Hi All,
I have long been working on another large project and as my target has now disappeared for the season behind trees in the West, I've been able to turn to processing and analysing the data. So here is a new Extreme Deep Field image of the famous Antennae galaxies in Corvus.
Link to large image
Link to full resolution image (5.5MB)
Other images in this gallery:
I managed to gather 75 hours for this image, over the first six months of the year. At times it was rather frustating because clouds kept interrupting my sessions. The weather has definitely been less cooperative this year than during the same period in 2013 when I was working on Centaurus A. Despite this I managed to collect enough data for a very deep image, and thanks to the larger aperture of my new telescope the limiting magnitude is also comparable to that of last year's effort, being around magnitude 25.
Apart from the Antennae itself, what I like most about this scene is the incredible number of distant background galaxies. This area in Corvus seems very rich indeed. The full resolution image is worth having a look at just to see all these faint galaxies littering the background. There are many beautiful interacting pairs and groups which would be fantastic targets in themselves if they were only closer.
I have also put together a
collage of some of these background galaxies.
About the image:
Following on from my previous
Extreme Deep Field project of Centaurus A, I turned my attention to a spectacular pair of colliding galaxies known as The Antennae, located around 45 million light years away in the Southern constellation of Corvus.
This
interacting galaxy pair was discovered in 1785 by William Herschel.
To obtain a unique deep view of the faint tidal streams and numerous distant background galaxies I gathered 75 hours on this target during 38 nights from January to June 2014.
This project was not blessed with the same long run of clear nights as I had enjoyed in 2013, so this amount of data took 6 months to accumulate, two months longer than the 120 hours I collected on Centaurus A the year before.<br>
However, the telescope used was my new larger 12.5" f/4 Serrurier Truss Newtonian telescope, which I built in late 2013. This telecope gathers approximately 156% the amount of light over the old 10" f/5. The total integrated signal is therefore theoretically approaching that of the Centaurus A image. The faintest stars and background galaxies visible in the raw image data have magnitudes between 24 and 25, confirmed via photometric calibration of the integrated FITS luminance file against the USNO catalogues.
Tidal Streams
The iconic features of these two interacting galaxies are the two long tidal streams expelled by the collision of the galaxies. The long upper (Southern) stream seems to actually be a loop and a very faint portion of the material appears falling back towards the galaxies. Along this stream several brighter blue knots can be found, culminating in the large extended clump at its end. These knots are composed of young hot blue stars, likely triggered by the violent forces induced by the collision.
The shorter lower (Northern) stream extends into a large faint fan shape with a little curl up towards the right.
Distant Background Galaxies
Behind the lower fan of speeding intergalactic stars lies a very rich and distant galaxy cluster whose members are visible as innumerable faint fuzzy spots in the area immediately at the end of the lower stream. This densely populated area extends further towards the left below the colliding galaxies.<br>
These background galaxies are so distant that their light is visibly reddened because of the
cosmological redshift. In fact, the entire background is littered with such distant background galaxies, and many of these can be seen through the two tidal streams and also through the extended shells and halos of the colliding galaxies. Judged by their colour and apparent size the faintest of these remote galaxy clusters lie several billion light years away.
Core Area
The main action is happening in the centre where intense starburst activity has been triggered by the merging of the two galaxies. Bright blue arcs of hot young O and B type stars light up the core area, together with the distinct magenta hue from massive glowing hydrogen nebulae. The two galaxy nuclei can still be seen separately, with nebulae, star streams and dark dust bands circling around them in a chaotic dance.
Galaxy Collisions
Based on computer simulations and observations of other colliding systems it is believed that around 1.2 billion years ago these galaxies were two independent spiral systems similar to our Milky Way. Over the following billion years or so the galaxies passed close to, and through, each other resulting in the long tidal tails being flung from the centre. During such a collision multiple shells and streams of material are expelled and our current view provides a snapshot in time of this entire spectacle. The two nuclei are now in the process of falling back towards each other again and the whole system will eventually merge to form one giant elliptical galaxy some time in the distant future.
Our Milky Way galaxy will likely share this fate in the future when it
collides with the Andromeda Galaxy. Although the large Andromeda Galaxy is approaching our own galaxy with the colossal speed of 110 km/s the two galaxies will not begin to merge for another 4 billion years.
Image details:
Date: 38 nights during January to June 2014
Telescope: Homebuilt 12.5" f/4 Serrurier Truss Newtonian
Exposure: LRGB 54:7:7:7 hours, total 75 hours @ -25C
Camera: QSI 683wsg with Lodestar guider
Filters: Astrodon LRGB E-Series Gen 2
Taken from my observatory in Auckland, New Zealand
I recommend viewing images via the links above as the small attached versions here are limited in resolution and quality.
Enjoy the view - all comments and critique welcome as always.
Regards,
Rolf
Antennae Galaxies Extreme Deep Field - 75 Hours
Spectacular image Rolf ! A first class write-up too, you've certainly done your homework there 
