An international team led by Dr. Indrani Das of Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) has shown, for the first time, how infalling gas from star-forming cores gradually transitions into planet-forming disks. Their findings, combining numerical simulations with Atacama Large Millimeter/submillimeter Array (ALMA) observations, are published today in The Astrophysical Journal.

Protoplanetary disks form around young stars when dense molecular cloud cores collapse under their own gravity. An outer shroud of gas and dust, known as the envelope, surrounds and feeds both the young star and the forming disk. While it is well understood that planets eventually form within these disks and follow Keplerian orbits, the mechanism that transforms rapid infalling gas motion from the envelope into ordered Keplerian motion within the disk has remained a mystery for decades.

Based on both theoretical and observational evidence, the recent study discovered that there exists a distinct transition zone at the envelope-disk interface of a young star-disk system, which Das named ENDTRANZ (Envelope Disk Transition Zone). The findings have established that infalling gas motions gradually transition into Keplerian motions across this transition zone. Crucially, this transition is far from abrupt and contradicts earlier infall models that are based on classical test-particle dynamics.

What happens to matter when gravity crushes it beyond the breaking point? Inside a neutron star, atoms are destroyed. Electrons are forced into protons. Nuclei dissolve into a sea of neutrons. And at the very center, even neutrons themselves may break apart into quarks — forming exotic states of matter that physicists still can’t fully explain.

In this video, we go inside a neutron star layer by layer. From the crystalline outer crust where neutron-rich nuclei sit in a lattice denser than anything on Earth, through the bizarre nuclear pasta phases where matter forms sheets, tubes, and bubbles of nuclear material, into the superfluid outer core where neutrons flow without friction and protons conduct without resistance, and finally into the mysterious inner core where densities reach five to ten times that of an atomic nucleus and the very concept of a \.

High-energy particles called galactic cosmic rays (GCRs) bombard unprotected objects in space, often causing damage. Earth, however, is protected by its magnetic field, which creates a protective shell around the planet that can deflect dangerous charged particles, like GCRs.

The moon is known to pass through the tail-like part of Earth’s magnetosphere, but a new study, published in Science Advances, suggests the moon might experience additional protection at another point in its orbit. Although this pocket of protection exists when the moon is outside of the magnetosphere, researchers believe the effects are still due to Earth’s magnetic field.

An anomalous dip in particle counts When the research team analyzed data taken from the Lunar Lander Neutron and Dosimetry (LND), onboard China’s Chang’E-4 lander, they were surprised to find that the LND experienced a 20% dip in GCR particles hitting detectors while the lander was on the moon’s far side. This occurred at a specific time during the lunar “morning” and only for about 2 days each lunar cycle. Since the LND took data over 31 cycles, the team could see that this was not just a one-off occurrence. This was unexpected because it was previously assumed that GCRs are evenly distributed in the space between Earth and the moon, outside Earth’s magnetosphere.

When laser flashes hit matter, electrons are knocked off their orbits around the atomic nuclei. This can generate extremely hot plasmas composed of charged particles—ions and electrons. Researchers at HZDR have now observed this ionization process in more detail than ever before. To do so, they combined two state-of-the-art lasers: the X-ray free-electron laser and the high-intensity optical laser ReLaX at the HED-HiBEF experiment station at the European XFEL in Schenefeld, near Hamburg. Their findings, published in Nature Communications, deliver fundamental insights into the interaction of high-energy lasers and matter under extreme conditions.

Ionization takes place extremely quickly—in picoseconds, within a few trillionths of seconds. In order to monitor this process in detail, laser pulses must be significantly shorter. “These are exactly the conditions provided by the two lasers that have pulse durations of just 25 and 30 femtoseconds—that is, trillionths of a second,” explains Dr. Lingen Huang, head of experimentation in HZDR’s Division of High-Energy Density.

Initially, an extremely intense flash of light strikes a delicate copper wire that is only about one-seventh the thickness of a human hair. The pulse intensity is approximately 250 trillion megawatts per square centimeter—concentrated on a tiny surface for an extremely short time. Values like this are otherwise achieved only under exceptional conditions, such as in extreme astrophysical environments like the immediate vicinity of neutron stars or during gamma-ray bursts.