Last week, NASA announced an exciting discovery! Researchers found evidence of a new planet in a galaxy far, far away! To be more precise, observations from the Chandra X-ray Observatory show a potential exoplanet outside of our galaxy – which is big news.
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A brief science lesson:
While we reside on Earth, a planet, we also inhabit the Solar System inside the Milky Way Galaxy inside the Universe. NASA has an interactive map of the Milky Way Galaxy that begins at the Solar System to help visualize how big it is (it takes a lot of scrolling to zoom out). However, there is more to the Universe than just us. Think of the Universe like a big box with a collection of boxes within. Immediately inside the Universe box, there are galaxy boxes.
Inside those galaxies are stars systems like our Solar System. Some star systems have more than one star or have a black hole in the mix. In theory, there are planets in those systems, just as there are planets here in the Milky Way’s other systems. Inside the Milky Way, astronomers have confirmed 4,461 planets outside our Solar System. These planets are called exoplanets because they are outside of our own system. It takes time and the right equipment to find them, though!
A branching-hierarchy descriptive view of the relationship between the Universe, galaxies, star systems, and planets. | Chart by Talyna / Geek Girl Authority. Thumbnail images from NASA.
Chandra: Just one of NASA’s many tools
First proposed in 1976 and launched in 1999, NASA’s Chandra X-Ray Observatory is a massive yet sensitive X-ray telescope. The Chandra telescope orbits Earth once every 64 hours and is named for Nobel Prize winner and astrophysicist Subrahmanyan Chandrasekhar. Chandra collects X-rays before they are absorbed by Earth’s atmosphere. It does this by catching incoming X-rays and guiding them down a series of specialized mirrors to highly sensitive instruments. Data collected by these instruments is relayed back to Earth for study.
Through the use of gyros, thrusters and positioning sensors, the Chandra X-Ray Observatory can be moved and pointed quite precisely. This allows researchers to target specific regions of space for observation. Recently, that target was just off the Ursa Major constellation, at the Messier 51 galaxy. Messier 51, M51 for short, is also known as the Whirlpool Galaxy.
Chandra in Space | Credit: NASA/CXC & J.Vaughan
Looking for what is missing
In closer star systems, the visible brightness of a star dims when an orbiting planet crosses between the star and Earth. This is how other exoplanets have been discovered and verified. Star systems outside of the Milky Way Galaxy, however, are extremely far away. Our instruments are not sophisticated enough to detect such changes. Some researchers decided we just might have the right instrument for the job, we just don’t realize it.
Rosanne Di Stefano and her colleagues decided to use the data-dip method of planet discovery in a new way. The Center for Astrophysics | Harvard & Smithsonian (CfA) used the Chandra X-Ray Observatory and its European Space Agency counterpart, XMM-Newton (another orbiting X-ray telescope), to study an array of locations. Instead of staying within the Milky Way Galaxy, the focus was on three other galaxies: M51, Messier 101 and Messier 104. Of the 238 star systems studied, 55 were inside M51. Both telescopes looked for interruptions in the systems’ X-ray emissions. The assumption: a planet would either partially block or completely obstruct X-rays emitted from a star the same way they would block visible light in closer systems.
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Tattooine, is that you?
The result: data indicates a new planet! To be more precise, the data suggests the discovery of the first extragalacitc exoplanet! Among all the data collected, only one potential exoplanet was identified. This does not mean there are no planets in the other star systems. There simply were none identified as transiting during the window of observation.
The recorded X-ray interruption comes from the M51-ULS-1 star system. This system is a binary – meaning there are two stars dancing through space. In the case of M51-ULS-1, the system has either a neutron star or a black hole alongside a second star that is about 20 times the size of the Sun. Being a neutron star or a black hole, the potential planet may have seen two suns in its sky before one went supernova and collapsed.
X-ray and Optical view of Messier 51 with a box around the M-51-ULS-1 star system alongside an illustration of the potentially newly discovered exoplanet | Image credit: X-ray: NASA/CXC/SAO/R. DiStefano, et al.; Optical: NASA/ESA/STScI/Grendler; Illustration: NASA/CXC/M.Weiss
The future of discovery
There is still a lot more study required to officially announce the discovery of a new exoplanet. Focused observation of the M51 galaxy, specifically the M51-ULS-1 star system where this X-ray dip occurred, is needed to find a discernable pattern. However, this could take decades because of how far away the system is and how often it orbits its binary stars. For comparison, all of the planets confirmed so far have been inside the Milky Way Galaxy and almost all are less than 3,000 light-years away. This potential new exoplanet is about 28 million light-years away!
Following the standard scientific process for planetary discovery, this announcement, made in Nature Astronomy, is intended as an alert to other researchers. The call to other scientists in this instance is two-fold, though. The first is to direct others to the same star system inside M51 to help identify the new planet. Secondly, it opens the possibility of re-examining portions of our own galaxy with the X-ray variation of the previously used technique for planetary discovery. There are locations within the Milky Way Galaxy that could benefit from X-ray review. Who knows how many more exoplanets could be discovered!
Feature image courtesy of NASA.
This article was originally published on 10/30/21.
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