NASA Announces Plan to Map Milky Way With Roman Space Telescope

NASA’s Nancy Grace Roman Space Telescope team has released detailed plans for a major survey that will reveal our home galaxy, the Milky Way, in unprecedented detail. In one month of observations spread over two years, the survey will reveal tens of billions of stars and explore previously unexplored structures.

“The Galactic Plane Survey will revolutionize our understanding of the Milky Way,” said Julie McEnery, lead scientist on the Roman project at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We will be able to explore the mysterious hidden side of our galaxy and its star-studded heart. Because of the scale and depth of the investigation, it will be a scientific mother lode.”

The Galactic Plane Survey is the first general astrophysics survey selected by Roman – one of several observational programs Roman will carry out in addition to his three main surveys and the Coronagraph technology demonstration. At least 25% of Roman’s five-year core mission is reserved for astronomers around the world to provide more studies beyond core programs, taking full advantage of Roman’s capabilities to conduct groundbreaking scientific research. Roman is scheduled to launch by May 2027, but the team is on track for a launch as early as fall 2026.

While the retired ESA (European Space Agency) Gaia spacecraft has mapped around 2 billion stars in the Milky Way in visible light, many parts of the galaxy remain hidden by dust. By observing infrared light, Roman will use powerful thermal vision capable of piercing this veil to see what lies beyond.

“It amazes me that we will be able to see through the densest part of our galaxy and explore it properly for the first time,” said Rachel Street, a senior scientist at Las Cumbres Observatory in Santa Barbara, Calif., and co-chair of the committee that selected the Galactic Plane Survey model.

The survey will cover nearly 700 square degrees (a region of the sky as large as about 3,500 full moons) along the Milky Way’s bright band — our front view of the disk-shaped structure containing most of our galaxy’s stars, gas and dust. Scientists expect the survey to map up to 20 billion stars and detect tiny changes in their positions through repeated high-resolution observations. And it will only take 29 days spread over the first two years of the mission.

Cosmic cradles

Stars are born from parent clouds of gas and dust. Roman will peer into the haze of these nesting sites to see millions of stellar embryos, newborn stars still swathed in shrouds of dust, wayward infant stars that brighten unpredictably, and young stars that may have planetary systems forming around them. Astronomers will study the birth rates of stars across a wide range of masses and assemble videos showing how stars change over time.

“This study will study so many stars in so many different stellar environments that we will sample every phase of a star’s evolution,” Street said.

Observing so many stars at different stages of development will provide a better understanding of the forces that shape them. Star formation is like a tug-of-war between gravity, radiation, magnetism and turbulence. Roman will help us study how these forces influence the collapse of gas clouds into full-fledged stars, smaller brown dwarfs – between objects much heavier than planets but not massive enough to burst into flames like stars – or new worlds.

Some stars are born in huge clusters called clusters. Roman will study nearly 2,000 young, loosely linked open clusters to see how the galaxy’s spiral arms trigger star formation. The study will also map dozens of ancient, densely populated globular clusters near the center of the galaxy, which could help astronomers reconstruct the early history of the Milky Way.

Comparing Roman’s snapshots of clusters scattered across the galaxy will allow scientists to study nature versus nurture on a cosmic scale. Because stars in a cluster generally share the same age, origin, and chemical composition, analyzing them allows astronomers to isolate environmental effects very precisely.

Checking the pulse

When they run out of fuel, Sun-like stars leave behind cores called white dwarfs, and heavier stars collapse to form neutron stars and black holes. Roman will find these stellar embers even when they are alone thanks to the ripples of space-time.

Anything with mass distorts the underlying fabric of the universe. When light from a background star passes through the gravitational well around an intervening object on its journey to Earth, its path curves slightly around the object. This phenomenon, called microlensing, can temporarily brighten the star. By studying these signals, astronomers can learn the mass and size of otherwise invisible foreground objects.

A separate survey – Roman’s Galactic Bulge Time-Domain Survey – will carry out in-depth microlensing observations over a smaller area in the heart of the Milky Way. The Galactic Plane Survey will make repeated observations over a shorter interval but across the entire center of the galaxy, giving us the first comprehensive view of this complex galactic environment. A clear view of the galaxy’s central bar will help astronomers answer the question of its origin, and Roman videos of the stars in this region will make it possible to study some ultra-tight binary objects at the very end of their lives through their interactions with close companions.

“Compact binaries are particularly interesting because they are precursors to gravitational wave sources,” said Robert Benjamin, a visiting professor at the University of Wisconsin-Whitewater and co-chair of the committee that selected the Galactic Plane Survey design. When neutron stars and black holes merge, the collision is so powerful that it causes ripples across the fabric of space-time. “Scientists want to know more about the pathways that led to these mergers. »

Roman’s repeated observations will also monitor the twinkling stars. Ground-based surveys detect thousands of bright star explosions, but often fail to see the faint, dust-obscured stars that produce them. Roman will identify the culprits and take high-resolution snapshots of the aftermath.

Some stars pulse rhythmically and the speed of their pulsation is directly linked to their intrinsic luminosity. By comparing their true brightness to how they appear from Earth, astronomers can measure distances across the galaxy. Roman will find these blinking stars farther away than ever before and track them over time, helping astronomers improve their cosmic measuring instruments.

“Combining the study of Roman’s galactic plane with other observations of the Milky Way will create the best portrait of the galaxy we’ve ever had,” Benjamin said.

Download additional images and videos from NASA’s Science Visualization Studio.

For more information on the Roman Space Telescope, visit:

https://www.nasa.gov/roman

By Ashley Balzer
NASA Goddard Space Flight CenterGreenbelt, Maryland.

Media contact:

Claire Andreoli
NASA Goddard Space Flight CenterGreenbelt, Maryland.
301-286-1940