M45 – The Pleiades, Seven Sisters, Subaru…

M45, also known as the Pleiades throughout the USA, or the Seven Sisters in Greek mythology, or Subaru in Japan, Persian name Soraya, is an open cluster of new – astronomically speaking – stars. This group of stars can be seen with the unaided eye, which is one of the reasons it is so popular among many people, and has been referenced long ago, and also mentioned by Homer around 750 B.C., by biblical Amos around 750 B.C. and by Hesio around 700 B.C. At least 6 of the stars can be seen with the unaided eye, with the number increasing to 9 or so under clear dark skies. On March 4, 1769, Charles Messier added the Pleiades to his list of clusters and nebula published in 1771. It wasn’t until long exposure photography that we realized that the stars of the Pleiades are imbedded in a nebulous material, which are a blue color, which indicates it is a reflection nebula. The brightest of the nebula around Meope was discovered on October 19, 1859 by Ernst Wilhelm Leberecht (Wilhelm) Tempel in Venice. It wasn’t until the later 1880s that the nebulae around Alcyone, Electra, Celaeno and Taygeta were found in photographs.

The nebulae found in the cluster are most likely part of a molecular cloud that is unrelated to the Pleiades star cluster. Many people have believed that the dust in the images is leftover from the formation of the stars, but it does not appear to be associated with the stars due to having different radial velocities. It is calculated that the stars of the Pleiades age is around 100 million years old, with a future lifetime expectancy of another 250 million years. By which time the stars will have spread out onto their own orbital paths. The ESA have determined the distance to the cluster using direct parallax measurements estimating a distance of 380 light-years. Using the Hubble Space Telescope and the Mount Palomar and Mount Wilson Observatories the distance is more accurately estimated to be 440 +/- 6 light-years.

Information from the Messier Catalog

M45 Location

M45 Location

My observations were short that night as it was a bit cold. I didn’t spend more time than I had to outside at the telescope. I did take a couple minutes to soak in the view of the Pleiades. There are no signs of nebula without photography, so even in my telescope it was just bright blue stars arranged in an almost Ursa Minor formation. As a kid I always thought the Pleiades was the little dipper, as it has a shape sort of similar; I believe that may just be due to the way the stars Maia, Electra, Merope, Alcyone, and Atlas form a bowl and handle shape like the dippers.

M45/Pleiades/Seven Sisters/Subaru 12-19-14

M45/Pleiades/Seven Sisters/Subaru 12-19-14

This image is 25 light frames at 5 minutes a piece, 25 Flat Frames, 25 Flat Dark Frames, and 12 Dark Frames. Stacked in a new-to-me software, IRIS and following a tutorial by Jim Solomon’s IRIS Cookbook with some small minor touches in Photoshop.

Equipment:
Omni XLT 150
CG-5 Advanced Series Go-To
PHD Autoguiding
Orion Starshoot Autoguider
Modified Canon 350D
Baader MPCC Mark III Coma Corrector

August 4th, 2011 Viewing Session – M27 and Coathanger Asterism

I went onto my back porch to do my viewing last night (all my observations were made on the 5th of August) because the two objects I was after were clearly visible even with the tree cover I have in my yard. I was after M27 – The Dumbbell Nebula, and I was after the asterism known as Brocchi’s Cluster, or Coat-hanger Asterism.

M27 – Dumbbell Nebula is a Planetary Nebula (magnitude 8.10) in the constellation Vulpecula which is latin for “little fox”. Vulpecula is very close to the constellation Cygnus, and just below it is the constellation Sagitta which is latin for “arrow”. I spent quite a bit of time looking for the Dumbbell Nebula because for some reason I couldn’t pinpoint it even with the help of Stellarium, and The Pocket Sky Atlas from Sky & Telescope. Once I finally found it I attempted to take a few pictures, then it dawned on me; I should get into trying to sketch objects I see. I found sketching to be a great way to study the detail of an object, and to spend quite a bit of time with it. The more time you spend looking at something the more you start to see. Also after sketching I wrote a few notes to help remember what I saw. My eye was wandering all over the eyepiece looking at all the stars. Some stars were only visible with averted vision while other were quite bright and easily seen looking directly at them. I used both my 32mm eyepiece giving me a magnification of 31.25, and the 12.5mm eyepiece giving me a magnification of 80. In both magnifications the nebula is very faint and fuzzy, although it seemed to me just as bright, if not a tad bit brighter in the 12.5mm surprisingly. Usually the higher the magnification the dimmer an object gets. I could just barely make out a dumbbell shape in the nebula through both eyepieces, detail was a bit better in the 12.5mm. While sketching and viewing I saw what I’m going to call space junk flying through my view through the eyepiece. It could have been a satellite but it was very dim and couldn’t see it with the naked eye, and stellarium didn’t show any satellites in the area at the time (12:45am Aug. 5th). With both eyepieces I wasn’t able to make out any color, which is normal when viewing. Color usually starts to show with long exposure photography or very very dark viewing areas that lack light pollution. I also noticed and took note that with the 12.5mm eyepiece the nebula seemed to almost “pop out” and appeared closer than the background stars in the field of view.

Photograph is 6 pictures stacked. ISO400 F3.1 30sec exposures.

Next was Brocchi’s Cluster/Coat-hanger Asterism which is an average of around a magnitude 6. Also in the constellation Vulpecula, but very close to Sagitta. With the naked eye from my back porch it looked like a very small fain cloudy/fuzzy light. I almost couldn’t see it, again averted vision was key in spotting it. I only used my 32mm eyepiece which just fit the entire thing into my view. No sense in using a higher magnification if I’m just going to see less of the object I’m looking at. The more I’m into astronomy the more I realize how important a good low power eyepiece truly is. In the cluster I was able to make out around 27 stars clearly, although a couple were only visible with averted vision (if you haven’t noticed averted vision helps A LOT when viewing). Of the 27 stars that I saw there were around 10 of the brightest ones that made up the coat-hanger shape. There is no nebulosity to this asterism it’s just a nice little open cluster of stars that happen to look like a coat-hanger just floating overhead.

I ended the night watching the ISS pass at 2:40am and was tempted to bring the scope back outside to look for Andromeda again since it was high up in the sky, but I was too tired and decided it can wait until it rises earlier or until next time if I can stay up late enough to view it. Another great night in the Adirondacks with great viewing.