days alien
always happens in the universe, such as the visit of comet , or a young star rising in the planetary system.
Or, 's hidden alien is heading towards other planets.
Of course, this alien is not an alien or spaceship in a science fiction movie.
It is just a small celestial body that is wandering aimlessly, Aomuamu. The name
sounds quite strange, right? In fact, this is its Hawaiian name "Oumuamua", which means " first come first served messenger ".
In October 2017, the astronomical team of Hawaii University found an unusual object in an observation because it was the first interstellar object to visit our solar system in .
Oumuamu, the first extra-solar body of the solar system,
, After completing the basic naming, NASA Near-Earth Observation Program has funded research on its long-term observations. The relevant plan is mainly to discover and track asteroids and comets near the Earth.
Although was originally divided into comet , in the early observations, people found that the performance of this celestial body was not simple.
It flew over the sun at a speed of 87.3 km/h and did not show what a comet should be.
Later observations found that this small celestial body was still accelerating slightly, which summarized it as a comet.
Aomumo's activity trajectory in the solar system
About the trajectory observations and conclusions aboutAomumo mainly come from Astronomical telescope in Hawaii, USA, and also Astronomical guards survey mission , as well as data from the Canadian-France-Hawaii telescope.
Oumuamu should have entered the solar system from a distance from the Milky Way
From the direct observation of the telescope, Oumuamu is small and not very bright, and it was not even found during the observation activities at first.
has too low magnitude and its brightness is limited to 13.5 and other . By October 2017, Aomumo had decayed to 23 and other .
In subsequent observations, the spectral analysis of of Haier Telescope showed that the spectrum of Aumuamu is mainly red, and is similar to the comet nucleus .
The recording of the William Herschel telescope shows that its signal-to-noise ratio has no characteristics. Various observation records show that the spectrum of Oumuamu is similar to that of D-type asteroids.
In addition, its motion trajectory is also very special. Aomumo does not have its own rotation axis, and its movement method may be carried out in the rolling state .
scientists believe that Aumuamu's unique way of movement may have originated from a collision in the celestial body system where it is located.
and the dissipation time scale of this movement is very long. It takes at least 31 billion years of consumption to terminate, so it has been in a rolling state.
After observing the light change curve in Aomumo , astronomers discovered that its light change curve has undergone huge changes.
can roughly infer what Oumamu looks like through the light change curve, but research observations show that it may be anything.
Oumuamu may be flat
Cosmic cigar or big pancake
Oumuamu's light change curve shows that its height is lengthened, may be like a cigar-shaped object , and compared with similar stretched objects in the solar system, Oumuamu's stretch length is even more exaggerated.
Oumuamu also shows the flat state of , which makes its appearance possible as a pancake or flat round sphere .
In short, such special morphological performance and large changes in the light change curve show that the movement state of Aomumo is very unstable.
The possibility of Aomumo's light change curve analysis
However, in a 2019 paper, researchers modeled it.
They found that the best model of Oumuamu is cigar-shaped, or 1:8 aspect ratio .
Oumuamu can show such a weird shape, and some scientists also said that this extreme shape may be due to evaporation.
The Oumuamu model built by digitalization
Theoretically speaking, it should not be like this before entering the solar system, at least it should be the appearance of 2:1.
One month after it reached its perihelion, it evaporated 92% of its mass due to the energy of the sun.
In addition to this, Oumuamu's light curve observations show that it may contain dense metal rocks .
Because of the long-term exposure to cosmic rays in interstellar space , these metal-containing rocks eventually turned into red .
Some people believe that there may be torin on the surface of Oumuamu, an organic compound produced by irradiation of under long-term exposure of the solar system, which can help scientists determine the age of the surface. The long-term exposure of
makes it slightly metallic red
The motion trajectory performance of Oumuamu is also a place that scientists are very puzzled. In the 80-day study, scientists found that its orbital criterion was 1.20, which means that its movement speed exceeds the sun's escape speed .
So, in this regard, Aomumo will only become a tourist in the solar system.
speculation that it is a comet is mainly from Aumuamu's non-gravity acceleration , which is consistent with the push of solar radiation pressure.
Oumuamu's own motion trajectory
During its closest position to the sun, the resulting velocity changes total about 17 meters per second . It is precisely because of this change that scientists point it initially at comets.
Comet Comet tail As an obvious feature, Oumuamu evaporates when approaching the sun, and the volatile matter inside the object will bring a comet-like effect.
However, this deflation process will cause spin changes due to Aomumo's own elongated shape , and eventually tear the object.
's own gas release may change its movement form
, but Aumuamu's spin stability shows that it is not affected by this situation , which makes scientists even more confused.
: To say where it comes from, astronomers believe that Aomumo's hometown should be in , the Vega galaxy , which may be part of one of the galaxies inside.
related research shows that Aumuamu's movement speed is close to the local stationary standard , which means that it has orbited the Milky Way many times, and may even originate from a completely different part of the Milky Way.
is the case now, scientists don’t know how long it has been parading in the universe.
However, the boldest guess of scientists about Aumuamu is light sail aircraft . Some scientists believe that the possible flat shape of Oumuamu and its state of being pushed away by the sun are like light sail .
and it rolls every 8 hours make people think about the movement rules inside, which is really similar to an aircraft.
Future Plan
However, the hypothesis of light sail aircraft proposed by American scientists was soon denied by Liu Shangfei, a professor of astronomy at Sun Yat-sen University.
In his opinion, if this thing is really a light sail vehicle, then its reflected light spot should be more than one, but there are multiple enemies with reflective spots, which is in line with the performance of light sail in the universe.
Real light sail aircraft
In addition From the magnitude of Aomumo , if it is a light sail aircraft , then its brightness should be very bright, but existing observations show that the surface of Aomumo is black and , which is difficult for people to discover.
For the present, all the possibility that Aomumo is a form factor detector is based on existing observations and it may be indecent to reason if you just think this conclusion is interesting.
But if you want to better explain Aumuamu's behavior and performance, scientists say that better scientific data from should be collected to illustrate this situation.
Currently, the UK's interstellar research initiative has launched the Lyra project . The project will launch a detector to Aumuamu for re-evaluation. It is expected to be completed within the next 5 to 25 years of .
Now the discussion on Aumuamu has become clearer, and scientists have placed more discussions in the study of celestial bodies.
According to past observations, nitrogen ice can explain why it does not have a deflation process .
nitrogen ice carrying equivalent mass to its own, can survive in interstellar medium for 500 million years and can reflect two-thirds of the sunlight.
If the situation is completely true, Oumuamu may be an exoplanet fragment , similar to dwarf planet , Pluto .
The future detector will conduct actual measurements on it
based on the theory of nitrogen ice, and some people have also proposed the possibility of hydrogen ice . Oumuamu may have a large amount of hydrogen ice, which, if true, suggests that it originated at the heart of the interstellar molecular cloud.
Because the heat of the sun will cause hydrogen to sublimate , thereby promoting Aomumo's movement.
However, is affected by the earth's atmosphere , which is difficult to directly observe. However, in later proof, Aomumo's hydrogen ice cannot be composed of small particles.
If you want to not evaporate in interstellar space, it must form near the solar system 40 million years ago.
Aumuamu's past data integration
Compared with the possible alien probe, more and more scientists believe it is just an ordinary celestial body.
But the truth will only be clear if you truly understand it. While it is not completely away from us, this mystery may continue and wait for the answer to appear.
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