Hunting molecules to find new planets
by Staff Writers
Geneva, Switzerland (SPX) Jun 22, 2018
Each exoplanet revolves around a star, like the Earth around the Sun. This is why it is generally impossible to obtain images of an exoplanet, so dazzling is the light of its star. However, a team of astronomers, led by a researcher from the University of Geneva (UNIGE) and member of NCCR PlanetS, had the idea of detecting certain molecules that are present in the planet's atmosphere in order to make it visible, provided that these same molecules are absent from its star.
Thanks to this innovative technique, the device is only sensitive to the selected molecules, making the star invisible and allowing the astronomers to observe the planet directly. The results appear in the journal Astronomy and Astrophysics.
Until now, astronomers could only very rarely directly observe the exoplanets they discovered, as they are masked by the enormous luminous intensity of their stars. Only a few planets located very far from their host stars could be distinguished on a picture, in particular thanks to the SPHERE instrument installed on the Very Large Telescope (VLT) in Chile, and similar instruments elsewhere.
Jens Hoeijmakers, researcher at the Astronomy Department of the Observatory of the Faculty of Science of the UNIGE and member of NCCR PlanetS, wondered if it would be possible to trace the molecular composition of the planets. "By focusing on molecules present only on the studied exoplanet that are absent from its host star, our technique would effectively "erase" the star,leaving only the exoplanet," he explains.
Erasing the star thanks to molecular spectra
The astronomers then compared the spectrum contained in the pixel with a spectrum corresponding to a given molecule, for example water vapour, to see if there is a correlation. If there is a correlation, it means that the molecule is present in the atmosphere of the planet.
By applying this technique to beta pictoris b, Jens Hoeijmakers notices that the planet becomes perfectly visible when he looks for water (H2O) or carbon monoxide (CO). However, when he applies his technique to methane (CH4) and ammonia (NH3), the planet remains invisible, suggesting the absence of these molecules in the atmosphere of beta pictoris b.
Molecules, new planetary thermometer
"This is why this technique allows us not only to detect elements on the surface of the planet, but also to sense the temperature which reigns there", explains the astronomer of the UNIGE. The fact that astronomers cannot find beta pictoris b using the spectra of methane and ammonia is therefore consistent with a temperature estimated at 1700 degrees for this planet, which is too high for these molecules to exist.
"This technique is only in its infancy", enthuses Jens Hoeijmakers. "It should change the way planets and their atmospheres are characterized. We are very excited to see what it will give on future spectrographs like ERIS on the Very Large Telescope in Chile or HARMONI on the Extremely Large Telescope which will be inaugurated in 2025, also in Chile," he concludes.
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.