NGC 7635, the Bubble Nebula
Image Credit: NASA/ESA Hubble Space Telescope/ Alexandra Nachman. Image processed using FITS Liberator and Photoshop CC.
Quick Stats
Name: NGC 7635
Nickname: Bubble Nebula
Distance: 7,100-8,000 light-years
Constellation: Cassiopeia (Northern Celestial Hemisphere)
NGC 7635 is famously known as the Bubble Nebula and for good reason — it looks exactly like a giant space bubble! And it is fairly large at around 7-10 light-years across. NGC 7635 is located about 7,100- 8,000 light-years away in the Constellation Cassiopeia. The Bubble Nebula has been shaped by the star inside of it. The star inside this bubble, BD+602522, has shaped the gas and dust surrounding it through stellar winds. These stellar winds are gaseous outflows that emanate from the star at four million miles per hour (about 7,000,000 km/hr)! This star is quite energetic and it is expected that in about 10-20 million years, it will explode in a supernova, seeding the area around it with heavy elements and potentially triggering star formation in nearby nebulous clouds!
BD+602522 is an incredibly luminous O-type star that is 40-45 times more massive than our own Sun and shines about a million times brighter. An O-type star is a very massive, blue-white star that will live fast before evolving into a white dwarf star. These hot, energetic stars only live for millions of years, which is relatively short compared to stars like our Sun that can live for billions of years. It is thought to be around 2 million years old with a hot temperature of 37,500 K. In comparison, our own Sun is around 5,778 kelvin! Currently BD+602522 gives off incredibly energetic radiation in the form of ultraviolet light. This light excites the gas molecules around it and causes those molecules to emit light which allows us to see the nebula.
You might have noticed that this star appears to be off-center and you would be correct! While it is attempting to form a perfect bubble, there are disparities in the gas surrounding the star that cause it to appear off center. The gas surrounding the star has different densities— some parts are more dense than others— and when the hot stellar winds encounter these colder, more dense gas regions, they are slowed. There are thicker regions of gas to the northeast of the star and less to the southwest, so when the stellar winds encounter the thicker gas, they have more to push against. Thus, to the southeast, the stellar winds meet less resistance and are able to push through the gas and create an off-center bubble.
I have learned a lot since I originally processed this image. When I first came across it in November 2020, I downloaded the image from the Hubble Legacy Archive as separate panels. Each filter, 658 for red, 656 for green, and 502 for blue, had four panels. The four panels combined to make one image. So I had to downlead 12 images total and then combine the four panels into one image for each filter, and then combine the three images into one color image. That was before I found out about this link here. That link brought me to a website that had all of the panels already combined into the three images for an easy download. It would've saved me a lot of trouble as I had to figure out how to even combine the panels in the first place. I was able to use the Microsoft Image Composite Editor, which is now retired and can no longer be downloaded.
So, two years later, in November 2022, I took the easy route and downloaded the available images from that NASA site linked above! My second process of this image is at the top of this article while my original image is below. While the colors appear much more vibrant in the image below, I have definitely improved on my processing. I am now able to color balance stars better, so they are white instead of purple, and I prefer a much more "natural" color balance of gold and blue in my images.
NGC 7635, the Bubble Nebula. My first process of this image.
Image Credit: NASA/ESA Hubble Space Telescope/ Alexandra Nachman. Image processed using FITS Liberator and Photoshop CC.
Because Hubble is funded by the US government, the data is free to the public, since we pay for it! This image is such a stunning image and I want everyone to be able to download and use this data! Below are links to resources so you can process your own image! Questions? Email me at peculiargalexyastro@gmail.com or reach out to me here!
RESOURCES
This image was taken over multiple days by the Hubble Space Telescope. These days were February 24, 25, 26, and 29 in 2016. It was an image created using three greyscale images assigned to the RGB channels in Photoshop CC. The images used were:
RED: hhlsp_heritage_hst_wfc3-uvis_bubble_nebula_f658n_v1_drc
GREEN: hlsp_heritage_hst_wfc3-uvis_bubble_nebula_f656n_v1_drc
BLUE: hlsp_heritage_hst_wfc3-uvis_bubble_nebula_f502n_v1_drc
Interested in learning how to process your own image? Check out the tutorial here!
Complete mosaics can be found here as well as more information about how the Hubble Heritage team created this image! New HST WFC3 Imaging of the Bubble Nebula.
These images are associated with HST Proposal 14471.
REFERENCES- ALL INFORMATION IN THIS ARTICLE WAS TAKEN FROM THE SITES BELOW
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