From discovering the largest galaxy to limiting the mass of tiny neutrinos, February 2022 witnessed some great discoveries in different areas of Physics and Astronomy. Here is a list of the top 5 findings of February 2022 that will leave you amazed.
February 2022 Discoveries
The first isolated black hole in the Milky Way
In the first detection of a free-floating black hole in the Milky Way, astronomers believe in having discovered the first isolated stellar-mass black hole wandering roughly 5000 light-years away in the constellation Sagittarius.
There should be billions of black holes in our galaxy, as per theories. However, detecting a black hole is not a straightforward task. As a black hole bends the path of light passing by it, scientists use indirect methods to discover the black holes by using this property in a technique called gravitational microlensing. In this phenomenon, when an object gets sufficiently aligned with a massive compact foreground object, the foreground object acts as a lens and bends the light coming from the background object. The bending of light due to the massive body’s gravitational field leads to two distorted images, resulting in a noteworthy magnification.
So far, this technique has been employed to detect planets and stars. And this is the first time that a black hole has been detected in this way. The Hubble Space Telescope observed the region portraying this effect on eight locations. The lens was observed to emit no light and had a mass higher than that expected for a white dwarf or a neutron star. This eventually hinted at the presence of a black hole.
The newly discovered black hole has a mass almost 7.1 times that of the Sun, and its event horizon is just 42 km across. Moreover, the black hole is moving at 45km/s, making it a runaway black hole that was probably ejected into space when its precursor star exploded in a supernova. With the first successful discovery of a lonely black hole, scientists now expect to discover many such isolated black holes in the future.
KATRIN experiment
In a breakthrough in particle physics, Researchers in Germany have reported the upper limit on effective electron antineutrino mass, an antimatter counterpart of electron neutrino, to be less than 0.8eV.
The first electron antineutrinos were observed in 1956, and since then, physicists have been trying to measure the mass of these particles directly. However, due to the extremely small masses of neutrinos, the direct measurements become quite tricky. One of the direct methods to probe the neutrino mass scale in the laboratory can be achieved by kinematic studies of weak-interaction processes, including beta-decay of tritium, which is a rare and radioactive isotope of hydrogen. And KATRIN, an acronym for Karlsruhe Tritium Neutrino, is now the most precise experiment in this regime.
The team used the beta decay of tritium to determine the neutrino’s mass via the energy distribution of electrons released in the decay process. They used a giant spectrometer and measured the energy of decay electrons with unprecedented precision achieved so far. Since the claim has been made with a 90% confidence level, this can be a significant step in the absolute mass determination of neutrinos.
Related articles:
- An Introduction To The Standard Model Of Particle Physics
- All You Need To Know About Gravitational Lensing
- Supernovae And Their Types
Biggest galaxy disvoverd so far
Marking one of the largest discoveries of the month, astronomers have discovered the largest galaxy known to date. Lurking some 3 billion light-years away, Alcyoneus is a radio galaxy spanning 16.3 million light-years, and it was found with the help of the data collected by the Low-Frequency Array(LOFAR).
With around 20,000 radio antennas, LOFAR aims to map the Universe at radio frequencies from ~10–240 MHz with greater resolution and greater sensitivity than previous surveys. First, astronomers reprocessed the data and eliminated all the possible compact radio sources, which might have interfered with detecting diffuse radio lobes. Then, they manually surfed through the remaining candidates, and Alcyoneus was found, spewing forth from a galaxy a few billion light-years away.
After measuring the giant lobes, the researchers used the Sloan Digital Sky Survey to understand the host galaxy in detail. Alcyoneus is a normal elliptical galaxy embedded in a filament of the cosmic web, clocking in at around 240 billion times the mass of the Sun. Moreover, it is graced with a supermassive black hole at its center, having a mass almost 400 million times the Sun.
Since both these parameters lie at the low end for giant radio galaxies, this can provide some clues as to what drives the growth of the mammoth radio lobes. Moreover, Alcyoneus and its host are suspiciously ordinary. The total low-frequency luminosity density, stellar mass, and supermassive black hole mass are all lower than expected for this scale’s giant radio galaxies. This suggests that massive galaxies or central black holes are not prerequisites to growing large radio giants.
In addition, Alcyoneus is sitting in a region of space with a lower density than average. Probably, this could have enabled its expansion. And it is believed that Alcyoneus is growing even bigger, far away in the cosmic dark.
Proxima d: A new planet orbiting our nearest neighbor
Researchers have found a new planet in our closest stellar neighborhood, Proxima Centauri. The star is already known to host two planets: Proxima b and Proxima c. And now, astronomers working with the European Southern Observatory’s Very Large Telescope in Chile have found evidence of another planet orbiting it.
Named Proxima d, this planet orbits Proxima Centauri at a distance of about four million kilometers. This distance is less than a tenth of Mercury’s distance from the Sun and lies within the range of the star’s habitable zone. At this distance, this third planet takes just five days to complete one orbit around Proxima Centauri. Moreover, the planet has a mass of just a quarter of Earth’s. This makes Proxima d the lightest planet orbiting this star system.
Proxima b was found with the radial velocity method, which can determine the presence of a planet or system of planets in a stellar environment by observing the tiny wobbles in the motion of a star created by an orbiting planet’s gravitational pull. However, since Proxima d is extremely light, it caused Proxima Centauri to move back and forth at around 40 centimeters per second only. Due to this, the initial signal picked up by VLT was feeble.
Following this observation, the team used a new precise instrument, Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO), to take the follow-up observations. Eventually, the presence of the third planet was confirmed.
Dying Stars can also give birth to new planets
A new study has found that even dying stars can give birth to brand new planets, contrary to what was believed earlier. This is because planets are known to form in the protoplanetary disk surrounding a young star. And this study has revealed that even dying stars can have such a disk surrounding them where planets can eventually form.
In a binary system, the constituent stars are of the same age but have different masses. So when one of the stars dies and expels out material into space, the gravitational pull of the second star can cause the ejected material from the dying star to form a new rotating disk. This disk would resemble the protoplanetary disk that the star had when it was young, and eventually, this disk can give birth to the second generation of planets.
It is worth noting that disks driving the formation of planets can form only in specific cases. The star must be a post-asymptotic giant and lie in a binary system. As a post-AGB star exhausts its hydrogen supply, the core primarily consists of inert carbon and oxygen. But the star’s outer layers expand and cool, turning the star into a red giant. When the core’s temperature again rises, helium fusion takes place, and this process delays the star’s cooling and expansion for a while.
However, when the star runs out of helium too, the cooling and the expansion continue. The star experiences thermal pulses and helium flashes in between the cooling. It loses a lot of its mass throughout this cycle and sheds it into space. But due to the gravitational presence of a binary partner, the ejected material doesn’t go far and forms a disk around the center.
Researchers analyzed evolved binary stars with disks and noticed a large cavity in the surrounding disk. This hinted that something around had collected all matter in the cavity area, and indirectly, this pointed at the presence of a planet. Moreover, there was a scarcity of heavy elements on the surface of the dying star. This further hinted at the possibility of particles rich in such elements being trapped by a planet.
As per the estimates, this phenomenon can occur in 10 percent of the binaries. However, the post-AGB disks are only between 10,000 and 100,000 years old. So it’s unknown if this provided sufficient time for a giant planet to form or not. Another possibility also says that a planet leading to a cavity might not be a second-generation planet. Rather, it can be a first-generation planet that survived the binary interaction phase.
Although it’s not yet confirmed if the speculated objects are second-generation planets or not, the corresponding evidence and results are pretty intriguing. Researchers now aim to use ESO’s giant telescopes in Chile to study the systems in more detail.
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Editor at ‘The Secrets Of The Universe’, I have completed my Master’s in Physics from Punjab, India and I am currently pursuing my doctoral studies on Radio Emissions of Exoplanets in Barcelona, Spain. I love to write about a plethora of topics concerned with planetary sciences, observational astrophysics, quantum mechanics and atomic physics, along with the advancements taking place in the space industry.
