Object Name: Messier 86
Alternative Designations: M86, NGC 4406
Object Type: Lenticular (S0) Galaxy
Right Ascension: 12 : 26.2 (h:m)
Declination: +12 : 57 (deg:m)
Distance: 60000 (kly)
Visual Brightness: 8.9 (mag)
Apparent Dimension: 7.5×5.5 (arc min)
Locating Messier 86: M86 and nearby M84, can be located by aiming almost exactly centered between Beta Leonis (Denebola) and Epsilon Virginis (Vindemiatrix). While you won’t catch them in the average finderscope, both galaxies can be seen in the same low (or medium) power eyepiece. Because this pair is bright and basic, it’s a great starhop starting point for observing the Virgo Cluster and other nearby Messier objects. For dark sky areas, the M84/86 pairing can often be spotted with smaller binoculars – and on clear, dark nights can easily be captured with larger ones. For telescope users, M86 will never have any definition because of its galactic type, but its high surface brightness qualities will make you appreciate it on those “less than perfect” nights.
What You Are Looking At: It’s heading our way… Messier 86 is the highest blue shift object in Charles’ entire catalog – is approaching us at 419 kilometers per second – or about 3 million miles per hour! “The supersonic motion of M86 produces pressure that is stripping gas from the galaxy and forming the spectacular tail. M86 has been pulled into the Virgo galaxy cluster and accelerated to a high speed by the enormous combined gravity of dark matter, hot gas, and hundreds of galaxies that comprise the cluster. The infall of the galaxy into the cluster is an example of the process by which galaxy groups and galaxy clusters form over the course of billions of years.” says C. Jones (et al). “The galaxy is no longer an “island universe” with an independent existence. It has been captured and its gas is being swept away to mix with the gas of the cluster, leaving an essentially gas-free galaxy orbiting the center of the cluster along with hundreds of other galaxies.”
With so many nearby galaxies – both visual and physical – it would almost be a given that any galaxy moving at such a reckless speed has got to be encountering its cluster members. Is it possible that M86 is catching others in its wake? “The environmental influence of cluster media on its member galaxies, known as Butcher-Oemler effect, has recently been subject to revision due to numerous observations of strong morphological transformations occurring outside the cluster virial radii, caused by some unidentified gas removal processes. In this context we present new XMM-Newton observations of M 86 group. The unique combination of high spatial and spectral resolution and large field of view of XMM-Newton allows an in-depth investigation of the processes involved in the spectacular disruption of this object.” says A. Finoguenov (et al of the Max Planck Institut. “We identify a possible shock with Mach number of 1.4 in the process of crushing the galaxy in the North-East direction. The latter is ascribed to the presence of a dense X-ray emitting filament, previously revealed in the RASS data. The shock is not associated with other previously identified features of M 86 X-ray emission, such as the plume, the north-eastern arm and the southern extension, which are found to have low entropy, similar to the inner 2 kpc of M 86. Finally, mere existence of the large scale gas halo around the M 86 group, suggests that the disruptions of M 86’s X-ray halo may be caused by small-scale types of interactions such as galaxy-galaxy collisions.”
History: M86 was discovered by Charles Messier in 1781. On the night of March 18 he writes: “Nebula without star, in Virgo, on the parallel and very near to the nebula above, No. 84: their appearances are the same, and both appear together in the same field of the telescope.”
The great Sir William Herschel would also observe M86 and felt he was able to get some resolution from this smooth, featureless galaxy. While we might not catch any details, his son John, also described some details: “Very bright; large; round; gradually brighter toward the middle where there is a nucleus; mottled.” One can only wonder how these great observers would have reacted had they known everything we know about things like Messier 86 today!
Enjoy your galaxy cluster adventures…
Top M86 image credit, Palomar Observatory courtesy of Caltech, M86 Chandra Image, M86 XMM Newton image and M86 color image courtesy of NOAO/AURA/NSF.