Detecting exoplanets based on relativity

Because of the often fainter appearance than mother stars, exoplanet planets are often found by indirect methods, ie through effects instead of direct observation. There have been many indirect methods proven to be effective and recently, a method based on Einstein's theory of relativity also showed high applicability when contributing to helping scientists discover Kepler planet. -76b.

Since being launched into orbit in March 2009, NASA's Kepler spacecraft has discovered more than 2700 exoplanets and 122 confirmed planets via transit methods. At this point, Kepler will look for a sign of a decline in the brightness of a host star as a planet passes by. Because the blur appears very fast and difficult to see, Kepler needs extremely high sensitivity. Using the sensitivity factor, a group of researchers from Tel Aviv University and the Harvard-Smithsonian Center for Astrophysics used a different method to detect the planet Kepler-76b.

First proposed in 2003 by Avi Loeb and Scott Gaudi, the new technique is based on the gravitational attraction that the planet impacts on the star it is orbiting. This attraction creates 3 observable effects. The team said:

The first effect , the bright star is as if it is being pulled closer to us because the photons from the star begin to overlap and the light is concentrated in the direction of the star's movement due to the relative effect. Conversely, when the star is pulled away, the light will fade.

The second effect , the team investigated the increase in luminosity that can occur when the extraterrestrial pulls the host star aside, causing the star to stretch like a rugby ball (pictured above). This increases the star's brightness because when stretched, the star has more visible surface areas. The third effect is less clear and requires observing the light from the star reflected by the orbiting planet.

The algorithm used to identify Kepler-76b was developed by Professor Tsevi Mazeh and graduate student Simchon Faigler at Tel Aviv University. He calls the algorithm BEER, short for "relativistic BEaming, Ellipsoidal, and Reflection / emission modulations".

Once discovered, Kepler-76b was confirmed again by two team members, David Latham at the celestial physics center (CfA) and Lev Tal-Or of Tel Aviv University. Latham will use the radial velocity observation data provided by the TRES spectrometer at the Whipple Observatory, Arizona, while Lev Tal-Or will exploit the same data from the SOPHIE spectrophotometer of the Haute- observatory. Provence, France. The method of radial velocity measurement is based on observing the fluctuations caused by the Doppler effect when the host star moves toward or away from the Earth in proportion to the gravity of the rotation around it. In addition, Kepler-76b is also confirmed by the exchange method when the planet flies across the host star.

The team calls Kepler-76b a "hot Jupiter" because it is 25% larger in diameter and nearly twice the mass of this giant gas planet. Kepler-76b is located about 2,000 light-years from Earth and is orbiting a class F star in the constellation Cynus with a cycle of 1.5 days. Because there is one face always facing the host star, the planet has a temperature of about 1982 degrees Celsius.

The team found that the hottest point of Kepler-76b is in fact not the closest to the star, but a location about 16,093km away. This was only observed once before and is a sign that the planet possesses super-fast jet currents that carry heat around it.

Like all methods of discovering extrasolar planets being used, the latest technology based on Einstein's theory of relativity also has its advantages and disadvantages. In terms of limitations, the above method cannot be used to detect Earth-sized planets. However, the method does not require high-precision spectral images such as radial velocity measurement and does not require the planet to fly across the star's illumination face when viewed from the Earth. as an exchange method.

The research team from Tel Aviv University has been published in detail in The Astrophysical Journal.