Tag Archives: floating

First-Ever Measurement of Floating Exoplanet’s Mass by Astronomers

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Gravitational microlensing surveys have unveiled populations of free-floating planets. Although their masses haven’t been directly measured due to distance-related challenges, statistics suggest that many of these rogue planets possess less mass than Jupiter. Recently, astronomers identified a groundbreaking microlensing event, termed KMT-2024-BLG-0792/OGLE-2024-BLG-0516. This event involved an exoplanet with approximately 21.9% of Jupiter’s mass, situated 9,785 light-years (3,000 parsecs) from the Milky Way’s center.

An artist’s impression of a free-floating exoplanet. Image credit: Sci.News.

Traditionally, planets are linked to stars, but research indicates that many traverse the galaxy independently.

Known as free-floating or rogue planets, these celestial bodies lack stellar companions.

Due to their low light emissions, they are primarily detected through their gravitational influences, a technique known as microlensing.

A significant challenge of this discovery method is determining the distances to these planets, complicating mass measurements.

This has left much of the data regarding these solitary objects speculative.

In a recent study, Dr. Subo Dong from Peking University and the National Astronomical Observatory of Japan and collaborators discovered a new free-floating planet, KMT-2024-BLG-0792/OGLE-2024-BLG-0516, via a brief microlensing event.

In contrast to prior approaches, they utilized a novel strategy by observing the microlensing phenomenon concurrently from Earth and space, leveraging multiple ground-based surveys alongside ESA’s Gaia space telescope.

Variations in the timing of light captured by these different locations facilitated measurements of microlens parallax, enabling researchers to calculate the planet’s mass and position through finite source modeling.

“Based on comparisons with the statistical characteristics of other microlensing events and simulation predictions, we conclude that this object didn’t originate as an isolated entity (like a brown dwarf) but likely formed within a protoplanetary disk (like a planet),” the astronomers noted.

“Subsequent dynamic processes likely ejected it from its formation site, resulting in a free-floating object.”

For further details, check out the study published in this month’s Science: paper.

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Subo Dong et al. 2026. Microlensing of free-floating planets caused by heavy objects in Saturn’s vicinity. Science 391 (6780): 96-99; doi: 10.1126/science.adv9266

Source: www.sci.news

Astronomers discover floating crystals preventing cooling in high-mass white dwarf stars

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Astronomers have proposed a new theory to explain why a mysterious population of white dwarfs has stopped cooling for at least 8 billion years.

This diagram shows a white dwarf and the moon. Image credit: Giuseppe Parisi.

White dwarfs are the remains of stars without a nuclear energy source that gradually cool over billions of years, eventually freezing from the inside out to a solid state.

Recently, it was discovered that a population of frozen white dwarfs maintains a constant brightness for a period comparable to the age of the universe, indicating the existence of an unknown, powerful energy source that inhibits cooling.

“We find that the classical picture that all white dwarfs are dead stars is incomplete,” said astronomer Dr Simon Bruin from the University of Victoria.

“To stop these white dwarfs from cooling, we need some way to generate additional energy.”

“We didn’t know how this happened, but now we have an explanation for this phenomenon.”

The researchers say that in some white dwarfs, the dense plasma inside them doesn’t just freeze from the inside out.

Instead, the solid crystals that form when frozen tend to float because they are less dense than the liquid.

As the crystals float upwards, the heavier liquid moves downwards.

As heavy material is transported toward the star’s center, gravitational energy is released, and this energy is enough to interrupt the star’s cooling process for billions of years.

Dr Antoine Bedard, an astronomer at the University of Warwick, said: “This is the first time this transport mechanism has been observed in any type of star, and it’s very interesting because it’s not every day that a completely new astrophysical phenomenon is discovered.”

“We don’t know why this happens in some stars and not others, but it’s probably due to the star’s composition.”

“Some white dwarfs are formed by the merger of two different stars,” Dr Bruin said.

“When these stars collide to form white dwarfs, the star’s composition changes, allowing the formation of floating crystals.”

White dwarfs are routinely used as an indicator of age, and the cooler a white dwarf is, the older it is considered to be.

However, the extra delay in cooling seen in some white dwarfs means that some stars at certain temperatures may be billions of years older than previously thought.

“This new discovery will not only require a revision of astronomy textbooks, but will also require a reexamination of the processes astronomers use to determine the age of stellar populations,” Dr. Blouin said.

of the team paper Published in today’s diary Nature.

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A. Bedard other. Buoyant crystals stop the white dwarf from cooling. Nature, published online March 6, 2024. doi: 10.1038/s41586-024-07102-y

Source: www.sci.news