NGC 4435/38 - Interacting Galaxies (Arp 120)
The two interacting galaxies NGC 4435/38 are located at a distance of roughly 50 million light-years in the constellation Virgo and are also
known as "Arp 120". The galaxies are about 10mag bright and can therefore be seen even in a smaller telescope.
NGC 4435: The smaller of the two galaxies is a lenticular galaxy of the Hubble Type "SB0". It is currently only 100,000 light-years
away from NGC 4438. Because a young stellar population has been found in the galaxy, it is currently assumed, that the two galaxies had a close
encounter with each other some 100 million years ago, which brought them within 15,000 light-years of each other. This resulted in a
starburst in NGC 4435.
NGC 4438: This galaxy looks the strangest of all the galaxies in the Virgo Cluster. Its heavily disturbed disk and the tidal tails make
it difficult to classify whether this galaxy is a lenticular or a spiral galaxy. Due to the interaction with NGC 4435 and with the neighboring
galaxy Messier 86, some gas filaments that have been torn out of NGC 4438 can be seen in long-exposure images. In addition, the galaxy is
racing through the Virgo Cluster at an immensely high speed, similar to Messier 86, which also results in a loss of gas.
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In my 20" telescope, the galaxy pair NGC 4435/38 offers a great sight, especially as the two galaxies are located within the Markarian chain.
While NGC 4435 looks like a normal lenticular galaxy, some details in NGC 4438 can be seen under a dark sky. The first thing that catches
the eye is the unusual, curved shape, which disappears smoothly into the darkness of the universe. Inside there is a brighter core area, which is surrounded
by two brighter shells on the western and eastern sides.
Really interesting! :)
