UPDATE: I’d like to thank Daniel Fiordalis and Astrospheric for receiving Astrophotograph of the Month for this image. If you are looking for the best astronomy weather forecast site and app, Astrospheric is it!
The Leo Triplet is a group of three galaxies in the constellation Leo. But you didn’t guess that!
This was my worst winter yet for astronomy, with not a single clear moonless night between Thanksgiving and the middle of March. Thankfully, March and April gave me many beautiful clear nights, and the Leo Triplet was a target that I have wanted to do for quite some time. Just a little bit north of the equator, I was able to get a lot of data on this target over six nights, aggregating a total of 33.1 hours of data. As with the Horsehead, I created a small stack of some of the best images from around the meridian and cleaned up the background. I used this as a reference for local normalization, since there were wildly varying backgrounds throughout the images due to shifting light pollution. This gave me an extremely clean background in my final integration.
The Leo Triplet is about 35 million light years away, making the age of the light that my telescope collected the same as the late Eocene era, when there was a major extinction level event, possibly caused by several meteors striking Siberia and the Chesapeake Bay. The group contains three beautiful spiral galaxies, one of which is edge-on.
M65 was discovered by Charles Messier and sometimes is incorrectly attributed to William Henry Smyth. It is an intermediate spiral galaxy that is 35 million light years away. Over all, the galaxy is low in star forming gas, so there is little ongoing star formation. The yellow color of it indicates that it is mostly composed of old stars, although there are a few slightly blue areas in the outer arms that indicate newly born stars. There are an estimated 200 billion stars in this galaxy.
M66 is also an intermediate spiral galaxy that was discovered by Charles Messier. It is 31 million light years away, making the distance between it and M65 about twice that of the distance between the Milky Way and Andromeda. An interaction with group member NGC 3628 has resulted in a particularly high concentration of central mass as well as the sweeping tidal arms to the lower right. There is very active star birth in this galaxy, with large blue areas containing new stars. It is also estimated that this galaxy contains around 200 billion stars.
NGC 3628 is the third member of the group, and it was discovered by William Herschel in 1784, a few years after Messier discovered the other two members. It has a 300,000 light-years long tidal tail, which can be made out in the full field image. It lies 35 million light years distant, and it is believed to be a barred spiral galaxy, with our view being of the bar end-on. Bars in galaxies are considered to be formed during interactions, and it is believed that this galaxy and M66 had a closer interaction in the past that formed their current shapes. There is a prominent dust band through the center.
Above the center of NGC 3628 is [HKK2009] dJ1120+1332, a low surface brightness dwarf galaxy that is orbiting NGC 3628. The star-like white dot in the top right of this dwarf galaxy is WISEA J112015.95+133240.6, a galaxy that is in the background, 564 million light years away.
Here is the full field,
Here is an annotation containing M, NGC, IC, and PGC catalogues,
As I’ve liked doing in recent pictures, I’ve rendered an annotation on the image using the Milliquas catalogue. The last image that I processed, the Hercules Galaxy Cluster, contained a quasar at redshift z = 3.87901 and a light travel time of 12.104 billion years. With the somewhat recent improvements to image weighting in PixInsight based on photometric SNR, my images go a bit deeper than they did just a couple years ago, and I was able to find a quasar in this image that is 14 times dimmer than my previous best. In the background of this image, I found WISEA J112129.71+132237.4, a quasar with an R-band magnitude of 21.20 and a redshift z = 5.400. This gives this quasar a light travel time of 12.643 billion years and a comoving radial distance of 26.578 billion light years. The universe was only 1.077 billion years old when the light left this quasar, about 8% of its life.