UGC 11105It appears dim, with a magnitude of 13.6, highlighting the differences in how the brightness of celestial objects located 110 million light-years away from Earth is perceived from Earth. This image of spiral galaxy UGC 11105 is not as bright and vibrant as some of the week’s other Hubble images. Located about 110 million light-years from Earth in the constellation Hercules, this faintly bright galaxy appears obscured by the bright foreground stars surrounding it. The Type II supernova that occurred in this galaxy in 2019 was no longer visible in this image, but it certainly dwarfed the galaxy at the time!

To be more precise, the apparent magnitude of UGC 11105 is about 13.6 in the optical light mode (this image was created using data covering the essence of the optical mode in addition to the ultraviolet data). Astronomers have different methods to measure the brightness of celestial objects, and apparent magnitude is one of them.

Concept of apparent size

First, the “visible” part of this magnitude refers to the fact that apparent magnitude merely describes how bright objects are. look like This is not the same as measuring how bright they actually are. For example, the variable star Betelgeuse is actually about 21,000 times brighter than our Sun, but because the Sun is much, much closer to Earth, Betelgeuse appears much dimmer than it is.

The “magnitude” part is a little more difficult to define because the magnitude scale does not have a unit associated with it; For example, mass measured in kilograms or length measured in meters. Values ​​of a quantity have value only relative to other values ​​of the quantity. Additionally, the scale is not linear, but a type of mathematical scale known as “inverse logarithmic”; This also means that smaller sized objects are brighter than larger sized objects.

Comparison of the brightness of UGC 11105 with other celestial objects

For example, the apparent magnitude of UGC 11105 is about 13.6 in the optical band, while the apparent magnitude of the Sun is about -26.8. On an inverse logarithmic scale, this means that even though UGC 11105 is a full galaxy, from our vantage point on Earth the Sun appears approximately 14 trillion times brighter than UGC 11105!

The faintest stars visible to the naked eye are about sixth magnitude; most galaxies are much fainter than this. However, Hubble is known to detect objects with apparent magnitudes up to a remarkable value of 31, so UGC 11105 does not pose much of a problem.