(ORDO NEWS) — An exoplanet so close to its parent star that its surface is likely an ocean of magma has just become the subject of a study that could show how these extreme worlds come into being.
Considered “hell planet”. is called 55 Cancri e (aka Janssen), and a new analysis of its orbit and the orbits of other exoplanets orbiting the star shows that Janssen most likely formed much farther away from the star, slowly moving towards it over time and melting in the process.
“We learned how this multi-planet system one of the systems with the largest number of planets we have discovered reached its current state,” says astrophysicist Lily Zhao of the Flatiron Institute. in New York.
All planetary systems have their own characteristics, but the Copernican system, located about 41 light years from us (almost in the neighborhood), has its own characteristics.
In addition to Janssen, five other exoplanets orbit the star: Galileo, Brahe, Harriot and Lipperhey, and all of them are further from Copernicus than their strange counterpart.
Copernicus (an orange dwarf slightly smaller than the Sun) about once every 18 hours. This is 1.85 times the radius of the Earth and about 8 times its mass.
This means that it is slightly denser than Earth and could be a fairly ordinary rocky super-Earth at a greater distance from its star.
But it’s not. This is definitely not true.
The temperature on the side facing the star averages 2573 Kelvin (2300 degrees Celsius, or 4172 degrees Fahrenheit), while on the night side facing away it is 950 Kelvin lower. It’s insanely hot and absolutely higher than molten magma.
What Janssen is inside is anyone’s guess, but studies show that its internal structure is very different from the rocky worlds in our solar system.
We are very limited in what information we can gather about exoplanets, even as close as the Copernican system, so to find out how Janssen did this, Zhao and her team set out to measure the orbits of five exoplanets around the star.
We already knew that Janssen’s orbit is different from that of the other four. This is because there are two main ways to detect exoplanets based on their influence on the parent star.
The first is a transit, when an exoplanet passes between us and a star, dimming its light slightly. A regular dip in starlight likely means an exoplanet is in orbit.
The second is radial velocity. It has to do with gravity. Every planet orbiting a star exerts a gravitational pull. Gravity, of course, is not as strong as that of a star, but it does cause the star to “wobble” slightly in place.
This can be seen from the change in the wavelength of light from the star. : stretches a little as the star moves away from us (redshift), and shrinks as the star moves towards us (blueshift).
All five Copernican exoplanets were discovered by radial velocity, but subsequent observations confirmed that Janssen and Galileo are the only planets passing by.
This means that it is possible that the two are not in the same orbital plane as Brahe, Harriot, and Lipperhey, and Galileo’s transit is so tangential that astronomers have been unable to measure its radius and temperature. therefore, it also does not coincide with the plane of Janssen’s orbit.
The researchers extracted more information about Janssen’s orbit. As the star rotates, the light from the side that rotates towards us shrinks slightly, and the light from the side that rotates to the side stretches slightly.
Using a powerful new instrument, the EXtreme PREcision Spectrometer (EXPRES) at the Lowell Observatory in Arizona, the team was able to see Janssen move across the star, from the blue side to the red side, tracking its path with high precision.
This showed that the exoplanet is moving along the equator of the star. Previous research has shown that Copernicus’ binary companion, a small red dwarf, likely perturbed the system by pulling exoplanets into an orbital plane highly tilted from the star’s axis of rotation.
Zhao and her colleagues believe that interactions between exoplanets may have pushed Janssen into a decaying orbit around the star, falling closer and closer.
As Copernicus rotates, it flattens slightly, creating a slight bulge around the equator, where the gravitational field is stronger. The exoplanet was naturally drawn into this region.
It is possible that Galileo does the same on a short 14.7-day orbit, although further analysis will be needed to find out. (Brage has a period of 44.4 days, Harriot has 260 days, and Lipperhey has 5574 days.)
The work demonstrates a way to study the history of exoplanets in very close orbits with their stars.
Of particular interest are exoplanets called hot Jupiters: gas giants with orbits of less than a day. These worlds are an interesting mystery because they are too close to their stars for a dense atmosphere to form on them. Internal migration is one way these scorching exoplanets can come so close to a star.
This work suggests that this model may be correct.
“Janssen’s spin-orbit alignment supports dynamically soft migration theories for ultrashort-period planets,” the researchers write, “namely, tidal dissipation due to low-eccentricity planet interactions and or planetary tides.”
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