Three space studies reveal clues about planets and cosmic structure

Three studies examine different parts of the cosmos

These recent studies look at three very different questions: whether a giant planet can orbit a small star, how a pair of neutron stars can end up in an extreme orbit, and whether faint light in galaxy clusters can reveal the shape of their larger haloes. A halo is the broad distribution of matter surrounding a galaxy or cluster. The third study concerns visible light that may help researchers infer the shape of that structure, rather than directly observing invisible matter.

Each paper is a new research report, not a final answer. All three are preprints, which means other scientists have not yet checked them through the usual peer-review process ¹²³. The authors of each report say it has been accepted for publication, but acceptance does not remove the need to treat new findings carefully. A single study rarely settles a scientific question. Other observations and independent checks can change how strongly a result is supported.

A Saturn-mass planet orbits a low-mass star

The researchers wanted to learn what kind of planet and star caused a change in the light recorded during the event OGLE-2013-BLG-1125/MOA-2013-BLG-584. They analysed observations from the OGLE and MOA surveys and several follow-up telescopes. They also used data from the Keck II telescope to add constraints to their model ¹. The method, called microlensing, uses the way gravity bends light to study a distant system.

The team reports a planet with about 105 times Earth’s mass, described as Saturn-mass, orbiting a star with about 0.139 times the Sun’s mass. The system is about one kiloparsec away, or roughly 3,260 light-years ¹. The result adds to a small sample of giant planets found around low-mass stars, which can help researchers test ideas about how planets form around different kinds of stars.

This is a measurement and model of a distant system, not a close-up image of the planet. The report does not establish how common such planets are, or which planet-formation explanation is correct. The work is a preprint and has not yet been checked by other scientists through peer review ¹.

Two neutron stars have an unusually stretched orbit

The researchers set out to describe a newly found binary system: two neutron stars orbiting one another. A neutron star is the compact remnant of a star. The team reported timing the radio pulses from one member, PSR J0653+0443, and measuring how the system’s orbit affects their arrival. Their report describes two components of about 1.4 solar masses each, with an orbital period of about 79 days ².

The striking result is the orbit’s eccentricity: 0.992387, close to the maximum value of 1 for an orbit that is still bound ². In plain terms, the stars’ separation changes greatly as they travel around one another. The pulsar also undergoes an 85-second eclipse when the orbit brings it behind material associated with its companion, according to the report. The authors say the extreme orbit points to a strong kick when the second neutron star formed in a supernova, and that this system challenges current ideas about binary-star evolution ².

The finding does not show how often systems like this form, or settle the details of the supernova. The authors estimate that a similar system would be difficult to detect, and describe it as a source of periodic gravitational-wave bursts. Their claims and measurements still require independent scrutiny: this paper is also a preprint, not yet peer reviewed ².

Faint cluster light grows more elongated farther out

This study asked whether intracluster light—the faint glow from stars spread between galaxies in a cluster—can help reveal the shape and orientation of the cluster’s halo. The Euclid Collaboration analysed images of 205 galaxy clusters selected using the eROSITA All-Sky Survey and the Dark Energy Survey. The clusters span a range of distances, and the researchers compared measurements in five light bands ³.

They found that the light’s shape measurements were broadly consistent across those bands. The central regions were relatively round, while the intracluster light became more elongated farther from the centre. Its measured ellipticity, a measure of how stretched a shape is, reached about 0.5 at the outer distance discussed in the report. The light was also more often aligned with the brightest galaxy in the cluster than with the distribution of smaller companion galaxies ³.

The study suggests that this faint light can trace the larger structure of a cluster. That matters because researchers use visible features to investigate the distribution of matter, including matter that cannot be seen directly. But these observations do not directly image dark matter, and the results do not establish every cluster’s shape. The researchers obtained robust orientation measurements for 63% of their sample, and the paper remains a preprint awaiting peer review ³.

The findings add clues, not final explanations

Together, the studies show how different observations can address different stages and scales of cosmic structure. The planet result adds one more example for theories of planet formation around small stars. The neutron-star pair gives researchers an unusual system to test explanations of how massive stars evolve and survive as binaries. The Euclid analysis explores whether faint starlight can help map the shape of galaxy-cluster haloes ¹²³.

None of the reports resolves its field’s wider questions. The planet study does not tell us how frequent such worlds are. The neutron-star result does not yet explain how often extreme systems form. And the cluster study uses light as a guide to structure; it is not a direct picture of invisible matter. These are early results reported in preprints, so further checking and observations will help show how broadly each finding applies.