Institute of Astronomy

Astronomy News

Detection of titanium oxide in the atmosphere of a hot Jupiter

14 September 2017 - 10:04am

Detection of titanium oxide in the atmosphere of a hot Jupiter

Nature 549, 7671 (2017). doi:10.1038/nature23651

Authors: Elyar Sedaghati, Henri M. J. Boffin, Ryan J. MacDonald, Siddharth Gandhi, Nikku Madhusudhan, Neale P. Gibson, Mahmoudreza Oshagh, Antonio Claret & Heike Rauer

As an exoplanet transits its host star, some of the light from the star is absorbed by the atoms and molecules in the planet’s atmosphere, causing the planet to seem bigger; plotting the planet’s observed size as a function of the wavelength of the light produces a transmission spectrum. Measuring the tiny variations in the transmission spectrum, together with atmospheric modelling, then gives clues to the properties of the exoplanet’s atmosphere. Chemical species composed of light elements—such as hydrogen, oxygen, carbon, sodium and potassium—have in this way been detected in the atmospheres of several hot giant exoplanets, but molecules composed of heavier elements have thus far proved elusive. Nonetheless, it has been predicted that metal oxides such as titanium oxide (TiO) and vanadium oxide occur in the observable regions of the very hottest exoplanetary atmospheres, causing thermal inversions on the dayside. Here we report the detection of TiO in the atmosphere of the hot-Jupiter planet WASP-19b. Our combined spectrum, with its wide spectral coverage, reveals the presence of TiO (to a confidence level of 7.7σ), a strongly scattering haze (7.4σ) and sodium (3.4σ), and confirms the presence of water (7.9σ) in the atmosphere.

Inferno world with titanium skies

14 September 2017 - 9:56am

The planet, WASP-19b, has about the same mass as Jupiter, but is so close to its parent star that it completes an orbit in just 19 hours and its atmosphere is estimated to have a temperature of about 2000 degrees Celsius. Such planets are known as ‘hot Jupiters’.

As WASP-19b passes in front of its parent star, some of the starlight passes through the planet’s atmosphere and leaves subtle molecular fingerprints in the light that eventually reaches Earth. “Detecting these molecules is no simple feat,” said lead author Elyar Sedaghati, an ESO fellow and recent graduate of TU Berlin. “We used an algorithm that explores many millions of spectra spanning a wide range of chemical compositions, temperatures, and cloud or haze properties in order to draw our conclusions.”

Using the FORS2 instrument on the European Southern Observatory’s Very Large Telescope in Chile, the team was able to carefully analyse this light and deduce that the atmosphere contained small amounts of titanium oxide, water and traces of sodium, alongside a strongly scattering global haze.

“Titanium oxide can substantially affect the behaviour of WASP-19b's atmosphere,” said co-author Ryan MacDonald, a PhD student at Cambridge’s Institute of Astronomy. “From altering its temperature structure, to driving strong winds, we are now one step closer to uncovering the nature of this extreme world.”

Titanium oxide (TiO) is rarely seen on Earth, but it in the atmospheres of hot planets like WASP-19b, it can absorb the incoming starlight in the same way that ozone absorbs the incoming sunlight in the Earth’s stratosphere. This causes a temperature inversion in the stratosphere whereby temperature increases with altitude. The energy from the absorbed starlight higher up in the atmosphere is released locally and causes the temperature to be higher in the upper atmosphere and lower further down, the opposite of the normal situation.

“TiO has been predicted to exist in hot Jupiters for over a decade but its conclusive detection has proved elusive in the past,” said co-author Dr Nikku Madhusudhan of Cambridge’s Institute of Astronomy, who oversaw the atmospheric analyses. “The clear detection of the molecule is a major observational advancement – it is an exciting time in exoplanetary science.”

The astronomers collected observations of WASP-19b over a period of more than one year. By measuring the relative variations in the planet’s radius at different wavelengths of light that passed through the exoplanet’s atmosphere and comparing the observations to atmospheric models, they could extrapolate different properties, such as the chemical content, of the exoplanet’s atmosphere.

This new information about the presence of titanium oxide and other metal oxides will allow a deeper understanding of the chemical and physical processes in exoplanetary atmospheres. Looking to the future, once astronomers are able to observe atmospheres of possibly habitable planets, the improved models will give them a much better idea of how to interpret those observations.

“This important discovery is the outcome of a refurbishment of the FORS2 instrument that was done exactly for this purpose,” said co-author Henri Boffin from ESO, who led the refurbishment project. “Since then, FORS2 has become the best instrument to perform this kind of study from the ground.”

Reference:
Elyar Sedaghati et al. “Detection of titanium oxide in the atmosphere of a hot Jupiter.” Nature (2017). DOI: 10.1038/nature23651

Adapted from an ESO press release.

An international team of astronomers has detected titanium oxide in the atmosphere of an exoplanet for the first time. The results, reported in the journal Nature, provide unique information about the chemical composition and the temperature and pressure structure of the atmosphere of this unusual and very hot world.

The clear detection of the molecule is a major observational advancement – it is an exciting time in exoplanetary science.Nikku MadhusudhanESO/M. KornmesserAn artist's impression showing the exoplanet WASP-19b


The text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

Yes

Cassini Spacecraft Makes Its Final Approach to Saturn

14 September 2017 - 9:51am
Cassini has begun transmitting data -- including the final images taken by its imaging cameras -- in advance of its final plunge into Saturn on Sept. 15.

Inferno World with Titanium Skies

14 September 2017 - 9:50am
Astronomers using ESO’s Very Large Telescope have detected titanium oxide in an exoplanet atmosphere for the first time. This discovery around the hot-Jupiter planet WASP-19b exploited the power of the FORS2 instrument. It provides unique information about the chemical composition and the temperature and pressure structure of the atmosphere of this unusual and very hot world. The results appear today in the journal Nature.

Cassini conducts last picture show

14 September 2017 - 9:49am

The Saturn probe takes some final images ahead of its mission-ending dive into the ringed planet.

Cassini’s 10 best pictures from its 13-year voyage around Saturn

13 September 2017 - 9:36am

On 15 September, NASA’s Cassini spacecraft will crash into Saturn, ending its mission with a bang. New Scientist looks back at 10 of its best images

Our sun probably didn’t steal Planet Nine from outer space

12 September 2017 - 10:22am

If there is a Planet Nine lurking in the outer reaches of our solar system, it was probably born close to the sun rather than snatched up from afar

Slingshot around Titan is the beginning of the end for Cassini

12 September 2017 - 10:22am

The Cassini spacecraft is passing by Titan on its final nosedive into Saturn. Plenty has been revealed about Saturn’s largest moon on Cassini’s 20-year mission

Cassini: Saturn probe turns towards its death plunge

12 September 2017 - 10:21am

The veteran space probe puts itself on a path to destruction in Saturn's atmosphere on Friday.

Low-oxygen dwarf galaxy shows us how the early universe looked

11 September 2017 - 10:03am

A star factory with the lowest oxygen level ever seen in such a galaxy could help us understand how the elements were distributed after the big bang

New tools for exploring the surface of Mars: the Planetary SUrface Portal (PSUP) and the iMars webGIS

8 September 2017 - 10:00am

In past decades, spacecraft have sent back huge amounts of complex data about Mars, providing a wealth of information about the planet. More than ever, the scientific community needs a way to sift through, compare, and analyse these data, prompting the development of two new tools for exploring the surface of the Red Planet: the iMars webGIS and the Planetary SUrface Portal (PSUP).

Discrete and broadband electron acceleration in Jupiter’s powerful aurora

7 September 2017 - 9:14am

Discrete and broadband electron acceleration in Jupiter’s powerful aurora

Nature 549, 7670 (2017). doi:10.1038/nature23648

Authors: B. H. Mauk, D. K. Haggerty, C. Paranicas, G. Clark, P. Kollmann, A. M. Rymer, S. J. Bolton, S. M. Levin, A. Adriani, F. Allegrini, F. Bagenal, B. Bonfond, J. E. P. Connerney, G. R. Gladstone, W. S. Kurth, D. J. McComas & P. Valek

The most intense auroral emissions from Earth’s polar regions, called discrete for their sharply defined spatial configurations, are generated by a process involving coherent acceleration of electrons by slowly evolving, powerful electric fields directed along the magnetic field lines that connect Earth’s space environment to its polar regions. In contrast, Earth’s less intense auroras are generally caused by wave scattering of magnetically trapped populations of hot electrons (in the case of diffuse aurora) or by the turbulent or stochastic downward acceleration of electrons along magnetic field lines by waves during transitory periods (in the case of broadband or Alfvénic aurora). Jupiter’s relatively steady main aurora has a power density that is so much larger than Earth’s that it has been taken for granted that it must be generated primarily by the discrete auroral process. However, preliminary in situ measurements of Jupiter’s auroral regions yielded no evidence of such a process. Here we report observations of distinct, high-energy, downward, discrete electron acceleration in Jupiter’s auroral polar regions. We also infer upward magnetic-field-aligned electric potentials of up to 400 kiloelectronvolts, an order of magnitude larger than the largest potentials observed at Earth. Despite the magnitude of these upward electric potentials and the expectations from observations at Earth, the downward energy flux from discrete acceleration is less at Jupiter than that caused by broadband or stochastic processes, with broadband and stochastic characteristics that are substantially different from those at Earth.

Jupiter’s powerful aurora is surprisingly different from Earth’s

7 September 2017 - 9:11am

We always assumed that auroras on Jupiter were caused by the same process that brings the swirling light shows to Earth. New observations show that they aren’t

The sun just belched out the strongest solar flare in 12 years

7 September 2017 - 9:10am

If your GPS has been acting funny, take it up with the sun. Our star has released the most powerful solar flare since 2005

Celebrating Europe's science highlights with Cassini

7 September 2017 - 9:09am

The international Cassini-Huygens mission has explored Saturn and its rings and moons for 13 years, and will conclude by plunging into the planet's atmosphere next week. This article highlights some of the mission's exciting discoveries led by European teams.

Meteor bursting into flames caught on camera.

6 September 2017 - 9:23am

A home security camera caught the moment a meteor over Canada burst into flames.

‘Impossible’ star explosions made by gas and solar wind pile-up

5 September 2017 - 10:07am

Stellar explosions often shine brighter than is theoretically possible without blowing up entirely. Debris cloud smash-ups could be amplifying the light

Asteroid Florence buzzes Earth in closest fly-by since 1890

5 September 2017 - 10:07am

A 4.4-kilometre-wide space rock whizzed past Earth on its closest orbit in over a century. This asteroid won’t get this close again until after 2500

Some of Uranus’s small moons are doomed to collide

5 September 2017 - 10:06am

The first measurement of the mass of a small Uranian moon suggests it will be obliterated after smashing into one of its neighbours in the next million years

Voyager 1 at 40: Scientists 'amazed' 1970s space probe still works

5 September 2017 - 10:05am

The Voyager 1 space probe was launched 40 years ago and continues to send back data from interstellar space.