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Exoplanets subject to meteorological variations

Date:
July 10, 2012
Source:
CNRS (Délégation Paris Michel-Ange)
Summary:
Astronomers have detected meteorological variations in the atmosphere of an exoplanet (a planet outside our own Solar System). The astrophysicists made the discovery while observing the exoplanet HD 189733b with the Hubble space telescope.
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"A stellar flare blasting an exoplanet": this artist's impression shows exoplanet HD HD189733b transiting in front of its star. The Hubble Space Telescope observed the transit in September 2010 and April 2011. The April 2011 observation took place just after a strong stellar flare (shown in the image) observed in the X-ray waveband by the Swift telescope. After the flare, the Hubble observations showed that the planet was losing over 1000 tonnes of gas per second. (In this image, the star's surface is inspired by observations of the Sun by the Solar Dynamics Observatory spacecraft.)
Credit: © NASA, ESA, L. Calçada

An international team from the Institut d'Astrophysique de Paris (CNRS/UPMC) and the Institut de Planétologie et d'Astrophysique de Grenoble (IPAG(1) -- CNRS/Université Joseph Fourier -- Grenoble 1) has detected meteorological variations in the atmosphere of an exoplanet (a planet outside our own Solar System). The astrophysicists made the discovery while observing the exoplanet HD 189733b with the Hubble space telescope.

This work could widen the scope of climate sciences and meteorology, still confined to studying the weather on planets in our Solar System, and give rise to a new sub-discipline, exo-meteorology. These findings are published in the 28 June 2012 issue of the journal Astronomy & Astrophysics Letters. Located 63 light years (600 000 billion km) from Earth, HD 189733b is a gas giant planet with a hazy atmosphere mainly composed of hydrogen (H2). Due to close proximity to its star (1/30th of the distance from Earth to the Sun), its upper atmosphere receives a huge amount of energy in the form of ultraviolet and X-ray radiation.

The researchers initially observed the star in order to confirm a result obtained in 2003 with the Hubble telescope for another exoplanet, HD 209458b , located in a different planetary system. They discovered that the hydrogen making up the topmost layer of the planet's atmosphere was spreading out in a huge plume, providing evidence that its atmosphere was evaporating into space. Recent observations of HD 189733b confirm the existence of this phenomenon on another exoplanet.

More importantly, they reveal meteorological variations in an exoplanet's atmosphere. In fact, the researchers observed HD 189733b on two occasions. In April 2010 they saw nothing unusual. However, in September 2011 they detected a huge cloud of gas six times larger than the planet itself. This shows that the state of the atmosphere had changed in the meantime, and that the scientists had found a meteorological difference on HD 189733b.

What caused the change? What is the effect of the star and its radiation on the weather in the exoplanet's upper atmosphere? To find out more, three new observations are already planned.

(1) IPAG is a laboratory belonging to the Observatoire des Sciences de l'Univers de Grenoble (OSUG).

(2) "An extended upper atmosphere around the extra-solar planet HD 209458b"; A. Vidal-Madjar et co.; Nature; 13 March 2003.


Story Source:

The above post is reprinted from materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:

  1. A. Lecavelier des Etangs, V. Bourrier, P.J. Wheatley, H. Dupuy, D. Ehrenreich, A. Vidal-Madjar, G. Hébrard, G.E. Ballester, J.-M. Désert, R. Ferlet, D.K. Sing. Temporal variations in the evaporating atmosphere of the exoplanet HD189733b. Astronomy & Astrophysics Letters, 28 June 2012 [link]

Cite This Page:

CNRS (Délégation Paris Michel-Ange). "Exoplanets subject to meteorological variations." ScienceDaily. ScienceDaily, 10 July 2012. <www.sciencedaily.com/releases/2012/07/120710093514.htm>.
CNRS (Délégation Paris Michel-Ange). (2012, July 10). Exoplanets subject to meteorological variations. ScienceDaily. Retrieved August 3, 2015 from www.sciencedaily.com/releases/2012/07/120710093514.htm
CNRS (Délégation Paris Michel-Ange). "Exoplanets subject to meteorological variations." ScienceDaily. www.sciencedaily.com/releases/2012/07/120710093514.htm (accessed August 3, 2015).

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