Although we have heard a lot about the discovery of exoplanets with the potential to be habitable or Earth-like in recent years, the discovery of a perfect analog of our world has not yet occurred. But we’re getting closer and closer, as shown by a new study, mainly conducted by Brazilian researchers.
The work, whose first author is Yuri Netto from the IAG-USP (Institute for Astronomy, Geophysics and Atmospheric Sciences of the University of São Paulo), was accepted for publication in the Astronomical Journal. The aim was to test the accuracy of Espresso, a new spectrograph installed in the VLT, an ESO (Southern European Observatory) telescope in Chile. This instrument was designed to search for terrestrial analogues, that is, Earth-mass exoplanets in an Earth-like orbit orbiting a star such as the Sun.
To do this, one would have to achieve an accuracy of 10 cm / s with the method of radial velocity measurement (the famous detection of the tumbling of stars when planets orbit them and pull them back and forth). (Think about it: measure every second a movement of only four inches from a star light-years away.)
The predecessor spectrograph of the espresso, the Harps, installed in La Silla, also in Chile, has an accuracy of 1 m / s. In other words, the goal is to improve the measures available ten fold. And by then he’s almost there.
The group made 24 observations of the star HIP 11915, spread over 60 nights. The star, located 175 light years away in the constellation Whale, was selected because it is a solar twin that has a planet analogous to Jupiter, which was discovered in 2015 with the harps, also by Brazilians, and is now in a phase is of low activity.
After observations and post-processing (intended to “clean up” the noise that is mainly created by the star’s activity), the researchers obtained reliable measurements of the radial velocity averaging 24 cm / s. This established the minimum qualification for espresso – in the worst case an accuracy of around 20 cm / s. It might sound frustrating, but it’s a great result.
It is expected that the greater the number of observations made, the greater the accuracy achieved. And 60 nights, as in this first study, is a very limited period of time to search for exoplanets: after all, to confirm evidence, the planet must travel at least one full circle around the star, which in the case of an analogue Perfect Earth would 360 Need days.
With more observations and processing improvements, it’s entirely possible for espresso to hit the coveted sensitivity range of 10 cm / s. And the HIP 11915 star, researchers remind us, would be a great place to look further. Finally, to the best of our knowledge, the similarity to the solar system is remarkable. Perhaps we will find the first perfect analogue on earth there?
This column is published in Folha Corrida on Mondays.
Follow Sidereal Messenger on Facebook, Twitter, Instagram and YouTube