Researchers have identified for the first time the direct record of an infrared glow resulting from the head-on collision between two exoplanets classified as ice giants. The astronomical event occurred in the ASASSN-21qj star system, positioned at a distance of approximately 1,800 light years from the planet Terra. The central star of this system has physical characteristics very similar to those of Sol and an age estimated at around 300 million years, a period considered young on the cosmic time scale.
The visual manifestation of this planetary shock was divided into two distinct phases of observation by terrestrial and space telescopes. Inicialmente, starting in 2018, the star showed a significant and persistent increase in luminosity in the infrared range, indicating an extreme heat source. Cerca two and a half years after this first thermal detection, the system underwent a deep and complex optical eclipse, caused by the collision debris passing in front of the star.
The celestial bodies involved in this event had masses equivalent to several tens of times the Earth’s mass, structurally resembling planets such as Netuno and Urano. The direct impact between these two planetary masses generated a vast cloud of vaporized and superheated debris, permanently altering the orbital configuration of that region of space. The simultaneous detection of heat and light blocking provided the evidence needed to confirm the shock.
Dynamics of stellar shock and formation of vaporized matter
The kinetic energy released at the moment of the collision between the two ice giants was immediately converted into extreme heat, triggering the instantaneous vaporization of rocks, ice and gases that made up the internal structure of the exoplanets. Esse physical process resulted in the formation of an expanded rotational structure known in astrophysics as synestia, which resembles a thick ring or toroid shape. The superheated material contained in this formation reached temperatures of around 1,000 Kelvin, which explains the intense emission of infrared radiation captured by observation instruments over a continuous period of approximately a thousand days.
As time progressed, the cloud resulting from the impact began a process of gradual expansion along the original orbit of the destroyed planets. Slow cooling and continued dispersal of debris in the space vacuum progressively reduced the visibility of the initial thermal glow. The particulate matter, now composed of fine dust and rocky fragments of various sizes, established a new trajectory around the host star, creating a mobile physical barrier capable of interfering with the propagation of starlight towards the observation points on Terra.
Continuous monitoring and discovery of thermal anomaly
The star ASASSN-21qj was already under regular monitoring by automated programs dedicated to searching for astronomical transients and luminosity variations in the night sky. The appearance of the infrared glow occurred unexpectedly for researchers, standing out for its persistence and anomalous intensity compared to the star’s standard behavior.
Preliminary analysis of the thermal data quickly indicated that the heat emission was not coming from the star itself, but rather from a hot, large body newly formed in its orbit. The detection required combining data from multiple observatories to isolate the exact source of infrared radiation in the system.
The process of identifying the phenomenon also included the crossing of public information and the scrutiny of open data. Variações unusual features in the object’s photometric records caught the attention of experts and enthusiasts, accelerating the targeting of more powerful telescopes to that specific coordinate in space.
Characteristics of optical obscuration in the system
The optical eclipse that followed the infrared glow had an extended duration of approximately 500 days. Esse obscuration occurred when the expanding debris cloud transited exactly the line of sight between the star ASASSN-21qj and telescopes positioned at Terra and out into space.
Photometric records revealed that the depth of the eclipse was highly variable, not presenting a uniform light blocking pattern. Essa characteristic is consistent with the passage of a cloud of particulate matter of irregular density, rather than a solid, spherical planetary body.
Spectral analysis of light blocking demonstrated a strong dependence on the observed wavelength. Isso provided scientists with confirmation that the obstructing material was composed predominantly of dust dispersed in an elongated orbit, capable of filtering certain colors of starlight more than others.
Irregularities detected during the 500 days of transit indicated that the debris cloud underwent orbital shear. The difference in gravitational speed stretched the dust formation, transforming the initial structure into a long trail of fragments that will continue to orbit the central star.
Similarities with the formation of the primitive Sistema Solar
Collisions of gigantic proportions are predicted and documented events in young stellar systems that are still going through the accretion and orbital stabilization phase. Primitive No Sistema Solar, an event of very similar physical dynamics occurred when a celestial body the size of Marte collided with the proto-Earth, ejecting the material that later coalesced to give rise to
The case documented in the ASASSN-21qj system offers the scientific community a rare opportunity to directly observe dynamic processes that occurred billions of years ago in our own cosmic neighborhood. Estudos astrophysicists indicate that impacts of this magnitude are mainly responsible for shaping the final chemical compositions and internal structures of rocky planets and ice giants.
Orbital distance and zone of occurrence of the phenomenon
Calculations based on the temperature of the debris and the transit time determined that the collision event occurred at a distance between 2 and 16 astronomical units from the main star. One astronomical unit is equivalent to the average distance between Terra and Sol, which places the shock in an intermediate region of the planetary system.
For purposes of comparison with the architecture of our Sistema Solar, this distance range corresponds to the vast space region located between the orbits of planet Marte and planet Urano. The location suggests that the destroyed ice giants orbited in a zone where temperatures allow the condensation of volatile elements, justifying the composition rich in frozen water and heavy gases.
Tracking chemical signatures and orbit evolution
The star system remains under close monitoring using advanced high-resolution spectroscopy instruments, with the aim of mapping the ongoing evolution of the debris cloud. Obtaining additional data over the next few years is critical to refining mathematical models of post-collision evolution and understanding how matter reorganizes in a vacuum. The orbital duration suggested by the exact 2.5-year delay between the peak infrared brightness and the start of the optical eclipse allows astronomers to estimate longer orbital periods and predict future transits of the remnant cloud. Pesquisas ongoing efforts seek to identify specific spectroscopic signals of chemical composition in the scattered debris, which could reveal the exact proportion of volatile materials and silicates released during the destruction of planetary mantles. The main star has maintained its overall thermodynamic and gravitational stability, serving as a constant beacon that illuminates the dust around it. Prolonged observation of this scenario will provide answers about the possibility of the remaining debris condensing again to form new smaller celestial bodies, irregular moons or even a permanent ring system around the star, definitively altering the classification and structure of the ASASSN-21qj system.
Validation of theoretical astrophysics models
The precise combination of optical and infrared photometry confirmed the temporal sequence of the event and aligned perfectly with the orbital travel time predicted by the laws of gravitation. Current computational models were able to reproduce the observed luminosity using the estimated mass of the planets and the appropriate distance, consolidating observational evidence about the final and violent stages of the formation of planetary systems in the universe.
