The finale of a star’s life has enthralled scientists for years, yet questions continue to surround the explosions of white dwarf stars — the most common path that stars take during the later stages of their evolution. New research, however, has shed light on the astounding variety of ways that a white dwarf star can explode, capturing almost 4,000 of these events scattered across the distant universe.
The explosions were detailed in a dataset and a collection of 21 associated studies published in a special issue of Astronomy & Astrophysics. The large sample size was obtained by Zwicky Transient Facility (ZTF), a Caltech-led astronomical sky survey at the Palomar Observatory in San Diego County.
The sheer amount of white dwarf explosions resulting from incidents like star collisions or star “cannibalism” may help to enlighten astrophysicists on dark energy and its potential role in the universe’s expansion.
A White Dwarf's End
At the end of most stars’ lives, they enter the white dwarf stage as they run out of nuclear fuel. The star’s outer layers are shed, and all that’s left is a core of hot matter that cools down over billions of years and eventually crystallizes.
However, a white dwarf’s story changes when it is part of a binary star system. In this arrangement, a white dwarf star usually pulls mass from a nearby companion star. When a white dwarf exceeds a threshold called the Chandrasekhar limit — about 1.4 times the mass of the Sun — it becomes primed to explode.
This type of explosion, known as a type Ia supernova, has historically been used by astrophysicists to measure distances in the universe, leading them to postulate that the universe is constantly accelerating. A murky piece of this process is dark energy, an intangible force that has been proposed based on the luminosity of type Ia supernovae. Type Ia supernovae are also referred to as “standard candles” due to their known luminosity, which acts as the basis for determining how far the supernovae are from Earth.
Read More: Supernova Helps Explain the Creation of Cosmic Dust Storms in Elliptical Galaxies
An Assortment of Explosions
The true nature of dark energy is still being debated, but the newly observed diversity of white dwarf explosions may lead to a better understanding of the concept. The nearly 4,000 supernovae events detected by ZTF represent the largest sample size to date, introducing an expanded perspective on the end of many white dwarf stars' lives.
“Thanks to ZTF’s unique ability to scan the sky rapidly and deeply, it has been possible to discover new explosions of stars up to one million times fainter than the dimmest stars visible to the naked eye,” said Kate Maguire, an astrophysics professor at Trinity College Dublin involved with the research, in a statement.
ZTF’s observations showed a range of different explosion events, including collisions of two stars and even instances of “cannibalism,” in which a white dwarf star consumes its companions in binary systems.
The array of explosions also varied in terms of luminosity, which will aid researchers in their search for answers to dark energy and the acceleration of the universe.
“The diversity of ways that white dwarf stars can blow up is much greater than previously expected, resulting in explosions that range from being so faint they are barely visible to others that are bright enough to see for many months to years afterwards,” said Maguire, in a statement.
Read More: A Light Echo From a Supernova Has Illuminated Interstellar Gas and Dust
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
European Space Agency. Gaia reveals how Sun-like stars turn solid after their demise
Center for Astrophysics. Neutron Stars and White Dwarfs
Jack Knudson is an assistant editor at Discover with a strong interest in environmental science and history. Before joining Discover in 2023, he studied journalism at the Scripps College of Communication at Ohio University and previously interned at Recycling Today magazine.
