Jump to content

NASA-Funded Study Assesses Pollution Near Los Angeles-Area Warehouses


NASA

Recommended Posts

  • Publishers

5 min read

Preparations for Next Moonwalk Simulations Underway (and Underwater)

Southern California warehouses
A recent NASA-funded study quantified higher levels of fine particulate air pollution near Southern California warehouses, a result of emissions from diesel trucks that transport goods to and from such facilities. Inhalation of these tiny particles can cause serious health problems.
Adobe Stock/Matt Gush

Satellite-based data offers a broad view of particulate air pollution patterns across a major West Coast e-commerce hub.

As goods of all shapes and sizes journey from factory to doorstep, chances are they’ve stopped at a warehouse along the way — likely several of them. The sprawling structures are waypoints in the logistics networks that make e-commerce possible. Yet the convenience comes with tradeoffs, as illustrated in a recent NASA-funded study.

Published in the journal GeoHealth, the research analyzes patterns of particulate pollution in Southern California and found that ZIP codes with more or larger warehouses had higher levels of contaminants over time than those with fewer or smaller warehouses. Researchers focused on particulate pollution, choosing Southern California because it is a major distribution hub for goods: Its ports handle 40% of cargo containers entering the country.

The buildings themselves are not the major particulate sources. Rather, it’s the diesel trucks that pick up and drop off goods, emitting exhaust containing toxic particles called PM2.5. At 2.5 micrometers or less, these pollutants can be inhaled into the lungs and absorbed into the bloodstream. Although atmospheric concentrations are typically so small they’re measured in millionths of a gram per cubic meter, the authors caution that there’s no safe exposure level for PM2.5.

“Any increase in concentration causes some health damage,” said co-author Yang Liu, an environmental health researcher at Emory University in Atlanta. “But if you can curb pollution, there will be a measurable health benefit.”

A data visualization shows the average concentration of PM2.5 particulate pollution in the Los Angeles region from 2000 to 2018
A data visualization shows the average concentration of PM2.5 particulate pollution in the Los Angeles region from 2000 to 2018, along with the locations of nearly 11,000 warehouses. Darker red indicates higher concentration of these toxic particles; small black circles represent warehouse locations.
NASA Earth Observatory

Growing Air Quality Research

Particulate pollution has been linked to respiratory and cardiovascular diseases, some cancers, and adverse birth outcomes, including premature birth and low infant birth weight.

The new study is part of a broader effort funded by the NASA Health and Air Quality Applied Sciences Team to use satellite data to understand how air pollution disproportionately affects underserved communities.

As the e-commerce boom of recent decades has spurred warehouse construction, pollution in nearby neighborhoods has become a growing area for research. New structures have often sprouted on relatively inexpensive land, which tends to be home to low-income or minority populations who bear the brunt of the poor air quality, Liu said.

Another recent NASA-funded study analyzed satellite-derived nitrogen dioxide (NO2) measurements around 150,000 United States warehouses. It found that concentrations of the gas, which is a diesel byproduct and respiratory irritant, were about 20% higher near warehouses.

Distribution Hub

For the GeoHealth paper, scientists drew on previously generated datasets of PM2.5 from 2000 to 2018 and elemental carbon, a type of PM2.5 in diesel emissions, from 2000 to 2019. The data came from models based on satellite observations, including some from NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) instruments.

The researchers also mined a real estate database for the square footage as well as the number of loading docks and parking spaces at nearly 11,000 warehouses across portions of Los Angeles, Riverside, and San Bernardino counties, and all of Orange County.

They found that warehouse capacity correlated with pollution. ZIP codes in the 75th percentile of warehouse square footage had 0.16 micrograms per cubic meter more PM2.5 and 0.021 micrograms per cubic meter more elemental carbon than those in the 25th percentile.

Similarly, ZIP codes in the 75th percentile of number of loading docks had 0.10 micrograms per cubic meter more PM2.5 and 0.014 micrograms per cubic meter more elemental carbon than those in the 25th percentile. And ZIP codes in the 75th percentile of truck parking spaces had 0.21 micrograms per cubic meter more PM2.5 and 0.021 micrograms per cubic meter more elemental carbon than those in the 25th percentile.

“We found that warehouses are associated with PM2.5 and elemental carbon,” said lead author Binyu Yang, an Emory environmental health doctoral student.

Although particulate pollution fell from 2000 to 2019 due to stricter emissions standards, the concentrations in ZIP codes with warehouses remained consistently higher than for other areas.

Researchers also found that the gaps widened in the holiday shopping season, up to 4 micrograms per cubic meter — “a significant difference,” Liu said.

Satellites Provide Big Picture

Satellite observations, the researchers said, were essential because they provided a continuous map of pollution, including pockets not covered by ground-based instruments.

It’s the same motivation behind NASA’s TEMPO (Tropospheric Emissions: Monitoring of Pollution) mission, which launched in April 2023 and measures air pollution hourly during daylight over North America. The release of TEMPO’s first maps showed higher concentrations of NO2 around cities and highways.

Meanwhile, NASA and the Italian Space Agency are collaborating to launch the MAIA (Multi-Angle Imager for Aerosols) in 2026. It will be the first NASA satellite mission whose primary goal is to study health effects of particulate pollution while distinguishing between PM2.5 types.
“This mission will help air quality managers and policymakers conceive more targeted pollution strategies,” said Sina Hasheminassab, a co-author and science systems engineer at NASA’s Jet Propulsion Laboratory in Southern California. Hasheminassab, like Liu, is a member of the MAIA science team.

News Media Contacts

Andrew Wang / Jane J. Lee
Jet Propulsion Laboratory, Pasadena, Calif.
626-379-6874 / 818-354-0307
andrew.wang@jpl.nasa.gov / jane.j.lee@jpl.nasa.gov

2024-134

View the full article

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Similar Topics

    • By NASA
      Peru’s Vice Minister of Defense Policies for Ministry of Defense César Medardo Torres Vega, NASA Administrator Bill Nelson, and Director of Peru’s National Commission for Aerospace Research and Development (CONIDA) Maj. Gen. Roberto Melgar Sheen meet in Lima, Peru, Nov. 14, 2024, where the U.S. and Peru signed a memorandum of understanding agreeing to study a potential sounding rocket campaign.Credit: U.S. Embassy Peru NASA and Peru’s National Commission for Aerospace Research and Development (CONIDA) laid the groundwork for a potential multi-year scientific rocket launch campaign in the South American country.
      Both countries signed a non-binding memorandum of understanding Thursday that includes safety training, a joint feasibility study for the potential campaign, and technical assistance for CONIDA on sounding rocket launches. Sounding rockets are small, low-cost rockets that provide suborbital access to space.
      “We are excited to look at the possibility of once again launching sounding rockets from Peru,” said NASA Administrator Bill Nelson, who signed on behalf of the United States. “This agreement deepens our international partnership with Peru and the scientific research we conduct because of the country’s location along the magnetic equator. Together we will go farther.” 
      Maj. Gen. Roberto Melgar Sheen, head of CONIDA, signed on behalf of Peru. Brian Nichols, assistant secretary for Western Hemisphere Affairs for the U.S. State Department, and Stephanie Syptak-Ramnath, U.S. ambassador to Peru, also participated, among other Peruvian officials. The event took place during the week of the Asia-Pacific Economic Cooperation forum beginning Nov. 9 in Lima.
      During his visit to Peru, Nelson also discussed the importance of international partnerships and collaboration in space and celebrated Peru’s signing of the Artemis Accords earlier this year.
      The United States and Peru have a long history of space cooperation. NASA conducted sounding rocket campaigns at CONIDA’s Punta Lobos launch base in 1975 and 1983.
      NASA uses sounding rockets to carry scientific instruments into space on suborbital flights to collect important science data and test prototype instruments. They yield invaluable data that enhance our understanding of Earth’s atmosphere and weather, our solar system, and the universe, and test equipment for deeper space travel.
      Understanding our Earth’s atmosphere and how it is influenced by the Sun is crucial to protecting ground and space-based assets that we rely on every day, from the power grid to weather data and even navigation. 
      For more information about NASA’s international partnerships, visit:
      https://www.nasa.gov/oiir
      -end-
      Meira Bernstein / Elizabeth Shaw
      Headquarters, Washington
      202-358-1600
      meira.b.bernstein@nasa.gov / elizabeth.a.shaw@nasa.gov
      Share
      Details
      Last Updated Nov 14, 2024 EditorJessica TaveauLocationNASA Headquarters Related Terms
      Office of International and Interagency Relations (OIIR) Sounding Rockets View the full article
    • By NASA
      2 min read
      NASA-Funded Study Examines Tidal Effects on Planet and Moon Interiors
      NASA-supported scientists have developed a new method to compute how tides affect the interiors of planets and moons. Importantly, the new study looks at the effects of body tides on objects that don’t have a perfectly spherical interior structure, which is an assumption of most previous models.
      The puzzling, fascinating surface of Jupiter’s icy moon Europa looms large in this newly-reprocessed color view, made from images taken by NASA’s Galileo spacecraft in the late 1990s. This is the color view of Europa from Galileo that shows the largest portion of the moon’s surface at the highest resolution. NASA/JPL-Caltech/SETI Institute Body tides refer to the deformations experienced by celestial bodies when they gravitationally interact with other objects. Think of how the powerful gravity of Jupiter tugs on its moon Europa. Because Europa’s orbit isn’t circular, the crushing squeeze of Jupiter’s gravity on the moon varies as it travels along its orbit.  When Europa is at its closest to Jupiter, the planet’s gravity is felt the most. The energy of this deformation is what heats up Europa’s interior, allowing an ocean of liquid water to exist beneath the moon’s icy surface.
      “The same is true for Saturn’s moon Enceladus.” says co-author Alexander Berne of CalTech in Pasadena and an affiliate at NASA’s Jet Propulsion Laboratory in Southern California. “Enceladus has an ice shell that is expected to be much more non-spherically symmetric than that of Europa.”
      The body tides experienced by celestial bodies can affect how the worlds evolve over time and, in cases like Europa and Enceladus, their potential habitability for life as we know it. The new study provides a means to more accurately estimate how tidal forces affect planetary interiors.
      In this movie Europa is seen in a cutaway view through two cycles of its 3.5 day orbit about the giant planet Jupiter. Like Earth, Europa is thought to have an iron core, a rocky mantle and a surface ocean of salty water. Unlike on Earth, however, this ocean is deep enough to cover the whole moon, and being far from the sun, the ocean surface is globally frozen over. Europa’s orbit is eccentric, which means as it travels around Jupiter, large tides, raised by Jupiter, rise and fall. Jupiter’s position relative to Europa is also seen to librate, or wobble, with the same period. This tidal kneading causes frictional heating within Europa, much in the same way a paper clip bent back and forth can get hot to the touch, as illustrated by the red glow in the interior of Europa’s rocky mantle and in the lower, warmer part of its ice shell. This tidal heating is what keeps Europa’s ocean liquid and could prove critical to the survival of simple organisms within the ocean, if they exist. The giant planet Jupiter is now shown to be rotating from west to east, though more slowly than its actual rate. NASA/JPL-Caltech The paper also discusses how the results of the study could help scientists interpret observations made by missions to a variety of different worlds, ranging from Mercury to the Moon to the outer planets of our solar system.
      The study, “A Spectral Method to Compute the Tides of Laterally Heterogeneous Bodies,” was published in The Planetary Science Journal. 
      For more information on NASA’s Astrobiology Program, visit:
      https://science.nasa.gov/astrobiology
      -end-
      Karen Fox / Molly Wasser
      Headquarters, Washington
      202-358-1600
      karen.c.fox@nasa.gov / molly.l.wasser@nasa.gov 
      Explore More
      2 min read NASA’s New Edition of Graphic Novel Features Europa Clipper
      NASA has released a new edition of Issue 4 of the Astrobiology Graphic History series.…


      Article


      6 days ago
      5 min read NASA: New Insights into How Mars Became Uninhabitable


      Article


      1 month ago
      14 min read The Making of Our Alien Earth: The Undersea Volcanoes of Santorini, Greece


      Article


      2 months ago
      Share








      Details
      Last Updated Nov 07, 2024 Related Terms
      Astrobiology View the full article
    • By USH
      While observing the Orion Nebula with his 12-inch Dobsonian telescope, a sky-watcher noticed an unusual flashing object. As stars appeared to drift due to Earth's rotation, this particular object while flashing approximately every 20 seconds clearly travels through deep space. 

      The observer wonders whether it might be a rotating satellite or not. However, this isn’t the first sighting of cigar-shaped UFOs or other mysterious objects traveling through space near the Orion Nebula, so it is quite possible that it could be an interstellar craft. 
      Over the years, I have shared several articles, complete with images and videos, documenting similar UFO sightings around the Orion Nebula. You can explore these under the tag: Orion Nebula. 
      Interestingly, these sightings have all occurred between November and February, suggesting there may be a seasonal pattern to these observations.
        View the full article
    • By NASA
      On Nov. 3, 1994, space shuttle Atlantis took to the skies on its 13th trip into space. During the 11-day mission, the STS-66 crew of Commander Donald R. McMonagle, Pilot Curtis L. Brown, Payload Commander Ellen Ochoa, and Mission Specialists Joseph R. Tanner, Scott E. Parazynski, and French astronaut Jean-François Clervoy representing the European Space Agency (ESA) operated the third Atmospheric Laboratory for Applications and Sciences (ATLAS-3), and deployed and retrieved the U.S.-German Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite (CRISTA-SPAS), as part of NASA’s Mission to Planet Earth. The remote sensing instruments studied the Sun’s energy output, the atmosphere’s chemical composition, and how these affect global ozone levels, adding to the knowledge gained during the ATLAS-1 and ATLAS-2 missions.

      Left: Official photo of the STS-68 crew of Jean-François Clervoy, left, Scott E. Parazynski, Curtis L. Brown, Joseph R. Tanner, Donald R. McMonagle, and Ellen Ochoa. Middle: The STS-66 crew patch. Right: The ATLAS-3 payload patch.
      In August 1993, NASA named Ochoa as the ATLAS-3 payload commander, and in January 1994, named the rest of the STS-66 crew. For McMonagle, selected as an astronaut in 1987, ATLAS-3 marked his third trip into space, having flown on STS-39 and STS-54. Brown, also from the class of 1987, previously flew on STS 47, while Ochoa, selected in 1990, flew as a mission specialist on STS-56, the ATLAS-2 mission. For Tanner, Parazynski, and Clervoy, all from the Class of 1992 – the French space agency CNES previously selected Clervoy as one of its astronauts in 1985 before he joined the ESA astronaut cadre in 1992 – STS-66 marked their first spaceflight.

      Left: Schematic illustration of ATLAS-3 and its instruments. Right: Schematic illustration of CRISTA-SPAS retrievable satellite and its instruments.
      The ATLAS-3 payload consisted of six instruments on a Spacelab pallet and one mounted on the payload bay sidewall. The pallet mounted instruments included Atmospheric Trace Molecule Spectroscopy (ATMOS), Millimeter-Wave Atmospheric Sounder (MAS), Active Cavity Radiometer Irradiance Monitor (ACRIM), Measurement of the Solar Constant (SOLCON), Solar Spectrum Measurement from 1,800 to 3,200 nanometers (SOLSCAN), and Solar Ultraviolet Spectral Irradiance Monitor (SUSIM).
      The Shuttle Solar Backscatter Ultraviolet (SSBUV) instrument constituted the payload bay sidewall mounted experiment. While the instruments previously flew on the ATLAS-1 and ATLAS-2 missions, both those flights took place during the northern hemisphere spring. Data from the ATLAS-3’s mission in the fall complemented results from the earlier missions. The CRISTA-SPAS satellite included two instruments, the CRISTA and the Middle Atmosphere High Resolution Spectrograph Investigation (MAHRSI).

      Left: Space shuttle Atlantis at Launch Pad 39B at NASA’s Kennedy Space Center in Florida. Middle: Liftoff of Atlantis on STS-66. Right: Atlantis rises into the sky.
      Following its previous flight, STS-46 in August 1992, Atlantis spent one and a half years at the Rockwell plant in Palmdale, California, undergoing major modifications before arriving back at KSC on May 29, 1994. During the modification period, workers installed cables and wiring for a docking system for Atlantis to use during the first Shuttle-Mir docking mission in 1995 and equipment to allow it to fly Extended Duration Orbiter missions of two weeks or longer. Atlantis also underwent structural inspections and systems upgrades including improved nose wheel steering and a new reusable drag chute. Workers in KSC’s Orbiter Processing Facility installed the ATLAS-3 and CRISTA-SPAS payloads and rolled Atlantis over to the Vehicle Assembly Building on Oct. 4 for mating with its External Tank and Solid Rocket Boosters. Atlantis rolled out to Launch Pad 39B six days later. The six-person STS-66 crew traveled to KSC to participate in the Terminal Countdown Demonstration Test, essentially a dress rehearsal for the launch countdown, on Oct. 18.
      They returned to KSC on Oct. 31, the same day the final countdown began. Following a smooth countdown leading to a planned 11:56 a.m. EST liftoff on Nov. 3, 1994, Atlantis took off three minutes late, the delay resulting from high winds at one of the Transatlantic Abort sites. The liftoff marked the third shuttle launch in 55 days, missing a record set in 1985 by one day. Eight and a half minutes later, Atlantis delivered its crew and payloads to space. Thirty minutes later, a firing of the shuttle’s Orbiter Maneuvering System (OMS) engines placed them in a 190-mile orbit inclined 57 degrees to the equator. The astronauts opened the payload bay doors, deploying the shuttle’s radiators, and removed their bulky launch and entry suits, stowing them for the remainder of the flight.

      Left: Atlantis’ payload bay, showing the ATLAS-3 payload and the CRISTA-SPAS deployable satellite behind it. Middle: European Space Agency astronaut Jean-François Clervoy uses the shuttle’s Remote Manipulator System (RMS) to grapple the CRISTA-SPAS prior to its release. Right: Clervoy about to release CRISTA-SPAS from the RMS.
      The astronauts began to convert their vehicle into a science platform, and that included breaking up into two teams to enable 24-hour-a-day operations. McMonagle, Ochoa, and Tanner made up the Red Team while Brown, Parazynski, and Clervoy made up the Blue Team. Within five hours of liftoff, the Blue Team began their sleep period while the Red Team started their first on orbit shift by activating the ATLAS-3 instruments, the CRISTA-SPAS deployable satellite, and the Remote Manipulator System (RMS) or robotic arm in the payload bay and some of the middeck experiments. The next day, Clervoy, operating the RMS, grappled CRISTA-SPAS, lifted it from its cradle in the payload bay, and while Atlantis flew over Germany, deployed it for its eight-day free flight. McMonagle fired Atlantis’ thrusters to separate from the satellite.

      Left: Ellen Ochoa and Donald R. McMonagle on the shuttle’s flight deck. Middle: European Space Agency astronaut Jean-François Clervoy in the commander’s seat during the mission. Right: Scott E. Parazynski operates a protein crystallization experiment in the shuttle middeck.

      Left: Joseph R. Tanner operates a protein crystallization experiment. Middle: Curtis L. Brown operates a microgravity acceleration measurement system. Right: Ellen Ochoa uses the shuttle’s Remote Manipulator System to grapple CRISTA-SPAS following its eight-day free flight.
      For the next eight days, the two teams of astronauts continued work with the ATLAS instruments and several middeck and payload bay experiments such as protein crystal growth, measuring the shuttle microgravity acceleration environment, evaluating heat pipe performance, and a student experiment to study the Sun that complemented the ATLAS instruments. On November 12, the mission’s 10th day, the astronauts prepared to retrieve the CRISTA-SPAS satellite. For the retrieval, McMonagle and Brown used a novel rendezvous profile unlike previous ones used in the shuttle program. Instead of making the final approach from in front of the satellite, called the V-bar approach, Atlantis approached from below in the so-called R-bar approach. This is the profile Atlantis planned to use on its next mission, the first rendezvous and docking with the Mir space station. It not only saved fuel but also prevented contamination of the station’s delicate sensors and solar arrays. Once within 40 feet of CRISTA-SPAS, Ochoa reached out with the RMS, grappled the satellite, and then berthed it back in the payload bay.

      A selection from the 6,000 STS-66 crew Earth observation photographs. Left: Deforestation in the Brazilian Amazon. Middle left: Hurricane Florence in the North Atlantic. Middle right: The Ganges River delta. Right: The Sakurajima Volcano in southern Japan.
      As a Mission to Planet Earth, the STS-66 astronauts spent considerable time looking out the window, capturing 6,000 images of their home world. Their high inclination orbit enabled views of parts of the planet not seen during typical shuttle missions.

      Left: The inflight STS-66 crew photo. Right: Donald R. McMonagle, left, and Curtis R. Brown prepare for Atlantis’ deorbit and reentry.
      On flight day 11, with most of the onboard film exposed and consumables running low, the astronauts prepared for their return to Earth the following day. McMonagle and Brown tested Atlantis’ reaction control system thrusters and aerodynamic surfaces in preparation for deorbit and descent through the atmosphere, while the rest of the crew busied themselves with shutting down experiments and stowing away unneeded equipment.

      Left: Atlantis makes a perfect touchdown at California’s Edwards Air Force Base. Middle: Atlantis deploys the first reusable space shuttle drag chute. Right: Mounted atop a Shuttle Carrier Aircraft, Atlantis departs Edwards for the cross-country trip to NASA’s Kennedy Space Center in Florida.
      On Nov. 14, the astronauts closed Atlantis’ payload bay doors, donned their launch and entry suits, and strapped themselves into their seats for entry and landing. Tropical Storm Gordon near the KSC primary landing site forced a diversion to Edwards Air Force Base (AFB) in California. The crew fired Atlantis’ OMS engines to drop out of orbit. McMonagle piloted Atlantis to a smooth landing at Edwards, ending the 10-day 22-hour 34-minute flight, Atlantis’ longest flight up to that time. The crew had orbited the Earth 174 times. Workers at Edwards safed the vehicle and placed it atop a Shuttle Carrier Aircraft for the ferry flight back to KSC. The duo left Edwards on Nov. 21, and after stops at Kelly Field in San Antonio and Eglin AFB in the Florida panhandle, arrived at KSC the next day. Workers there began preparing Atlantis for its next flight, STS-71 in June 1995, the first Shuttle-Mir docking mission. Meanwhile, a Gulfstream jet flew the astronauts back to Ellington Field in Houston for reunions with their families. As it turned out, STS-66 flew Atlantis’ last solo flight until STS-125 in 2009, the final Hubble Servicing Mission. The 16 intervening flights, and the three that followed, all docked with either Mir or the International Space Station.
      “The mission not only met all our expectations, but all our hopes and dreams as well,” said Mission Scientist Timothy L. Miller of NASA’s Marshall Space Flight Center in Huntsville, Alabama. “One of its high points was our ability to receive and process so much data in real time, enhancing our ability to carry out some new and unprecedented cooperative experiments.” McMonagle said of STS-66, “We are very proud of the mission we have just accomplished. If there’s any one thing we all have an interest in, it’s the health of our planet.”
      Enjoy the crew narrate a video about the STS-66 mission.
      Explore More
      3 min read Halloween on the International Space Station
      Article 4 days ago 9 min read 60 Years Ago: The First Flight of the Lunar Landing Research Vehicle
      Article 5 days ago 11 min read 35 Years Ago: STS-34 Sends Galileo on its Way to Jupiter
      Article 2 weeks ago View the full article
    • By NASA
      3 min read
      Buckle Up: NASA-Funded Study Explores Turbulence in Molecular Clouds
      This image shows the distribution of density in a simulation of a turbulent molecular cloud. NASA/E. Scannapieco et al (2024) On an airplane, motions of the air on both small and large scales contribute to turbulence, which may result in a bumpy flight. Turbulence on a much larger scale is important to how stars form in giant molecular clouds that permeate the Milky Way.
      In a new NASA-funded study in the journal Science Advances, scientists created simulations to explore how turbulence interacts with the density of the cloud. Lumps, or pockets of density, are the places where new stars will be born. Our Sun, for example, formed 4.6 billion years ago in a lumpy portion of a cloud that collapsed.
      “We know that the main process that determines when and how quickly stars are made is turbulence, because it gives rise to the structures that create stars,” said Evan Scannapieco, professor of astrophysics at Arizona State University and lead author of the study. “Our study uncovers how those structures are formed.”
      Giant molecular clouds are full of random, turbulent motions, which are caused by gravity, stirring by the galactic arms and winds, jets, and explosions from young stars. This turbulence is so strong that it creates shocks that drive the density changes in the cloud.
      The simulations used dots called tracer particles to traverse a molecular cloud and travel along with the material. As the particles travel, they record the density of the part of the cloud they encounter, building up a history of how pockets of density change over time. The researchers, who also included Liubin Pan from Sun Yat Sen University in China, Marcus Brüggen from the University of Hamburg in Germany, and Ed Buie II from Vassar College in Poughkeepsie, New York, simulated eight scenarios, each with a different set of realistic cloud properties.  
      This animation shows the distribution of density in a simulation of a turbulent molecular cloud. The colors represent density, with dark blue indicating the least dense regions and red indicating the densest regions. Credit: NASA/E. Scannapieco et al (2024) The team found that the speeding up and slowing down of shocks plays an essential role in the path of the particles.  Shocks slow down as they go into high-density gas and speed up as they go into low-density gas. This is akin to how an ocean wave strengthens when it hits shallow water by the shore.   
      When a particle hits a shock, the area around it becomes more dense. But because shocks slow down in dense regions, once lumps become dense enough, the turbulent motions can’t make them any denser.  These lumpiest high-density regions are where stars are most likely to form.
      While other studies have explored molecular cloud density structures, this simulation allows scientists to see how those structures form over time. This informs scientists’ understanding of how and where stars are likely to be born.
      “Now we can understand better why those structures look the way they do because we’re able to track their histories,” said Scannapieco.
      This image shows part of a simulation of a molecular cloud. The colors represent density, with dark blue indicating the least dense regions and red indicating the densest regions. Tracer particles, represented by black dots, traverse the simulated cloud. By examining how they interact with shocks and pockets of density, scientists can better understand the structures in molecular clouds that lead to star formation. NASA/E. Scannapieco et al (2024) NASA’s James Webb Space Telescope is exploring the structure of molecular clouds. It is also exploring the chemistry of molecular clouds, which depends on the history of the gas modeled in the simulations. New measurements like these will inform our understanding of star formation.
      View the full article
  • Check out these Videos

×
×
  • Create New...