Leo 1 Dwarf Galaxy

[drja...@aol.com]

Leo 1 is a dwarf galaxy, part of our Local Group of galaxies, which based on Wikipedia and other websites, is some 800,000 + light years from us. Its estimated diameter is 2000 light years and the dwarf galaxy has an estimated mass of 25 million solar masses. By contrast, estimates of the mass of our galaxy are 1.5 trillion solar masses and 87,000 light years across (but about 1000 ly thick)

Leo 1 was discovered only in the 1950s, from Palomar Observatory's 48" camera plates. Most stars in Leo 1 are estimated to have formed between 7 million and 1 million years ago, when star formation stopped. One hypothesis is that a close approach to our galaxy stripped off the gas clouds needed for further star formation. It is believed that Leo 1 contains a super massive central black hole and that the dwarf galaxy is dominated by dark matter. Star composition is largely hydrogen and helium, which indicates ancient formation, of interest for galaxy evolution work. Leo 1 is therefore an object being studied in some detail.

Leo 1 has no discernible structures such as spiral arms. Low surface brightness makes it hard to observe without a large telescope, though imaging by medium sized telescopes reveals the dwarf galaxy as a scatter of stars visually somewhat similar to open star clusters. My image with a 30mm objective and 150mm focal length shows the dwarf galaxy as a faint elliptical smudge at 12 o'clock to Regulus in the constellation of Leo. You may have to turn up screen brightness to see it.

Dwarf mini, 30/150mm, EQ mode, 148 exposures @ 30 seconds each, gain 60, stacked in DwarfVision.

[tcos...@gmail.com]

That's a nice image James. Your Dwarf mini obviously handles bright stars well as any blooming is kept under control and you've managed the contrast between the very bright star Regulus and the faint galaxy very well.
I've not heard of Leo 1 before so thanks for sharing
Tim C

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[trevsie7]

Hi James, like Tim I hadn't heard of Leo 1 before. It is very faint, I could only see it by moving the image around but as Tim says, your Dwarf must have good optics to capture it so close to the bright star with no halo and no significant blooming.

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[drja...@aol.com]

Tim/Trev

Thank you for your comments.  

The Dwarf's optics and low light Sony sensor combination does seem good.  I also used the many short exposures approach hoping to limit problems with Regulus being nearby in the sky.

I hadn't heard of Leo 1 either.  It came up in one of the 'what to image this month' websites.  Dwarf planets I knew about, but not dwarf galaxies.  It was interesting investigating Leo 1.   It's clearest in images viewed on a small screen like a phone.

Wikipedia lists 61 dwarf galaxies.  I wonder if the TEC would be ideal for imaging Leo 1 or others.

James

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On 20 Mar 2026, at 20:53, trevsie7 <trevs...@gmail.com> wrote:



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