Object of the Week - Jan 28th, 2018 - NGC 4395 = UGC 7524 = MCG 6-27-53 = PGC 40596 in Canes Venatici
R.A.: 12h25m49.0s Dec.: +33°32'49"
Apparent size of 13.2 by 11.0 arcmin
Magnitude: 10.80 B
Type; SABdm C (per Simbad)
NGC 4395 was discovered on Jan 2, 1786, by William Herschel and is the second largest galaxy in the CVn I galaxy group, with only NGC 4244 being larger. It is a tumultuous oddball galaxy, with several bright ionized hydrogen (HII) regions, three of which received their own NGC designations, those being NGC 4399, NGC 4400, and NGC 4401. Here is a labeled DSS pic…
NGC 4395 has a recessional velocity of only about 320 km/sec, which corresponds to a distance of about 15 million light years, fairly close as galaxies go, and this calculates to a diameter of about 55,000 light years, or about ½ the diameter of our own Milky Way Galaxy. NGC 4395 has a couple of very interesting features. While it is very unusual for a Magellanic spiral (Sm) to host an Active Galactic Nucleus (AGN), NGC 4395 holds the distinction of containing the faintest and nearest Seyfert nucleus currently known, as well as one of the intrinsically weakest nuclear x-ray sources observed to date (Ho & Ulvestad, 2001). Nearly all galaxies are known to contain a supermassive black hole in the center, and NGC 4395 has one of the smallest known such black holes, being six times smaller than the one at the center of our own Milky Way Galaxy.
Visually, NGC 4395 is a very low surface brightness spiral galaxy, and it takes a little work to fully appreciate it all. In my 25” dob, using a 106X eyepiece it took a while before I could hold the full extent of the galaxy with direct vision. Using higher power, the central core is still pretty dim, but is bigger and brighter than any of the HII knots, which are all faint and small, and barely detectable. Without a good reference photo I would have been lost.
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