NGC 1904 is an old globular cluster in the Southern constellation Lepus (NGC 1904). It was discovered by Pierre Méchain in 1780 and has since been a topic of argument between astronomers, as the cluster may have been a part of another galaxy. It is a part of the Messier Catalogue, which Méchain helped create. It is designated as Messier 79, and can be observed faintly with binoculars.

A study conducted by B. Lanzoni et al (2007) showed a big population of blue stragglers in NGC 1904. They observed 39 blue stragglers, which they attributed to mass transfer binaries. They did not attribute it to young stars, as it is a very old globular cluster, with little to no star generating areas.

In order to study NGC 1904, and determine many of its empirical statistics such as age, metallicity, distance, and reddening among others, I observed the cluster five times in each of the B band for 290 seconds, the V band for 145 seconds, and the R band for 96 seconds using the Prompt5 telescope in Cerro Tololo. This was observed via Skynet, and included other settings as well. Once I received the images, I collected them into the Skynet sister site Afterglow and used their auto photometer feature to collect all the data on the stars visible. Once I had the data, I put it into the Astromancer tool, collected Gaia data as well, and found a isochrone model to fit the data. I found that NGC 1904 has a RA proper motion of 2.46 mas/yr, Dec proper motion of -1.61 mas/yr, distance of 10.43 kpc, 258 stars, an age of 12589.25 myrs, a metallicity of -1.35 solar, and a reddening of 0.04 mag. See below for a chart with the isochrone model attached.

 

The blue stragglers were very apparent to see in the diagram and were difficult to fit in to the isochrone model, but I believe I made it work. Older clusters tend to create difficulty, and I believe this isochrone and the data I collected are a decent enough representation of the cluster.

I plotted the Gaia data, and found that the isochrone fit better on that data rather than my own, as shown below:

The Milky Way Star Clusters Catalog also had an approximation on most of the data and I found my data to be relatively close in all aspects apart from distance, which they listed as 12.89 kpc. When I added that to my isochrone model, it was a much tighter fit to the data.

Overall, this project was an interesting look into star formation. I am lucky that I chose an older star cluster, as blue stragglers are a very interesting concept, one I wish I would be able to continue learning about.