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When stars are born, they do it inside a molecular cloud. Astronomers long assumed that the “crèche” supplied all the nutrients that protostars needed to form. However, it turns out they get help from outside the nest.

A new study by scientists at the Max Planck Institute for Extraterrestrial Physics delved into the role of streamers and filaments in the star-birth process. Think of them as channels that extend out from the interior of the stellar creche, sometimes out as far as 10,000 astronomical units (about 0.15 light-years). The research team found a connection between these streamers and filaments and star-formation activity. Essentially, the streamers provide a star-forming disk with fresh gas to nourish the baby star as it grows.

Star Formation at a Glance

The standard story about star birth goes like this: cool, dense molecular clouds are the crèches of stars. The material begins to accumulate preferentially in one part of the cloud. These clouds are mostly hydrogen but also contain other elements. For example, supernova explosions seed nearby molecular clouds with heavier elements (such as iron).

As the cloud contracts, its own self-gravity pulls in more and more material. Eventually, the temperatures and pressures get high enough in the “overdense” region that a protostar begins to shine. It continues to grow, attracting more and more material. At some point, nuclear fusion begins in the core of the region, and that’s when the star is born.

This whole process takes millions of years and also involves magnetic fields and other factors. However, when astronomers noticed strange streamers and filaments in star birth regions, they wondered what roles they played in the process. They also speculated about the origins of these structures.

Looking at Protostars in Barnard 5

A team at Max Planck, led by Ph.D. student Maria Teresa Valdiva Mena, focused on a particularly interesting star in the Barnard 5 region of the sky. This is a molecular cloud that lies in the direction of the constellation Perseus. There are actually several protostars in the area, but one sports two filaments. To get a handle on what’s happening there, the team used the Atacama Large Millimeter Array (ALMA) in Chile, along with two other telescopes to study the filaments. “Our aim was to trace the journey of gas from outside of the filament that contains the protostar to the protostellar disks, bridging the gap between different scales of star formation,” said Valdivia-Mena, lead author of the study.

The gas flow in Barnard 5 at three different scales. Fresh gas (left) moves inside filaments toward condensations (black contours) and the protostar (yellow). Yellow curve shows the streamer transporting material toward the protostellar disk. Right images zoom into the streamer, with red and blue showing outflows toward the disk (brown). Courtesy MPE.
The gas flow in Barnard 5 at three different scales. Fresh gas (left) moves inside filaments toward condensations (black contours) and the protostar (yellow). The yellow curve shows the streamer transporting material toward the protostellar disk. Right images zoom into the streamer, with red and blue showing outflows toward the disk (brown). Courtesy MPE.

The three different telescopes showed that the streamers are conducting chemically fresh gas from the larger nebula into the birth envelope. The ALMA data actually showed a streamer feeding right into the protostellar disk surrounding a soon-to-be-born star. The streamers and filaments seem to be an integral part of the starforming process by providing material from other parts of the nebula.

“These results are very exciting because they show that the star-formation process is a multiscale process,” said Jaime Pineda, second author of the Barnard 5 study. “Accretion flows and streamers connect the young stellar objects with the parental cloud. This dynamic process of feeding the young star might even affect the whole disk and planet formation process, although we need future observations to confirm this.”

Protostars and Planets

It isn’t just stars that are influenced by these flows of fresh gas into a birth cloud. Their future planets will show the chemical influence exerted by filaments and streamers. Just as a quick review, a star’s planets form from material in the protostellar
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Amazing Amateur Images of April 8th’s Total Solar Eclipse

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The last total solar eclipse across the Mexico, the U.S. and Canada for a generation wows observers.

Did you see it? Last week’s total solar eclipse did not disappoint, as viewers from the Pacific coast of Mexico, across the U.S. from Texas to Maine and through the Canadian Maritime provinces were treated to an unforgettable show. The weather threw us all a curve-ball one week out, as favored sites in Texas and Mexico fought to see the event through broken clouds, while areas along the northeastern track from New Hampshire and Maine onward were actually treated to clear skies.

Many eclipse chasers scrambled to reposition themselves at the last minute as totality approached. In northern Maine, it was amusing to see tiny Houlton, Maine become the epicenter of all things eclipse-based.

Tales of a Total Solar Eclipse

We were also treated to some amazing images of the eclipse from Earth and space. NASA also had several efforts underway to chase the eclipse. Even now, we’re still processing the experience. It takes time (and patience!) for astro-photos to make their way through the workflow. Here are some of the best images we’ve seen from the path of totality:

Tony Dunn had an amazing experience, watching the eclipse from Mazatlan, Mexico. “When totality hit, it didn’t look real,” Dunn told Universe Today. “It looked staged, like a movie studio. the lighting is something that can’t be experienced outside a total solar eclipse.”

Totality with prominences.
Totality on April 8th, with prominences. Credit: Tony Dunn.

Dunn also caught an amazing sight, as the shadow of the Moon moved across the low cloud cover:

#Eclipse2024 #Mazatlan The shadow of the Moon crosses the sky. pic.twitter.com/9FEf4TTK8r

— Tony Dunn (@tony873004) April 14, 2024

Black Hole Sun

Peter Forister caught the eclipse from central Indiana. “It was my second totality (after 2017 in South Carolina), so I knew what was coming,” Forister told Universe Today. “But it was still as incredible and beautiful as anything I’ve ever seen in nature. The Sun and Moon seemed huge in my view—a massive black hole (like someone took a hole punch to the sky) surrounded by white and blue flames streaking out. Plus, there was great visibility of the planets and a few stars. The memory has been playing over and over in my head since it happened—and it’s combined with feelings of awe and wonder at how beautiful our Universe and planet really are. The best kind of memory!”

Totality
Totality over Texas. Credit: Eliot Herman

Like many observers, Eliot Herman battled to see the eclipse through clouds. “As you know, we had really frustrating clouds,” Herman told Universe Today. “I shot a few photos (in) which you can see the eclipse embedded in the clouds and then uncovered to show the best part. For me it almost seemed like a cosmic mocking, showing me what a great eclipse it was, and lifting the veil only at the end of the eclipse to show me what I missed…”

Totality
Totality and solar

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The Solar Wind is Stripping Oxygen and Carbon Away From Venus

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The BepiColombo mission, a joint effort between JAXA and the ESA, was only the second (and most advanced) mission to visit Mercury, the least explored planet in the Solar System. With two probes and an advanced suite of scientific instruments, the mission addressed several unresolved questions about Mercury, including the origin of its magnetic field, the depressions with bright material around them (“hollows”), and water ice around its poles. As it turns out, BepiColombo revealed some interesting things about Venus during its brief flyby.

Specifically, the two probes studied a previously unexplored region of Venus’ magnetic environment when they made their second pass on August 10th, 2021. In a recent study, an international team of scientists analyzed the data and found traces of carbon and oxygen being stripped from the upper layers of Venus’ atmosphere and accelerated to speeds where they can escape the planet’s gravitational pull. This data could provide new clues about atmospheric loss and how interactions between solar wind and planetary atmospheres influence planetary evolution.

The study was led by Lina Hadid, a CNRS researcher at the Plasma Physics Laboratory (LPP) and the Observatoire de Paris. She was joined by researchers from the Institute of Space and Astronautical Science (ISAS) at JAXA, the Max Planck Institute for Solar System Research (MPS), the CNRS Research Institute in Astrophysics and Planetology (IRAP), the Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), the Institute for Geophysics and Extraterrestrial Physics (IGEP), the Space Research Institute (SRI), and multiple universities.

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Schematic view of planetary material escaping through Venus magnetosheath flank. Credit: Thibaut Roger/Europlanet 2024 RI/Hadid et al.

While Venus does not have an intrinsic magnetic field like Earth, it has a weak magnetic field that results from the interaction of solar wind and electrically charged particles in Venus’ upper atmosphere. Surrounding this “induced magnetosphere” is the “magnetosheath,” a region where the solar wind is slowed and heated. In August 2021, BepliColombo’s two spacecraft – the ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO, aka. Mio) – passed by Venus on the final leg of their journey toward Mercury, using the planet’s gravity to adjust its course and its upper atmosphere to shed speed.

The two spacecraft spent 90 minutes passing through the tail of the magnetosheath and the magnetic regions closest to the Sun. The mission controllers used this opportunity to gather data on the number and mass of charged particles it encountered using Mio‘s Mass Spectrum Analyzer (MSA) and the Mercury Ion Analyzer (MIA), which are part of the probe’s Mercury Plasma Particle Experiment (MPPE). The team also relied on Europlanet’s Sun Planet Interactions Digital Environment on Request (SPIDER) space weather modeling tools to track how atmospheric particles propagated through the magnetosheath.

As Hadid explained in a Europlanet Society release, analysis of this data provides insight into the chemical and physical processes driving atmospheric escape from this region of the magnetosheath:

“This is the first time that positively charged carbon ions have been observed escaping from Venus’s atmosphere. These are heavy ions that are usually slow moving, so we are still trying to understand the mechanisms that are at play. It may be that an electrostatic ‘wind’ is lifting them away from the planet, or they could be accelerated through centrifugal processes.”

In particular, these findings could help scientists to deduce what happened to Venus’ surface water. Like Earth, much of Venus’ surface was once covered in oceans, which disappeared about 700 million years ago. The most widely-held theory is that this coincided with a massive resurfacing event that flooded the atmosphere with carbon
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Are Titan’s Dunes Made of Comet Dust?

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A new theory suggests that Titan’s majestic dune fields may be have come from outer space. Researchers had always assumed that the sand making up Titan’s dunes was locally made, through erosion or condensed from atmospheric hydrocarbons. But researchers from the University of Colorado want to know: Could it have come from comets?

The dunes of Titan

When the Cassini spacecraft arrived in orbit around Saturn, nobody had ever seen beneath the thick soupy atmosphere of Titan. So when it dropped the Huygens lander, and began probing Titan with cloud-penetrating radar, scientists were surprised to learn that Titan has a very earth-like appearance. It has a thick nitrogen atmosphere, rain, rivers, oceans and massive dune fields. But unlike the dunes of Earth’s sandy deserts in Namibia and southern Arabia, Titan’s dunes are enormous, and fill massive fields covering more than an eighth of the giant moon’s surface. These dunes are about 100 meters tall, 1 to 2 km wide at the base, and can stretch for hundreds of kilometers in length.

Dunes on Earth are made from sand, which is blown by the wind and heaped into drifts. Individual sand particles are nudge and blown by the wind with enough force to make them bounce and scatter, in a process called saltation. If the particles don’t bounce, then they cannot pile up on top of each other, but if the wind is able to lift them off the ground completely then they simply blow away. Saltation depends on the size and mass of the sand particles and the strength of the wind, but also needs the particles to be dry so that they can move freely without sticking together.

Titan’s geology

Titan is the second largest moon in the entire Solar System, beaten only by Ganymede, orbiting Jupiter. It is Saturn’s largest moon, and very old. Unlike most of Saturn’s moon, which were captured over time, Titan would have formed together with Saturn billions of years ago. Despite having so many features in common with Earth, it is a very different place. It is so intensely cold that, instead of water, its rain and rivers are made from liquid hydrocarbons like methane. Water, on the other hand, is frozen into hard ice; rocks on Titan are made from water ice, instead of granite and basalt, and Titan’s equivalent of lava and magma are made from liquid water and ammonia.

This means that sand on Titan is not made from silica eroded from larger rocks, since those materials are not found on the surface. One popular theory is that it could instead be made from ice. When liquid methane rains and flows, it could erode the water-ice bedrock, grinding chunks together to a sand of ice grains. An alternative idea is that the sand particles are instead made from tholins. These are found all over the colder regions of the Solar System, where cold hydrocarbons in comets or the outer atmospheres of planets and moons react with ultraviolet light from the Sun to create complex compounds. Tholins formed in the dry atmosphere of Titan could clump together with static electricity to form small grains of soot that then settle to the ground, creating both dust and sand.

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Comet 109P/Swift-Tuttle captured during its last pass by Earth on Nov. 1, 1992. Credit: Gerald Rhemann

What do comets have to do with this?

But a paper presented at this year’s Lunar and Planetary Science Conference (LPSC) suggests a new idea: What if the sand came from comets? Comets, as we know, are made from materials left over from the creation of the Solar System. Most of the primordial gas and dust that collapsed from an ancient nebula to form the Solar System would have ended up in the Sun, with the bulk of the remains forming the planets. But this still would still have left a lot of material floating free, and some of that would have gradually coalesced into lumps of dust and ices, which we see today as comets. When comets are nudged into elliptical orbits and pass through the inner Solar System, some of their ice heats up and sublimates into gas which blows out, carrying dust with it. This dust is scattered throughout the Solar System, concentrated along the various comet’s orbits. Individual grains often collide with the Earth, which we see as meteors, burning high in our atmosphere. Recent surveys in Antarctic ice

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