M92 has a dense concentration of stars, so I was really happy to be able to capture so many of them. Please do look at the full resolution to see all the stars!
M92 Details- M92 is often overlooked due to its proximity of M13, although is only a little smaller and less bright compared to M13. M92 is actually one of the brightest Globular Clusters in absolute magnitude in our galaxy. M92 is considerably more densely packed compared to M13, and thus the core is more difficult to resolve, which may be why it gets less attention.
- At 26,800 light-years, it’s tidal radius is 15.17’, with an actual radius od 54.5 light-years.
- M92 is thought to be 14.2 billion years old – almost the same age as the universe. It is one of the oldest clusters known and possibly the single oldest globular in our galaxy. It is almost totally composed of hydrogen and helium, while heavier elements (which astronomers call metals), are extremely low, only 0.5% of the Sun’s levels. Thus, it is one of the most metal poor objects in our galaxy.
- M92 is estimated to weigh in as much as 330,000 solar masses. Indeed, the James Webb Telescope recently detected even more stars, too faint and cool for even the HST, some with only 1/10th our Sun’s mass. The total number of stars is estimated to be 300,000!
- M92 is an Oosterhoff type II (OoII) globular cluster, which means it belongs to the group of metal-poor clusters with longer period RR Lyrae variable stars: currently 17 of these variable stars are known.
- If anyone has a wide FOV, fast optics and lots of time, and wants a real challenge, a team of astronomers using the Canada-France-Hawaii Telescope discovered a new stellar stream emanating from the M92 globular cluster. This new stream suggests that M92 is actively being disrupted by tidal forces caused by our Milky Way core.
My imagingMy total integration was 21.5 hours. The first 17 hours with my L-eNhance HO filter, the last 14.5 hours with my L-eXtreme HO filter. I must use a NB filter due to my severe light pollution. I don’t find there is a lot of contrast difference with the two filters, though the L-eXtreme though does a better job in reducing the LP background and gradients, so I’m tending to use it more and more. This target started out as something to do around full moon, but I kept picking up fainter and fainter stars, so I felt I had to keep going with my integration. whenever the moon was obtrusive.
My processing:I calibrated and stacked in DSS, then in StarTools I did a background wipe, a 1.41x bin (71%), digital development stretch, HDR, deconvolution, initial color, star reduction, and superstructure isolation. In Photoshop I used NoiseXterminator to reduce noise, and made some color, curves and levels adjustments. The final image is cropped a little.
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