Einstein ring: Weighing a star with light

TL;DR

This paper provides an accessible introduction to gravitational lensing and Einstein rings, illustrating how they can be used to measure stellar masses, exemplified by the white dwarf Stein 2051 B.

Contribution

It offers a simplified, up-to-date explanation of Einstein rings and demonstrates their application in measuring the mass of a star for non-expert readers.

Findings

Measurement of Stein 2051 B's mass using Einstein ring

Accessible educational approach for non-experts

Clarification of gravitational lensing principles

Abstract

In 1936, Albert Einstein wrote a brief article where he suggested the possibility that a massive object acted as a lens, amplifying the brightness of a star. As time went by, this phenomenon, known as gravitational lensing, has become a powerful research tool in astrophysics. The simplest and symmetrical expression of a gravitational lens is known as Einstein ring. This model has recently allowed the measurement of the mass of a star, the white dwarf Stein 2051 B. The purpose of this work is to show an accessible and uptodate introduction to the effect of gravitational lensing, focused on the Einstein ring and the measurement of the mass of Stein 2051 B. The intended audience of this article are non-graduate students of physics and similar fields of study, and requires only basic knowledge of classical physics, modern physics, algebra and trigonometry.