Star Cores Reveal Explosive Secrets

New models show massive stars end in surprisingly structured explosions.

Scientists have revealed how giant stars, much heavier than our Sun, might explode, shedding light on rare, super-bright stellar deaths.

How do the biggest stars die? That's the question researchers tackled by studying Very Massive Stars (VMS), those over 100 times the Sun's mass. Their fiery ends create some of the universe's most dramatic events: supernovae. Understanding these stellar explosions helps astronomers decode the history of elements in the cosmos.

To peek inside these massive stars, scientists used a specialized computer program, the Tycho evolutionary code version 6.92. They modeled the hearts of these stars, called helium cores, with masses from 8 to 160 times our Sun. These simulations tracked the star's life from its birth through its death throes, right up until its core collapsed.

Four Ways Stars Can Die

The study found four ways these stellar giants can end their lives, depending on their mass:

1. Core-Collapse Supernova (CCSN)
2. Pulsational Pair-Instability Supernova (PPI)
3. Pair-Instability Supernova (PISN)
4. Pair-Instability Core Collapse (PICC)

For the most massive CCSN candidates, the models showed something unexpected.

"The outstanding novel features of these models are:

1. Relatively large Fe-cores, up to about 3 M⊙, and a large amount (up to about 10 M⊙) of Si-group elements.
2. Comparatively low central density and high central entropy.
3. A comparatively shallow density profile."

Imagine a giant onion where the iron core, the very center, is surprisingly large, and the layers around it are less squashed than expected.

These findings suggest that the largest core-collapse supernovae, like cosmic fireworks, will have a different initial setup. This unique structure and composition—a huge iron core and less dense outer layers—could significantly "impact their explosion outcomes," meaning how they explode and what they leave behind in space.

Limitations & Next Steps

The team noted that accurately modeling the intricate "pulsations" within these stars remains numerically complex. Future research will need to explore how their results might change if different methods are used to account for things like:

• Internal mixing within the stars
• How much material the stars lose over time

These new insights bring us closer to understanding the spectacular final moments of the universe's most colossal stars.