High Winds and Ruby Clouds Predicted for hot Jupiter HAT-P-7b

Scientists have spotted weather systems on a gas giant planet beyond our solar system for the first time ever, and it's definitely out of this world. It's entirely possibly that wild winds are blowing ruby and sapphire clouds on the blazing "hot Jupiter" planet HAT-P-7b over 1,000 light years away.

Researchers used NASA's Kepler space telescope to study the light reflected by the planet 16 times larger than Earth and watch how its atmosphere changed over a period of time.

"HAT-P-7b is a tidally locked planet, with the same side always facing its star. We expect clouds to form on the cold night side of the planet, but they would evaporate quickly on the hot dayside," explains the University of Warwick's Dr. David Armstrong, who led the research. "These results show that strong winds circle the planet, transporting clouds from the night side to the dayside. The winds change speed dramatically, leading to huge cloud formations building up then dying away."

The team noticed that the brightest point on the planet would shift its position, likely due to variable winds and violent storm systems. Because the planet is so much hotter than ours, the scientists had to speculate about what elements could possibly form the "morning" clouds observed at dayside temperatures of 1,700°C, hot enough to melt iron.

Two possibilities are corundum and perovskite. Corundum is the mineral that forms rubies and sapphires on Earth and it would probably make for some colorful clouds being blown around HAT-P-7b.

"Perhaps clouds of ruby are moving around this planet, appearing and disappearing in a stunning display," Armstrong suggests.

link.

PSO J318.5-22: a Free Floating 8 Jupiter Mass With Clouds and Weather

Variability in a Young, L/T Transition Planetary-Mass Object

Authors:

Biller et al

Abstract:

As part of our ongoing NTT SoFI survey for variability in young free-floating planets and low mass brown dwarfs, we detect significant variability in the young, free-floating planetary mass object PSO J318.5-22, likely due to rotational modulation of inhomogeneous cloud cover. A member of the 23±3 Myr β Pic moving group, PSO J318.5-22 has Teff = 1160+30−40 K and a mass estimate of 8.3±0.5 MJup for a 23±3 Myr age. PSO J318.5-22 is intermediate in mass between 51 Eri b and β Pic b, the two known exoplanet companions in the β Pic moving group. With variability amplitudes from 7-10% in JS at two separate epochs over 3-5 hour observations, we constrain the rotational period of this object to greater than 5 hours. In KS, we marginally detect a variability trend of up to 3% over a 3 hour observation. This is the first detection of weather on an extrasolar planetary mass object. Among L dwarfs surveyed at high-photometric precision (less than 3%) this is the highest amplitude variability detection. Given the low surface gravity of this object, the high amplitude preliminarily suggests that such objects may be more variable than their high mass counterparts, although observations of a larger sample is necessary to confirm this. Measuring similar variability for directly imaged planetary companions is possible with instruments such as SPHERE and GPI and will provide important constraints on formation. Measuring variability at multiple wavelengths can help constrain cloud structure.

Weather on Exoplanets

Cloudy for the morning, turning to clear with scorching heat in the afternoon."

While this might describe a typical late-summer day in many places on Earth, it may also apply to planets outside our solar system, according to a new study by an international team of astrophysicists from the University of Toronto, York University and Queen's University Belfast.

Using sensitive observations from the Kepler space telescope, the researchers have uncovered evidence of daily weather cycles on six extra-solar planets seen to exhibit different phases. Such phase variations occur as different portions of these planets reflect light from their stars, similar to the way our own moon cycles though different phases.

Among the findings are indications of cloudy mornings on four of them and hot, clear afternoons on two others.

"We determined the weather on these alien worlds by measuring changes as the planets circle their host stars, and identifying the day-night cycle," said Lisa Esteves, a PhD candidate in the Department of Astronomy & Astrophysics at the University of Toronto, and lead author of the study published today in The Astrophysical Journal.

"We traced each of them going through a cycle of phases in which different portions of the planet are illuminated by its star, from fully lit to completely dark," said Esteves.

link.

paper originally appeared here on The Dragon's Gaze as an arxiv pre print last summer.

Breaking News: The Weather of WASP-43b as Seen by the Hubble

A team of scientists using the NASA/ESA Hubble Space Telescope have made the most detailed map ever of the temperature of an exoplanet's atmosphere, and traced the amount of water it contains. The planet targeted for both of the investigations was the hot-Jupiter exoplanet WASP-43b.

WASP-43b WASP-43b is a planet the size of Jupiter but with double the mass and an orbit much closer to its parent star than any planet in the Solar System. It has one of the shortest years ever measured for an exoplanet of its size -- lasting just 19 hours.

A team of astronomers working on two companion studies have now created detailed weather maps of WASP-43b. One study mapped the temperature at different layers in the planet's atmosphere, and the other traced the amount and distribution of water vapour within it -- detail is shown in the video created by the team.

"Our observations are the first of their kind in terms of providing a two- dimensional map of the planet's thermal structure," said Kevin Stevenson from University of Chicago, USA, lead author of the thermal map study. "These maps can be used to constrain circulation models that predict how heat is transported from an exoplanet's hot day side to its cool night side."

The planet has different sides for day and night because it is tidally locked, meaning that it keeps one hemisphere facing the star, just as the Moon keeps one face toward Earth. The Hubble observations show that the exoplanet has winds that howl at the speed of sound from a day side that is hot enough to melt iron -- soaring above 1500 degrees Celsius -- to the pitch-black night side that sees temperatures plunge to a comparatively cool 500 degrees Celsius.

To study the atmosphere of WASP-43b the team combined two previous methods of analysing exoplanets for the first time.

By looking at how the parent star's light filtered through the planet's atmosphere -- a technique called transmission spectroscopy -- they determined the water abundance of the atmosphere on the boundary between the day and night hemispheres.

In order to make the map more detailed the team also measured the water abundances and temperatures at different longitudes. To do this they took advantage of the precision and stability of Hubble's instruments to subtract more than 99.95% of the light from the parent star, allowing them to study the light coming from the planet itself -- a technique called emission spectroscopy. By doing this at different points of the planet's orbit around the parent star they could map the atmosphere across its longitude.

"We have been able to observe three complete rotations -- three years for this distant planet -- during a span of just four days," explained Jacob Bean from the University of Chicago, USA, leader of the research project. "This was essential in allowing us to create the first full temperature map for an exoplanet and to probe its atmosphere to find out which elements it held and where."

Finding the proportions of the different elements in planetary atmospheres provides vital clues to understanding how planets formed.

"Because there's no planet with these tortured conditions in the Solar System, characterising the atmosphere of such a bizarre world provides a unique laboratory with which to acquire a better understanding of planet formation and planetary physics," said Nikku Madhusudhan of Cambridge University, UK, co-author of both studies. "In this case the discovery fits well with pre-existing models of how such planets behave."

The team found that WASP-43b reflected very little of its host star's light. An atmosphere like that on Earth, with clouds that reflect most of the sunlight, is not present on WASP-43b, but the team did find water vapour in the planet's atmosphere.

"The planet is so hot that all the water in its atmosphere is vapourised, rather than condensed into the icy clouds we find on Jupiter," said team member Laura Kreidberg of the University of Chicago, lead author of the study mapping water on the planet.

link.