M65 - Spiral Galaxy in Leo
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Messier 65 — or M65 — also cataloged as NGC 3623, is one of the best-known spiral galaxies visible from mid-northern latitudes. It resides in the constellation Leo, about 40 million light-years (≈12.3 Mpc) from Earth. Charles Messier added it to his catalog on March 1, 1780.
At first glance M65 appears tranquil. It contains little gas and dust, so large-scale star formation is currently rare. Nevertheless, analysis of its spiral arms shows that new stars formed there relatively recently. Overall, older stellar populations dominate, and the galaxy remains comparatively quiet across most of the electromagnetic spectrum.
Observations
April 26, 2025, around 12:30 AM – Jaworzno, Poland
Conditions: high light pollution
The night was clear, although the sky looked slightly hazy. Isolated clouds drifted in near the end of the session but did not interfere with the observations.
M65 is part of the famous Leo Triplet (Arp 317) — a tight group of three gravitationally interacting galaxies that also includes M66 and NGC 3628 (Photo 1).
Radio observations from the NRAO VLA Sky Survey reveal a radio source roughly two arcminutes from M65’s center. Its nature remains uncertain — no optical counterpart or detailed spectroscopy has yet confirmed what it might be. Although M65 hosts an active galactic nucleus, its emission is modest; the galaxy is classified as a LINER (Low-Ionization Nuclear Emission-line Region).
A subtle warp in M65’s disk, visible through amateur telescopes, hints at past encounters with its neighbors. Evidence suggests that members of the Leo Triplet began interacting roughly 800 million years ago, possibly perturbing M65’s structure. There are also indications of an inner stellar bar, although confirmation is difficult because we observe the disk at a steep inclination.
To date, astronomers have recorded a single supernova in M65 — SN 2013am — proof that younger, massive stars capable of explosive endings still inhabit this seemingly quiet galaxy.
Photo 1 Parameters:
- Total exposure time: 90 minutes (stack of 90 RAW frames at 60s each, using an appropriate number of dark, bias, and flat frames)
- ISO: 1600
- Maksutov-Cassegrain telescope (100/1400), prime focus exposure
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: equatorial mount with tracking, aligned using the drift method and controlled by a custom-built system.
Further readings:
- Duan Z., Multicolor Photometry and Stellar Population Synthesis Study of the Interacting Galaxies of the Leo Triplet, The Astronomical Journal, 2006, 132(4), pp. 1581-1592
- König M., Binnewies S., Bildatlas der Galaxien: Die Astrophysik hinter den Astrofotografien, Kosmos, 2019
- Rots A. H., Detection of a Long H I Plume Emerging from NGC 3628, The Astronomical Journal, 1978, 83(3), pp. 219-223
Marek Ples