The planet Proxima Centauri, the Sun’s nearest neighbor, has been discovered to have one of the lowest mass planets ever discovered. Proxima d is only a quarter the mass of Earth, which makes it difficult for astronomers to find small rocky planets. Even though the promising signal discovered from that direction was an error, its finding suggests that there is a star system worth visiting if plans for interstellar travel may just be realized. Despite being only 4.2 light-years away, Proxima Centauri is such a faint star that it is invisible to the naked eye. Because of its location, which is too far south for most Northern Hemisphere telescopes, it has been overlooked as a system to research.
All of that has altered in recent years, with the disclosure in 2016 of a planet that was not only similar in mass to Earth, but also falls within Proxima’s habitable zone, at least potentially. Four years after the discovery of Proxima b, the possible discovery of the far more distant Proxima c was announced. Proxima d, an even smaller planet orbiting extraordinarily near to the star itself, has now been discovered, according to a paper published in Astronomy and Astrophysics.
The Proxima-Proxima d distance is barely a tenth of the distance between the Sun and Mercury, at 4 million kilometers (2.5 million miles), and orbiting takes only five days. Because of Proxima’s low brightness, this region isn’t the blazing hellscape it would be in our own Solar System, but temperatures on Proxima d’s surface are estimated to be around 90 degrees Celsius (190 degrees Fahrenheit). Nonetheless, the discovery has sparked interest because to the possibility of more discoveries surrounding this and other stars. In a statement, first author Dr Joo Faria of Portugal’s Instituto de Astrofsica e Ciências do Espaço said, “The discovery demonstrates that our closest stellar neighbor appears to be crammed with exciting new worlds, within reach of further study and future exploration.”
Proxima is known for being a sourpuss. This has sparked controversy over whether it has a habitable zone at all, or whether its outbursts would completely remove any atmosphere that a planet like Proxima b would have. It also caused the confirmation of Proxima d to be postponed. Observations using the European Southern Observatory’s Very Large Telescope confirmed Proxima b and hinted at the presence of an extra planet, but the data was masked by the star’s eruptive nature. Despite its low mass, which causes a wobble of only 39 cm/s, Faria and co-authors have gathered the additional observations that allow them to be convinced that Proxima d exists (1.4 kmph or 0.9 mph). The radial velocity (also known as the Doppler wobble) approach has been used to find the lightest planet yet discovered.
A scorching-hot globe only twice the mass of Mars that is likely devoid of an atmosphere isn’t very appealing. Dr. Pedro Figueira of the ESO, on the other hand, believes its significance lies in the fact that we were able to find it at all. “It demonstrates that the radial velocity method has the potential to reveal a population of light planets similar to our own,” Figueira added. Because of Proxima’s proximity, observatories like the JWST and the upcoming Extremely Large Telescope may be able to reveal information about its planets that will be unattainable for a long time for more distant stars.
Furthermore, if the proposal of laser-launching tiny cameras to a fifth of the speed of light proves feasible, we may be able to send a mission there during the lifetimes of individuals alive today, which is improbable for more fascinating, but further away, planets.