Sunday, November 28

Create a “field guide” to alien worlds

Create a “field guide” to alien worlds

By combining observations from the Hubble Space Telescope with theoretical models, a team of astronomers led by researchers from the University of Arizona has obtained insights into the chemical and physical makeup of a variety of exoplanets known as “hot Jupiters.” The new study is the first to look at such a large population of alien worlds and could provide insight into planet formation in general.

Although only 10% of the stars have around them an exoplanet with the characteristics of a “Hot Jupiter”, actually a significant percentage of all extrasolar planets discovered so far fall into this group. Apparently, this is because they have larger dimensions and are more luminous than other exoplanets, thus facilitating their identification with currently available technologies.

Very close to his star

This variety of alien worlds located outside the Solar System presents some conditions similar to the planet Jupiter: they are huge and gaseous planets, but they have high temperatures. Its magnitude ranges from one third of the dimensions of Jupiter to 10 masses of it.

Another of its main characteristics is that oThey bite their host star into extreme closeness, even closer than Mercury does around the Sun, the innermost planet in the Solar System. In these distant and strange worlds, a “year” lasts only a few hours, or at most a few days.

Their close orbits determine that the exoplanets known as “hot Jupiters” follow a path linked to their star at great speed: one side receives all the stellar radiation, while the other is kept in absolute darkness. So far, in the most extreme cases, surface temperatures have been recorded that reach almost 2,760 degrees Celsius.

A more precise and detailed observation

According to a Press release, the new study published recently in the journal Nature Astronomy offers information that confirms and expands the knowledge about this variety of alien worlds, providing a Orientative «guide» to discover a large number of extrasolar planets hitherto unknown.

Through a method called “Secondary eclipse”, the astronomers extracted information from the observations that allowed them to delve into the atmospheres of exoplanets and obtain data on its structure and chemical composition. With current technologies, scientists can only appreciate one point: the combined light source of the exoplanet and its star.

However, the new method enriches the look. It involves repeated observations of the same system, registering the planet at different locations in its orbit and discovering its behavior even when it hides behind the star that shelters it.

Related topic: They discover a giant and infernal alien world.

Molecular composition of exoplanets

In this way, scientists were able to isolate the light emitted by the stars and differentiate it from the emissions of the stars, accessing valuable information about exoplanets. Thanks to this, they were able to determine characteristics that seem to be repeated in 19 alien worlds studied, and that they would be common to all exoplanets of the “hot Jupiter” type.

For example, the results suggest that all extrasolar planets of this variety probably contain similar sets of molecules, such as water and carbon monoxide, along with lower concentrations of other molecules. Apparently, the differences between each star would be related mainly to the relative amounts of the aforementioned molecules.

According to astronomers, the new research will allow us to fully characterize these alien worlds and learn more about their training process, a knowledge that later could be useful to discover unknown aspects of the conformation of the planets in general throughout the cosmos.


A unique hot Jupiter spectral sequence with evidence for compositional diversity. Mansfield, M., Line, M.R., Bean, J.L. et al. Nature Astronomy (2021).DOI:

Photo: artist’s recreation showing a “hot Jupiter” -type exoplanet orbiting near one of the stars in the rich ancient star cluster Messier 67, located 2,500 to 3,000 light-years from Earth in the constellation Cancer. Credit: ESO / L. Calçada.

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