Gravitationally Lensed Supernovae are Another Way to Measure the Expansion of the Universe

Hubble Space Telescope image of a gravitational lens.
This Hubble Space Telescope image shows the powerful gravity of a galaxy embedded in a massive cluster of galaxies producing multiple images of a single distant supernova far behind it.

Supernova are a fascinating phenomenon and have taught us much about the evolution of stars. The upcoming Nancy Grace Roman telescope will be hunting the elusive combination of supernovae in a gravitational lens system. With its observing field 200 times that of Hubble it stands a much greater chance of success. If sufficient lensed supernovae are found then they could be used to determine the expansion rate of the Universe. 

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Giant Star Seen 150 Days Before it Exploded as a Supernova

Artist's impression of a supernova remnant. Credit: ESA/Hubble

Supernovae are relatively rare. It might not seem like it, but that’s because they’re so bright we can see them in other galaxies a great distance away. In fact, in 2022, astronomers spotted a supernova over 10 billion light-years away.

Any time astronomers spot a supernova, it’s an opportunity to learn more about these rare, cataclysmic explosions. It’s especially valuable if astronomers can get a good look at the progenitor star before it explodes.

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This Galaxy Hosted One of the Most Powerful Supernovae Ever Seen

This NASA Hubble Space Telescope image is of the small galaxy known as UGC 5189A. This otherwise unremarkable galaxy was the site of an extraordinarly luminous supernova in 2010. ESA/Hubble & NASA, A. Filippenko

In 2010, an exceptionally luminous supernova exploded in a small galaxy about 150 million light-years away called UGC 5189A. The Hubble Space Telescope has kept its eye on this galaxy because of the extraordinary supernova, which for three years released more than 2.5 billion times the energy of our Sun in visible light alone.

Though the supernova, named SN 2010jl, died down years ago, astronomers are still watching its aftermath.

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Black Holes and Neutron Stars are Finally Linked to Supernovae

A star in a binary system dies in a catastrophic explosion. Such supernovae often result in neutron stars or black holes. Courtesy ESO/L. Calçada
This artist’s impression is based on the aftermath of a supernova explosion as seen by two teams of astronomers with both ESO’s Very Large Telescope (VLT) and ESO’s New Technology Telescope (NTT). The supernova observed, SN 2022jli, occurred when a massive star died in a fiery explosion, leaving behind a compact object — a neutron star or a black hole. This dying star, however, had a companion which was able to survive this violent event. The periodic interactions between the compact object and its companion left periodic signals in the data, which revealed that the supernova explosion had indeed resulted in a compact object.

Everybody knows that the explosive deaths of supermassive stars (called supernovae) lead to the creation of black holes or neutron stars, right? At least, that’s the evolutionary path that astronomers suggest happens. And, these compact objects exist throughout the Universe. But, no one’s ever seen the actual birth process of a neutron star or black hole in action before.

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1,500 New Type 1A Supernova Found as Part of the Dark Energy Survey

An example of a supernova discovered by the Dark Energy Survey within the field covered by one of the individual detectors in the Dark Energy Camera. The supernova exploded in a spiral galaxy with redshift = 0.04528, which corresponds to a light-travel time of about 0.6 billion years. In comparison, the quasar at the right has a redshift of 3.979 and a light-travel time of 11.5 billion years. Image Credit: DES Collaboration/NOIRLab/NSF/AURA/M. Zamani

Supernova explosions are fascinating because they’re so cataclysmic, powerful, and awe-inspiring. They’re Nature’s summer blockbusters. Humans have recorded their existence in ancient astronomical records and stone carvings, and in our age, with telescopes.

Now, the Dark Energy Survey (DES) has uncovered the largest number of Type 1A supernovae ever found with a single telescope.

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JWST and Chandra Team Up for a Stunning View of Supernova Remnant Cassiopeia A

This image of Cassiopeia A comes from a combination of data from the Chandra X-ray telescope and the James Webb Space Telescope. Credit: X-ray: NASA/CXC/SAO; Optical: NASA/ESA/STScI; IR: NASA/ESA/CSA/STScI/Milisavljevic et al., NASA/JPL/CalTech; Image Processing: NASA/CXC/SAO/J. Schmidt and K. Arcand

NASA’s long-lived Chandra X-ray Observatory teamed up with JWST for the first time, producing this incredibly detailed image of the famous supernova remnant Cassiopeia A. JWST first looked at the remnant in April 2023, and noticed an unusual debris structure from the destroyed star, dubbed the “Green Monster.” The combined view has helped astronomers better understand what this unusual structure is, plus it uncovered new details about the explosion that created Cas A.

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Multiple Supernova Remnants Merging in a Distant Nebula

The nebula 30 Doradus B seen in x-ray, optical, and visible light. Credit: X-ray: NASA/CXC/Penn State Univ./L. Townsley et al.; Optical: NASA/STScI/HST; Infrared: NASA/JPL/CalTech/SST; Image Processing: NASA/CXC/SAO/J. Schmidt, N. Wolk, K. Arcand

The key to astronomy is careful observation. Unlike many sciences, astronomers can’t often do their work in a lab. Sure, they can build space telescopes and large ground observatories, but even with tools as simple as sticks and stones astronomers were able to change our understanding of the Universe with patience and observation. That tradition still holds true today, as a recent study in The Astronomical Journal shows.

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Webb Sees a Supernova Go Off in a Gravitationally Lensed Galaxy – for the Second Time

NASA’s James Webb Space Telescope has spotted a multiply-imaged supernova in a distant galaxy designated MRG-M0138. Image Credit: NASA, ESA, CSA, STScI, Justin Pierel (STScI) and Andrew Newman (Carnegie Institution for Science).

Nature, in its infinite inventiveness, provides natural astronomical lenses that allow us to see objects beyond the normal reach of our telescopes. They’re called gravitational lenses, and a few years ago, the Hubble Space Telescope took advantage of one of them to spot a supernova explosion in a distant galaxy.

Now, the JWST has taken advantage of the same lens and found another supernova in the same galaxy.

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JWST Delivers A Fantastic New Image Of Supernova Remnant Cassiopeia A

Like a shiny, round ornament ready to be placed in the perfect spot on a holiday tree, supernova remnant Cassiopeia A (Cas A) gleams in a new image from the NASA/CSA/ESA James Webb Space Telescope. Image Credit: NASA/CSA/ESA

Astronomy is all about light. Sensing the tiniest amounts of it, filtering it, splitting it into its component wavelengths, and making sense of it, especially from objects a great distance away. The James Webb Space Telescope is especially adept at this, as this new image of supernova remnant (SNR) Cassiopeia A exemplifies so well.

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Can a Dead Star Keep Exploding?

This is an artist’s representation of AT2022tsd, an explosion in a distant galaxy. The image shows one possible explanation for the strange object. It could be a black hole accreting matter from a disk and powering a jet. Variation in the jet's direction could produce the observed rapid flashes. Image Credit: Robert L. Hurt/Caltech/IPAC

In September 2022, an automated sky survey detected what seemed to be a supernova explosion about one billion light-years away. The Zwicky Transient Facility (ZTF) spotted it and gave it the name AT2022tsd. But something was different about this supernova. Supernovae explode and shine brightly for months, while AT2022tsd exploded brightly and then faded within days.

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