Hubble telescope captures rare ‘light echo’ from supernova

The researcher of the Institute of Space Sciences (ICE-CSIC) and member of the IEEC Lluís Galbany participates in the article, published in the Astrophysical Journal Letters

The explosion of a star, known as a 'supernova', sends an intense burst of light in all directions. On rare occasions, though, rings of light or ‘light echoes’ spread out from the original supernova position, in the months and years that follow. This is what a recently published article in the Astrophysical Journal Letters claims. 

The study is based on observations with the Hubble Space Telescope (HST) made by an international team of astronomers including the researcher Lluís Galbany, astrophysicist of the Institute of Space Sciences (ICE-CSIC) and member of the Institute of Space Studies of Catalonia (IEEC). The team, which also includes researchers from the UCD School of Physics (Dublin), the University of Aarhus (Denmark), the Hofstra University in Hempstead (New York) and the European Southern Observatory (Garching), has merged the Hubble images in a short gif-video. The animation first shows the supernova explosion at the very centre, followed by light rings which appeared when light from the explosion hit various layers of dust in the vicinity.

"The data set is remarkable and enabled us to produce very impressive colored images and animations that exhibit the evolution of the light echoes over a five-year period. It is a rarely seen phenomenon previously only documented in a handful of other supernovae,” said the lead scientist Professor Maximillian Stritzinger of Aarhus University. 

The astrophysicist Dr Morgan Fraser of the UCD said: “While the James Webb Space Telescope has drawn much attention, its predecessor Hubble continues to provide incredible images of the universe. The HST has now been observing the sky for over three decades, so we can find things like this light echo that evolve slowly over many years.”

Also, Lluís Galbany comments: “The blast wave from this powerful supernova explosion is racing outwards at over 10,000 kilometres per second. Ahead of this blastwave is an intense flash of light emitted by the supernova, and this is what is causing the expanding rings we can see in the images.” And add: “Supernovae are of interest as these cosmic explosions produce many of the heavy elements such as carbon, oxygen and iron, which make up our galaxy, stars and our planet.”

The galaxy Centaurus A 

Caption: Colored images of the light echo associated with SN 2016adj. The dashed line highlights the position of the main light echo ring as it expands from the position of the supernova from 300 to 580 days post-explosion, along with a prevalent dust lane. The dust lane extends from east-northeast to west-southwest direction and clearly obscures both portions of the light echo and the background stars.
Credits: ICE-IEEC, UCD, Aarhus University, Hofstra University, European Southern Observatory.
 
The supernova in question, named SN 2016adj, was first seen in 2016 and belongs to the well-known peculiar galaxy Centaurus A, situated between 10 and 16 million lightyears from Earth. For five and a half years, the astronomers watched the area around the supernova after it slowly faded away. 

Centaurus A is full of dust lanes and when the sideways spreading light from the supernova hit these dusty areas over time, they lit up further and further away from the original supernova position, creating a series of expanding rings of emission called light echoes.

The variations in these rings during the years of observation enables researchers to probe the lay-out of the dust lanes in the galaxy near the explosion. The data suggests that the dust is distributed in columns with large holes in between, resembling a chunk of Swiss cheese.

Professor Stritzinger said: “Centaurus A is a huge elliptical galaxy. These are mostly quiet, dust-free and without younger stars prone to go off as supernovae, but Centaurus A is obviously different. It is a strong radioastronomical source and it contains prominent dust lanes with new stars forming within. This is a sign that it has ‘recently’ gobbled up another smaller spiral galaxy, and matters have not yet settled down, as it might in a couple of hundreds of millions of years. Observing the development of these light echoes will help us gain more insight into these violent galaxy collisions.”

Up to now, four distinct light echoes produced by four different sheets of dust have been observed. The team plans to follow up on the observations with the HST in the future, hoping that more light rings will emerge. 

Press release made in collaboration with the Communication Offices of the Institute of Space Sciences (ICE-CSIC), the UCD School of Physics, Aarhus University, Hofstra University in Hempstead and the European Southern Observatory (ESO).

GIF
Caption: Animation of colored images exhibiting the light echoes of SN 2016adj over a five-and-a-half-year period. The main light echo produced by SN 2016adj is visually apparent 75 days after explosion and is observed to expand radially over the next 5 years. Note some of the images contain a conspicuous saturation spike associated with a foreground star. At the top: number of days since the explosion.
Credits: ICE-IEEC, UCD, Aarhus University, Hofstra University, European Southern Observatory.

Links
– IEEC
– Hubble Space Telescope
– Institute of Space Sciences (ICE-CSIC)
– University of Aarhus
– Hofstra University 
– European Southern Observatory

More information
This research is presented in a paper entitled “Hubble Space Telescope Reveals Spectacular Light Echoes Associated with the Stripped-envelope Supernova 2016adj in the Iconic Dust Lane of Centaurus A”, by Maximilian D. Stritzinger et al.,appeared in the journal Astrophysical Journal Letters on 22 October 2022. DOI: 10.3847/2041-8213/ac93f8

The Institute of Space Studies of Catalonia (IEEC  — Institut d’Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centers, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC’s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors. 
 
IEEC is a private non-profit foundation, governed by a Board of Trustees composed of Generalitat de Catalunya and four other institutions that each have a research unit, which together constitute the core of IEEC R&D activity: the Universitat de Barcelona (UB) with the research unit ICCUB — Institute of Cosmos Sciences; the Universitat Autònoma de Barcelona (UAB) with the research unit CERES — Center of Space Studies and Research; the Universitat Politècnica de Catalunya · BarcelonaTech (UPC) with the research unit CTE — Research Group in Space Sciences and Technologies; the Spanish Research Council (CSIC) with the research unit ICE — Institute of Space Sciences. The IEEC is a CERCA (Centres de Recerca de Catalunya) center.

Contacts
IEEC Communication Office
Barcelona, Spain
E-mail: comunicacio@ieec.cat 

Lead Researcher at IEEC
Barcelona, Spain
Lluís Galbany
Institute of Space Studies of Catalonia (IEEC)
Institute of Space Sciences (ICE-CSIC)
E-mail: lgalbany@ieec.cat, lgalbany@ice.csic.es