- The interstellar object 3I/ATLAS is identified by NASA as a comet with an unusual anti-tail.
- Harvard's Avi Loeb suggests the anti-tail may be a swarm of solid objects near 3I/ATLAS.
- Images show a tear-drop shaped coma extending toward the Sun by about an arcminute.
The interstellar object 3I/ATLAS, which NASA clearly described as a comet, still sparks intense debate among astronomers due to its unusual "anti-tail" pointing toward the Sun. Harvard astrophysicist Avi Loeb suggests this feature might not be a typical comet tail, but rather a swarm of solid objects accompanying 3I/ATLAS.
While writing a new Medium blog post, Loeb said that the post-perihelion images of the interstellar object showed a tear-drop shape of its coma with an extension by about an arcminute towards the Sun, with the JPL Horizons reporting a non-gravitational acceleration during the same period.
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He suggested that this unusual anti-tail could be comprised of a swarm of non-evaporating objects, unlike typical comet tails composed of gas and dust. Loeb proposes that these objects don't experience the same non-gravitational acceleration as 3I/ATLAS, causing them to appear closer to the Sun.
"If 3I/ATLAS is surrounded by a swarm of objects that do not share its non-gravitational acceleration, then these objects will tend to be closer to the Sun relative to 3I/ATLAS, because 3I/ATLAS is pushed away from the Sun relative to the objects through its non-gravitational acceleration," he wrote.
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"At the current separation of 3I/ATLAS from the Sun of 270 million kilometers, the displacement would imply that the objects are closer to the Sun than 3I/ATLAS by about 54,000 kilometers, corresponding to an angular separation of 0.7 arcminutes in the sky. This separation is comparable to the sunward elongation of the teardrop glow around 3I/ATLAS."
The objects could be rocky fragments, structures formed during interstellar travel, or something entirely different. NASA has confirmed 3I/ATLAS is a natural comet, but Loeb's theory highlights the object's unusual behaviour, leaving room for further investigation.
"If the anti-tail is indeed associated with a swarm of non-evaporating objects around 3I/ATLAS, the interesting question is what is the nature of these objects? Are they rocky fragments or something else?" Loeb asked.
