The transit event causes a small drop in the observed starlight, which can then be detected. Fifty-five exoplanets have been detected this way since the observation of the first transiting planet HD 209458 b in 1999.
When the planet revolves around its star or when it goes behind, the light coming from the system also varies, though the resulting smaller modulation is much harder to detect. This is mostly due to the small amount of light emitted by these exoplanets which are believed to be as dark as coal and reflect little of the incoming starlight. Fortunately, some of these planets are very hot, thus emitting light, mostly at infrared wavelengths.
Up to now, detections of this kind have only been made using the Spitzer infrared space telescope. This week, Astronomy & Astrophysics is publishing the two first ground-based detections of thermal emission from transiting, hot-Jupiter exoplanets, from two independent teams of astronomers that used different approaches.
One team includes Ernst De Mooij and Ignas Snellen (University of Leiden, Netherlands) who used the William Hershel 4.2 meter telescope in La Palma (Canary Islands, Spain) to observe the star TrES-3 and its planet TrES-3b. To be able to detect the light coming from the planet, they observed the planet exactly at the time when it passes behind the star. They observed the event at infrared wavelengths, where the planet is at its brightest compared to the star (even if the planet is still much fainter than the star!) As they detected the light coming from the planet, they estimated the temperature of its atmosphere to about 2000 Kelvins. This indicates that the day side of the planet is extremely hot.
The other team, involving David Sing (IAP, France) and Mercedes Lopez-Morales (Carnegie Institution of Washington, USA), had a different approach. They looked at a much fainter star and its planet, OGLE-TR-56b. This planet is one of the most irradiated planets known so far, both because the planet is very close to the star and because the star is very hot. To detect the slight modulation in light that occurs when the planet passes behind its star, they used the 8 meter Very Large Telescope (ESO, Chile) and the 6.5 meter Magellan Telescopes (Las Campanas, Chile) and were able to observe this event at visible wavelengths. Indeed, the planet OGLE-TR-56b is heated so much by its star that it emits detectable amounts of light in the visible wavelengths, and not only in the infrared as TrES-3b does. Hence, Sing and Lopez-Morales measured the record-high temperature of a planetary atmosphere: 2700 Kelvins. As in the case of TrES-3b, such a high day-side temperature indicates that winds cannot redistribute the heat efficiently from the day side to the night side.
These two independent results are very interesting for astronomers and planetary scientists because they allow a direct probe of the temperature of these planetary atmospheres, and because they show that such measurements can be made from ground-based observatories, and not only when using space telescopes.
Jennifer Martin | alfa
FAST detects neutral hydrogen emission from extragalactic galaxies for the first time
01.07.2020 | Chinese Academy of Sciences Headquarters
First exposed planetary core discovered
01.07.2020 | Universität Bern
Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...
With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.
Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...
A research team from the Max Planck Institute for the Structure of Dynamics (MPSD) and the University of Oxford has managed to drive a prototypical antiferromagnet into a new magnetic state using terahertz frequency light. Their groundbreaking method produced an effect orders of magnitude larger than previously achieved, and on ultrafast time scales. The team’s work has just been published in Nature Physics.
Magnetic materials have been a mainstay in computing technology due to their ability to permanently store information in their magnetic state. Current...
The Venus flytrap (Dionaea muscipula) takes only 100 milliseconds to trap its prey. Once their leaves, which have been transformed into snap traps, have...
NASA-NOAA's Suomi NPP satellite observed a huge Saharan dust plume streaming over the North Atlantic Ocean, beginning on June 13. Satellite data showed the dust had spread over 2,000 miles.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland, Colin Seftor, an atmospheric scientist, created an animation of the dust and aerosols from the...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
01.07.2020 | Physics and Astronomy
01.07.2020 | Power and Electrical Engineering
01.07.2020 | Physics and Astronomy