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3829 - JAMES
WEBB - lots of new stuff to learn? There is no one single sensor that can
collect data in all of those different wavelengths at the same time. Therefore, scientists have developed a
plethora of instruments that are extremely good at collecting data in one
specific spectrum, such as radio (ALMA), or mid-range infrared (James
Webb).
--------- 3829 - JAMES WEBB - lots of new stuff to learn?
- How can imaging systems interact with different
wavelengths of light. The
electromagnetic spectrum is extremely large.
It includes all types of light, such as radio, infrared, x-rays,
ultraviolet and visible light.
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- The down side of specialization is that those
instruments are blind in other spectral ranges.
If a scientific team is only observing in one type of light, there is a
chance that they could miss important aspects of a phenomena they are studying
that are only visible in a different spectral band.
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- There are many telescopes in those
locations, such as the Atacama desert or Hawaii’s Mauna Kea, that are extremely
large, and can provide very high resolution images in specific spectral bands,
such as radio, microwaves, or infrared.
Infrared is particularly useful as there is a lot of physical data
points that can be obtained in a single measurement, such as pressure,
temperature, and molecular abundances.
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- If
scientists are unable to coordinate simultaneous observations, then they
would lose out on the spectra that the observatories closer to home can
provide. Another advantage that
earth-based observatories have over their in situ counterparts is their ability
to image a whole planet at once.
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- Many orbiter or fly by missions are only
capable of measuring part of their subject at a single point in time. This results in a loss of contextual
understanding, as dynamic phenomena that might be observed in a single place by
the in situ spacecraft might not be present over the entire surface of the
planet or moon. Support from earth-based
telescopes, whether on the ground or in space, could provide that larger
context that the spacecraft itself lacks.
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- This sort of coordination to cover all of
the spectral bases has already been accomplished with one in situ planetary
mission: the Juno spacecraft currently in orbit around Jupiter. The resulting coordination between the Juno
spacecraft and a series of earth-based observatories resulted in over 40 papers
that used data from more than one observational source of the Jupiter system
during that time.
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- Mars is of particular interest, as it is
the most studied planet outside of Earth, and the only one with active rovers
physically on its surface. Scientists
interested in understanding where the methane from Mars’ atmosphere comes from
would certainly benefit from a coordinated observational campaign between
several of the orbiters around Mars (TGO and MAVEN), and earth-based telescopes
such as NASA’s Infrared Telescope Facility in Hawaii.
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- The orbiters around Mars provide excellent
two-dimensional slices of spectral data as they are passing over a specific
strip of the planet. However,
observatories closer to Earth can provide data on the entire hemisphere of the
planet that is facing them, and add a layer of depth that would allow
scientists to piece together a three-dimensional picture that would be
impossible using only data from the orbiters.
-
- There are still some limitations to
earth-based observations, such as the fact that methane is present in Earth’s
atmosphere as well, which could skew the data when looking at Mars. To get around this problem, scientists came
up with an ingenious method of only observing Mars while it is moving away from
(or toward) Earth at more than 13 kilometers a second. This differential speed red- (or blue-)
shifts the spectral signature of the Martian methane enough that it can be
differentiated from that simply present in Earth’s atmosphere.
-
- Another particularly interesting target of
joint observations is Titan, which has been the subject of intense scrutiny in
recent years due to its hydrocarbon lakes, and its methane/ethane based
hydrological cycle.
-
- The moon Titan is so interesting it is
about to receive it’s own in situ visitor in the form of the Dragonfly
mission. When Dragonfly lands in 2034,
the white paper team hopes that many Earth-based telescopes will turn their
eyes toward Titan, as the data collected from the surface can then be
coordinated with more remote observations.
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- Dragonfly will be equipped a mass
spectrometer, which allows the detection of molecules which are impossible to
see remotely, and reveals the full composition of the atmosphere. Earth-based observation could in turn provide
context for these measurements.
-
- Dragonfly's lander will be the first to
reach Titan's surface, and can provide local data to any coordinated
observation program. The mission will
prove an excellent opportunity for coordinated observations. It can provide on
the ground data that can be contextualized with other, larger observatories.
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- Those combined observations will focus on
the organic chemistry that is taking place on the moon. A particularly useful Earth-based tool is
ALMA, the observatory that held the conference that kicked off the white
paper. ALMA is a series of radio
telescopes, which are particularly good at observing organic compounds and
making detailed maps of its observational subjects. Both capabilities would be particularly
helpful in helping the Dragonfly mission, and ALMA’s operators are already very
familiar with Titan.
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- The array actually used Titan as a
calibration target for a number of years after it first launched, due to its
brightness and seeming stability. The
wealth of observations allowed researchers to study Titan and the evolution of
its atmosphere, revealing dynamic processes, and leading to improved
understanding of the moon. Unfortunately, it also revealed Titan is actively
changing, making it less suitable as a flux calibration target. The ALMA team then switched to using a pulsar
for future calibrations.
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- All of the data the ALMA team has
collected, as well as almost all astronomical data from all of the
observatories that might be conscripted into the joint observational efforts is
eventually made free to the public. However, unless the data on a given object
was collected simultaneously by more than one observatory, the benefits of
coordination are lost as transient phenomena would not be present in both those
sets of data.
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- There
might be some simultaneous data of an object collected by more than one
observational platform buried in their data archives.
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- JWST was launched on December 2st, 2021. Now
it’s in a halo orbit at the Sun-Earth L2 point, where it will hopefully continue
operating for 20 years.
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- One of the JWST’s first images was of the
“Cosmic Cliffs.” The Cosmic Cliffs are the edge of an active star-forming
region in NGC 3324, a star cluster near the Carina Nebula. The image shows the
intense ultraviolet energy from hot young stars that shape the region, carving
out cavernous gaps and leaving towers of gas that resist the radiation.
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- The JWST’s powerful infrared capabilities
can focus on molecular hydrogen, the main ingredient in stars. It’s an excellent
tracer for star-forming activity because as young stars grow, they take in the
hydrogen and eject some of it in jets and polar outflows. It’s called stellar
feedback, and these jets carve out caverns in the clouds of gas and dust in the
image.
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- Young, still-forming protostars are obscured
from view by the dense molecular clouds that spawn them. But the JWST has the
power to see inside these clouds. Scrutinizing young stars inside the clouds is
one of the telescope’s four main science objectives.
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- The more astronomers learn about young stars
forming elsewhere, the more they learn about how our own Sun formed and how our
Solar System came to be. The JWST is expanding and deepening our understanding
of the complex mechanisms behind their formation.
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- Understanding how young stars form is one
of the primary quests in astrophysics today. The collective light from the
first stars helped drive the reionization of the early Universe. Before the
Epoch of Reionization, a dense fog of primordial gas obscured the Universe.
During Reionization, light from young stars helped clear the haze from the
Universe and allowed light to travel.
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- Astrophysicists can’t study the formation
of the very first stars, but they can watch young stars forming today and work
their way towards a more solid understanding of the Epoch of Reionization.
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- This isn’t the first time astronomers have
studied the young stars forming in this region. The Hubble looked at it 16
years ago. And while the Hubble can’t discern as much detail as the James Webb,
it revealed enough for the study authors to compare how the jets and outflows
have changed in the intervening years. The measurements show the speed and
direction in which the jets move, necessary details for understanding young
stars.
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- Future observations will be more thorough
and detailed. They’ll help shed even more light on one of the hottest topics in
astronomy: how young stars drive planetary formation.
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- Feedback mechanisms mark young stars.
They’re still growing, and as they accrete gas from the clouds they’re embedded
in, they emit some of it back into their surroundings with their jets. The gas
outflows help shape their protoplanetary disks and the formation of planets
like ours. A better understanding of these outflows leads to a better
understanding of planets and, by complex extension, the likelihood of life
appearing elsewhere.
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- Our Solar System likely formed in a cluster
similar to the one in this study. Astronomers aren’t certain yet, but by uncovering
the details in NGC 3324, they may shed some light on our origins.
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- The JWST can gather ancient light from the
first stars and galaxies and peer deep inside stellar cocoons to show us how
stars are born. The results are fascinating scientific understandings, but
along with answering our scientific questions, the JWST does something else. It
gives context to humanity’s existence in the Universe’s Life Era.
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- The Sun is no different than other stars.
The same forces drove its birth and evolution, and the Sun would’ve emitted the
same outflows and polar jets as the young stars in this image. Those feedback
mechanisms would’ve shaped the protoplanetary disk that the Earth formed in. So
every time we see images of young stars elsewhere, we learn something about our
origins.
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January 16, 2022 JAMES WEBB
- lots of new stuff to learn? 3821
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--------------------- --- Wednesday, January 18, 2023 ---------------------------
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