Hubble Watches Asteroid Gault Coming Apart

Hubble Watches Asteroid Gault Coming Apart

Hubble Watches Asteroid Gault Coming Apart
Image Credits: NASA

The Hubble Space Telescope of NASA observes an asteroid, called Gault that is disintegrating rapidly by throwing off material into its surroundings.

Gault is located at a distance of 344 million kilometers from the Sun and was discovered, for the first time, in 1988. Since then, several observations have been made of this asteroid but the evidence gathered by Hubble is the first sign of disintegration. According to astronomers, there are approximately 800,000 asteroids in the asteroid belt between Mars and Jupiter. Despite that, it is an extremely rare event which generally occurs once a year.

The images captured by the Hubble Space Telescope revealed a couple of narrow, comet-like tails of dusty debris streaming from the 4-kilometer-wide Gault. Each of these tails refers to an episode during which the asteroid sheds its material, gently. The disintegration of Gault gives an ideal opportunity to astronomers to study the composition of space rocks without visiting the asteroid. Olivier Hainaut, an Astronomer from the European Southern Observatory who is also a member of the observing team, acknowledged the fact in the following words:

“We didn’t have to go to Gault. We just had to look at the image of the streamers, and we can see all of the dust grains well-sorted by size. All the large grains (about the size of sand particles) are close to the object and the smallest grains (about the size of flour grains) are the farthest away because they are being pushed fastest by pressure from sunlight.”

YORP Effect

The heating of an asteroid results in the emission of infrared radiation from its surface. In addition to heat, these radiations also carry angular momentum, which causes the asteroid to continually spin faster. Ultimately, the surface of the asteroid becomes unstable as the centrifugal force overcomes the gravitational force. As a result, dust and rubble are drifted into the surrounding space, following a series of landslides. This procedure is known as the YORP Effect and Gault is only the 2nd asteroid whose disintegration is linked with this phenomenon. The estimates of the researching team suggest that the spinning speed of Gault could have been increasing for more than 100 million years.

Disintegrating Gault

In order to determine the recent astronomical activity of Gault, several ground-based telescopes and space-based facilities were used and a collective effort of all of them enabled the astronomers to come up with this discovery. The first debris tail was observed by the Asteroid Terrestrial-Impact Last Alert System (ATLAS) of NASA on 5th Jan 2019. Similarly, the telescopes of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) also verified the existence of this tail.

The Isaac Newton Telescope and the Canada-France-Hawaii Telescope observed the second, shorter debris tail in the mid of the month to indicate that both the dust events occurred around 28th October 2018 and 30th December 2018, respectively. A lot of other observations from different parts of the world, including India and Spain, confirmed that Gault is certainly disintegrating. The fact that researchers didn’t found any signs of more widely distributed debris, the idea of an asteroid collision causing the outbursts was discarded.

The observations of the Canada-France-Hawaii Telescope exposed that the long tail is 4,800 kilometers wide while it stretches over an area of 800,000 kilometers. In contrast to that, the shorter stream is nearly 200,000 kilometers in length. Both the narrow streamers of Gault suggested that the dust was released in short bursts (ranging from a few hours to few days). They were strong enough to accumulate enough debris to make a dirtball of about 150 meters if compacted together. Having said that, scientists believe that these tails will start fading in coming months because the dust will get dispersed into the interplanetary space.

Future Prospects

In the past, the limited capabilities of telescopes and observatories made it extremely difficult to observe active asteroids. However, advancements like Pan-STARRS and ATLAS allow astronomers to discover all the misbehaving asteroids like Gault. Hainaut referred to that by saying,

“Asteroids such as Gault cannot escape detection anymore. That means that all these asteroids that start misbehaving get caught.”

All the recent scientific achievements urge the astronomers to find more similar dust events to enhance our understanding of active asteroids.

Leave a Reply

Your email address will not be published. Required fields are marked *