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Have you ever looked through your telescope and felt like you were being watched? These two galaxies in the Virgo cluster form a pair of cosmic eyes that stare right back at you! These two oval-shaped galaxies, NGC 4438 (left) and NGC 4435, are nicknamed “The Eyes” since they resemble a pair of eyes glowing in the dark when seen in a moderate-sized telescope. This image was taken by the Very Large Telescope at Paranal in Chile, using the FORS2, a visual and near ultraviolet FOcal Reducer and low dispersion Spectrograph for the VLT.
These eyes have likely changed in shape over time, and astronomers can see evidence that the pair probably both were spiral galaxies in the past. The contents of NGC 4438 have been stripped out by a violent process: a collision with another galaxy. This clash has distorted the galaxy’s spiral shape, much as could happen to the Milky Way when it collides with its neighboring galaxy Andromeda in three or four billion years.
Although the two eyes look similar at their centers, their outskirts could not be more different. NGC 4435 is compact and seems to be almost devoid of gas and dust. In contrast, NGC 4438 has a lane of obscuring dust just below its nucleus, with young stars visible just left of its center, and gas extends at least up to the edges of the image.
ESO, the European Southern Observatory, is a collaboration between 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious program focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organizing cooperation in astronomical research.
See more about this image at the ESO website.
The ESO press release mentions the possibility of a past encounter with the large Virgo elliptical galaxy M 86. In 2008 an extensive bridge of ionized hydrogen was found connecting M 86 with NGC 4438 and that discovery, combined with other data, strongly suggested a past encounter: http://arxiv.org/PS_cache/arxiv/pdf/0810/0810.0711v2.pdf
A striking composite image of NGC 4438/M 86 with the hydrogen-alpha tail can be found here: http://www.noao.edu/outreach/press/pr08/images/M86.jpg
The paper’s authors argue that the smaller galaxy NGC 4435 is unlikely to be involved as it displays no tidal distortions and has a much higher velocity than nearby NGC 4438.
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IIRC, Leland Copeland originally referred to NGC 4435/38 as “The Eyes” in descriptions of the pair back in the 1940’s.
No, but the buxom woman, across the street, thought that I was watching her!