The Hubble image shows a Single Star shining above a Galaxy with an Irregular background

The irregular galaxy Arp 263 lurks in the background in this  NASA/ESA Hubble Space Telescope image, but the view is dominated by the star's photobomber, the bright star BD 17 2217. Arp 263 - also known as NGC 3239 - is a diffuse, irregular star formation with recently formed astronomical galaxies. it was born from the merger of two galaxies. It is located approximately 25 million light years away in the constellation Leo. ESA/Hubble and NASA, J. Dalcanton, A. Filippenko

This week's Hubble Space Telescope image is as remarkable for its composition as for the object it shows. A composite of two different exposures combined, it shows the star BD 17 2217 shining above the irregular background galaxy Arp 263.

Irregular galaxies are irregular in structure, unlike elliptical galaxies or spiral galaxies like our Milky Way. Arp 263 is diffuse and cloudy, with some areas glowing from star formation, while other areas appear almost empty. Such galaxies are usually formed by interactions with other galaxies, which can form when a massive galaxy passes by and pulls the parent galaxy out of shape. As for Arp 263, it is believed that its irregular shape was formed by the merger of two galaxies.

Unusual thing about this image is the way it was created and the effect it has on the diffraction peaks of bright objects. These sharpening of light are caused by the geometry of the mirror used by Hubble to observe distant objects. Typically, Hubble images show four diffraction peaks (compared to the six visible diffraction peaks seen in James Webb Space Telescope images), but in this case eight diffraction peaks are visible from the brighter objects. This is because two different sets of data have been combined to create the image, each taken from a different angle, so you see twice as many spikes.

"The foreground pet star BD 17 2217 is decorated with two sets of intersecting diffraction peaks. The interaction of light with the internal structure of Hubble means that concentrated bright objects like stars are surrounded by four visible spikes," Hubble scientists explain. "Because this image of BD 17 2217 was created from data from two Hubbles, spikes surround this stellar photobomb in both images. The spikes are at different angles because Hubble faced a different way when the two data sets were collected."