Monthly Archives May 2021

Concept art by 21 / Borisov. Image: NRAO / AUI / NSF / S. Dagnello

In the summer of 2019, amateur astronomer Gennadiy Borisov spotted a rogue comet that originated in a star system far beyond the Sun. The comet, named 2I / Borisov, was just the second interstellar intruder ever to be identified in our solar system, after sighting the bizarre ‘Oumuamua object in 2017.

While ‘Oumuamua sparked heated controversy over its strange nature and possible origins, 2I / Borisov fascinated scientists for the opposite reason: it looked roughly like local comets orbiting the Sun, suggesting that the visitor may come from a system very similar to our own.

Now, independent findings from two research teams have strengthened this link between our solar system and the mysterious birthplace of 2I / Borisov, while also revealing a surprising new twist on local and interstellar comets.

Piotr Guzi and Michał Drahus, two scientists from Jagiellonian University in Poland, announced the “unexpected discovery” of nickel vapor in the atmosphere of 2I / Borisov, according to a study published Wednesday in Nature. Although it is well known that heavy metals such as iron and nickel exist as solids inside comets, these elements had never been seen except in gaseous form when comets approach stars, causing extreme heating which triggers the sublimation of the metals into vapor.

This is why Guzi and Drahus were caught off guard by clear evidence of gaseous nickel in the coma or the atmosphere of 2I / Borisov, even though the interstellar comet was about twice as far from the Sun as Earth at the time of the team observations in January 2020 At this distance, the comet’s temperature was estimated to be around -93 ° C, well below the conditions of 425 ° C that normally produce gaseous nickel.

Yet the team’s observations, obtained by the sophisticated X-shooter spectrograph at the European Southern Observatory’s Very Large Telescope, showed evidence of nickel gas over several nights, “effectively removing[ing] the possibility of confusion with a background source or instrumental artefacts, ”according to the study.

“Atomic nickel was a truly unexpected discovery, as observation of the gaseous form of any metal was considered to be limited only to warm environments, such as comets grazing the sun passing a few solar rays from the surface of the Sun. “Guzi said in an email.

“The two brightest nickel lines were clearly visible in our combined spectrum, but since we knew of no typical emissions at these wavelengths, we first made sure that they were present in the spectra taken each night. , and not in the background of the sky. and that they are not artefacts, ”he continued. “Yet it took us a long time to discover their true nature. “

To potentially explain the discovery, Guzi and Drahus propose that heavy metal vapor can be released at cold temperatures through a process known as photodissociation, in which photons (light particles) stimulate a nickel-containing molecule on the surface. to sublimate into gas.

The team’s findings would be quite intriguing in themselves, but they also coincide with the publication of a decades-long compositional study of comets in our solar system, led by University of Liège astronomer Jean Manfroid. . Using observations collected since 2002, the Manfroid team discovered that nickel and iron “are ubiquitous in cometary atmospheres, even far from the Sun”, according to a study also published on Wednesday in Nature.

“We learned of the other document while ours was already under review,” Guzi said. “The fact that the presence of nickel was detected both in the coma of the first known interstellar comet and in a collection of comets originating in our planetary system is simply astonishing.”

“This opens up a new perspective for understanding how the formation of planetary systems takes place in the galaxy since comets are seen as the remnants of this process,” he added.

The new research also strengthens the hypothesis that 2I / Borisov could have originated from a star system very similar to ours, as these studies identify yet another property that the interstellar visitor shares with our own local comets. If scientists find more interstellar comets that look like 2I / Borisov, it could hint at the existence of many solar system analogues across the Milky Way.

“We might expect the conditions at the place of their birth, as well as the chemical makeup of the interstellar cloud from which their original planetary system originated, to be similar to the interstellar cloud from which our solar system was born.” , Guzi said.

“It would be interesting to study the composition of other interstellar comets in the future to compare them with 2I / Borisov,” he continued. “Unfortunately, we don’t know when such an object will appear. The other fascinating question is what is the source of the metallic atoms in the gases surrounding the cometary nucleus.

Fortunately, these tantalizing questions could be answered in the years to come, as next-generation observatories will increase the speed at which interstellar visitors are spotted. In particular, the Vera C. Rubin observatory in Chile, which is due to enter service in the coming years, should speed up the detections of these mysterious intruders.

A larger census of interstellar objects will provide vital information about their distant home systems, highlighting how unique our own cosmic neighborhood is as part of the Milky Way.

“This is an important period in the history of planetary science, because we have the opportunity to study objects born in distant planetary systems and which have been ejected from their homes on their way to our cosmic neighborhood,” Guzi concluded.

Instruments aboard NASA’s Voyager 1 spacecraft, which nine years ago left the far reaches of our solar system, picked up the faint, monotonous sound of outer space

Scientists exploring the far reaches of our solar system have detected a strange “buzz”.

The instruments aboard NASA’s Voyager 1 spacecraft, which nine years ago left the far reaches of our solar system, picked up the low, monotonous sound.

Experts said this was due to the constant vibrations of small amounts of gas found in the near vacuum of interstellar space.

It represents the background noise present in the vast expanse between star systems, according to a study published this week in the journal Nature Astronomy.

These vibrations, called persistent plasma waves, have been identified at radio frequencies in a narrow bandwidth over a period of three years as Voyager 1 travels through interstellar space.

Stella Koch Ocker, PhD student in astronomy at Cornell University and lead author of the study, said: “The persistent plasma waves we have just discovered are far too weak to actually be heard with the human ear.

“If we could hear it, it would sound like a single stable note, playing constantly but changing very slightly over time.”

The Voyager 1 spacecraft, launched in September 1977, is currently located about 14.1 billion kilometers from Earth, about 152 times the distance between our planet and the sun, and continues to obtain and transmit data.

Having visited the enormous planets Jupiter and Saturn decades ago, Voyager 1 now provides a glimpse into interstellar space.

Voyager 1 has previously detected gas disturbances in interstellar space triggered by occasional flares from our sun.

The new study reveals stable vibrations unrelated to solar activity that could be a constant feature in interstellar space.

This hum has a frequency of about 3 kilohertz (kHz).

“When the oscillations of the plasma are converted into an audio signal, it looks like a varying tone. It’s a bit strange,” said James Cordes, professor of astronomy at Cornell University and co-author of the study.

“Voyager 1 will continue, but its power supply will most likely run out this decade after up to 50 years of service.

“Conceptual designs are underway for future probes aimed at going beyond the Voyager spacecraft.

“This is the message that I find appealing: our reach extends into interstellar space.”

Outside of our solar system, sound comes from the plasma existing in the interstellar interstellar medium. (Symbolic photo: ESO Twitter)

There is no wind in the interstellar region outside of our solar system, but beyond that there is something very interesting for our scientists. Our astronomers are very interested in the gases found in interstellar space, the interstellar medium, the ISM. Recently, NASA’s Voyager-1 vehicle heard the sound of this interstellar medium. Very light noise The Voyager-1 spacecraft has landed in space outside of our solar system. You can always send signals from there. According to this study published in Nature Astronomy, the sound is much lighter, coming from the plasma waves of the interstellar medium captured by the interstellar spacecraft. Stella Coach Ocker, a researcher at Shamley Cornell University, said in the study that the narrow frequency band produces very light and attractive sound. What is happening in this interstellar mediumIn this interstellar medium, ionized, molecular and molecular gases, as well as stellar dust, have a cosmic form. The cosmic form is a combination of high energy molecular centers and protons that move all over space. These radiations, among other substances present in the interstellar medium, are extremely harmful to humans. The role of the heliosphere Our sun protects the universe from radiation by forming a heliosphere outside the solar system. It is a bubble that surrounds the solar system, preventing cosmic rays from entering the solar system, which are made up of charged particles from the sun. But the sun cannot stop them completely.

These radiations do not reach the surface of the Earth Cosmic rays also enter the heliosphere. In such a case, the Earth’s magnetic field and atmosphere change the direction of this radiation or make it ineffective. Now Wiser-1 has reached the heliosphere of the Sun. Density in space outside the solar system is increasing, so learn how to get this information In 2012, the solar system was overtaken Voyager 1 now faces the interstellar through the heliosphere. NASA launched Wiser 1 in 1977, which overtook our solar system in 2012. Visor was sent outside the solar system to explore the outer planets of our solar system, if possible.

The sound starts as soon as the heliosphere comes out Voyager 1 has traveled 38 billion kilometers so far, roughly 150 times the distance between our Sun and Earth. It takes 12 hours for the light to reach the earth. Since 2017, plasma waves at a distance of about 23 billion kilometers have echoed continuously. This plasma is a diffusing gas which is found in a particular state between the stars. Find out how Saturn became a weird and shaped magnetic field It’s like a kind of light rain of particles. This is due to the very moderate activity that occurs in the interstellar medium. We do not know what this activity is. This heat is caused by the oscillation of the plasma or the sound of virtual heat caused by the action of electrons in the plasma. However, this finding may reveal plasma concentrations in the interstellar medium.