- 4272 -
ROMAN MISSION -
plans for discovering planets.
NASA's Roman mission will study Milky Way's flickering lights and will
provide one of the deepest-ever views into the heart of our Milky Way galaxy.
The mission will monitor hundreds of millions of stars in search of tell-tale
flickers that betray the presence of planets, distant stars, small icy objects
that haunt the outskirts of our solar system, isolated black holes, and more.
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4272 - ROMAN
MISSION - plans for discovering planets
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- Roman will likely
set a new record for the farthest-known exoplanet, offering a glimpse of a
different galactic neighborhood that could be home to worlds quite unlike the
more than 5,500 Stars with Planets that are currently known.
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- Roman's long-term
sky monitoring represents a boon to what scientists call “time-domain
astronomy”, that studies how the universe changes over time. Roman will join a
growing, international fleet of observatories working together to capture these
changes as they unfold.
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- Roman's “Galactic
Bulge Time-Domain Survey” will focus on the Milky Way, using the telescope's
infrared vision to see through clouds of dust that can block our view of the
crowded central region of our galaxy.
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- When Roman
launches, expected by May 2027, the mission will scour the center of the Milky
Way for microlensing events, which occur when an object such as a star or
planet comes into near-perfect alignment with an unrelated background star from
our viewpoint.
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- Because anything
with mass warps the fabric of space-time, light from the distant star bends
around the nearer object as it passes close by. The nearer object therefore
acts as a natural magnifying glass, creating a temporary spike in the
brightness of the background star's light. That signal lets astronomers know
there's an intervening object, even if they can't see it directly.
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- The survey will
involve taking an image every 15 minutes around the clock for two months. Astronomers will repeat the process six times
over Roman's five-year primary mission for a combined total of more than a year
of observations.
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- This will be one
of the longest exposures of the sky ever taken. The higher density of stars in one
direction will yield more than 50,000 microlensing events, which will reveal
planets, black holes, neutron stars, trans-Neptunian objects, and enable
exciting stellar science.
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- The survey will
cover relatively uncharted territory when it comes to planet-finding. That’s important
because the way planets form and evolve may be different depending on where in
the galaxy they’re located. Our solar system is situated near the outskirts of
the Milky Way, about halfway out on one of the galaxy’s spiral arms.
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- A recent Kepler
Space Telescope study showed that stars on the fringes of the Milky Way possess
fewer of the most common planet types that have been detected so far. Roman
will search in the opposite direction, toward the center of the galaxy, and
could find differences in that galactic neighborhood.
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- Astronomers expect
the survey to reveal more than a thousand planets orbiting far from their host
stars and in systems located farther from Earth than any previous mission has
detected. That includes some that could lie within their host star's habitable
zone, the range of orbital distances where liquid water can exist on the
surface, and worlds that weigh in at as little as a few times the mass of the
moon.
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- Roman can even
detect "rogue" worlds that don't orbit a star at all using
microlensing. These cosmic castaways may have formed in isolation or been
kicked out of their home planetary systems. Studying them offers clues about
how planetary systems form and evolve.
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- Roman's
microlensing observations will also help astronomers explore how common planets
are around different types of stars, including binary systems. The mission will
estimate how many worlds with two host stars are found in our galaxy by
identifying real-life "Tatooine" planets.
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- Some of the
objects the survey will identify exist in a cosmic gray area. Known as brown
dwarfs, they're too massive to be characterized as planets, but not quite
massive enough to ignite as stars. Studying them will allow astronomers to
explore the boundary between planet and star formation.
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- Roman is also
expected to spot more than a thousand neutron stars and hundreds of
stellar-mass black holes. These heavyweights form after a massive star exhausts
its fuel and collapses. The black holes are nearly impossible to find when they
don't have a visible companion to signal their presence, but Roman will be able
to detect them even if unaccompanied because microlensing relies only on an
object's gravity.
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- The mission will
also find isolated neutron stars, the leftover cores of stars that weren't
quite massive enough to become black holes.
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- Astronomers will
use Roman to find thousands of Kuiper belt objects, which are icy bodies
scattered mostly beyond Neptune. The telescope will spot some as small as about
six miles across (about 1 percent of Pluto's diameter), sometimes by seeing
them directly from reflected sunlight and others as they block the light of
background stars.
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- Microlensing
creates spikes in a star’s brightness, while transits have the opposite effect.
Since both methods involve tracking the amount of light we receive from stars
over time, astronomers will be able to use the same data set for both methods.
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- A similar type of
shadow play will reveal 100,000 transiting planets between Earth and the center
of the galaxy. These worlds cross in front of their host star as they orbit and
temporarily dim the light we receive from the star. This method will reveal
planets orbiting much closer to their host stars than microlensing reveals, and
likely some that lie in the habitable zone.
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- Scientists will
also conduct “stellar seismology” studies on a million giant stars. This will
involve analyzing brightness changes caused by sound waves echoing through a
star's gaseous interior to learn about its structure, age, and other
properties.
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- All of these
scientific discoveries and more will come from Roman's Galactic Bulge
Time-Domain Survey, which will account for less than a fourth of the observing
time in Roman's five-year primary mission. Its broad view of space will allow
astronomers to conduct many of these studies in ways that have never been
possible before, giving us a new view of an ever-changing universe.
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December 15, 2023 ROMAN MISSION
- discovering planets 4272
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Monday, December 18, 2023 ---------------------------------
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