For the first time, the atmosphere of the super-Earth has been analyzed - but do not make any vacation plans to visit it. The planet is too close to its star (subject to a temperature of 3600 degrees Fahrenheit or 2000 Celsius) and has an atmosphere consisting mainly of hydrogen and helium, like gas-giant planets.
Hydrogen and helium are the basic elements in the young solar systems, since these are the elements that make up the young stars. Usually, small planets tend to lose hydrogen and helium over time into space, so their gravity is quite low; light elements volatilize due to the radiation of a star that pushes them out of the atmosphere. The gas giants can hold these elements due to their strong gravity.
Sometimes on small planets the atmosphere of helium or hydrogen is replaced by a secondary atmosphere, as it happened on Earth. Our mixture of nitrogen, oxygen, and carbon dioxide probably came from internal processes (such as volcanism) and plant evolution.
"We did not expect that Planet 55 of Cancer e would retain most of its primary gas atmosphere," Ingo Waldman, a researcher at University College London, who wrote a post-doctoral dissertation, told Discovery News via e-mail. Waldman noted that the planet is the only known super-Earth with such a high temperature, but astronomers thought that it would lose most of its atmosphere due to the intense radiation of its parent star. Why it holds hydrogen and helium is not clear. Astronomers have several dimensions of planetary atmospheres outside the Solar System, but these are gas giants that are easier to spot in telescopes. When a large planet passes in front of its star's disk, the elements found in the telescope change slightly. This change is believed to represent the atmosphere of the planet.
The team decided to try out this method for a smaller planet, but one that is in orbit of a bright star, to make it easier to distinguish the atmosphere of the planet from the elements of the parent star. A strong candidate for this work is the wide-angle camera 3 (WFC3) of the Hubble Space Telescope, which was installed by astronauts in 2009 and is usually used to track stars or the formation of galaxies.
“The WFC3 camera on the Hubble is a very sensitive device, not originally intended for observing bright stars, and the device will be a bit perederzhivat like the camera of your cell phone, directed towards the Sun,” said Waldman. “In 2012, a scan mode was introduced to solve this problem. In essence, we now quickly move the Hubble along the star spots and“ smear ”the spectrum across the detector. This solves the overexposure problem, but makes data analysis very complicated.
An additional problem is the distance of 55 Cancer close to the star e. It revolves around a star of the Sun type, which is only 40 light years away from Earth. Since the star is so bright, Waldman said, the scan speed should be much faster than the one used previously. The team examined the situation and developed a method that can extract a viable signal from the data, a signal that was strong enough to detect elements in the atmosphere of a small planet. “If we were able to do this with Hubble, we are very confident that we can significantly improve measurements with future instruments,” said Waldman, pointing to the future Web Telescope of James Webb (JWST), Transiting Exoplanet Survey Satellite (TESS) and PLAnetary Transits and Oscillations stars (PLATO) telescopes as examples. "These next-generation tools will make the field of exoplanetary spectroscopy wide open and allow us to understand what we cannot even imagine today. In other words, we are really on the verge of transferring planetary science from our Solar System to the Galaxy."
Waldman says that researchers have two future directions of research: to look at the atmospheres of the super-Earth in a broader sense, as well as to make follow-up observations of Cancer 55. There seems to be hints of hydrogen cyanide in the atmosphere, but to confirm this you will need a telescope , such as JWST, which can be observed in the range of longer waves than the Hubble.
The study will be published in the Astrophysical Journal, and is now available in advance on the Arxiv publications website.
