Since the start of space exploration, scientists have been able to map out the solar system and estimate how enormous the entire Milky Way. Recently, the first candidate planet was identified in a galaxy nearly 23 million light-years away from Earth. The findings have been published in Cornell University's journal Astrophysics.
The alien planet, called M51-ULS-1b, belongs to the M51 Whirlpool Galaxy near the Ursa Major constellation. The team shared that the planet's radius is slightly smaller than Saturn.
"X-ray transits can now be used to discover more planets in external galaxies and also planets orbiting XRSs inside the Milky Way," the authors wrote. Methods on Earth cannot be used to detect cosmic bodies beyond our Galaxy, they noted.
The binary star system that the planet orbits "is young and massive," wrote the team. One of the components is a remnant of a star that could be a black hole or a neutron star. The second component is a massive star.
Discovering Exoplanets
Since the first exoplanet discovery in 1995, scientists have been using transit detection and radial-velocity measurements to detect the signature of planets outside the Solar system. The two methods have resulted in the discovery of over 4,300 exoplanets.
Using radial-velocity measurements relies on the movement of a star as it orbits a planet in response to a gravitational pull. From a distance, the star's actions create a light signature. Blue indicates shorter wavelengths, while red suggests longer wavelengths.
On the other hand, the transit method, also known as transit photometry, measures the light curve of stars as an exoplanet passes. This method also enables observers to estimate the size of the detected planet. A small planet slightly affects the brightness of a nearby star, while a more massive planet has a more significant impact on the star's light curve.
Since the stellar remnant in the binary is small, if the exoplanet passes Earth's line of sight, it would create a complete eclipse. The eclipse was observed in 2012, where the X-ray source dimmed for about three hours as the Chandra X-ray Observatory was recording data.
Read Also: New Study Finds at Least 45 Planets With Qualities Similar to Earth
X-Ray Imaging of Other Galaxies
The data was not noticed by scientists since Chandra's goal at the time was to "detect X-ray emission from very hot regions of the Universe such as exploded stars, clusters of galaxies, and matter around black holes," according to NASA. Chandra was able to capture vivid images of other galaxies, supernovas, nebulas, and many others.
The single transit of the extragalactic planet "will lead to more detailed studies of planets and other low-radius objects in external galaxies," the authors wrote. Discovering M51-ULS-1b also revealed that studying X-ray transits can reveal existing invisible systems such as low-mass stars and brown dwarfs.
In conclusion, they stated that the discovery of planets and other objects in external galaxies could establish connections with the Sun's environment in the Milky Way, provide insight into the mutual evolution of stellar and binary orbits, expand the realm within which we can search for extraterrestrial life. Extending the search will expand the scope of what we can say about our place in the universe."
Read Also: It's Raining Iron on a Distant Exoplanet
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