A team led by Kevin Wagner of the University of Arizona has found a sign indicating that an exoplanet is orbiting Alpha Centauri A – part of our closest three-dimensional star system, along with Alpha Centauri B and Proxima Centauri.
A planet was already known to exist in the arable zone around Proxima Centauri, but that world, orbiting the dwarf star M, does not appear to be alive. Alpha Centauri A is a dwarf G similar to our own sun. The recently discovered signal comes from within the star’s arable zone, and means that a planet is present about five to seven times the size of Earth, orbiting Alpha Centauri at a speed around on one to two times the distance of the Earth from the Sun.
The discovery was announced by the NEAR (New Earths in the Alpha Centauri Region) program, which is managed by the Southern European Observatory (ESO) and managed in collaboration with Breakthrough Initiatives. NEAR uses variable optics on a large ground-based telescope to compensate for atmospheric biases, along with other methods to reduce noise in the data. It also requires a coronograph to block most of the host star’s light in infrared (thermal) waves. That way, it’s easier to detect any heat signal from an orbiting exoplanet. The program has recorded more than 100 hours monitoring the Centauri system since its launch in May 2019.
Wagner confirms that the new signal is not certain to come from an exoplanet. It could also be a large cloud of dust, requiring more observation. Even if confirmed, the most likely signal is coming from the gaseous planet Neptune rather than a large, rocky planet much larger than Earth.
However, if there is indeed Super-Earth in the Alpha Centauri cultivation zone, the virtues taste good. A planet of this type and size in a Mars-like orbit (about an hour and a half from outer Earth’s orbit) could be even more hospitable than life on Earth. Today Mars only lives in borders – too small, and with too little internal energy to sustain the magnetosphere and its original atmosphere. If Mars had been the size of Earth, or at best larger, it would have seemed to have kept up with the early oceans and the dense atmosphere, making it far more fit for life.
In their last paragraph, the authors suggest that we may not have to wait long for a response, as we are approaching the technical ability to image directly an arable zone above the Earth orbiting Alpha Centauri. All we need is a feature of two improvements in intention, or a quadruple improvement in finding small objects. I bet we’ll do that soon.
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