GALAXY
The Cigar Galaxy
— Messier 82 —
Processed by Nicolas Rolland, Paris. 46 hours gathered by Bernard Miller at Dark Sky New Mexico, Animas, USA.
The red plumes above and below this galaxy are not part of it. They are gas on their way out.
A starburst, lit by a neighbour
Messier 82 is a starburst galaxy: it forms stars at a rate most galaxies never approach, and it has been doing so for tens of millions of years. It lies about 12 million light-years away in Ursa Major, and it puts out roughly five times the light of the Milky Way from a body a third the size. The cause is not internal. Some hundreds of millions of years ago it passed close to its neighbour M81, and the encounter drove gas inward and compressed it — the burst has been running ever since, on the fuel that pass delivered.
The wind coming out of it
A burst of that size cannot be contained. Massive stars form, burn through their fuel in a few million years and explode, and thousands of them doing so in the same small volume drive a wind out of the galaxy perpendicular to its disc. That is what the red filaments are: ionised hydrogen, thrown some ten thousand light-years clear of the disc at hundreds of kilometres a second. Part of it will fall back. Part of it is leaving for good, taking with it material that would otherwise have made the next generation of stars.
The first galaxy I photographed
This is also the first galaxy I ever pointed a telescope at, a C9.25 EDGE HD on a Losmandy G11 mount, in January 2014 — and the reason I looked was SN 2014J, which had appeared here days earlier and was the nearest type Ia supernova in decades. I photographed it for the first time in May 2017. Four supernovae have been recorded in Messier 82 altogether: SN 1986D, SN 2004am, SN 2008iz and SN 2014J. In a galaxy making massive stars this quickly, that is not a coincidence either.
Forty-six hours, six of them in hydrogen
A Planewave CDK17 at f/6.8 with an FLI Proline 16803, from Dark Sky New Mexico in Animas, across two campaigns in 2017 and 2022 — forty-six hours in all, nineteen of them luminance at twenty minutes a frame and six in H-alpha at thirty. Those six hours are the ones that matter here. The disc and the dust lanes come out of the broadband; the wind does not, because it is emission and almost nothing else, and a luminance frame records the galaxy with the plumes barely showing. Six hours is enough to establish where the filaments are and how far they reach. It is not enough to follow them to their end — the wind fades outward with no clear edge, and where it stops in this frame is a function of the exposure rather than of the gas. Bernard Miller gathered the data at Animas.
