University Of São Paulo Shares Participation In Investigation With The James Webb Telescope On The Death Of A Star

A few thousand years ago, a dying star gave rise to the Southern Ring Nebula (NGC 3132) in the constellation of Vela. As it lay dying, it blew its outer layers into space. This spawned a cloud, which is now illuminated by the light from what’s left of the star itself.

The mystery behind the “crime scene” could be better investigated through some of the first images obtained by the James Webb Space Telescope (JWST), launched in December 2021. The satellite’s lenses targeted NGC 3132, whose images were analyzed recently by 69 researchers around the world. The photos from space, revealed in July 2022, allow us to infer what gave rise to the shape of the planetary nebula, the name given to this type of structure.

The international collaboration revealed the existence of hitherto unknown stars, culminating in the article that made the cover of the journal Nature Astronomy in December 2022 and was featured in newsletters from NASA (North American Space Agency) and the Space Telescope Science Institute , institution that manages the use of the telescope. The analysis had the significant participation of five Brazilian researchers, including a professor at the Institute of Astronomy, Geophysics and Atmospheric Sciences (IAG) at USP and other former researchers at the institute.

The work of the Brazilians on the article was led by Isabel Aleman, a graduate of USP’s Institute of Physics (IF), with a master’s and doctorate from the IAG. She, who is now a postdoctoral researcher at the Federal University of Itajubá (Unifei), was one of the organizers of the collaboration led by Orsola De Marco, a professor at Mcquarie University, in Australia.

Hektor Sthenos Alves Monteiro, who also holds a degree in Physics and a PhD in Astronomy from USP, has been researching this same nebula since his master’s degree at IAG. Today he is a professor and researcher at Unifei. Both, in addition to Professor Claudia, spoke with the Jornal da USP report .

Elementary, my dear James Webb
The images from the new telescope were essential for identifying the chemical elements and deducing the existence of stars not yet seen. “The work was based on ten images that the JWST obtained in several very different wavelengths and that show emissions of different atomic and molecular species of the gas that make up the nebula”, explains Isabel. The study reveals that, in addition to the two stars already known, the nebula may be composed of up to three other non-visible stars.

JWST captures infrared light, which passes through clouds of gas and dust. In this way, it is complementary to the Hubble telescope, being a kind of successor to the Spitzer telescope, launched in 2003 and retired in 2020, but with superior precision. In addition, the James Webb Telescope provides much greater detail about the distribution of energy at different wavelengths, breaking light down like a rainbow.


Several theories and techniques were used in the analysis of the images, a benefit of the diversity of researchers involved in the collaboration. For data analysis and modeling, specific computational codes were developed for the study. “In general, we astronomers have to develop the software we use to explain the science behind what we observe”, adds Isabel. “In this work, there’s everything from software that performs theoretical modeling to treatment of data coming from the telescope, because the images need to be manipulated to extract results”, clarifies Hektor.


Claudia Mendes de Oliveira, a professor at the IAG, provided the data she obtained in 2016 with the then doctoral student Bruno Quint and with Professor Philippe Amram, from the Marseille Observatory, at the Southern Astrophysical Research Telescope (Soar). To collect this information, the scientists used a new module called SAM-FP (Soar Adaptive Module Fabry-Perot), built with funding from the São Paulo Research Foundation (Fapesp). This instrument provides increased sharpness through adaptive optical correction. The data and images obtained made it possible to study, among other things, the movements and chemical abundance of planetary nebulae like NGC 3132.

Isabel contributed with the interpretation of the images that show the emission of molecular hydrogen gas, as well as computational models that helped to understand which atoms and molecules were responsible for the emission seen in each image. Hektor developed a three-dimensional model to explain the observed emission and determine the nebula’s chemical composition and true matter distribution. “For this model, the data in the visible spectral range obtained with Soar were essential”, points out Professor Claudia. Professor Denise Gonçalves, from the Federal University of Rio de Janeiro (UFRJ) also contributed to the work.

Only two stars that make up the star system at the center of the nebula are visible in the JWST images. The novelty, the existence of more stars, was revealed by the analysis and models made in the study. To reconstruct the events that led to the death of the star and which gave rise to the structure, astronomers investigated the traces left at the “crime scene”. The team reconstituted the facts of the past based on the already known behavior of other groups of stars and the shape of the gas and dust clouds in the system.

Before dying, the main star “danced” with the closest companion stars. It would have been at that moment that these stars launched pairs of opposing jets, whose trails can be observed on the edges of the ionized nebula. The unseen stars may be hidden behind the brightness of the central star or may have merged with it.

Isabel is didactic: “The gas in the nebula is not spherically symmetrical, it is not uniformly distributed. If it were just one star, one would imagine that everything would be ejected with spherical symmetry. The system has a bright ring that is irregular. The region of the most ionized central gas has symmetrically opposed nozzles, as if they were produced by jets. On the outside, there are structures in the form of arches and thorns”.

The actual proximity of the two observable stars was determined by the European Space Agency’s (ESA) Gaia space telescope, launched in 2013. The masses determined for these stars already indicated that the system’s stability depended on the existence of other unidentified stars.

The clues collected by the JWST were the presence of a dusty disk around the central star that generated the cloud of ionized gas. This indicates an interaction with some nearby star not yet observed. With the three-dimensional reconstruction of the gas cloud, it was possible to identify multiple jets of ionized gases. Furthermore, the way in which the jets appear can only be explained if there is a fourth star, also close to the central star. Even the possibility of a fifth star was pointed out, through the separation between the thin arcs of matter external to the main ring, which are actually spirals.

international operation
The project to investigate the images returned by James Webb began at the International Astronomical Union’s Commission on Planetary Nebulae (IAU) when the first images from the telescope were released. In all, 69 scientists from around the world joined the work. NGC 3132 was one of the first five objects officially imaged by JWST in July 2022.

Instead of competing for an interpretation of the images presented, astronomers from all over the world joined the project to analyze the data in a collaborative way, as Isabel says: “Everyone was so excited that the work went into the weekend and into the night. The discussions were extremely rich, with researchers contributing their different specialties”.

According to her, advances in astronomy help us understand our place in the Universe and how it works: “We understand atomic physics better by studying this type of system with such different physical conditions, for example. The densities in planetary nebulae can be much lower than what we can reproduce in laboratories on Earth.”

Hektor says he is working on a new article, to be published in 2023, bringing more details about the 3D structure and the physical and chemical properties of the system. He plans to present updated data from that study at the IAU’s Planetary Nebula Symposium in September. The findings will start from the model made with Soar data. Isabel works continuously with the JWST, participating in groups that study nebulae through observations from this telescope.