SPACE/COSMOS
A cosmic chameleon escapes classification
The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences
image:
Blazar BL Lacertae is an active galaxy, emitting from its core a plasma jet that is directed towards Earth (artistic image).
view moreCredit: Source: NASA/JPL-Caltech
Blazars are active galaxies that emit narrow jets of ionised matter from their centres, aimed towards Earth. Depending on properties of the electromagnetic radiation emitted by the jets, astronomers divide such objects into different, clearly defined classes. However, with the BL Lacertae blazar, located in the background of the Lizard constellation, things turn out to be not quite so simple.
Once again, the distant cosmos has surprised researchers. Until now, it seemed that blazars – active galaxies emitting jets of matter towards us – could be divided into fairly distinct groups according to the electromagnetic radiation they generate. This hitherto clear situation has just become very complicated. In the prestigious astronomical journal Astronomy & Astrophysics, a Polish-German team of scientists from the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow and the University of Heidelberg (HU) report recent observations of a blazar which, for unknown reasons, escapes the current classification.
The object now known as BL Lacertae was discovered in 1929 in the background of the Lacerta (Lizard) constellation. Initially, astronomers regarded it as one of many variable stars in our galaxy. However, later observations led to a surprising discovery: what looked like a star in fact appeared to lie as far as 900 million light years away – so it certainly could not be a star.
Of the hundreds of billions of galaxies visible within the observable Universe, some are active galaxies. These are galaxies whose nuclei emit large amounts of electromagnetic radiation, presumably as a result of the complex processes that occur when matter falls into the central supermassive black hole. In some galaxies, narrow jets of ionised matter ejected from near the poles of the black hole over gigantic distances, in extreme cases even exceeding a million light-years, are a spectacular sign of activity. If the jet runs towards Earth, astronomers call the galaxy producing it a blazar. BL Lacertae turned out to be just such an object.
“Blazars are interesting for many reasons, not least because the orientation of the jets and the enormous velocities of their particles, close to the speed of light, lead to a variety of effects described by the theory of relativity. Emission from blazars is observed at various electromagnetic wavelengths, ranging from radio to very high-energy gamma rays,” explains Dr. Alicja Wierzcholska (IFJ PAN) and specifies: “We focused on the analyses of the energy of electromagnetic radiation emitted by one of the earliest discovered blazars: BL Lacertae. Why did we focus on this particular one? Because of its activity in recent years and some interesting features of the radiation emitted by it, which we had already noticed during earlier observation sessions.”
The reported observations took place in 2020-2023. They were carried out in orbit around the Earth with instruments from the American Neil Gehrels Swift Observatory satellite; only in the hard X-ray range were they complemented by data from the NuSTAR space telescope. In addition to the X-ray range which was of most interest to the Polish-German researchers, the optical and ultraviolet regions of the spectrum were also recorded. This is because the electromagnetic radiation produced by blazars extends from the radio range through the optical, ultraviolet and X-ray regions to gamma radiation of the highest energies.
Blazars are subdivided into flat spectrum radio quasars and BL Lacertae objects (BL Lacs), which are characterised by weaker emission lines and whose name is derived precisely from the BL Lacertae blazar. Within the BL Lacs, a further division is possible. Indeed, diagrams showing the entire energy spectrum of blazars resemble volcanic cones: they have two peaks separated by an arched depression. If the spectral ‘volcano’ is shifted towards the high-energy side, the BL Lacertae object is classified as HBL (High-frequency peaked BL Lac), if towards the low-energy side – as LBL (Low-frequency peaked BL Lac), while objects with an intermediate shift are referred to as IBLs (Intermediate BL Lacs).
“BL Lacertae objects lend themselves quite unambiguously to being assigned to a specific type. Blazar BL Lacertae has so far been considered a representative of the intermediate class, the IBL. It was therefore with no small degree of surprise that we noticed that in the X-ray range it looked like an HBL at some phases of the observation period, at others like an LBL, and at other times ‘politely’ gave the impression of an IBL-type object. As if this were not enough, these sorts of changes occurred very quickly. This is unusual behaviour, the physical basis of which we are not yet able to explain,” says Dr. Wierzcholska, and emphasises that there were more surprises: the recorded X-ray activity of the blazar turned out to be a record in the entire history of its observations.
It is currently assumed that separate physical phenomena involving different populations of particles in the jet are responsible for the existence of the two peaks in the spectra of blazars. Many astrophysicists agree with the assumption that the low-energy peak is related to electrons and the synchrotron radiation they emit. There is no consensus of opinion for the second peak. Perhaps it too is a consequence of the electrons’ behaviour, for example, their collisions with low-energy photons, which would result in an increase in the photons’ energy (this is known as inverse Compton scattering). However, other hypotheses have also been put forward, for example those involving hadrons (i.e. clusters of quarks such as protons or neutrons). But in order to explain the behaviour of the BL Lacertae blazar, it would be necessary to point to something more: not only the physical processes responsible for the formation of the two peaks, but above all the mechanism responsible for their rapid switching. One could venture to say that before this happens, many an astrophysicist-theorist will spend many a sleepless night.
The computational part of the research was carried out thanks to the Academic Computer Centre Cyfronet AGH. On the Polish side the work was funded by a grant from the National Agency for Academic Exchange.
The Henryk Niewodniczański Institute of Nuclear Physics (IFJ PAN) is currently one of the largest research institutes of the Polish Academy of Sciences. A wide range of research carried out at IFJ PAN covers basic and applied studies, from particle physics and astrophysics, through hadron physics, high-, medium-, and low-energy nuclear physics, condensed matter physics (including materials engineering), to various applications of nuclear physics in interdisciplinary research, covering medical physics, dosimetry, radiation and environmental biology, environmental protection, and other related disciplines. The average yearly publication output of IFJ PAN includes over 600 scientific papers in high-impact international journals. Each year the Institute hosts about 20 international and national scientific conferences. One of the most important establishments of the Institute is the Bronowice Cyclotron Centre (CCB), which is an infrastructure unique in Central Europe, serving as a clinical and research centre in the field of medical and nuclear physics. In addition, IFJ PAN runs four accredited research and measurement laboratories. IFJ PAN is a member of the Marian Smoluchowski Kraków Research Consortium: “Matter-Energy-Future”, which in 2012-2017 enjoyed the status of the Leading National Research Centre (KNOW) in physics. In 2017, the European Commission granted the Institute the HR Excellence in Research award. As a result of the categorization of the Ministry of Education and Science, the Institute has been classified into the A+ category (the highest scientific category in Poland) in the field of physical sciences.
CONTACTS:
Dr. Alicja Wierzcholska
Institute of Nuclear Physics, Polish Academy of Science
tel.: +48 12 6628274
email: alicja.wierzcholska@ifj.edu.pl
SCIENTIFIC PUBLICATIONS:
“Exceptional X-ray activity in BL Lacertae”
A. Wierzcholska, S. Wagner
Astronomy & Astrophysics 2025, 693, A299
DOI: 10.1051/0004-6361/202451349
LINKS:
The website of the Institute of Nuclear Physics, Polish Academy of Sciences.
Press releases of the Institute of Nuclear Physics, Polish Academy of Sciences.
IMAGES:
IFJ250312b_fot01s.jpg
HR: http://press.ifj.edu.pl/news/2025/03/12/IFJ250312b_fot01.jpg
Blazar BL Lacertae is an active galaxy, emitting from its core a plasma jet that is directed towards Earth (artistic image). (Source: NASA/JPL-Caltech)
Journal
Astronomy and Astrophysics
Article Title
Exceptional X-ray activity in BL Lacertae
NASA atmospheric wave-studying mission releases data from first 3,000 orbits
NASA/Goddard Space Flight Center
Following the 3,000th orbit of NASA’s AWE (Atmospheric Waves Experiment) aboard the International Space Station, researchers publicly released the mission’s first trove of scientific data, crucial to investigate how and why subtle changes in Earth’s atmosphere cause disturbances, as well as how these atmospheric disturbances impact technological systems on the ground and in space.
“We’ve released the first 3,000 orbits of data collected by the AWE instrument in space and transmitted back to Earth,” said Ludger Scherliess, principal investigator for the mission and physics professor at Utah State University. “This is a view of atmospheric gravity waves never captured before.”
Available online, the data release contains more than five million individual images of nighttime airglow and atmospheric gravity wave observations collected by the instrument’s four cameras, as well as derived temperature and airglow intensity swaths of the ambient air and the waves.
This image shows AWE data combined from two of the instrument’s passes over the United States. The red and orange wave-structures show increases in brightness (or radiance) in infrared light produced by airglow in Earth’s atmosphere.
NASA/AWE/Ludger Scherliess
“AWE is providing incredible images and data to further understand what we only first observed less than a decade ago,” said Esayas Shume, AWE program scientist at NASA Headquarters in Washington. “We are thrilled to share this influential data set with the larger scientific community and look forward to what will be discovered.”
Members of the AWE science team gather in the mission control room at Utah State University to view data collected by the mapping instrument mounted on the outside of the International Space Station.
SDL/Allison Bills
Atmospheric gravity waves occur naturally in Earth’s atmosphere and are formed by Earth’s weather and topography. Scientists have studied the enigmatic phenomena for years, but mainly from a few select sites on Earth’s surface.
“With data from AWE, we can now begin near-global measurements and studies of the waves and their energy and momentum on scales from tens to hundreds and even thousands of kilometers,” Scherliess said. “This opens a whole new chapter in this field of research.”
Data from AWE will also provide insight into how terrestrial and space weather interactions affect satellite communications, and navigation, and tracking.
“We’ve become very dependent on satellites for applications we use every day, including GPS navigation,” Scherliess said. “AWE is an attempt to bring science about atmospheric gravity waves into focus, and to use that information to better predict space weather that can disrupt satellite communications. We will work closely with our collaborators to better understand how these observed gravity waves impact space weather.”
AWE’s principal investigator, Ludger Scherliess, briefs collaborators of initial analysis of early AWE data. Information from the NASA-funded mission is helping scientists better understand how weather on Earth affects weather in space.
SDL/Allison Bills
The tuba-shaped AWE instrument, known as the Advanced Mesospheric Temperature Mapper or AMTM, consists of four identical telescopes. It is mounted to the exterior of the International Space Station, where it has a view of Earth.
As the space station orbits Earth, the AMTM’s telescopes capture 7,000-mile-long swaths of the planet’s surface, recording images of atmospheric gravity waves as they move from the lower atmosphere into space. The AMTM measures and records the brightness of light at specific wavelengths, which can be used to create air and wave temperature maps. These maps can reveal the energy of these waves and how they are moving through the atmosphere.
To analyze the data and make it publicly available, AWE researchers and students at USU developed new software to tackle challenges that had never been encountered before.
“Reflections from clouds and the ground can obscure some of the images, and we want to make sure the data provide clear, precise images of the power transported by the waves,” Scherliess said. “We also need to make sure the images coming from the four separate AWE telescopes on the mapper are aligned correctly. Further, we need to ensure stray light reflections coming off the solar panels of the space station, along with moonlight and city lights, are not masking the observations.”
As the scientists move forward with the mission, they’ll investigate how gravity wave activity changes with seasons around the globe. Scherliess looks forward to seeing how the global science community will use the AWE observations.
“Data collected through this mission provides unprecedented insight into the role of weather on the ground on space weather,” he said.
AWE is led by Utah State University in Logan, Utah, and it is managed by the Explorers Program Office at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Utah State University’s Space Dynamics Laboratory built the AWE instrument and provides the mission operations center.
By Mary-Ann Muffoletto
Utah State University, Logan, UT
NASA Media Contact: Sarah Frazier
TOI-1453 c: a key sub-Neptune in a system of two exoplanets
Discovery a super-Earth and a sub-Neptune 250 light years away from our solar system
University of Liège
image:
Artists view of TOI-1453
view moreCredit: Martin Farnir
Astronomers have discovered two exoplanets around TOI-1453, a star about 250 light years away. These two exoplanets, a super-Earth and a sub-Neptune, are common in the galaxy, yet are absent from our system. This discovery paves the way for future atmospheric studies to better understand these types of planets.
Astrophysicists have once again enriched our knowledge of the cosmos with a new discovery: two small planets orbiting TOI-1453. Located at around 250 light years from Earth in the Draco constellation, this star is part of a binary system (a pair of stars orbiting each other) and is slightly cooler and smaller than our Sun. Around this star are two planets, a super-Earth and a sub-Neptune. These are types of planets that are absent from our own solar system, but paradoxically constitute the most common classes of planet in the Milky Way. This discovery sheds light on a planetary configuration that could provide valuable clues to the formation and evolution of planets.
Using data from NASA's Transiting Exoplanet Survey Satellite (TESS) and the HARPS-N high-resolution spectrograph, the researchers were able to identify TOI-1453 b and TOI-1453 c, the two exoplanets orbiting TOI-1453. "The two planets present an interesting contrast in their characteristics," explains Manu Stalport, astrophysicist at the University of Liège and first author of the publication. TOI-1453 b is a super-Earth, slightly larger than our planet, and probably rocky. It completes its orbit in just 4.3 days, making it a very close planet to its star. In contrast, TOI-1453 c is a sub-Neptune, about 2.2 times the size of Earth but with an extraordinarily low mass of just 2.9 Earth masses. This makes it one of the least dense sub-Neptunes ever discovered, which raises questions about its composition."
Transit and radial velocity
Detecting exoplanets remains a complex task. The team relied on two key methods to confirm their discoveries. The transit method (TESS data) measures the size and orbital period as the planet passes in front of its host star, causing a slight decrease in brightness. The second method used is radial velocity measurement (HARPS-N data), which involves observing the variations in the velocity of a star under the effect of the gravity of a planet orbiting it. By studying the gravitational influence exerted by the planets on their host star, the researchers were able to measure their masses and densities.
"All these observations have revealed that TOI-1453 c is extremely light for its size, suggesting that it could have a thick hydrogen-rich atmosphere or a composition dominated by water. This makes it an ideal candidate for future atmospheric studies," enthuses Manu Stalport. Understanding their formation and evolution could provide clues about the development of planetary systems, including our own."
What's more, the two planets orbit in a configuration close to a 3:2 resonance, meaning that for every three orbits of the inner planet, the outer planet completes almost exactly two. Such resonances are considered a natural consequence of orbital migration, offering clues as to how the planets move and settle into their final orbits.
This discovery opens up new research prospects. Observational instruments such as the James Webb Space Telescope (JWST) could analyse TOI-1453 c's atmosphere to determine its main composition. If this planet has a substantial hydrogen-rich atmosphere or a water-dominated interior, it could redefine our understanding of sub-Neptunes and their formation.
Journal
Astronomy and Astrophysics
Article Title
TESS and HARPS-N unveil two planets transiting TOI-1453. A super-Earth and one of the lowest mass sub-Neptunes
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