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O Brazil has two more good reasons to look at the sky: two new meteor showers were discovered by Brazilian astronomers, and these rains are associated with asteroids also discovered by Brazilians.

Since its founding in 2014, the BRAMON, Brazilian Meteor Observation Network, has already recorded hundreds of thousands of meteors across Brazil. It is a collaborative network formed basically by amateur astronomers working on a voluntary basis to monitor our skies.

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In 2017, BRAMON announced the first meteor showers discovered by Brazilians, and since then, it has conquered an increasingly relevant level in meteor science in the world. In an article published in May edition of MeteorNews magazine, the network made its most recent discoveries official: two new meteor showers that may be associated with two asteroids near the Land discovered by the Brazilian observatory SONE.

Magazine cover and home page of the article written by BRAMON. Credits: Reproduction / MeteorNews
Magazine cover and home page of the article written by BRAMON. Credits: Reproduction / MeteorNews

The technical definition of a meteor shower is not yet a scientific consensus, but it is assumed that it is formed by meteoroids (small fragments of space rock around the Salt) that have a common origin and a similar orbit. Thus, the search for new meteor showers basically consists of searching for a certain amount of meteors with similar orbits. The association with a parental body (comet or asteroid from which the fragments that form the meteor shower originated) is desirable, but it is rarely possible at first, mainly because the majority of the rains are formed by long-term comets, which take plenty of time to visit the inner solar system.

However, the research carried out by Lauriston Trindade, Alfredo Dal'Ava and Cristóvão Jacques, followed a different path. They used software to scan the BRAMON database, looking for meteors recorded over the network with orbits similar to the 32 asteroids close to Earth discovered by SONEAR. Thus, if a meteor shower was found, it would already be associated with a possible parental body.

As a result, 20 meteors were found with orbits similar to asteroid 2017 NT5, and 16 with orbits similar to 2019 OK, an asteroid about 100 meters long that generated a great uproar in the scientific community when it was discovered in July 2019, passing dangerously close to Earth.

Same meteor recorded at ADJ1 stations in Sumaré, SP and SMZ6 in São Paulo, SP. This meteor was one of 16 identified in the survey as associated with asteroid 2019 OK. Credits: Alfredo Dal'Ava / Sérgio Mazzi / BRAMON
Same meteor recorded at ADJ1 stations in Sumaré, SP and SMZ6 in São Paulo, SP. This meteor was one of 16 identified in the survey as associated with asteroid 2019 OK. Credits: Alfredo Dal'Ava / Sérgio Mazzi / BRAMON

The association between meteor showers and asteroids is not very common. Most of them are formed by particles left by comets in previous passages through the internal solar system. But there are also a few cases of association with asteroids, such as Quadrantids, associated with asteroid 2003 EH1 and Gemínidas, associated with asteroid 3200 Phaeton.

Some known processes can cause an asteroid to release particles in order to form the dust trail that can generate a meteor shower. An impact, for example, can send an immense amount of particles into space, and can also accelerate the rotation of the body, causing the dust on its surface to be ejected by the centrifugal force.

The thermal stress generated by changes in temperature, the sublimation of ice inside it and the gravitational disturbances caused by the approach of other bodies, can also fragment the asteroid. In addition, it may actually be an extinct comet, which has already lost all its volatile material, as appears to be the case with the asteroid 3200 Phaeton, which generates Gemínidas.

Particles ejected from the asteroid Bennu. Credits: Osiris-Rex / NASA
Particles ejected from the asteroid Bennu. Credits: Osiris-Rex / NASA

To reinforce the association between the new rains and the asteroids, the research had to go back in time, studying the orbital evolution of the asteroids and meteoroids until 5 years ago, considering the gravitational influences of the great bodies of the Solar System. The research concluded that, even with the orbital changes that occurred in the past, the orbits remained identical to each other, indicating that the meteors of these rains were probably generated by particles ejected from the asteroids discovered by SONEAR.

The orbit (green line) and the position of the asteroid 2019 OK on approach in 2019 (top view) and the average orbit of the 17 Capricornids meteor shower on the blue line. Credits: BRAMON
The orbit (green line) and the position of the asteroid 2019 OK on approach in 2019 (top view) and the average orbit of the 17 Capricornids meteor shower on the blue line. Credits: BRAMON

The rain associated with the 2017 NT5 was named as omega Sagittariids and the one associated with 2019 OK is the 17 Capricornids. Both have maximum in July (23 and 19, respectively), but are less rains, with only a few meteors per hour. However, this association allows asteroids to be studied indirectly through their meteors. They also show the excellence that Brazilian amateur astronomy has achieved.

Both BRAMON and SONEAR carry out their activities on a voluntary basis, without any type of remuneration or foreign investment, driven only by the desire to contribute to science. And by the way, you've been doing it very well!

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