M79 and Multiple star HR 1771 (ADS 3954)

[AusGuy]

Face towards the centre of the Milky Way and then turn right around and face away from it. You are now looking in the direction of the globular cluster Messier 79 which lies in the constellation Lepus. This, and the fact that its distance is 42,000 light years makes M79 atypical of most globulars which are grouped around the galactic centre. Its size is about 118 light years. Dipping into popular commentary on the internet, it seems that M79 (in company with three other globulars) has immigrated from the Canis Major dwarf galaxy which is being torn apart by its close encounter with the Milky Way. However, the globular itself is zipping away from us at 720,000 kph.

At 8 seconds individual exposures this image can only hint at the wealth of stars the globular contains as shown in much longer exposure images. Apparently most of its brighter stars are red giants but in this image there seem to be quite a few faint blue stars scattered around. It would be tempting to assume that they are blue stragglers but apparently not. Only 39 blue stragglers were detected in a 2007 study and they were concentrated at the core.

The bright star at the lower right goes by many catalogue names including HR 1771 and ADS 3954. It is a multiple star system. The bright A component as seen here is magnitude 4.98. The next brightest component B is magnitude 6.56 but it is currently so visually close to A that it's lost in A's glare. However magnitude 9.2 component C is currently 3” away from A and can be seen to A's left.

Vixen R200SS; SW AZ-EQ6 Pro; ZWO ASI294MC Pro cooled to -10 deg; Baader MPCC.

SharpCap livestack 11 x 8 seconds at 400 gain with later minor processing in Photoshop.

Edited March 26, 2021 by AusGuy

[Mike JW]

Hi, Only the other day I was thinking that you had not posted anything and was wondering if your were OK. M79 is always tricky for us in GB due to it always being low down in the murk. Visually in a big Dob it lacked the sparkle of higher up globular clusters. I have never even bothered to point the scope/camera at it, so great to have your post with such an interesting read as well.

HR 1771 - I always like to see doubles and multiples ( a once favourite astro pursuit of mine with a high contrast scope).

Mike