Fornax - the Furnace

The brightest star in Fornax is alpha at magnitude 3.86. Lying at a distance of 40 light years, this creamy star was observed by Sir John Herschel in 1835 and found to be double. The primary star is a subgiant of class F8, its 7th magnitude companion lying only 2” away, hiding in its glare. The magnitude difference between it and the primary, about 3 magnitudes (or 15x fainter) makes resolution difficult at the best of times. The secondary is also suspected to be a long period variable, with a range of 2 magnitudes, though it has been near maximum for some years now.

The unusual planetary nebula NGC 1360 shouldn't be missed, its large bright elliptical glow enclosing an 11th magnitude central star. Lying around 1000 light years away, the central area appears brighter and an uninvolved 9th magnitude star lies on the eastern edge. Curiously missed by both Dunlop and Sir John Herschel, it was discovered by Lewis Swift in 1857 and later by Winnecke. James Kaler recorded it as:

“…a most unusual object, one of the few known large, high-excitation planetaries…analysis of the spectrum sets a lower limit for the central star’s temperature of 85,000° K and the luminosity is at least 540 times that of the Sun…from it’s brightness and angular diameter (over 6 arc minutes) I estimate that NGC 1360 is 1,100 light years away. It’s diameter is over 2 light years, roughly twice as big as the famous Ring Nebula in Lyra and about half the size of the largest planetaries known.”

Edwin Hubble, photographing the sky in 1939, stumbled across a large conglomeration of faint stars hidden among many brighter foreground Milky Way stars. This group, known as a dwarf elliptical galaxy, lies at a distance somewhere between 600,000 and 800,000 light years, being a member of what is known as the Local Group. Its 19th magnitude and fainter stars, spanning a diameter of 15,000 light years, make visual observation next to impossible. There are only 7 of these galaxies known, though they are suspected to be fairly common in the universe. There are 5 globular clusters within this system, the brightest being NGC 1049, appearing as an 11th magnitude hazy starlike object with a brighter centre.

NGC 1097 is arguably the nicest galaxy in this region, being a barred spiral oriented almost face-on and appearing bright in the smallest of apertures. It lies around 2º north-northwest of beta, easy in a finderscope. Using medium powers on this delight, around 100x for a 20cm mirror, you may discover two faint spiral arms trailing off each end of the bar. Those with larger mirrors should look 2’ northwest of this galaxy’s northern spiral arm and discover a tiny faint elliptical galaxy, NGC 1097A.

NGC 1365 is another beautiful barred spiral galaxy, oriented face-on, and superb in larger telescopes. Discovered by Sir John Herschel and described by him as:

“A very remarkable nebula. A decided link between the nebula M51 and M27. Centre very bright; somewhat extended, gradually very much brighter to the middle: a 13th magnitude star near the edge of the halo involved. The area of the halo very faint; general position of the longer axis 20.8 whole breadth = 3’.”

Hartung writes:

“…this barred spiral is the best object of its type for the southern observer. Photos disclose very well-marked bar features in an elliptical system 6.8’ x 3.2’ which 30cm shows as a bright round diffuse centre across which is a broad faint bar about 3’ long in PA 70 deg. From the ends of this come streams of faint nebulosity, from the preceding end in PA 20 deg. And from the following end in PA 200 deg, so that the general shape is that of a large open imperfect ellipse with dark areas on either side of the bar. Smaller apertures show correspondingly less but 15cm indicates the bright central region clearly.”

The bar across this galaxy appears bright and the spiral arms are there though not as bright as NGC 1097. A 25cm telescope should show this structure but a 15cm will probably show the bar surrounded by a faint round glow.

In the southeast corner of Fornax lies the Fornax Galaxy Cluster, a group of about 18 brightish galaxies and many fainter members. Lying at a probable distance of 100 million light years, this region is a delight to wander in. Forget about star hopping, the latest craze here is galaxy hopping. A wide field eyepiece giving a 1º field of view will enclose 9 of the brighter galaxies within its borders. NGC 1380, 1374, 1379, 1381, 1386, 1387, 1389 and the two very bright elliptical galaxies, NGC 1399 and 1404.

NGC 1380 is a spiral, appearing large and round with a brighter central area. Herschel saw it as:

‘…a very bright; large; round; pretty suddenly brighter towards the middle. A fine nebula.”

NGC 1374 is a small, bright and round glow with a brighter central region. Two faint galaxies lie in the same field, NGC 1373 and NGC 1375. NGC 1379 appears round with a bright core region and lies near two others, NGC 1381 and NGC 1387.NGC 1381 is a small and faint elliptical glow of light with a brighter middle. NGC 1387 was recorded by Herschel as:

“globular cluster, vB, R, gmbM, 90 arcseconds…”

It appears to the telescope as a small round glow with a bright centre. NGC 1389 is a small, faint and round galaxy with a much brighter middle. NGC 1386 is a large and extended galaxy, faint with a brighter central core. The two brightest galaxies in this region are the ellipticals NGC 1399 and NGC 1404. The latter is very prominent, appearing round with a much brighter central region and some mottling across its face. NGC 1399 appears larger than its neighbour though still bright and easy with a brighter middle. Both NGC 1399 and NGC 1404 are displayed well in small telescopes and contrast well with the surrounding star field.

Another galaxy worth hunting down is NGC 1427 about 1º east of NGC 1399. It is an elliptical galaxy appearing as an elongated faint haze with some hint of central brightening. Larger instruments do better with this one.

The brightest galaxy in Fornax is NGC 1316 (Fornax A), a barred spiral of a peculiar type. Similar in type to NGC 5128 (Centaurus A) in Centaurus, it is a source of intense radio energy. Only 6’ away to the north lies the faint small galaxy NGC 1317, easy to overlook for those impatient ‘tourists’ eager for instant gratification. Patience can be a virtue.

NGC 1255 is a bright spiral galaxy around 3.5º north of the bright star alpha. It is easily seen in small apertures under a dark sky while medium telescopes will show a bright nucleus encircled by a mottled glow. Other galaxies worth observing are the spiral NGC 1406, the barred spiral NGC 1371, the spiral NGC 1385 and the bright barred spiral NGC 1398.