There are better pictures of NGC4216, a Galaxy you can find in Virgo’s Constellation. My idea, however, to capture it was two-folded: to capture it “as it appears to be” from my rooftop in Mexico City, but mostly to capture and understand the supernova explosion that happened there a few weeks ago and that you can find (WOW!) in my photograph.
SN 2024gy was discovered by Koichi Itagaki this year, on January 4. It was swiftly identified as a type 1a supernova. Let me tell you a little bit more about this type of star explosion. It turns out that type 1a supernovae happen only in binary star systems, normally consisting of a red giant star and a white dwarf, but it can also consist of two white dwarfs or a white dwarf and a not so big main sequence star.
Due to its density, the white dwarf steals mass from the fluffy, less dense star, producing an accretion disk around itself. This way, the small white dwarf gains slowly more and more mass, until it reaches a critical mass limit, known as the Chandrasekhar limit in honor of its discoverer. The deal is that at this limit the “repulsive” pressure exerted by the electrons of the white dwarf no longer resists the extra gravitational push of the extra mass gained.
A few moments after this collapse happens it explodes in a very luminous supernova. This way an ephemeral “new star” (that is why they are called “novae”) appears in our night sky. You can easily find this supernova in the inverted version of my picture.
But, how do we know that this explosion corresponds to this type of supernova? We can tell that thanks to spectroscopy. Spectroscopy allows us to measure, through the study of the star’s light, what elements (and some other awesome facts) are present in a star, a galaxy or, in this case, in the early remnants of a supernova. When silicone is present, in those specific peaks shown in the spectrum taken by Robin Leadbeater, we can tell for sure that the explosion corresponds to a type 1a supernova
Perhaps the most awesome part of this, is that these type of supernovae are very helpful to measure large distances in our cosmos. In fact, by measuring them we were able to tell that the Universe in which we live is not only expanding, but actually accelerating its expansion.
To be able to learn things like this, and by actually be capable of capturing them with my own means, is what it keeps me going in this amazing hobby.
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