Journey to find Earth's twin brothers

Does the Earth have twins that exist somewhere in our galaxy? Astronomers are getting closer in the process of searching for Earth-sized planets with orbits like Earth. NASA's Kepler spacecraft has just been launched into space to search for such worlds. Once successful, the next question to guide the new generation of research will be: Can the planet live? Does it have an atmosphere like Earth? Finding answers to these questions is not easy.

Thanks to the large lens and convenient space in space, the James Webb space telescope (scheduled to be launched in 2013) will give astronomers the first opportunity to search for answers. words for these questions. In a new study, Lisa Kaltenegger (of the Harvard-Smithsonian Center for Astrophysics) and Wesley Traub (belonging to the Jet Laboratory) analyzed the ability of Earth-like planets to analyze the atmosphere. on JWST's hypothesis in the process of passing through the sun when part of the star's light will be filtered through the planet's atmosphere. They found that JWST can identify certain gases known as biomarkers, such as ozone or methane, only in the worlds closest to Earth.

Kaltenegger said: 'We will have to be very lucky to be able to decipher the Earth-like planets' atmosphere when passing through it even when we know for sure that it is similar to Earth. We will need to do it many times, perhaps a hundred times, even for stars that are close to us for 20 light years. Although the work is very difficult, it will still be an interesting attempt to find out the properties of a planet's atmosphere far away from us. '

In the event of moving across the sun, a distant planet outside the solar system passes in front of its star. When the planet passes through that star, the atmosphere in the atmosphere absorbs a small amount of the star's light, leaving special marks for each gas. By dividing the star's light into rainbow colors or spectra, astronomers can observe to find those traces. Kaltenegger and Traub have studied whether these traces can be discovered by JWST. Their research was approved for publication in The Astrophysical Journal.

The idea of ​​a fictional twin-born artist is revolving around a star like the Sun. The new study shows that it is difficult to determine the atmosphere of an Earth's atmosphere, including the application of a new generation of technologies such as the James Webb Space Telescope. If there really is a world like Earth that exists with us, then by observing astronomers can detect indicators for life such as methane or ozone. (Photo: David A. Aguilar (CfA))

Kaltenegger and Traub first discovered an Earth-like world around a Sun-like star. To search for signals in a process that moves across the sun, stars and planets must be very close to the Earth. The only star like the Sun is close enough to be Alpha Centauri A. However, no single twin planet that resembles Earth has been discovered, but the technology is only slowly reaching its ability to detect worlds. like the Earth. The study also included a list of planets orbiting red dwarf stars. These stars are called M-type stars, which are the most numerous in the Milky Way. They are much more popular than the G-type gold stars like the Sun. They are also colder, dimmer and smaller than the Sun.This makes it easier to find Earth-like planets during its traversal phase M star.

This technique has many challenges. If the Earth is just the size of a basketball, the atmosphere will be just as thin as a sheet of paper, so the resulting signal is also extremely small. Furthermore this method will work when the planet passes in front of its star, but each such phase lasts only a few hours.

An Earth-like world will have to orbit a red dwarf hot enough to hold water in liquid form. As a result, the planet will spin faster, each move across the sun will last only a few hours or only a few minutes. It will also have many times to move across the sun over a specified period of time. Astronomers can increase the opportunity to detect the atmosphere by adding signals from many different motions, which make red dwarfs a target because they often have transitions. action across the sun.

An Earth-like planet orbiting a star like the Sun will spend 10 hours moving across the sun once a year. 100 observations of this movement will take 10 years. Conversely, if there is a twin Earth orbiting a medium-sized red dwarf, there will be movement across the sun for 1 hour but every 10 days. A total of 100 observations of motion will take less than 3 years.

Kaltenegger said: 'Nearby red dwarfs are the best opportunities to detect biomarkers in the Earth-like atmosphere. Traub added: 'Essentially, light photons directly from the planet could prove a more effective way of analyzing the atmospheric characteristics of Earth-like worlds than analytical techniques. motion across the sun '.

Both NASA's Spitzer and Hubble space telescopes have studied the atmospheric composition of extrasolar planets containing extremely hot giant gas. The analysis of the 'fuzzy blue spot' will be the next step of research, which can be done by observing hundreds of movements across the sun of a planet or by blocking the light of stars that concentrate on studying. Directly save the planet's light.

The most suitable scenario is that Alpha Centauri A becomes the home of an Earth-like planet that has never been discovered. At that time astronomers will just need to observe the number of certain moves across the sun to decipher the planet's atmosphere while confirming the existence of the Earth's first twin brother.

The research was partially funded by NASA.

Refer:
L. Kaltenegger, WA Traub.Transits of Earth-Like Planets.The Astrophysical Journal, 2009;(in press)