New insights into seasons on a planet outside our solar system
Observations of a hot Jupiter may also advance our understanding of
planet origins and evolution
Date:
January 13, 2022
Source:
McGill University
Summary:
Imagine being in a place where the winds are so strong that they
move at the speed of sound. That's just one aspect of the atmosphere
on XO-3b, one of a class of exoplanets (planets outside our solar
system), known as hot Jupiters. The eccentric orbit of the planet
also leads to seasonal variations hundreds of times stronger than
what we experience on Earth.
FULL STORY ========================================================================== Imagine being in a place where the winds are so strong that they move at
the speed of sound. That's just one aspect of the atmosphere on XO-3b,
one of a class of exoplanets (planets outside our solar system), known
as hot Jupiters.
The eccentric orbit of the planet also leads to seasonal variations
hundreds of times stronger than what we experience on Earth. In a recent
paper, a McGill- led research team, provides new insight into what
seasons looks like on a planet outside our solar system. The researchers
also suggest that the oval orbit, extremely high surface temperatures
(2,000 degrees C- hot enough to vaporize rock) and "puffiness" of XO-3b
reveal traces of the planet's history.
The findings will potentially advance both the scientific understanding
of how exoplanets form and evolve and give some context for planets in
our own solar system.
==========================================================================
Hot Jupiters are massive, gaseous worlds like Jupiter, that orbit
closer to their parent stars than Mercury is to the Sun. Though not
present in our own solar system, they appear to be common throughout
the galaxy. Despite being the most studied type of exoplanet, major
questions remain about how they form.
Could there be subclasses of hot Jupiters with different formation
stories? For example, do these planets take shape far from their parent
stars -- at a distance where it's cold enough for molecules such as
water to become solid - - or closer. The first scenario fits better with theories about how planets in our own solar system are born, but what
would drive these types of planets to migrate so close to their parent
stars remains unclear.
To test those ideas, the authors of a recent McGill-led study used data
from NASA's retired Spitzer Space Telescope to look at the atmosphere
of exoplanet XO-3b. They observed eccentric seasons and measured wind
speeds on the planet by obtaining a phase curve of the planet as it
completed a full revolution about its host star.
Looking at atmospheric dynamics and interior evolution "This planet is an extremely interesting case study for atmospheric dynamics and interior evolution, as it lies in an intermediate regime of planetary mass where processes normally neglected for less massive hot Jupiters may come into
play," says Lisa Dang, the first author of a paper published recently in
The Astronomical Journal, a PhD student at McGill University's Department
of Physics. "XO-3b has an oval orbit rather than the circular orbit
of almost all other known hot Jupiters. This suggests that it recently
migrated toward its parent star; if that's the case, it will eventually
settle into a more circular orbit." The eccentric orbit of the planet
also leads to seasonal variations hundreds of times stronger than what
we experience on Earth. Nicolas Cowan, a McGill professor explains: "The
entire planet receives three times more energy when it is close to its
star during a brief sort of summer, than when it is far from the star."
The researchers also re-estimated the planet's mass and radius and found
that the planet was surprisingly puffier than expected. They suggest
and that the possible source of this heating could be due to leftover
nuclear fusion.
Excess warmth and puffiness due to tidal heating? Observations by
Gaia, an ESA (European Space Agency) mission, found that the planet is
puffier than expected which indicate its interior may be particularly energetic. Spitzer observations also hints that the planet produces
much of its own heat as XO-3b's excess thermal emission isn't seasonal
-- it's observed throughout the year on XO-3b. It's possible that the
excess warmth is coming from the planet's interior, through a process
called tidal heating. The star's gravitational squeeze on the planet
oscillates as the oblong orbit takes the planet farther and then closer
to the star. The resulting changes in interior pressure produce heat.
For Dang, this unusual hot Jupiter provides an opportunity to test ideas
about which formation processes may producer certain characteristics
in these exoplanets. For example, could tidal heating in other hot
Jupiters also be a sign of recent migration? XO-3b alone won't unlock
the mystery, but it serves as an important test for emerging ideas about
these scorching giants.
========================================================================== Story Source: Materials provided by McGill_University. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Lisa Dang, Taylor J. Bell, Nicolas B. Cowan, Daniel Thorngren,
Tiffany
Kataria, Heather A. Knutson, Nikole K. Lewis, Keivan G. Stassun,
Jonathan J. Fortney, Eric Agol, Gregory P. Laughlin, Adam Burrows,
Karen A.
Collins, Drake Deming, Diana Jovmir, Jonathan Langton,
Sara Rastegar, Adam P. Showman. Thermal Phase Curves of
XO-3b: An Eccentric Hot Jupiter at the Deuterium Burning
Limit. The Astronomical Journal, 2021; 163 (1): 32 DOI:
10.3847/1538-3881/ac365f ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2022/01/220113120739.htm
--- up 5 weeks, 5 days, 7 hours, 13 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)