Comet makes a pit stop near Jupiter’s asteroids

After traveling several billion miles toward the sun, a comet-like young object moving among the major planets has found a temporary parking space along the way. The object has settled near a family of ancient asteroids, called Trojans, orbiting the sun next to Jupiter. This is the first time a comet-like object has been seen near a Trojan population.

The unexpected visitor belongs to a class of frozen bodies found in space between Jupiter and Neptune. Called “Centaurs,” they become active for the first time when heated as they approach the Sun, and move dynamically to become more like a comet.

Visually illuminated images by NASA’s Hubble Space Telescope show the volatile object showing signs of comet activity, such as a tail, hovering in the form of jets, and a coma full of dust and gas. Earlier observations by NASA’s Spitzer Space Telescope revealed a similarity to a comet and the gases that guided its activity.

“Only Hubble has found comet-like functional features so far away at such a high level, and the images clearly show these features, such as a broad tail that is about 400,000 miles long and high-resolution features near the nucleus caused by coma and jets, ”said Hubble lead researcher Bryce Bolin of Caltech in Pasadena, California.

Describing the capture of Centaur as a rare event, Bolin said, “The visitor had to have entered Jupiter’s orbit at just the right path in order to have this kind of arrangement that would seems to share its orbit with the planet. We study how he was captured by Jupiter and landed among the Trojans. But we think it could be related to the fact that it happened relatively close to Jupiter. “

The team’s paper will appear in the February 11, 2021 issue of The Astronomical Journal.

The research team’s computer simulations show that the frozen object, known as P / 2019 LD2 (LD2), appeared to be approaching Jupiter about two years ago. The planet then punished the wayion to the co-orbital space of a Trojan asteroid group, leading Jupiter around 437 million miles.

The moving object was discovered in early June 2019 by an Asteroid telescope at the University of Hawaii’s Last Alert System (ATLAS) located on the extinct volcanoes, one on Mauna Kea and one on Haleakala. Japanese amateur astronaut Seiichi Yoshida fell off the Hubble team into a potential comet operation. The astronauts then scanned archive data from the Zwicky Transient Facility, a wide-area study conducted at the Palomar Observatory in California, and realized that the object was clearly active in images from April 2019.

They followed up with comments from the Apache Point Observatory in New Mexico, which also disrupted the activity. The team saw the comet using Spitzer just days before the observatory retired in January 2020, and identified gas and dust around the comet’s nucleus. These comments prompted the team to use Hubble to take a closer look. With the help of Hubble’s sharp vision, the researchers identified the tail, coma structure and size of the dust grains and the ejection speed. These images helped them to confirm that the features are the result of a relatively new comet-like activity.

While the LD2 situation is surprising, Bolin questions whether this pit stop could be a common draw for some sunset comets. “This could be part of the path from our solar system through the Jupiter Trojans to the inner solar system,” he said.

The unexpected guest may not stay among the asteroids for a long time. Computer simulations indicate that he will have another close encounter with Jupiter in about two more years. The hefty planet will start the comet from the system, and continue its journey to the inner solar system.

“The interesting thing is that you actually catch Jupiter whipping this object around and changing its orbital behavior and introducing it into the internal system,” said team member Carey Lisse of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland. “Jupiter takes control of what goes with comets once they get into the internal system by changing the orbitan.”

The frozen interloper is apparently one of the newest members of the comet “bucket brigade” to kick out of his frigid home in the Kuiper belt and into the vast planet region through interaction with an object. another Kuiper belt. Located outside the orbit of Neptune, the Kuiper belt is a haven of frozen debris, left over from the construction of our planets 4.6 billion years ago, containing millions of objects, and from time to time these objects are close to missing or hitting which changes the orbit significantly from the Kuiper belt into. into the vast planet region.

The frozen brigade’s bucket brigade suffers a bumpy ride as they set in the sunset. They secretly kick from one outer planet to the next in a celestial ball-pin game before reaching the inner solar system, warming up as they get closer to the Sun. The researchers say the objects spend as much or even more time around the major planets, drawing heavily – about 5 million years ago – as they do into the planet. internal system where we live.

“An internal system, ‘short-term’ comets break about once a century,” Lisse explained. “So, in order to maintain the number of local comets we see today, we are of the the idea that the brigade must deliver a new short – lived comet bucket about once every 100 years. “

Seeing prohibited activity on a comet 465 million miles away from the Sun (where the intensity of sunlight is 1 / 25th as strong as Earth) surprised the researchers. “We were delighted to see that the comet had just begun to become active for the first time so far away from the Sun at speeds where water ice is only beginning to move away,” said Bolin. .

Water remains frozen on a comet until it reaches about 200 million miles from the Sun, where heat from sunlight converts ice water into gas that escapes from the nucleus in the form of jets. The activity therefore indicates that the tail may not be waterlogged. In fact, comments from Spitzer showed the presence of carbon monoxide and carbon dioxide gas, which may have led to the formation of the tail and the jets seen on the comet orbiting Jupiter. These filters do not require much sunlight to heat their frozen form and convert them to gas.

As soon as the comet is kicked out of Jupiter’s orbit and continues its journey, it may encounter the big planet again. “Short-lived comets like LD2 meet the adventure by being thrown into the Sun and completely dislodged, hitting a planet, or getting too close to Jupiter again and getting a out of the solar system, which is the norm, “Lisse said.” Symbols show that, in about 500,000 years, there is a 90% probability that this object will be out of the solar system and into an interspecific comet. “

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The Hubble Space Telescope is a project of international collaboration between NASA and ESA (European Space Agency). The telescope will be controlled by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science activity. STScI is run for NASA by the Association of Universities for Research in Astronomy, in Washington, NASA’s DC Jet Dedication Laboratory, a division of Caltech in Pasadena, California, managed the Spitzer mission for the Science Mission Steering Group NASA in Washington, DC Science activity carried out. at IPAC ‘s Spitzer Science Center at Caltech. The Spitzer complete science catalog is available through the Spitzer data archive, which is housed at the IPAC Infrared Science Archive. The spaceship operation was based at Lockheed Martin Space in Littleton, Colorado.

Credits: NASA, ESA, and B. Bolin (Caltech)

Claire Andreoli

NASA Goddard Space Flight Center

301-286-1940

[email protected]

Donna Weaver / Ray Villard

Institute of Space Telescope Science, Baltimore, Maryland

410-338-4493 / 410-338-4514

[email protected]/[email protected]

Calla Cofield

Jet Dedication Laboratory, Pasadena, California

626-808-2469

[email protected]

Bryce Bolin

Caltech, Pasadena, California

[email protected]