Pictures of the sky can show us cosmic wonders; movies can bring them to
life. Movies from NASA’s NEOWISE space telescope are revealing motion and
change across the sky.
Every six months, NASA’s Near-Earth Object Wide Field Infrared Survey
Explorer, or NEOWISE, spacecraft completes one trip halfway around the Sun, taking images in
all directions. Stitched together, those images form an “all-sky” map showing
the location and brightness of hundreds of millions of objects. Using 18
all-sky maps produced by the spacecraft (with the 19th and 20th to be released
in March 2023), scientists have created what is essentially a time-lapse movie
of the sky, revealing changes that span a decade.
Each map is a tremendous resource for astronomers, but when viewed in sequence as a time-lapse, they serve as an even stronger resource for trying to better understand the universe. Comparing the maps can reveal distant objects that have changed position or brightness over time, what’s known as time-domain astronomy.
New
time-lapse movies from NASA’s NEOWISE mission give astronomers the opportunity
to see objects, like stars and black holes, as they move and change over time.
The videos include previously hidden brown dwarfs, a feeding black hole, a
dying star, a star-forming region, and a brightening star. They combine more
than 10 years of NEOWISE observations and 18 all-sky images, enabling a
long-term analysis and a deeper understanding of the universe.
“If you go outside and look at the night
sky, it might seem like nothing ever changes, but that’s not the case,” said
Amy Mainzer, principal investigator for NEOWISE at the University of Arizona in
Tucson. “Stars are flaring and exploding. Asteroids are whizzing by. Black
holes are tearing stars apart. The universe is a really busy, active place.”
NEOWISE was originally a data processing
project to retrieve asteroid detections and characteristics from WISE – an
observatory launched in 2009 and tasked with scanning the entire sky to find
and study objects outside our solar system. The spacecraft used cryogenically
cooled detectors that made them sensitive to infrared light.
Not visible to the human eye, infrared
light is radiated by a plethora of cosmic objects, including cool, nearby stars
and some of the most luminous
galaxies in the universe.
The WISE mission ended in 2011 after the onboard coolant – needed for some
infrared observations – ran out, but the spacecraft and some of its infrared
detectors were still functional. So in 2013, NASA repurposed it to track
asteroids and other near-Earth objects, or NEOs. Both the mission and the
spacecraft received a new name: NEOWISE.
This
illustration shows the Wide-field Infrared Survey Explorer (WISE) spacecraft in
Earth orbit. The WISE mission concluded in 2011, but in 2013 the spacecraft was
repurposed to find and study asteroids and other near-Earth objects (NEOs). The
mission and spacecraft were renamed NEOWISE. Credits: NASA/JPL-Caltech Full image and caption
Growing
Wiser
Despite the shift, the infrared telescope
has continued to scan the sky every six months, and astronomers have continued
to use the data to study objects outside our solar system.
For example, in 2020, scientists released
the second iteration of a project called CatWISE: a catalog of objects from 12
NEOWISE all-sky maps. Researchers use the catalog to study brown dwarfs, a
population of objects found throughout the galaxy and lurking in the darkness
close to our Sun. Although they form like stars, brown dwarfs don’t accumulate
enough mass to kick-start fusion, the process that causes stars to shine.
Because of their proximity to Earth,
nearby brown dwarfs appear to move faster across the sky compared to more
distant stars moving at the same speed. So one way to identify brown dwarfs
amid the billions of objects in the catalog is to look for objects that move. A
complementary project to CatWISE called Backyard
Worlds: Planet 9 invites
citizen scientists to sift through NEOWISE data for moving objects that
computer searches might have missed.
With the original two WISE all-sky maps,
scientists found about 200 brown dwarfs within just 65 light-years of our Sun.
The additional maps revealed another 60 and doubled the number of known
Y-dwarfs, the coldest brown dwarfs. Compared to warmer brown dwarfs, Y-dwarfs
may have a stranger
story to tell in
terms of how they formed and when. These discoveries help illuminate the
menagerie of objects in our solar neighborhood. And a more complete count of
brown dwarfs close to the Sun tells scientists how efficient star formation is
in our galaxy and how early it began.
Watching the sky change over more than a
decade has also contributed to studies of how stars form. NEOWISE can peer into the
dusty blankets swaddling
protostars, or balls of hot gas that are well on their way to becoming stars.
Over the course of years, protostars flicker and flare as they accumulate more
mass from the dust clouds that surround them. Scientists are conducting
long-term monitoring of almost 1,000 protostars with NEOWISE to gain insights
into the early stages of star formation.
NEOWISE’s data has also improved
understanding of black holes. The original WISE survey discovered
millions of supermassive black holes at the centers of distant galaxies. In a recent
study, scientists used NEOWISE data and a technique
called echo mapping to
measure the size of disks of hot, glowing gas surrounding distant black holes,
which are too small and too distant for any telescope to resolve.
“We never anticipated that the spacecraft
would be operating this long, and I don’t think we could have anticipated the
science we’d be able to do with this much data,” said Peter Eisenhardt, an
astronomer at NASA’s Jet Propulsion Laboratory and WISE project scientist.
More
About the Mission
NASA's Jet Propulsion Laboratory in
Pasadena, California, manages and operates the NEOWISE mission for NASA's
Planetary Defense Coordination Office within the Science Mission Directorate in
Washington. The principal investigator, Amy Mainzer, is at the University of
Arizona. The Space Dynamics Laboratory in Logan, Utah, built the science
instrument. Ball Aerospace & Technologies Corp. of Boulder, Colorado, built
the spacecraft. Science data processing takes place at IPAC at Caltech in
Pasadena. Caltech manages JPL for NASA.
JPL managed and operated WISE for NASA's Science Mission Directorate. Edward Wright at UCLA was the principal investigator. The mission was selected competitively under NASA's Explorers Program managed by the agency's Goddard Space Flight Center in Greenbelt, Maryland.
For more information about NEOWISE, visit:
https://www.nasa.gov/neowise
For more information about WISE, visit: http://www.nasa.gov/wise
Source: NASA Telescope Takes 12-Year Time-Lapse Movie of Entire Sky | NASA
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