---
title: "Protective “Cocoons” Could Block Deadly Stellar Gamma-Ray Bursts"
description: "Astrophysicists just uncovered why some dying stars' supernovae appear to lack high-energy gamma ray bursts. A protective cocoon has been blocking them."
date: "2019-01-21"
modified: "2019-01-21"
authors:
  - name: "Dan Robitzski"
    link: "https://futurism.com/authors/danrobitzski"
url: "https://futurism.com/the-byte/high-energy-cocoons-supernovae"
categories:
  - "Off-World"
  - "Space"
tags:
  - "Black holes"
  - "space"
  - "supernova"
  - "the digest"
---

# Protective “Cocoons” Could Block Deadly Stellar Gamma-Ray Bursts

![Astrophysicists just uncovered why some dying stars' supernovae appear to lack high-energy gamma ray bursts. A protective cocoon has been blocking them.](<https://futurism.com/wp-content/uploads/2019/01/high-energy-cocoons-supernovae.jpg>)
*\<em\>Image: NASA\</em\>*

## Extinction Event

Sometimes, when a gigantic star reaches the end of its life, its inner core begins to collapse and it bursts out a cataclysmically powerful beam of energy called a gamma-ray burst (GRB). Along with the accompanying supernova, they can burn more brightly than an entire galaxy — some scientists have suggested that if one hit Earth, it could [cause an extinction event](<https://www.nature.com/news/2003/030922/full/news030922-7.html>).

But that's not always the case. When examining dying stars, astronomers often see a GRB followed by a supernova or hypernova, but sometimes they just see the supernova. Until now, scientists had no idea why the GRBs were missing from those stellar explosions.

It turns out that when a star dies, it not only expels a gamma-ray burst but also a "cocoon" made of high-energy particles taken from the GRB itself. These cocoons sometimes grow so strong that they can actually block GRBs, according to [research published last week](<https://www.nature.com/articles/s41586-018-0826-3>) in the journal *Nature*.

## Shields Up

The research suggests that every supernova may be preceded by a GRB. But sometimes the gamma-ray bursts transfer so much of their own energy to these cocoons that there's not enough left for the GRB to break through, [according to *Astronomy*](<http://www.astronomy.com/news/2019/01/astronomers-may-have-finally-connected-supernovae-and-gamma-ray-bursts>).

"The jet transfers a significant part of its energy to the cocoon and, if it manages to reach the surface of the star, will produce the gamma-ray emission that we know as a GRB," Luca Izzo, an astrophysicist at the Institute of Astrophysics of Andalusia who conducted the research, said in an [institute-published press release](<https://www.iaa.csic.es/en/news/observations-rare-hypernova-complete-picture-death-most-massive-stars>).

If the gamma rays gave away too much energy to reach the surface of the dying star, which will then [become either a neutron star or a black hole](<https://futurism.com/astronomer-birth-black-hole>), then the GRB will stay trapped and it will appear as though the GRB never existed at all to any astronomers watching the spectacle.

**READ MORE:** [Astronomers may have finally connected supernovae and gamma-ray bursts](<http://www.astronomy.com/news/2019/01/astronomers-may-have-finally-connected-supernovae-and-gamma-ray-bursts>) \[*Astronomy*\]

***More on space: [Ultra-Detailed New Image of Nearby Galaxy Shows Stars Being Born](<https://futurism.com/hubble-image-triangulum-galaxy>)***

## Author
Dan Robitzki is a senior reporter for Futurism, where he likes to cover AI, tech ethics, and medicine. He spends his extra time fencing and streaming games from Los Angeles, California.

### Author social links  
[Twitter](<https://x.com/danrobitzski>)