Chapter 1: Understanding White Dwarfs

Recently, we received an intriguing question from one of our readers: When do the oldest white dwarfs reach their cooling point? In addition, they inquired about the characteristics of the superdense material making up these stars—Is it entirely smooth, or does it have any irregularities? Lastly, what would a cooled white dwarf look like if illuminated by sunlight?

White dwarfs emerge as the remnants of stars that lack the mass needed to evolve into neutron stars. As a star exhausts its hydrogen fuel in the core, it contracts and raises its temperature until helium fusion begins. Once the helium is depleted, the cycle repeats with carbon ignition.

This paragraph will result in an indented block of text, typically used for quoting other text.

An Artistic Representation of a White Dwarf

This cycle of contraction and expansion persists until the star can no longer ignite a new element. At this point, it ejects its outer layers, leaving behind a bare core known as a white dwarf. At this stage, the temperature of the dwarf can reach several tens to hundreds of millions of degrees. However, within moments of shedding its outer layers, the temperature plummets to hundreds of thousands of degrees. As the dwarf cools, the rate of temperature decline slows significantly.

Sirius B: A White Dwarf Captured by Hubble

In a few thousand years, the white dwarf's temperature drops to tens of thousands of degrees. The oldest known white dwarfs, estimated to be around 13 billion years old, have cooled to just below 4000 Kelvin. To reach a chilling 5 Kelvin, they will require approximately a quadrillion additional years—a time span that is a hundred thousand times greater than the age of the Universe itself.

The surface of a white dwarf is smooth and resembles a nearly perfect sphere, emitting no visible light. The composition of a white dwarf varies depending on the mass of the original star, and due to its immense density, all elements exist in a metallic state. Discussing the reflective qualities of a black dwarf is complex and less documented, making it challenging to describe accurately.

Clap if you want to see more space-related articles in your feed!

Subscribe to our channel and submit your questions, which I will address in future articles.

If you appreciate my work, consider supporting me by becoming a Medium member for just $5 a month, helping us produce even better content.

Chapter 2: The Cooling Process of White Dwarfs

The first video titled "Why White Dwarf Stars Unexpectedly Stop Cooling Down" delves into the fascinating phenomenon of white dwarfs and their cooling process. It explains how various factors influence their temperature stabilization over time.

The second video, "The Last Light Before Eternal Darkness – White Dwarfs & Black Dwarfs," explores the final stages of white dwarfs and their transformation into black dwarfs, shedding light on the mysteries of stellar evolution.