The atmosphere of a rare exoplanet “shouldn’t exist” baffles astronomers!

The discovery of the extraordinary exoplanet LTT 9779b was announced a month ago, just 260 light-years away, and was quickly identified as a prime candidate for continuing to study its exotic atmosphere.

LTT 9779b is slightly larger than Neptune and orbits a Sun-like star. However, it appears to be very close to its star, as the planet rotates once every 19 hours; Despite the scorching heat that has to be exposed during this proximity, the LTT 9779b still has a great atmosphere.

Infrared observations collected by the now retired Spitzer Space Telescope included the planet’s host star, and astronomers have now analyzed this data and published their findings in two studies.

In the first article, a team led by astronomer Ian Crossfield of the University of Kansas described the temperature profile of the LTT 9779b.

In the second article, a team led by astronomer Diana Dragomir of the University of New Mexico characterizes the atmosphere of an exoplanet.

“For the first time we have measured the light coming from this planet that shouldn’t be there. This planet is exposed to so much radiation from its star that its temperature exceeds 3,000 degrees Fahrenheit, “Crossfield said. [1650 درجة مئوية] And its atmosphere can evaporate completely. However, Spitzer’s observations show us his atmosphere via infrared light. ”

The research team studied the phase curve of an exoplanet in infrared light. Since thermal energy is emitted by infrared radiation, light of this wavelength can tell us the temperature of cosmic bodies several light years away.

And it orients the system so that the planet passes between us and the star, giving us wide-ranging views day and night. Therefore, to calculate the exoplanet’s temperature, astronomers can use the general system’s variable light as the orbit of LTT 9779b.

Interestingly, the hottest time of day for the LTT 9779b is just a boom at noon, when the sun is directly in the sky.

This, in turn, allows for some conjecture about the LTT 9779b’s atmosphere.

“The planet is much cooler than we expected, indicating that it reflects much of the falling starlight it collides with, presumably due to daytime clouds,” said astronomer Nicholas Cowan, of the Institute for Research. on exoplanets (iREx) and McGill University. The planet also has a lot of heat in addition to its night side, but we think we understand that: starlight is likely to absorb high up in the atmosphere, as energy is rapidly radiated into space. ”

To further investigate LTT 9779b’s atmosphere, Dragomir and his colleagues focused on the secondary eclipse, when the planet passes behind the star. This results in a weaker attenuation of the system’s light more than it does when the planet passes in front of the star – known as a transit – but this attenuation can help us understand the thermodynamic structure of a planet outside the solar system.

The researchers combined data from Spitzer’s secondary eclipse with data from NASA’s TESS space telescope for exoplanets. This made it possible to obtain the atmospheric emission spectrum LTT 9779b; That is, the wavelengths of light are absorbed and amplified by the elements contained in it. And they found that the particles absorb some wavelengths, possibly carbon monoxide.

This is to be expected for such a hot planet. Carbon monoxide has been detected in gas giants that also orbit very close to their stars. Gas giants are more massive than hot Neptune and use their much higher gravity to maintain their atmosphere. It was assumed that planets the size of Neptune didn’t have to be big enough to do this.

Finding carbon monoxide in Neptune’s warm atmosphere could help us understand how this planet formed and why it maintains its atmosphere.

Research such as this will provide us with an excellent toolkit and experience to explore the atmospheres of worlds, which are also potentially habitable.

Both articles were published in The Astrophysical Journal Letters.

Source: ScienceAlert