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Home , Denebola, Theta Leonis

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The Trio in Leo comprises three fairly easy-to-find spiral galaxies located on the rear leg of Leo the Lion: M65 (mag 9.3), M66 (mag 9.0), and NGC 3628 (mag 9.5). Don't confuse this triplet with the slightly fainter trio of galaxies located under the Lion's belly (M95-M96-M105). ------• ------. •

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Theta

Denebola The Trio in Leo • • •

To get to the trio, start at the large distinctive triangle of forming Leo's rear hip, composed of Beta (), Delta, and . With Theta in the northern part of your finderscope (as shown in the 50 view below), you should see a triangle of mag 5-6 stars that will lead you to a mag 7.1 (arrowed in the finderscope view), which sits in the midst ofthe galaxy trio as shown in the 10 eyepiece view.

M65, M66 and NGC 3628 are galactic neighbors: each of them is about 35 million light from us. Although all three are spiral galaxies, each of them is oriented a little differently when seen from our perspective. The brightest of the three, M66, presents nearly face-on, giving us a clear view of its spiral arms. M65 is more tilted, but still displays the details of its spiral structure. The faintest of the three, NGC 3628, shows us an edge-on view, split in two by a dark equatorial dust band that has been warped by gravitational interactions with the other two nearby galaxies. In small telescopes, they all appear as patches of haze, with M66 showing us a wide oval, M65 a thin oval, and NGC 3628 a narrow streak that can be difficult to pick out in scopes under 6".

While you're in the neighborhood, move your scope from Leo's hindquarters to his neck for a look at Aigieba, a bright star above . Algieba is a wonderful double consisting of two gorgeous golden-orange components, roughly 4 arcseconds apart, one of them shining at mag 2.3 and the other at mag 3.5. Use at least 60-75x to cleanly separate the two stars. To me, they often look like the headlights of a car barreling towards us out of the depths of space.

Finally, take a minute to scan the sky north of Leo, where you'll find a 45-arcminute that looks like an upside-down sailboat floating among the stars of the Leo Minor. To reach the sailboat, start at Epsilon (mag 3.0) and Mu (mag 3.9) Leonis, two of the stars above Algieba that form Leo's head. Counting the 2%° distance from Epsilon to Mu as one step, take 2~ more steps in the same direction to reach the sailboat, whose brightest star is mag 6.5 yellow giant 22 Leo Minoris. The eyepiece view below (unreversed image, north at top) shows stars to mag 10. If you're under reasonably dark skies, you'll be able to spot the sailboat in most binoculars, but in light-polluted skies, you'll need a telescope: the boat will look right-side-up if you use a reflector, but upside down and reversed if you use a refractor or Schmidt-Cassegrain scope. The sailboat was first described by Dan Hudak, an amateur astronomer from Ohio, and was later popularized by Phil Harrin~ton and other binocular astronomy writers .

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~heta 3628 I • 11 degree field 3628 ~ • \stars to mag 10.5 ~c .~degree field \ c '~65. stars to mag 7.5 M66 • M65

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Rick Gering I

NAA Public Outreach I April 2019

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