Gemini South's high-def version of 'A Star is Born'
Sharpness of star-forming image matches expected resolution of Webb Space Telescope

Date:
October 5, 2020
Source:
Rice University
Summary:
NASA's James Webb Space Telescope is still more than a year from
launching, but the Gemini South telescope in Chile has provided
astronomers a glimpse of what the orbiting observatory should
deliver.



FULL STORY ========================================================================== NASA's James Webb Space Telescope is still more than a year from
launching, but the Gemini South telescope in Chile has provided
astronomers a glimpse of what the orbiting observatory should deliver.


========================================================================== Using a wide-field adaptive optics camera that corrects for distortion
from Earth's atmosphere, Rice University's Patrick Hartigan and Andrea
Isella and Dublin City University's Turlough Downes used the 8.1-meter telescope to capture near-infrared images of the Carina Nebula with the
same resolution that's expected of the Webb Telescope.

Hartigan, Isella and Downes describe their work in a study published
online this week in Astrophysical Journal Letters. Their images, gathered
over 10 hours in January 2018 at the international Gemini Observatory,
a program of the National Science Foundation's NOIRLab, show part of a molecular cloud about 7,500 light years from Earth. All stars, including Earth's sun, are thought to form within molecular clouds.

"The results are stunning," Hartigan said. "We see a wealth of detail
never observed before along the edge of the cloud, including a long series
of parallel ridges that may be produced by a magnetic field, a remarkable almost perfectly smooth sine wave and fragments at the top that appear
to be in the process of being sheared off the cloud by a strong wind."
The images show a cloud of dust and gas in the Carina Nebula known as the Western Wall. The cloud's surface is slowly evaporating in the intense
glow of radiation from a nearby cluster of massive young stars. The
radiation causes hydrogen to glow with near-infrared light, and specially designed filters allowed the astronomers to capture separate images of
hydrogen at the cloud's surface and hydrogen that was evaporating.

An additional filter captured starlight reflected from dust, and combining
the images allowed Hartigan, Isella and Downes to visualize how the
cloud and cluster are interacting. Hartigan has previously observed the
Western Wall with other NOIRLab telescopes and said it was a prime choice
to follow up with Gemini's adaptive optics system.



========================================================================== "This region is probably the best example in the sky of an irradiated interface," he said. "The new images of it are so much sharper than
anything we've previously seen. They provide the clearest view to date of
how massive young stars affect their surroundings and influence star and
planet formation." Images of star-forming regions taken from Earth are
usually blurred by turbulence in the atmosphere. Placing telescopes in
orbit eliminates that problem. And one of the Hubble Space Telescope's
most iconic photographs, 1995's "Pillars of Creation," captured the
grandeur of dust columns in a star- forming region. But the beauty of
the image belied Hubble's weakness for studying molecular clouds.

"Hubble operates at optical and ultraviolet wavelengths that are blocked
by dust in star-forming regions like these," Hartigan said.

Because near-infrared light penetrates the outer layers of dust in
molecular clouds, near-infrared cameras like the Gemini South Adaptive
Optics Imager can see what lies beneath. Unlike traditional infrared
cameras, Gemini South's imager uses "a mirror that changes its shape to
correct for shimmering in our atmosphere," Hartigan said. The result:
photos with roughly 10 times the resolution of images taken from
ground-based telescopes that don't use adaptive optics.

But the atmosphere causes more than blur. Water vapor, carbon dioxide and
other atmospheric gases absorb some parts of the near-infrared spectrum
before it reaches the ground.

"Many near-infrared wavelengths will only be visible from a space
telescope like the Webb," Hartigan said. "But for near-infrared
wavelengths that reach Earth's surface, adaptive optics can produce
images as sharp as those acquired from space." The advantages of each technique bode well for the study of star formation, he said.

"Structures like the Western Wall are going to be rich hunting
grounds for both Webb and ground-based telescopes with adaptive
optics like Gemini South," Hartigan said. "Each will pierce the dust
shrouds and reveal new information about the birth of stars." Video: https://www.youtube.com/watch?v=HBHcJM9Tbt4&feature=emb_logo

========================================================================== Story Source: Materials provided by Rice_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. Patrick Hartigan, Turlough Downes, Andrea Isella. A JWST Preview:
Adaptive-optics Images of H2, Br-g, and K-continuum in Carina's
Western Wall. The Astrophysical Journal, 2020; 902 (1): L1 DOI:
10.3847/2041- 8213/abac08 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/10/201005112118.htm

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