🔭 astrophysics

JWST observations of SN 2024abup: First Detection of CO in a broad-lined Type Ic Supernova and Constraints on r-process Nucleosynthesis

This paper presents the first JWST near- to mid-infrared observations of the broad-lined Type Ic supernova SN 2024abup, revealing the earliest detection of carbon monoxide in a core-collapse supernova and suggesting a potential role for such events in early-universe dust production while finding no compelling evidence for r-process nucleosynthesis due to spectral blending.

Original authors: Manisha Shrestha, Lindsey A. Kwok, David J. Sand, Stan Bartmentloo, Collin Christy, Anders Jerkstrand, K. Azalee Bostroem, Jennifer E. Andrews, Kate D. Alexander, Yize Dong, Carl E. Fields, Emily Hoan

Published 2026-06-30

📖 5 min read🧠 Deep dive

CC BY 4.0

Original authors: Manisha Shrestha, Lindsey A. Kwok, David J. Sand, Stan Bartmentloo, Collin Christy, Anders Jerkstrand, K. Azalee Bostroem, Jennifer E. Andrews, Kate D. Alexander, Yize Dong, Carl E. Fields, Emily Hoang, Griffin Hosseinzadeh, Brian Hsu, Daryl Janzen, Saurabh W. Jha, Joel Johansson, Jeniveve Pearson, M. J. Lundquist, Darshana Mehta, Aidan Martas, Maryam Modjaz, Bernhard Müller, Conor L. Ransome, Aravind P. Ravi, Mathieu Renzo, Nicolás Meza Retamal, Bhagya Subrayan, Nathan Smith, Stefano Valenti, Sergiy Vasylyev, Giacomo Ricigliano, Peter J. Brown, Moira Andrews, Joseph Farah, D. Andrew Howell, Curtis McCully, Megan Newsome, Kathryn Wynn, Ryan Chornock, Natalie LeBaro, Raffaella Margutti, Melissa Shahbandeh, Chris Ashall, Peter Hoeflich

Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). ✨ This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer

The Big Picture: Catching a Cosmic Firework in 4K

Imagine a massive star, much bigger than our Sun, running out of fuel and collapsing in on itself. This triggers a spectacular explosion called a supernova. Specifically, this paper is about SN 2024abup, a very bright, fast-moving explosion that happened relatively close to us (about 23 million light-years away) in a galaxy called NGC 0681.

Scientists used the James Webb Space Telescope (JWST)—the most powerful space camera we have—to take a "4K Ultra HD" picture of this explosion in infrared light (heat radiation) about 41 days after its peak brightness. This is the first time we've ever looked at this specific type of supernova with such powerful infrared eyes.

The Two Big Questions

The scientists had two main mysteries they wanted to solve with this observation:

The "Heavy Metal" Mystery (r-process): When stars explode, they forge heavy elements like gold, platinum, and uranium. We know neutron star collisions make these, but we aren't sure if these specific supernovae do too. It's like asking: Is this factory also making gold, or just regular steel?
The "Dust" Mystery: The early universe was dusty, but we didn't know where all that dust came from because the stars that usually make dust (old, dying stars) take too long to live. These massive explosions are short-lived, so maybe they are the "dust factories" of the early universe.

What They Found

1. The "Gold" Hunt: Mostly Empty Handed

The team looked for the specific "fingerprint" of heavy elements (r-process elements) in the light coming from the explosion.

The Analogy: Imagine trying to find a specific needle in a haystack, but the haystack is made of other needles that look almost exactly the same.
The Result: They saw some blurry spots in the data that could be heavy elements. However, when they ran computer models using only common elements (like oxygen, carbon, and magnesium), those models explained the blurry spots just as well.
The Verdict: They couldn't prove that heavy elements like gold or platinum were made here. The "noise" from the common elements was too loud. They concluded that if heavy elements were made, they are hidden in the mix, and we need even better data to separate them.

2. The "Dust" Discovery: A New Ingredient Found

This is the most exciting part of the paper.

The Discovery: They found clear evidence of Carbon Monoxide (CO) gas.
The Analogy: Think of the explosion as a hot kitchen. To bake a cake (dust), you first need to cool the oven down. Carbon Monoxide acts like a giant fan, blowing heat away from the center of the explosion.
Why it matters: Finding CO this early (only 54 days after the explosion) is a record-breaking speed. It means the "oven" is cooling down fast, which is the perfect recipe for dust to start forming.
The Dust: They also saw a "glow" in the infrared that looked like warm dust. They estimate there is already a small amount of dust forming (about the mass of a small asteroid), made of materials like graphite and silicate. This is the first time anyone has found CO or signs of dust forming in this specific type of fast-moving supernova.

3. The "Engine" Check: No Jet Found

Some of these explosions are powered by a super-fast jet of energy shooting out like a laser beam (which creates Gamma-Ray Bursts).

The Test: The team used radio telescopes to listen for the "whoosh" of this jet.
The Result: Silence. They heard nothing.
The Verdict: This explosion didn't have a powerful jet, or if it did, it was pointing in a direction we couldn't see, or it was very weak. This tells us that not every one of these massive explosions creates a high-speed jet.

The "Recipe" of the Explosion

By analyzing the light, the scientists figured out what the star was made of before it blew up:

It was a massive star that had already lost its outer layers of hydrogen and helium (like an onion that's been peeled down to the core).
It exploded with incredible force, moving debris at speeds of 18,000 km/s (fast enough to circle the Earth in a second).
It produced a decent amount of "nickel" (which powers the light of the explosion) and a lot of oxygen and magnesium.

Summary

This paper is like a detailed autopsy of a cosmic explosion.

Did it make gold? Maybe, but we can't tell yet because the common elements are hiding the evidence.
Did it make dust? Yes! We found the "starter" (CO gas) and the "glow" of early dust. This suggests these explosions are likely major contributors to the dust that filled the early universe.
Did it shoot a jet? No, or at least not one we could detect.

The main takeaway is that while we still need to solve the mystery of whether these stars make heavy elements, we now know for sure that they are excellent at cooling down and starting to build the dust that makes up the building blocks of new stars and planets.

Technical Summary: JWST Observations of SN 2024abup

Problem and Motivation
Broad-lined Type Ic supernovae (SN Ic-bl) are energetic explosions of massive, stripped-envelope stars. They are hypothesized to be potential sites for rapid-neutron capture (r-process) nucleosynthesis, potentially contributing to the chemical enrichment of the early universe, and are also proposed as significant sources of cosmic dust. While binary neutron star mergers (e.g., GW170817/AT 2017gfo) are confirmed r-process sites, their merger rates may be insufficient to explain observed cosmic abundances, necessitating alternative channels like collapsars (SN Ic-bl). However, theoretical predictions regarding r-process production in collapsars are conflicting, and observational evidence in SN Ic-bl spectra has been inconclusive due to limited infrared (IR) data and the blending of spectral features. Furthermore, while carbon monoxide (CO) and dust have been detected in some core-collapse supernovae, they had not been previously identified in SN Ic-bl events. This paper addresses the need for high-quality, broad-wavelength spectroscopic data to constrain r-process production and investigate dust formation in this specific class of transients.

Methodology
The authors present multi-wavelength observations of the nearby SN Ic-bl SN 2024abup, located in NGC 0681 at a distance of 23.3 ± 1.6 Mpc. The dataset includes:

JWST Spectroscopy: Near- to mid-infrared (NIR+MIR) spectra (1–14 µm) obtained 41 days after the V-band maximum (54 days post-explosion) using NIRSpec (medium resolution, 1–5 µm) and MIRI/LRS (low resolution, 5–14 µm).
Optical Spectroscopy: Contemporaneous optical spectra from the Las Cumbres Observatory (FLOYDS spectrographs).
Radio Observations: Limits on off-axis jets derived from Very Large Array (VLA) observations at 84 and 211 days post-explosion.
Data Reduction: Custom extraction of the MIRI/LRS data was performed to mitigate contamination from the host galaxy's dust lane, which was not adequately handled by standard pipeline reductions.
Modeling: The observed spectrum was compared against a non-local thermodynamic equilibrium (NLTE) spectral synthesis model generated by the code SUMO. The model utilized a massive star progenitor (12 M $_\odot$ helium core) that underwent complete envelope stripping, containing no r-process elements. This allowed for a direct search for unmodeled features that could indicate r-process production.
Comparative Analysis: The spectrum was compared to other transients, including SN 1998bw (canonical SN Ic-bl), AT 2017gfo (kilonova), GRB 230307A (LGRB with kilonova-like emission), and SN 2023dbc (Type Ic/Ib).

Key Results

Spectral Identification and CO Detection:
- The JWST spectrum reveals broad, blended features dominated by C, O, Mg, and Fe.
- First Detection of CO in SN Ic-bl: A broad feature at ~4.6 µm is identified as the fundamental ro-vibrational mode of carbon monoxide (CO). This represents the earliest detection of molecules in a core-collapse supernova to date. The SUMO model suggests a CO mass of $\sim 1.9 \times 10^{-5} M_\odot$ .
- Dust Continuum: The spectrum exhibits a continuum excess at wavelengths $> 1.5$ µm compared to the model and SN 2023dbc. This is qualitatively fitted by heated dust (silicate and graphite) with masses of $\sim 0.05 M_\odot$ and $\sim 0.009 M_\odot$ at temperatures of 300 K and 700 K, respectively.
Constraints on r-Process Nucleosynthesis:
- The authors searched for specific r-process lines (e.g., [Rb III], [Pd III], [Br IV], [Se III], [Sn I]) predicted by recent models.
- While some broad features in the SN 2024abup spectrum align with predicted r-process wavelengths, the SUMO model (which contains no r-process elements) successfully reproduces most of these features using only light and intermediate-mass elements (C, O, Mg, Fe, etc.).
- The authors conclude that the observed features are more likely attributable to non-r-process elements, though blending with potential r-process ions cannot be definitively ruled out without higher-quality data or more complex models.
- Upper limits on ionic masses were calculated under LTE, optically thin assumptions, suggesting the data is sensitive enough to probe masses down to $\sim 10^{-4} M_\odot$ , but the current epoch may still be optically thick for some lines.
- Comparison with AT 2017gfo and GRB 230307A shows that the feature at ~2.1 µm in SN 2024abup is better explained by Mg II rather than the [Te III] line seen in kilonovae.
Explosion Properties and Jet Constraints:
- Explosion parameters derived from light-curve fitting and expansion velocities ( $v \approx 18,200$ km s $^{-1}$ ) place SN 2024abup within the normal range for SN Ic-bl, with a nickel mass of $0.24 \pm 0.01 M_\odot$ and kinetic energy of $8.9 \pm 3.1 \times 10^{51}$ erg.
- Radio observations yielded no detection, providing deep upper limits. These non-detections rule out the presence of a standard relativistic jet viewed at on-axis or moderately off-axis angles, suggesting the progenitor lacked significant pre-explosion mass loss or that any jet was intrinsically weak.

Significance and Claims
The paper claims that SN 2024abup provides the first JWST+MIR observation of a SN Ic-bl, offering critical constraints on the physics of these explosions.

Dust Formation: The detection of CO and the continuum excess provide the first evidence that SN Ic-bl can produce dust and molecules, supporting their potential role as dust producers in the early universe.
r-Process Limits: The study demonstrates that while SN Ic-bl are theoretically viable r-process sites, current spectral data is insufficient to confirm their production due to the complexity of blending non-r-process features. The authors emphasize that definitive answers regarding r-process production in collapsars require future observations during the nebular phase and improved models that include r-process ions to disentangle blended lines.
Progenitor Stripping: Comparisons with SN 2023dbc highlight differences in helium content (absence of He I in SN 2024abup), suggesting a more completely stripped progenitor.

The authors maintain a modest stance, noting that the lack of clear r-process signatures does not rule out their production but rather highlights the difficulty of detecting them in the presence of broad, blended features from abundant elements. The work underscores the necessity of high-quality IR spectroscopy to resolve these ambiguities.