s peek into the early universe and more

More than words

The James Webb Space Telescope, or JWST, has been a big success, thanks in large part to senior project scientist Jane Rigby, who is also an advocate for LGBTQ+ astronomers, Lisa Grossman reported in “The telescope whisperer” (SN: 8/12/23, p. 24).

“Thank you for including the article on Jane Rigby…. She is clearly an outstanding scientist, a leader in her field and certainly deserves the recognition this article gave her,” reader Dorothy Tepper wrote. “The only way this article came up short was that there are no photographs of her actually doing any science…. I would have liked to see photos of her at work; for example, using a telescope, designing or working on equipment, leading a meeting of scientists or engineers or giving a keynote address at an important meeting. Photographs of female scientists actually doing science or engineering work are important for female students and young scientists to see so they have strong role models. I would appreciate it very much if you keep this suggestion in mind for future articles featuring female scientists.”

Far out

JWST has discovered many distant galaxies dating to the early universe that are bigger, brighter and more mature than expected, Lisa Grossman reported in “Extravagance of early galaxies” (SN: 8/12/23, p. 18).

Astrophysicist Brant Robertson and colleagues analyzed four early galaxies detected by a project called the JWST Advanced Deep Extragalactic Survey, or JADES, Grossman reported.

Astrophysicist Cosmin Ilie of Colgate University in Hamilton, N.Y., wrote that three of those four objects may instead be stars powered by dark matter, not galaxies. Ilie and his team published their findings in the July 25 Proceedings of the National Academy of Sciences.

Science News covered that study in “Have ‘dark stars’ come into view?” (SN: 8/26/23, p. 8). The scientists ran computer simulations of how much light a potential dark star might emit at various wavelengths. The team compared those simulated patterns with the objects’ photometry — how bright the objects appear in JWST images using different filters — and found three of the objects to be consistent with the dark star patterns.

These dark stars are still hypothetical, and some scientists are skeptical. Robertson, of the University of California, Santa Cruz, contends that the four objects are indeed galaxies. To identify the objects as dark stars, it’s important to compare the simulated patterns with not only the photometry, but also the spectroscopy of the objects, which yields a more precise analysis, he says. Spectroscopy sifts light coming directly from the objects into much finer wavelengths, similar to how passing sunlight through a prism creates a rainbow. Robertson says his team looked at both the photometry and spectra of the four objects and found that each were consistent with the known photometry and spectra of galaxies.

Space time

Glowing cosmic clouds show that the dormant supermassive black hole at the Milky Way’s center suddenly brightened and let out a brief pulse of X-rays roughly 200 years ago, Lisa Grossman reported in “The Milky Way’s heart raced about 200 years ago” (SN: 8/12/23, p. 4).

Given that the Milky Way’s center is about 26,000 light-years away from Earth, reader Jerry Kreuscher wondered how scientists could know about an event that happened there 200 years ago.

The story described the event as observed from Earth, says associate news editor Christopher Crockett, who holds a Ph.D. in astronomy. So “200 years ago” really means about 26,200 years ago in real time. “Writing about space is tricky,” Crockett says. “Every event has a built-in delay due to light’s speed limit. Astronomers themselves often talk in terms of when cosmic events were observed on Earth since the delay is implied (or, in some cases, not known).” But it’s true: We don’t know what happened to the Milky Way’s heart 200 years ago. We won’t know for roughly another 25,800 years, Crockett says. “With any luck, Science News will be around to cover it.”