What does a regular star look like?

TL;DR

This paper explores the optical appearance of regular stars acting as gravitational lenses, proposing distinctive observational features that differentiate them from black holes, with implications for future astronomical searches.

Contribution

It introduces the idea that regular stars can produce unique lensing images, including the potential absence of secondary images, which can help identify them observationally.

Findings

Regular stars may produce images with no secondary images.

Distinct optical features can differentiate regular stars from black holes.

Potential observational criteria for identifying regular stars.

Abstract

Recently, astronomers discovered unusual Einstein cross images of the galaxy HerS-3, which feature a bright central spot. Motivated by studies of images produced by regular stars, it has been proposed that optical appearances caused by compact stars acting as gravitational lenses may account for this central bright spot. We further suggest that images produced by regular stars exhibit additional characteristics distinct from those of ordinary black holes, such as the possible partial or complete absence of secondary images. These phenomena may serve as favorable observational criteria for identifying regular stars in future searches.