Astronomers Find Possible Super Earth In Our Solar System - Astrophysicists by means of data from the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered a distant object in the direction of Alpha Centauri. The object seems to be in the outer area of our solar system, and depending on its distance could be a hypothesized “super-Earth.”
ALMA is proficient of precise observations at short microwave wavelengths, usually produced by cold gas and dust. But objects on the edge of our solar system also produce light in this range, and would be too cool and distant to be observed by infrared telescopes. In 2014, ALMA discovered a faint object in the direction of Alpha Centauri A & B. The object was again observed in May of this year, this time more clearly. Given that the object is within a few arcseconds of the Alpha Centauri system, it would appear reasonable to believe that it could be part of that system, perhaps gravitationally bound as Alpha Centauri D.
The Centauri system is around 4 light years away, and at that distance (given the object’s brightness at submillimeter wavelengths) it would have to be a red dwarf star. But such a star would also be evidently visible in the infrared, so if this object is Alpha Centauri D we should have seen it long ago.
Since it doesn’t appear to be part of the Alpha Centauri system, it must be nearer and compatibly smaller. With just two observations it isn’t likely to conclude the object’s orbit, so we can only guess at its distance and size. One likelihood (and the one I think most likely) is that it’s an extreme trans-Neptunian object around 100 astronomical units away from the Sun, which is further than Sedna at 86 AU. This would make it the most distant known object in the solar system, but possibly smaller than Pluto.
Another prospect (which appears more likely to the object’s discoverers) is that it is around 300 AU away and approximately 1.5 times the size of Earth, making it the first “super-Earth” discovered in our solar system. Observations of trans-Neptunian objects have led to some assumption that one or two super-Earth’s could lurk in the outer solar system, so it’s not out of the question. There’s reason to be cautious of this idea, though, because of its location. Alpha Centauri is around 42 degrees away from the ecliptic. Most large solar system lay within a few degrees of the ecliptic, and even Sedna’s orbit is only inclined approximately 12 degrees from it. The chances of a super-Earth with such a highly inclined orbit appears very unlikely.
A third prospect is that the object is a cool brown dwarf around 20,000 AU away. Such an object should also be observable in the infrared, so there would still be the question as to why it wasn’t found by earlier infrared sky surveys. It’s nearness to Alpha Centauri would appear to make such an object easy to find.
The only way to know for sure is to collect more observations. Either by tracking its motion or by collecting observations at other wavelengths we can ultimately get a handle on its size and distance. Whether dwarf planet, super-Earth or small star, it appears clear that something is lurking on the outer edge of our solar system.
ALMA is proficient of precise observations at short microwave wavelengths, usually produced by cold gas and dust. But objects on the edge of our solar system also produce light in this range, and would be too cool and distant to be observed by infrared telescopes. In 2014, ALMA discovered a faint object in the direction of Alpha Centauri A & B. The object was again observed in May of this year, this time more clearly. Given that the object is within a few arcseconds of the Alpha Centauri system, it would appear reasonable to believe that it could be part of that system, perhaps gravitationally bound as Alpha Centauri D.
The Centauri system is around 4 light years away, and at that distance (given the object’s brightness at submillimeter wavelengths) it would have to be a red dwarf star. But such a star would also be evidently visible in the infrared, so if this object is Alpha Centauri D we should have seen it long ago.
Since it doesn’t appear to be part of the Alpha Centauri system, it must be nearer and compatibly smaller. With just two observations it isn’t likely to conclude the object’s orbit, so we can only guess at its distance and size. One likelihood (and the one I think most likely) is that it’s an extreme trans-Neptunian object around 100 astronomical units away from the Sun, which is further than Sedna at 86 AU. This would make it the most distant known object in the solar system, but possibly smaller than Pluto.
Another prospect (which appears more likely to the object’s discoverers) is that it is around 300 AU away and approximately 1.5 times the size of Earth, making it the first “super-Earth” discovered in our solar system. Observations of trans-Neptunian objects have led to some assumption that one or two super-Earth’s could lurk in the outer solar system, so it’s not out of the question. There’s reason to be cautious of this idea, though, because of its location. Alpha Centauri is around 42 degrees away from the ecliptic. Most large solar system lay within a few degrees of the ecliptic, and even Sedna’s orbit is only inclined approximately 12 degrees from it. The chances of a super-Earth with such a highly inclined orbit appears very unlikely.
A third prospect is that the object is a cool brown dwarf around 20,000 AU away. Such an object should also be observable in the infrared, so there would still be the question as to why it wasn’t found by earlier infrared sky surveys. It’s nearness to Alpha Centauri would appear to make such an object easy to find.
The only way to know for sure is to collect more observations. Either by tracking its motion or by collecting observations at other wavelengths we can ultimately get a handle on its size and distance. Whether dwarf planet, super-Earth or small star, it appears clear that something is lurking on the outer edge of our solar system.
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