Hubble maps temperature, water vapour on wild exoplanet

An artist's conception of exoplanet WASP-43b orbiting an orange dwarf star roughly 260 light-years from Earth. 

About twice as massive as Jupiter, WASP-43b heats up to about 3,000 degrees Fahrenheit during its closest passes by its star, a temperature hot enough to melt steel. 

Credit: NASA, ESA

A team of scientists including a University of Colorado Boulder professor used NASA's Hubble Space Telescope to make the most detailed global map yet of the glow from a giant, oddball planet orbiting another star, an object twice as massive as Jupiter and hot enough to melt steel.

The Hubble observations show that the planet, called WASP-43b, is no place to call home.

It's a world of extremes, where winds howl at the speed of sound from a 3,000-degree-Fahrenheit dayside to a pitch-black nightside when temperatures plunge to a relatively cool 1,000 degrees Fahrenheit, still hot enough to melt silver.

The map provides information about temperatures at different layers of the planet's atmosphere and traces the amount and distribution of water present.

The findings have ramifications for understanding the atmospheric dynamics and the formation of giant planets like Jupiter, said team leader Jacob Bean of the University of Chicago.

"These measurements have opened the door for a new kind of comparative planetology."

A paper on the subject was published online Oct. 9 in Science Express.

As a ball of predominately hot hydrogen gas, there are no surface features on WASP-43b like oceans or continents that can be used to track its rotation, said CU-Boulder Assistant Professor Jean-Michel Désert, second author on the new study.

Only the drastic temperature difference between the dayside and nightside can be used by remote observers to mark the passage of a day on the strange, gaseous planet, he said.

"WASP-43b is extreme in many ways," said Désert. "It's the size of Jupiter with twice its mass. Its orbit around its host star, called an orange dwarf, takes only about 19 hours – the blink of an eye compared to the 365 days it takes Earth to orbit the sun."

Désert said the study is compelling to those trying to understand planetary formation. "Basically it is like taking a planet like Jupiter into a giant laboratory, then warming it at such a high temperature that all of the atoms and molecules comprising its atmosphere are in a gas phase."

Another bizarre thing about WASP-43b is its orbit. It orbits so close to its host star it always "shows" the same hemisphere, a phenomena similar to the orbit of the moon around Earth that is known as known as "tidal locking."

Discovered in 2011, WASP-43b is 260 light-years away, too distant to be photographed, but because its orbit is observed "edge-on" to Earth, astronomers detected it by observing regular dips in the light of its parent star as the planet passed in front of it, said Désert of CU-Boulder's Department of Astrophysical and Planetary Sciences.

More information: "Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy," by K.B. Stevenson et al. Science, 2014. www.sciencemag.org/lookup/doi/… 1126/science.1256758

ESA's Rosetta: Measuring the temperature of Comet 67P /Churyumov–Gerasimenko

The first temperature measurements of comet 67P/Churyumov–Gerasimenko were made between 13 and 21 July, when Rosetta closed in from 14 000 km to the comet to just over 5000 km. 

The observations were made by the spacecraft’s visible, infrared and thermal imaging spectrometer, VIRTIS, and revealed an average surface temperature of –70ºC. 

This implies the surface is predominantly covered in dust rather than ice, which would yield a lower temperature. 

The finding does not exclude localised patches of ice. The observations were made when the comet was roughly 555 million kilometres from the Sun. 

Credit: ESA

ESA's Rosetta spacecraft has made its first temperature measurements of its target comet, finding that it is too hot to be covered in ice and must instead have a dark, dusty crust.

The observations of comet 67P/Churyumov–Gerasimenko were made by Rosetta's visible, infrared and thermal imaging spectrometer, VIRTIS, between 13 and 21 July, when Rosetta closed in from 14 000 km to the comet to just over 5000 km.

At these distances, the comet covered only a few pixels in the field of view and so it was not possible to determine the temperatures of individual features but, using the sensor to collect infrared light emitted by the whole comet, scientists determined that its average surface temperature is about –70ºC.

The comet was roughly 555 million kilometres from the Sun at the time, more than three times further away than Earth, meaning that sunlight is only about a tenth as bright.

Although –70ºC may seem rather cold, importantly, it is some 20–30ºC warmer than predicted for a comet at that distance covered exclusively in ice.

"This result is very interesting, since it gives us the first clues on the composition and physical properties of the comet's surface," says VIRTIS principal investigator Fabrizio Capaccioni from INAF-IAPS, Rome, Italy.

1P/Halley comet

Indeed, other comets such as 1P/Halley are known to have very dark surfaces owing to a covering of dust, and Rosetta's comet was already known to have a low reflectance from ground-based observations, excluding an entirely 'clean' icy surface.

The temperature measurements provide direct confirmation that much of the surface must be dusty, because darker material heats up and emits heat more readily than ice when it is exposed to sunlight.

"This doesn't exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features," adds Dr Capaccioni.

In addition to global measurements, the sensor will study the variation of the daily surface temperature of specific areas of the comet, in order to understand how quickly the surface reacts to solar illumination.

In turn, this will provide insight into the thermal conductivity, density and porosity of the top tens of centimetres of the surface. This information will be important in selecting a target site for Rosetta's lander, Philae.

It will also measure the changes in temperature as the comet flies closer to the Sun along its orbit, providing substantially more heating of the surface.

"Combined with observations from the other 10 science experiments on Rosetta and those on the lander, VIRTIS will provide a thorough description of the surface physical properties and the gases in the comet's coma, watching as conditions change on a daily basis and as the comet loops around the Sun over the course of the next year," says Matt Taylor, ESA's Rosetta project scientist.

"With only a few days until we arrive at just 100 km distance from the comet, we are excited to start analysing this fascinating little world in more and more detail."

Rosetta is an ESA mission with contributions from its member states and NASA.

Rosetta's Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.

Rosetta will be the first mission in history to rendezvous with a comet, escort it as it orbits the Sun, and deploy a lander.

Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed.

By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in-situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System, as well as answering questions regarding the origin of Earth's water and perhaps even life.

Newly discovered celestial object defies categories

This is an image of the ROXs 42B system obtained with the Keck telescope. 

The star is located in the center of the masked region. 

ROXs 42Bb orbits at about 150 astronomical units (AU). 

(1 AU=the distance from Earth to the Sun.) 

The other object ("c") is a likely unrelated background star. 

Credit: Thayne Currie

An object discovered by astrophysicists at the University of Toronto (U of T) nearly 500 light years away from the Sun may challenge traditional understandings about how planets and stars form.

The object is located near and likely orbiting a very young star about 440 light years away from the Sun, and is leading astrophysicists to believe that there is not an easy-to-define line between what is and is not a planet.

Thayne Currie

"We have very detailed measurements of this object spanning seven years, even a spectrum revealing its gravity, temperature, and molecular composition. Still, we can't yet determine whether it is a planet or a failed star – what we call a 'brown dwarf'. Depending on what measurement you consider, the answer could be either," said Thayne Currie, a post-doctoral fellow in U of T's Department of Astronomy & Astrophysics and lead author of a report on the discovery published this week in Astrophysical Journal Letters.

Named ROXs 42Bb for it's proximity to the star ROXs 42B, the object is approximately nine times the mass of Jupiter, below the limit most astronomers use to separate planets from brown dwarfs, which are more massive.

However, it is located 30 times further away from the star than Jupiter is from the Sun.

"This situation is a little bit different than deciding if Pluto is a planet. For Pluto, it is whether an object of such low mass amongst a group of similar objects is a planet," said Currie.

"Here, it is whether an object so massive yet so far from its host star is a planet. If so, how did it form?"

Most astronomers believe that gas giant planets like Jupiter and Saturn formed by core accretion, whereby the planets form from a solid core that then accretes a massive gaseous envelope.

Core accretion operates most efficiently closer to the parent star due to the length of time required to first form the core.

An alternate theory proposed for forming gas giant planets is disk instability – a process by which a fragment of a disk gas surrounding a young star directly collapses under its own gravity into a planet. This mechanism works best farther away from the parent star.

More information: The discovery is reported in a study titled "Direct imaging and spectroscopy of a candidate companion below/near the deuterium-burning limit in the young binary star system, ROXs 42B" which can also be viewed on arXiv.org at arxiv.org/abs/1310.4825.

Currie will present these and other findings at the annual meeting of the American Astronomical Society in Washington, DC this week.

East Antarctic temp plummets to -95C

East Antarctica has set a global record for soul-crushing cold, according to newly analysed data.

The remote region plunged as low as minus 94.7C (minus 135.8F) in August 2010, the Nasa satellite data revealed.

Then on July 31 this year, it came close again, at minus 92.9C (minus 135.3F). The old record was minus 89.2C (minus 128.6F).

Ice scientist Ted Scambos, at the US National Snow and Ice Data Centre, announced the cold facts at the American Geophysical Union scientific meeting in San Francisco.

"It's more like you'd see on Mars on a nice summer day in the poles," Mr Scambos said. "I'm confident that these pockets are the coldest places on Earth."

However, it will not be in the Guinness Book of World Records because these were satellite-measured figures, not from thermometers, he added.

"Thank God, I don't know how exactly it feels," Mr Scambos said.

Most of the time researchers need to breathe through a snorkel that brings air into the coat through a sleeve and warms it up "so you don't inhale by accident" the cold air, Mr Scambos said.

Waleed Abdalati, an ice scientist at the University of Colorado and Nasa's former chief scientist, and Mr Scambos said this is likely to be an unusual random reading in a place that has not been measured much before and could have been colder or hotter in the past and we would not know.

"It does speak to the range of conditions on this Earth, some of which we haven't been able to observe," Mr Abdalati said.

NASA LANDSAT-5 (LDCM) satellite takes the Salton Sea's temperature

The Salton Sea in Southern California and nearby irrigated fields stand out in this image taken March 24, 2013, by the Thermal Infrared Sensor (TIRS) instrument on the Landsat Data Continuity Mission (LDCM) satellite. 

Darker areas of the image are cooler, while lighter areas are warmer. 

Credit: USGS/NASA's Earth Observatory.

An image from an instrument aboard NASA's Landsat Data Continuity Mission or LDCM satellite may look like a typical black-and-white image of a dramatic landscape, but it tells a story of temperature.

The dark waters of the Salton Sea pop in the middle of the Southern California desert. Crops create a checkerboard pattern stretching south to the Mexican border.

If you looked at the Salton Sea in person, your eyes would not see anything presented in the LDCM image.

Instead of showing visible light, the image shows the amount of heat, or thermal energy, radiating from the landscape and detected by the Thermal Infrared Sensor, or TIRS, instrument on LDCM. Cooler areas are dark, while warm areas are bright.

The dark squares in the LDCM's image of the Salton Sea are fields where plants can absorb irrigation water before sweating it off through a process called transpiration.

Just like when people sweat, plants cool down when they transpire.

The combination of transpiration and water evaporating from the ground itself, evapotranspiration, drops the temperature of the irrigated land.

Those cool temperatures, indicating healthy, well-watered plants, are picked up by TIRS.

Dennis Reuter

"What you're looking at is infrared light that's generated by the Earth itself," said Dennis Reuter, TIRS instrument scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.

TIRS is one of two instruments on the newest spacecraft in the Landsat family, launched Feb. 11 and currently in its on-orbit calibration and checkout phase.

While its partner instrument records reflected sunlight, TIRS complements that view with temperature readings across swaths of Earth's surface.

The Goddard-designed detectors in the TIRS instruments can pick up two different bands of thermal infrared energy, which excite electrons and create an electrical signal.

With TIRS measuring the strength of those signals, corresponding to temperatures on the ground, scientists can generate images like this one of the Salton Sea.

The view you get from TIRS is similar to what you've seen on television crime shows when cops use thermal imagers to track warm-bodied suspects moving around inside of a building. With Landsat, though, scientists use the thermal bands to track down water.

Dark pixels representing cool spots and light pixels of hot spots are key to helping water managers determine where the valuable resource is being used for irrigation, especially in the arid western United States.

Absolute Zero May not Be So "Absolute"

Physicists don’t tend to use universal language freely, so since Lord Kelvin dubbed the base measure of his temperature scale “absolute zero,” that should be a sign that there is reason for the “absolute” nature of the measure to be taken seriously.

Unlike the centigrade scale, where 0 degrees marks the freezing point of fresh water, or the Fahrenheit scale, where 0 is the stable temperature of a mix of water, ice, ammonium chloride and sea salt, 0 Kelvin—absolute zero—is, theoretically, the coldest thing imaginable.

This is the temperature when all motion comes to a crawl, when molecules stop quivering and atoms stop moving.

In Nature, Zeeya Merali reports on the work of Stefan Braun and colleagues, a group of physicists that managed to overthrow Kelvin’s absolutism by creating “an atomic gas with a sub-absolute-zero temperature for the first time.”

Through an elaborate approach—harnessing lasers and rapidly-flipping magnetic fields—the scientists figured out how to push atoms to temporarily take on energies below absolute zero. The scientists manipulated a cloud of potassium atoms trapped by lasers, says Merali:

At positive temperatures, the atoms repel, making the configuration stable. The team then quickly adjusted the magnetic fields, causing the atoms to attract rather than repel each other.

“This suddenly shifts the atoms from their most stable, lowest-energy state to the highest possible energy state, before they can react,” says Schneider. “It’s like walking through a valley, then instantly finding yourself on the mountain peak.”

At positive temperatures, such a reversal would be unstable and the atoms would collapse inwards. But the team also adjusted the trapping laser field to make it more energetically favourable for the atoms to stick in their positions.

This result, described today in Science, marks the gas’s transition from just above absolute zero to a few billionths of a Kelvin below absolute zero.

Researchers imagine that if new materials could somehow be made out of below-freezing atoms, then they would probably act in some mighty strange ways.

Saturn's moons Mimas and Tethys bear 'Pac-Man' signatures

Saturn's moons Mimas (left) and Tethys are now both known to exhibit the curious temperature patterns.

Astronomers have seen that the temperature of Saturn's moon Tethys has hotter regions uncannily like the 1980s arcade game character Pac-Man.

A similar feature was spotted in 2010 on Mimas, another Saturnian moon.

A report in Icarus suggests the effect is due to high-energy electrons bombarding the sides of the moons that face their direction of orbital travel.

That compacts the surfaces to a hard, icy texture that does not heat or cool as rapidly as the unaffected surface.

Thermal images of both moons were obtained by the Cassini-Huygens mission, launched in 1997 to study the Saturn system in detail.

The temperatures seen by the spacecraft are distinctly chilly - the warmest parts of Tethys were at - 183C, but inside the "mouth" of the Pac-Man shape it was 15C cooler still.

At the time of the finding of the first Pac-Man shape on Mimas, scientists were unsure what might be the cause, theorising that differing surface textures probably played a role.

The existence of another such shape nearby has cemented the idea that fast-moving electrons are responsible.

"Finding a second Pac-Man in the Saturn system tells us that the processes creating these 'Pac-Men' are more widespread than previously thought," said Carly Howett, of the Southwest Research Institute in Texas and lead author of the study.

"The Saturn system - and even the Jupiter system - could turn out to be a veritable arcade of these characters," she said.

BAE's ADAPTIV technology renders vehicles invisible to infrared

Infrared imaging is used for a range of military applications - such as target acquisition, night vision, homing and tracking - which means that any vehicle with some kind of infrared “invisibility cloak” would hold significant advantages on the battlefield.

BAE Systems has tested just such a technology that not only allows vehicles to blend into their surroundings, but can also let it mimic other vehicles or natural objects.

Dubbed "ADAPTIV," the patented infrared cloaking technology developed at BAE consists of sheets of hexagonal panels that act as pixels when attached to the exterior of the vehicle.

These pixels can individually change temperature very rapidly and combine to display an infrared image of the background scenery captured from cameras onboard the vehicle, allowing even a moving tank to match its surroundings.

BAE has also put together a library of images to display the heat signature of other vehicles, such as cars, trucks, and natural objects, such as large rocks.

Venus Temperature distribution

Temperature distribution within Venus and local mobilisation at the surface. Credit: DLR

It may seem downright bizarre, but a new model of Venus' super-hot atmosphere suggests its greenhouse gases may actually be cooling the planet's interior. 

These gases initially cause Venus' temperature to rise, but at a certain threshold, they can trigger dynamic processes – which researchers call "mobilization" – in the planet's crust that cool the mantle and overall surface temperature, researchers found.

Venus surface temperature, on average, is a scorching 860 degrees Fahrenheit (460 degrees Celsius).

3-D perspective of the Venusian volcano, Maat Mons generated from radar data from NASA’s Magellan mission. Credit: NASA/JPL

El Niño is gathering pace in the Pacific

El Niño is experiencing a late-fall resurgence. Recent sea-level height data from the Ocean Surface Topography Mission/Jason-2 oceanography satellite show that a large-scale, sustained weakening of trade winds in the western and central equatorial Pacific during October has triggered a strong, eastward moving, wave of warm water, known as a Kelvin wave.

In the central and eastern equatorial Pacific, this warm wave appears as the large area of higher-than-normal sea surface heights (warmer-than-normal sea surface temperatures) between 170 degrees east and 100 degrees west longitude. A series of similar, weaker events that began in June 2009 initially triggered and has sustained the present El Niño condition.

This image was created with data collected by the U.S./French satellite during a 10-day period centered on November 1, 2009. It shows a red and white area in the central and eastern equatorial Pacific that is about 10 to 18 centimeters (4 to 7 inches) above normal. These regions contrast with the western equatorial Pacific, where lower-than-normal sea levels (blue and purple areas) are between 8 to 15 centimeters (3 and 6 inches) below normal. Along the equator, the red and white colors depict areas where sea surface temperatures are more than one to two degrees Celsius above normal (two to four degrees Fahrenheit).

"In the American west where we are struggling under serious drought conditions, this late-fall charge by El Niño is a pleasant surprise, upping the odds for much needed rain and an above-normal winter snowpack," said JPL oceanographer Bill Patzert.