First candidate for a planet in an external galaxy
In a surprise paper, a team of researchers from the US and China found the first evidence of a candidate planet in another galaxy.
The Whirlpool Galaxy – M51
The planetary candidate resides in the M51 Whirlpool Galaxy and is approximately 23 million light years away. M51 is relatively close to Ursa Major, also known as the "Big Bear". The researchers observed what they thought was a planetary transit that lasted approximately three hours (see Figure 1 below).
Do external galaxies heat planetary systems? Many lines of argument suggest that the answer must be "yes". However, in the foreseeable future, the question cannot be answered using the most successful methods in our own galaxy. We report a different approach that focuses on bright x-ray sources (XRS). M51-ULS-1b is the first planetary candidate found for creating a full, short-lived solar eclipse of a bright XRS. M51-ULS-1b has a most likely radius that is slightly smaller than Saturn. It orbits one of the brightest XRS in the external galaxy M51, the Whirlpool galaxy, which is 8.6 megaparsecs from Earth. It is the first candidate for a planet in an external galaxy.
The paper: https://arxiv.org/pdf/2009.08987
If confirmed, it will be named M51-ULS-1b.
Further analysis of the system is required before the object can be confirmed as an actual planet revealed by a planetary transit. However, if it is confirmed as a planet, researchers believe it will likely be about the size of Saturn or slightly smaller.
September 28, 2020 in astronomy.