Click for original image.
Cool image time! The picture to the right, reduced and sharpened to post here, was taken using the Hubble Space Telescope and was done as part of a larger research project studying what astronomers call Type 1a supernovae.
NGC 3810, the galaxy featured in this image, was the host of a Type Ia supernova in 2022. In early 2023 Hubble focused on this and a number of other galaxies to closely examine recent Type Ia supernovae. This kind of supernova results from a white dwarf exploding, and they all have a very consistent brightness. That allows them to be used to measure distances: we know how bright a Type Ia supernova should be, so we can tell how far away it must be from how dim it appears.
One uncertainty in this method is that intergalactic dust in between Earth and a supernova blocks some of its light. How do you know how much of the reduction in light is caused by distance, and how much by dust? With the help of Hubble, there’s a clever workaround: take images of the same Type Ia supernovae in ultraviolet light, which is almost completely blocked by dust, and in infrared light, which passes through dust almost unaffected. By carefully noting how much light comes through at each wavelength, the relationship between supernova brightness and distance can be calibrated to account for dust. Hubble can observe both these wavelengths of light in great detail with the same instrument. That makes it the perfect tool for this experiment, and indeed, some of the data used to make this beautiful image of NGC 3810 were focused on its 2022 supernova. You can see it as a point of light just below the galactic nucleus, or in the annotated image here.
Can you spot the supernova? If you can’t without checking the annotated or original image, don’t be disappointed. It is there but hard to distinguish unless you know where to look.
This supernova however does illustrate the advances in astronomical observational capabilities in the past two decades, resulting not from the giant big ground-based telescopes that cost a fortune and take decades to build nor from the space telescopes like Hubble and Webb that get all the press. These new capablities come from sophisticated smaller telescopes designed to do daily surveys of the entire sky, combined with software that can quickly compare images each day and identify anything that changed.
For example, this 2022 supernova was the 18,142nd discovered that year. That total exceeds the entire number of supernovae that had been discovered in all history prior to this century.
