The discovery of the extraordinary Exoplanet LTT 9779B was first announced a month ago. Just 260 light-years away, the planet was immediately pegged as an excellent candidate for a follow-up study of its exotic atmosphere. But it turns out we didn’t have to wait too long to learn more.
The LTT 9779B is slightly larger than Neptune, orbiting a Sun-like star – fairly common so far. But two things are really strange. It is very close to its star, the planet orbits once every 19 hours; And, despite the intense heat, it must be close, the LTT 9779B still has a significant atmosphere.
Infrared observations now collected by the retired Spitzer Space Telescope include the planet’s host star, and astronomers have now analyzed that data, publishing its results in a few studies.
In the first paper, a team led by University of Kansas astronomer Ian Crossfield described the temperature profile of LTT9779B.
In the second paper, a team led by New Mexico University astronomer Diana Dragomir characterized the exoplanet atmosphere.
“For the first time, we measured light coming from this planet that shouldn’t exist,” Crossfield said.
“The planet is irradiated so intensely by its star that its temperature is over 3,000 degrees Fahrenheit. [1,650 degrees Celsius] And its atmosphere could have completely evaporated. However, our Spitzer observations show the planet’s atmosphere through infrared light.
Exoplanet phase curve. (ESA)
He and his team studied the phase curvature of the exoplanet in infrared light. Here’s what it means: Because thermal energy is emitted as radiant infrared radiation, light of this wavelength can tell us the temperature of cosmic objects many light-years away.
The system is oriented in such a way that the planet passes between us and the stars, giving us a clear view of both the night and day sides of the planet. Thus, to calculate the temperature of the exoplanet, astronomers can use the changing light of the overall system as an LTT 9779B orbit.
Interestingly, the hottest time of day for the LTT9779B is the afternoon, when its sun is directly overhead. On Earth, the hottest time of the day is a few hours in the afternoon, as heat enters the Earth’s atmosphere faster than it returns to Earth.
In turn, this allows some educated speculation about the atmosphere of the LTT 9779B.
“The planet is colder than expected, indicating that the day’s clouds are probably reflecting most of the light of the event that affected it,” said Nicholas Cowan, an astronomer at Exoplanets (IREX) and McGill University’s research institute. In Canada.
“Even the planet does not transfer more heat to its nocturnal space, but we think we understand that: the stars that are absorbed are probably absorbed higher in the higher atmosphere, from which the rays quickly turn into space.”
To further investigate the atmosphere of LTT 9779B, Dragomir and his colleagues focused on a secondary eclipse when the planet passes behind the star. Called a transition – the system’s light fades dimmer than when the planet passes in front of a star, but that dim dimming can help understand the thermal composition of the exoplanet atmosphere.
“Hot Neptune is rarely seen, and in one of such extreme environments it is difficult to explain because its mass is not so large in capturing the atmosphere for too long,” Dragomire said.
“So how did it operate? The LTT 9779B scratched our heads, but the fact that there is such an atmosphere gives us a unique way to examine this type of planet, so we decided to examine it with another telescope.”
The researchers linked Spitzer secondary eclipse data to data from NASA’s exoplanet-hunting space telescope TESS. This allowed them to receive emission spectrum from the atmosphere of LTT 9779B; That is, the wavelength of light is absorbed and amplified by the elements in it. They found that some wavelengths were being made possible by atoms – perhaps carbon monoxide.
This is not unexpected for such a hot planet. Carbon monoxide has been found in hot Jupiter-gas giants, which orbit stars even closer. But gas giants are much larger than the hot Neptune, and use their high gravity to maintain their atmosphere. It was thought that Neptune-sized planets should not be large enough to do so.
Finding carbon monoxide in the atmosphere of hot Neptune can help us understand how this planet came to be, and why its atmosphere is.
So, while we know more about the LTT 9779B, there is still much to be done. Future observations have given us answers to these questions and others such as what the atmosphere is made of, and the Exoplanet has made a very big start, and is currently in the process of rapidly shrinking.
Research like this will give us an excellent toolkit and experience for exploring the potential habitable world environment.
“If anyone is going to believe what astronomers said about finding signs of life or oxygen oxygen in another world, we have to show that we can really do it on simple materials,” Crossfield said.
“In that sense, these big, hot planets like the LTT 9779B act like training wheels and show that we really know what we’re doing and can do everything right.”
Two papers have been published Astrophysical Journal Letters, Here and here.
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