A recent research shed fresh light on what seasons may look like on a planet beyond our solar system. The research, headed by McGill University, was published in ‘The Astronomical Journal.’
The study began with one element of the atmosphere of XO-3b, one of a type of exoplanets (planets beyond our solar system): the winds were so intense that they travelled at the speed of sound.
It is referred to as a hot Jupiter.
The planet’s eccentric orbit also resulted in seasonal fluctuations hundreds of times greater than what we experience on Earth.
According to the researchers, the round orbit, extraordinarily high surface temperatures (2,000 degrees C- hot enough to melt rock), and “puffiness” of XO-3b may also provide clues of the planet’s past.
The discoveries might help scientists understand how exoplanets arise and evolve and provide context for planets in our solar system.
Hot Jupiter
Hot Jupiters are large, gaseous planets similar to Jupiter that circle their parent stars closer than Mercury does the Sun.
Though they were not found in our solar system, they looked to be widespread across the cosmos.
Despite being the most researched exoplanet, many concerns concerning how they develop remain unanswered.
Could there be hot Jupiter subclasses with distinct formation stories?
For example, did these planets form distant from their parent stars – at a distance where elements such as water can solidify – or closer?
The first scenario corresponded more closely to beliefs about how planets in our own solar system were formed, but what drove these planets to travel so close to their parent stars remained unknown.
To put such theories to the test, the authors of a new McGill-led research examined the atmosphere of exoplanet XO-3b using data from NASA’s decommissioned Spitzer Space Telescope.
They estimated wind speeds and detected eccentric seasons on the planet by collecting a phase curve of the planet as it finished a full circle around its home star.
Lisa Dang, the paper’s first author and a PhD student in McGill University’s Department of Physics:
“This planet is an extremely interesting case study for atmospheric dynamics and interior evolution because it lies in an intermediate regime of planetary mass where processes normally ignored for less massive hot Jupiters may come into play.”
She added that XO-3b’s orbit is oval instead of the circular orbits of practically all other known hot Jupiters.
This indicates that it has lately moved toward its parent star; if so, it will soon settle into a more circular orbit.
Unique Features
The planet’s eccentric orbit also resulted in seasonal fluctuations hundreds of times greater than what we experience on Earth.
Nicolas Cowan, a McGill professor, noted the whole planet gets three times more energy when it is near to its star during a short type of summer.
The researchers also recalculated the planet’s mass and radius, discovering that it was considerably puffier than predicted.
They proposed that the cause of this heating may be residual nuclear fusion.
Gaia, an ESA (European Space Agency) mission, discovered that the planet was puffier than predicted, indicating that its interior may be unusually active.
Spitzer data also suggested that the planet generated most of its own heat, since XO-3b’s excess thermal emission was not seasonal, but was recorded all year.
The surplus heat was likely generated by the planet’s interior, a process known as tidal heating.
The star’s gravitational pull fluctuated as its elliptical orbit carried it further and then closer to the star.
Heat was created as a consequence of the variations in internal pressure.
Dang saw this very hot Jupiter as a chance to test theories about which formation processes may result in certain traits in these exoplanets.
XO-3b alone will not solve the enigma, but it will serve as a critical test for new theories concerning these searing giants.
