M82 is a magnitude 8.4 galaxy in Ursa Major, presenting to us edge-on. It was long thought to be an "irregular" galaxy, but it was recently discovered that it has two symmetrical spiral arms emanating from a central bar, so now it is considered to be a spiral galaxy. It is a spectacular example of a "starburst galaxy," having undergone a relatively recent collision or near-collision with its much larger neighbor, M81 (most estimates put this as having happened about 600 million years ago). The gravitational forces in such events typically cause a surge in star-forming activity, with young stars being being born in the center of M82 ten times as fast as they are inside our Milky Way galaxy. Radiation and energetic particles from these newborn stars carve into the surrounding gas, and the resulting galactic wind compresses enough gas to make millions of more stars. The rapid rate of star formation in this galaxy eventually will be self-limiting. When star formation becomes too vigorous, it will consume or destroy the material needed to make more stars. The starburst will then subside, probably in a few tens of millions of years.

The red streamers emanating from the center of the galaxy are comprised of ionized hydrogen gas, believed to have been ejected from the center of the galaxy during star formation and the subsequent high rate of supernovas.

It is estimated to be approximately 12 million light years from earth, and approximately 25,000 light years in diameter.

This is my second time imaging this object. My first was 19 years earlier, with more primitive equipment (smaller scope; much smaller camera chip; low-end mount, all from my front yard in light-polluted Redmond, Washington). If you would like to compare, it's posted here. You also might be interested to compare this effort to that of the Hubble (yes, size matters!).

Technical Information:

HaLRGB: 1200:1425:180:180:240 (that's over 53 hours of keepers included in this image); Ha data consists of 60 twenty-minute images, woven into both the luminance data and the red-filtered data. Luminance layer consists of data from 55 fifteen-minute images, 24 five-minute images, and 16 thirty-minute images through the luminance (clear) filter (plus the Ha data); R, and G consist of fifteen-minute images; B consists of twenty-minute images. I gathered Ha data to enhance the spectacular red tendrils. All images were unbinned.

Equipment: RC Optical Systems 14.5 inch Ritchey-Chretien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 camera with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP Expert/Scheduler, working in concert with TheSky X Professional Edition.

Processing: All images calibrated (darks, bias and sky flats), aligned, combined and cropped in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, deconvolution, HDR combine/HDR Mulitscale Transform and Multiscale Linear Transform of luminance data and noise reduction) done in Pixinsight; some cleanup finish work was done in Photoshop CC.

Location: Data acquired remotely with my equipment hosted by Sierra Remote Observatories, Auberry, California, USA.

Date: Images taken on many nights from November 2020 into May 2021. Image posted May 14, 2021.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

Seeing: Generally excellent, with individual calibrated luminance frames varying from 1.4 to 1.9 arcsecond FWHM.

CCD Chip temperature: -25C

Copyright 2021 Mark de Regt

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