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Mintaka. A Very Close Double.

Hello again. I hope you are all feeling well after Christmas and New Year. Another slow start to the year as regards imaging. The only let up in the clouds was January 12th, and so I imaged a few objects. One of them was IC 417 (The Spider Nebula) in the constellation of Auriga. However, I am having some difficulty trying to tease out the very faint nebulosity, so that will be a future image. The same night I also imaged Mintaka, a very close double star in the constellation of Orion.


Graphic showing some of the main stars of Orion.


Mintaka is the seventh brightest star in the constellation of Orion, and it is part of the three stars that make up the well known Orion's Belt asterism. It is also a very close double star. Mintaka is also known as Delta Orionis and Mintaka Aa1. I believe that the very close star is Mintaka Ab. However, there seems to be some doubt about that as the system also comprises Mintaka Aa2, HD 36485 and Mintaka B. The primary star, Mintaka, is a bright blue giant star of spectral type O9.5II. It is more than 190,000 times more luminous than our Sun, and it has an apparent magnitude of 2.23. Temperatures on Mintaka are at around 29,500 K, which means that it is 5.1 times hotter than our Sun (5,778 K). It is also a fast-spinning star, having a rotational speed of 150 km / 93.2 mi per second. Mintaka Ab is the second brightest star and the second hottest, being around 63.000 times more luminous than the Sun. Mintaka Aa2 is the third brightest star of the system, and the third hottest. HD 36485 is the fourth brightest star in the Mintaka system, and the fourth hottest. And last but not least is Mintaka B which is the faintest star of the system. Mintaka is the closest star to Earth from Orion's Belt, situated at 1,200 light-years.


Mintaka and its very close companion as imaged by me, the author on January 12th 2024.


As you can see in my image above, the companion star is very close to Mintaka as it appears from our viewpoint. However, in a modest telescope and camera the double is easily split. Split, in double star terminology means that you can see two stars as opposed to just one, which is how it looks to the naked eye. All the stars in the Mintaka star system formed around 12 million years ago in the Orion B1 Association, which is part of the Orion Molecular Cloud Complex. All of these stars are very young in comparison to our Sun. Gravity pulls the gas and dust from the molecular cloud, and when it reaches the right temperatures, it results in the multiple stars which form the Mintaka star system. All of these stars have comparatively short lifespans. They will eventually explode as supernovas.


Now, if you look at my image, you can see two grey ghostly patches, just off centre to the botom right. The large patch is IC 423 and the small patch is IC 424. These are both reflection nebulae that were discovered by Williamina Fleming, who was a Scottish/American astronomer. She observed them on June 27, 1888. It is very probable that Mintaka is one of the stars lighting these nebulae up. As an aside, these nebulae were a consolation prize for me, as I did not know that they would be captured along with Mintaka. Obviously, they are not very bright as I only imaged the area for 30 minutes with 60 second exposures, which is more than enough to capture Mintaka. So, I was very surprised when I saw the nebulae. But, what a great find!


My actual plate solve of the Mintaka area.


To finish this post, I thought I would show you this image, above, of my actual plate solve of the Mintaka area. A plate solve is an astrometric solution of your original image. The software looks at your image and tells you the actual objects that you have captured in your image. This service is free at Astrometry.net Of course, you have to have your own image for this to work. I hope you have enjoyed this blog/post and as usual any comments are welcome good or bad. See you next time. Until then, keep safe..




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