Space

First exoplanets spotted beyond the Milky Way

Thousands of exoplanets, like the Kepler-11 system (pictured), have been found within the Milky Way, but a new study has spotted the first extragalactic exoplanets some 3.8 billion light-years away
Thousands of exoplanets, like the Kepler-11 system (pictured), have been found within the Milky Way, but a new study has spotted the first extragalactic exoplanets some 3.8 billion light-years away
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Gravitational microlensing has helped astronomers discover exoplanets beyond the Milky Way
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Gravitational microlensing has helped astronomers discover exoplanets beyond the Milky Way
Thousands of exoplanets, like the Kepler-11 system (pictured), have been found within the Milky Way, but a new study has spotted the first extragalactic exoplanets some 3.8 billion light-years away
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Thousands of exoplanets, like the Kepler-11 system (pictured), have been found within the Milky Way, but a new study has spotted the first extragalactic exoplanets some 3.8 billion light-years away

As of January 2018, well over 3,500 planets have been confirmed from outside our Solar System, and that number is constantly growing. All of these have been spotted within our neighborhood of the Milky Way, but with numbers like that it was basically a given that planets were pretty common across the universe. Now astrophysicists from the University of Oklahoma (OU) have confirmed that assumption with the first detection of extragalactic exoplanets.

A couple of candidates for planets beyond the Milky Way have been detected before, but so far none have been confirmed. There's a suspicious-looking anomaly in our galactic neighbor Andromeda, but studies are ongoing. In 2010 a planet dubbed HIP 13044 b was "discovered" about 2,000 light-years from Earth, and while it was initially believed to have originated in another galaxy before being swallowed up by the Milky Way, a later study found no evidence that the planet existed at all.

Detecting exoplanets anywhere is no easy feat, thanks to the vast distances involved. Even within our home galaxy, the farthest planets found so far are SWEEPS-04 and SWEEPS-11, which are about 27,000 light-years from Earth – that's only about a quarter of the width of the Milky Way. Most exoplanets are found through the "transit method", where telescopes like Kepler watch for dips in the brightness of stars that indicate planets have passed between them and us. Unfortunately, our most advanced telescopes have a limit on how far they can see, so to peer deeper into the universe astronomers need to pull out some other tricks.

Gravitational microlensing has helped astronomers discover exoplanets beyond the Milky Way
Gravitational microlensing has helped astronomers discover exoplanets beyond the Milky Way

Gravitational lensing is one such technique. Massive objects like black holes and galaxies can curve the fabric of spacetime so much that light bends as it passes by, and astronomers use these objects as "lenses" to study extremely distant stars, galaxies and supernovae. Microlensing applies this phenomenon in reverse, using a bright background light source to study the characteristics of the "lens" object itself.

In this case, the light source was a distant quasar, and the OU team used it to spot exoplanets in the lensing galaxy. Objects can have distinct signatures in the way they bend light, allowing scientists to characterize their size and mass. Functionally, it works in a similar way to the transit method, except it can be applied at much greater distances – this galaxy, for example, lies over 3.8 billion light-years from Earth, making these exoplanets the most distant ever detected by a gigantic margin.

The researchers examined data gathered by NASA's Chandra X-ray Observatory, and after calculating the models on supercomputers, they were able to identify the signatures of around 2,000 objects, ranging in mass from that of the Moon to that of Jupiter.

"We are very excited about this discovery," says Xinyu Dai, lead researcher on the study. "This is the first time anyone has discovered planets outside our galaxy. These small planets are the best candidate for the signature we observed in this study using the microlensing technique. We analyzed the high frequency of the signature by modeling the data to determine the mass."

The research was published in Astrophysical Journal Letters.

Source: University of Oklahoma

4 comments
Bob
I still think the "transit method" is looking mostly at persistent sun spots on other stars much like the eleven year cycle on our own sun which often produces individual sunspots that endure for months. To claim they have found a gravitational lens that allows this in other galaxies and are using models to prove it seems to be quite a stretch. First, the gravitational lens would have to be of incredible quality and perfect focus. Second, models don't prove anything except the preconceived assumptions used to make the models. I don't doubt there are exoplanets but the scientific proof seems to be getting more nebulous all the time.
b@man
Agreed Bob... there is no space/time relationship at all. Time is ALWAYS "now" and speed only affects only what we perceive as matter, not time. Silly that people who do not know what time is appoint anomalies to it, to help explain their bogus theories. Consciousness creates the universe in real time. We stream consciousness and that streaming is what we perceive as the passing of time. Everything we consider "matter" is the same way. Take time out of Einstein's equations and you start to understand reality, or what we perceive as reality.
Sisko
Bob made some very good points. It seems that scientists are making more assumptions and then basing their conclusions on them, and calling the whole thing "established scientific fact".
Don Duncan
"Massive objects...can curve the fabric of spacetime..."? I read this and wonder if the users of such terms are trying to sound "scientific" or esoteric or both. What is spacetime? What makes up its "fabric"? Can you show me that fabric without reference to light? My point is: light curves. It can't travel in a straight line because no such thing exists, i.e., the distance between two points is NOT a straight line, but an infinite number of routes. Imagine you are at the North Pole and you are tracking magnetic waves. What is the shortest route a wave can take to the South Pole? There is an infinite # of paths around the globe. I think what they said was: "We found an extragalactic bright light source and looked at objects blocking the light, then using what we know about this phenomenon in our galaxy, we might have found planets."