NASA’s Nancy Grace Roman Space Telescope will help scientists better understand our Milky Way galaxy’s less sparkly components—gas and dust strewn between stars, known as the interstellar medium.
One of Roman’s major observing programs, the Galactic Plane Survey, will peer through our galaxy to its most distant edge, mapping roughly 20 billion stars—about four times more than have currently been mapped. Scientists will use data from these stars to study the dust their light travels through, contributing to the most complete picture yet of the Milky Way’s structure, star formation, and the origins of our solar system.
Our Milky Way galaxy is home to more than 100
billion stars that are often separated by trillions of miles. The spaces in
between, called the interstellar medium, aren’t empty — they’re sprinkled with
gas and dust that are both the seeds of new stars and the leftover crumbs from
stars long dead. Studying the interstellar medium with observatories like
NASA’s upcoming Nancy Grace Roman Space Telescope will reveal new insight into
the galactic dust recycling system.
Credit: NASA/Laine Havens; Music credit: Building Heroes by Enrico Cacace
[BMI], Universal Production Music
“With Roman, we’ll be able to turn
existing artist’s conceptions of the Milky Way into more data-driven models
using new constraints on the 3D distribution of interstellar dust,” said
Catherine Zucker, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts.
Solving Milky
Way mystery
Scientists know how our
galaxy likely looks by combining observations of the Milky Way
and other spiral galaxies. But dust clouds make it hard to work out the details
on the opposite side of our galaxy. Imagine trying to map a neighborhood while
looking through the windows of a house surrounded by a dense fog.
Roman will see through the “fog” of dust using a specialized camera and filters that observe infrared light — light with longer wavelengths than our eyes can detect. Infrared light is more likely to pass through dust clouds without scattering.
This artist’s concept visualizes different types of
light moving through a cloud of particles. Since infrared light has a longer
wavelength, it can pass more easily through the dust. That means astronomers
observing in infrared light can peer deeper into dusty regions.
Credit: NASA’s Goddard Space Flight Center
Light with shorter wavelengths, including blue light produced by stars,
more easily scatters. That means
stars shining through dust appear dimmer and redder than they actually are.
By comparing the observations
with information on the source star’s characteristics, astronomers can
disentangle the star’s distance from how much its colors have been reddened.
Studying those effects reveals clues about the dust’s properties.
“I can ask, ‘how much redder and
dimmer is the starlight that Roman detects at different wavelengths?’ Then, I
can take that information and relate it back to the properties of the dust
grains themselves, and in particular their size,” said Brandon Hensley, a
scientist who studies interstellar dust at NASA’s Jet Propulsion Laboratory in
Southern California.
Scientists will also learn about
the dust’s composition and probe clouds to investigate the physical processes
behind changing dust properties.
Clues in dust-influenced
starlight hint at the amount of dust between us and a star. Piecing together
results from many stars allows astronomers to construct detailed 3D dust maps.
That would enable scientists like Zucker to create a model of the Milky Way,
which will show us how it looks from the outside. Then scientists can better
compare the Milky Way with other galaxies that we only observe
from the outside, slotting it into a cosmological perspective of galaxy
evolution.
“Roman will add a whole new
dimension to our understanding of the galaxy because we’ll see billions and
billions more stars,” Zucker said. “Once we observe the stars, we’ll have the
dust data as well because its effects are encoded in every star Roman detects.”
Galactic life
cycles
The interstellar medium does more
than mill about the Milky Way — it fuels star and planet formation. Dense blobs
of interstellar medium form molecular clouds, which can gravitationally collapse
and kick off the first stages of star development. Young stars eject hot winds
that can cause surrounding dust to clump into planetary building
blocks.
“Dust carries a lot of
information about our origins and how everything came to be,” said Josh Peek,
an associate astronomer and head of the data science mission office at the
Space Telescope Science Institute in Baltimore, Maryland. “Right now, we’re basically
standing on a really large dust grain — Earth was built out of lots and lots of
really tiny grains that grew together into a giant ball.”
Roman will identify young
clusters of stars in new, distant star-forming regions as well as contribute
data on “star factories” previously identified by missions like NASA’s
retired Spitzer Space Telescope.
“If you want to understand star
formation in different environments, you have to understand the interstellar
landscape that seeds it,” Zucker said. “Roman will allow us to link the 3D
structure of the interstellar medium with the 3D distribution of young stars
across the galaxy’s disk.”
Roman’s new 3D dust maps will
refine our understanding of the Milky Way’s spiral structure, the pinwheel-like
pattern where stars, gas, and dust bunch up like galactic traffic jams. By
combining velocity data with dust maps, scientists will compare observations
with predictions from models to help identify the cause of spiral
structure—currently unclear.
The role that this spiral pattern
plays in star formation remains similarly uncertain. Some theories suggest that
galactic congestion triggers star formation, while others contend that these
traffic jams gather material but do not stimulate star birth.
Roman will help to solve mysteries like these by providing more data on dusty regions across the entire Milky Way. That will enable scientists to compare many galactic environments and study star birth in specific structures, like the galaxy’s winding spiral arms or its central stellar bar.
NASA’s Nancy Grace Roman Space Telescope will
conduct a Galactic Plane Survey to explore our home galaxy, the Milky Way. The
survey will map around 20 billion stars, each encoding information about
intervening dust and gas called the interstellar medium. Studying the
interstellar medium could offer clues about our galaxy’s spiral arms, galactic
recycling, and much more.
Credit: NASA, STScI, Caltech/IPAC
The astronomy community is
currently in the final stages of planning for Roman’s Galactic Plane Survey.
“With Roman’s massive survey of the
galactic plane, we’ll be able to have this deep technical understanding of our
galaxy,” Peek said.
After processing, Roman’s data will
be available to the public online via the Roman Research Nexus and the Barbara A. Mikulski Archive for Space
Telescopes, which will each provide open access to the data for years to come.
“People who aren’t born yet are
going to be able to do really cool analyses of this data,” Peek said. “We have
a really beautiful piece of our heritage to hand down to future generations and
to celebrate.”
Roman is slated to launch no later
than May 2027, with the team working toward a potential early launch as soon as
fall 2026.
The Nancy Grace Roman Space
Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt,
Maryland, with participation by NASA’s Jet Propulsion Laboratory and
Caltech/IPAC in Southern California, the Space Telescope Science Institute in
Baltimore, and a science team comprising scientists from various research
institutions. The primary industrial partners are BAE Systems Inc. in Boulder,
Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific
& Imaging in Thousand Oaks, California.
Download additional images
and video from NASA’s Scientific Visualization Studio.
For more information about the Roman Space Telescope, visit: https://www.nasa.gov/roman
By Laine Havens
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Source: How
NASA’s Roman Mission Will Unveil Our Home Galaxy Using Cosmic Dust - NASA
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