New images of Comet 3I/ATLAS reveal that the interstellar visitor glows green and hides its tail, but that doesn’t mean there’s anything wrong.
As the comet approaches the Sun, it forms an atmosphere, or coma. This cloud of gas and dust grows larger and brighter as the sun heats the comet’s ice and other material, sublimating it into gas that astronomers can observe. In this case, as with most comets that fly close to our star, the atmosphere is brightest when viewed through a green filter.
you may like
Zhang used the filter to detect diatomic carbon (C2) particles that glowed green. He pointed out that comets contain many large molecules containing carbon and hydrogen (hydrocarbons). Then, as the comet approaches the Sun, ultraviolet (UV) light breaks down these molecules.
“It’s the same reason why you get a sunburn if you stay in the sun for too long without sunscreen,” Chan told LiveScience. “Ultraviolet light destroys our DNA. [in our skin cells]They are similar types of molecules in the sense that they are larger and contain carbon. ”
When this happens in a comet, some of the molecular clumps become two carbon atoms stuck together, or diatomic carbon, and are easy for astronomers to detect.
Although the comet appears to be missing its dust tail in the image, it is still present. Chang noted that if you look closely at the image, you can see that the left side of the comet is slightly brighter than the right side. This slight asymmetrical glow occurs because the tail is essentially seen head-on, with the tail directly behind the comet and angled slightly to the left. In other words, the comet’s apparent lack of a tail is nothing to be excited about.
Comet 3I/ATLAS has become a celestial celebrity since its discovery in July. Much of the buzz stems from speculation that the comet could be an alien spacecraft, even though most astronomers are convinced that the interstellar visitor is a comet from an unknown star system in the Milky Way.
But describing 3I/ATLAS as just an ordinary comet would be doing this rare solar system invader an injustice. The comet is only the third interstellar visitor ever recorded and could be the oldest comet ever observed, with some studies suggesting it is about 3 billion years older than our solar system.
After briefly disappearing behind the Sun, comet 3I/ATLAS only recently became visible from Earth again, reaching its closest point to our star, known as perihelion, on October 29th. Because comets tend to be most active at perihelion, this post-perihelion phase opens an important window for astronomers who want to learn more about a comet’s gas and composition.
you may like
Preliminary studies suggest that long-term exposure to cosmic radiation has given comet 3I/ATLAS a thick irradiated crust that no longer resembles that of its host system. If this crust is confirmed, it could mean that scientists will have a harder time deciphering the origin of 3I/ATLAS. This is because 3I/ATLAS will eject irradiated material rather than the original material from its home system.
Zhang previously made the first optical observation of 3I/ATLAS from Earth after perihelion using the Lowell Discovery Telescope on Halloween (October 31). Similar to his first observation, the new sighting took place in the twilight of morning. From our vantage point, the comet is moving northward away from the northeastern horizon. At present, it is possible to observe the comet in the early morning when it rises above the horizon.
Zhang took multiple images of the comet using different filters. The image of diatomic carbon, which he first posted on his comet blog on Wednesday, roughly depicts what the comet would look like if humans could see it with the naked eye.
On October 28, Zhang and his colleagues posted research results on the preprint server arXiv suggesting that comet 3I/ATLAS brightened rapidly prior to perihelion, becoming noticeably bluer than the Sun. The green color in the new image does not mean that the comet changed color after perihelion; it may have changed color earlier.
Zhang noted that in astronomical terms, bluer or redder usually refers to longer (red) or shorter (blue) wavelengths of light, and this observation is consistent with the latter. Comets appear much brighter when viewed through a blue filter than through a red filter, but the blue filter is a mixture of green and blue and is actually less sensitive to pure blue.
“It’s the brightest of the bluest filters we have,” Zhang said.
The Lowell Discovery Telescope was probably one of the largest telescopes that could point close enough to the horizon to observe Comet 3I/ATLAS just after perihelion, Chang said. However, he noted that the comet is high enough above the horizon that it can be seen by many large telescopes, and even a small personal telescope with a 6-inch (15 centimeter) lens can detect it.
Expect more exciting discoveries about this comet to be announced in the coming months.
Source link
