For the first time, scientists have used NASA’s IXPE (Imaging X-ray Polarimetry Explorer) to directly measure the magnetic fields of PSR J1101-6101, a pulsar located within what is often known as the Lighthouse Nebula. The results provide new insight into the structure of some of the most extreme objects in the cosmos, as NASA continues to explore the secrets of how the universe works. A paper describing the results published Thursday in the Astrophysical Journal.

• A pulsar is a type of neutron star with a strong magnetic field that spins incredibly fast. The pulsar at the center of the Lighthouse Nebula rotates 16 times per second.
• Neutron stars are the leftover cores of massive stars, formed at the end of their life cycles, which have more mass than the Sun. They are condensed to the size of a city, making them natural laboratories for studying extreme physics.

• Polarization is a property of light that describes the direction of the vibrations of its electric field. The degree of polarization is a measure of how aligned those vibrations are with each other.

In June 2025, IXPE spent almost 18 days focused on the Lighthouse Nebula.

Astronomers studied two narrow X-ray branches extending from the pulsar to better understand how electrons interact with this energy system at nearly the speed of light. The longer stem is known as the “filament” and the shorter one is the “trail.”

When the pulsar’s high-energy particles collide with gas in interstellar space, they form a shock arc, like the bow wave that forms at the front of a speeding ship. Most of the particles are trapped behind this arc shock, forming the turbulent trail behind the pulsar.

Researchers have suspected since 2008 that higher-energy particles escape through this arc shock into interstellar space, flowing along the galaxy’s magnetic field lines to create the nebula’s long, thin filament.

“We wanted to test that theory,” said Jack Dinsmore, an undergraduate at Stanford University who led the study. “The ‘smoking gun’ would come from measuring the polarization of light, which indicates the direction of the magnetic field. If the magnetic field points along the filament, that confirms that the particles in the filament are flowing along the field.”

One challenge with these measurements is that the Lighthouse Nebula is relatively faint. To address this, IXPE scientists developed advanced analysis methods that use every bit of data, avoiding simplifying steps that could limit information. With these new tools and new observations from the Lighthouse, the scientific team successfully measured the polarization of the filament. These techniques also made it possible to measure the polarization of the wake and the pulsar emission signal.

Their analysis confirmed with more than 99% confidence that the magnetic field does indeed align with the particle flow.

While the parallel direction confirms models of the particle’s motion, the degree of polarization was high enough to raise new questions.

“Many of the filament models assume strong magnetic turbulence,” said Roger Romani, a Stanford University professor and co-author of this paper. “The high degree of polarization we measured indicates lower turbulence than these models require.”

The IXPE observations also showed that the magnetic field responsible for the X-ray emission had to be parallel to the trace. However, the authors collected radio frequency observations that showed a magnetic field pointing almost exactly perpendicular.

“The striking divergence in magnetic field orientations observed between radio and “This marks the first clear indication that particles of different energies occupy distinct regions within the system, suggesting the presence of multiple and potentially very different acceleration mechanisms at work.”

The IXPE mission, which continues to provide unprecedented data enabling groundbreaking discoveries about celestial objects across the universe, is a joint mission of NASA and the Italian Space Agency with scientific partners and collaborators in 12 countries. It is led by NASA’s Marshall Space Flight Center in Huntsville, Alabama, and BAE Systems, Inc. manages spacecraft operations along with the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder.

Learn more about IXPE’s current mission here:

https://www.nasa.gov/ixpe