Musca the Fly and the Chamaeleon

"I know you have fallen in love

with the proud star Canopus of Carina.

You hope to become nicer,

that is the reason

you always change your colors.

Sorry for your illusions,

I must be sincere:

you are just a starry lizard,

and Canopus will always be

above you.

But...dream poor Chamaeleon!

Who knows...?"

Chamaeleon by Andrei Dorlan Gheorghe (2003)

Musca appeared on Lacaille's chart of 1763, having originally been designated as Apis the Bee by Bayer 160 years earlier. It owes it's invention to Pieter Keyser and Frederick de Houtman sometime after 1595. Lying directly south of Crux, it is made up of a group of prominent stars, the brightest alpha at magnitude 2.7. Though a relatively small constellation of 132 sq. degrees, it has a number of interesting double stars and deep sky objects to keep the observer busy.

Alpha is a hot B2-type subgiant lying around 430 light years distant. It has a computed luminosity of 1200 Suns and appears to be slightly variable, ranging from magnitude 2.66 to 2.73. It has 9 times the Sun's mass and 5 times its radius.

Southeast of alpha lies the Cepheid variable star R Muscae. This yellow star fluctuates in brightness from magnitude 5.93 to 6.73 within a period of 7.5 days.

Beta Muscae is a blue-white star, shining prominently at 3rd magnitude. High telescopic magnification will split this star into 2 equal components of 4th magnitude, separated by a relatively close 1.6". Distance figures vary from 290 to 470 light years. If this last figure is taken, then beta has a computed luminosity of around 580 Suns.

Epsilon is a 4th magnitude red giant and marks the right wing of our Fly. The left wing is represented by magnitude 3.6 delta, an orange giant. Completing this field is 3.8 magnitude gamma, a B-type main sequence star marking Musca's tail

The lovely double star h4498 with components of magnitude 7.0 and 8.0 lies in a busy field. They appear yellow and white, in fine contrast with one another. The brighter member has a very close companion unresolved in amateur telescopes with a very close 0.1" separation.

Another fine star system with a similar colour contrast is theta Muscae. It too lies within a rich star field. Their respective magnitudes are 5.7 and 7.3 and spectral class is WC6 (Wolf Rayet star) and O9. The wide O9 companion is not bound to the system but line of sight only. The Wolf Rayet star has two close unseen O-type companions.

There are two globular clusters in Musca, one fairly difficult because of its faint and loose concentration. Starting with the easier of the two, NGC 4833 is fairly compact but easily resolved, many of the stars appearing in small curves and arcs. A magnitude 8.7 foreground star lies on the northern edge. Look for this cluster 42' to the north northwest of delta Muscae.

By contrast, search for NGC 4372. Discovered by James Dunlop on April 30 1826, this 'shy' and unobtrusive globular is difficult to detect with a cursory glance. The difficulty is with the obscuration by interstellar dust, rather heavy in this region, thereby rendering the stars rather faint. The bright star HD 107947 of magnitude 6.8 lies close and does the observer no favour. Its dazzling glare all but overwhelms this cluster. If this star is put out of the eyepiece field, the globular may be seen to the south as a large scattering of loosely clustered stars, reminiscent of an open cluster.

Near NGC 4372 lies the Dark Doodad Nebula, a dusty cloud that stretches around 3 degrees in length and a good target for binoculars. Part of the Musca molecular cloud, it received it's name from Dennis di Cicco in 1986.

Image from Uranometria 2000.0 Deep Sky Atlas

IC 4191 is a small planetary nebula with a bright blue disk, making it easily picked out from the surrounding stars. There is an orange star of magnitude 6.4 nearby to the south as a guide.

Sir John Herschel discovered an unusual gaseous nebula in 1835 , describing it as "a very strange object". NGC 5189 lies in the northeastern corner of Musca, close to neighbouring Circinus and Centaurus. The star field here is very beautiful and the object itself appears pretty bright with some structure evident. Telescopes in the 30cm plus range will show a gaseous 'S' shape with a distinct blue or green-blue colour to the overall nebula.

Classified for many years as a gaseous nebula, it is now catalogued as a planetary nebula residing some 3,000 light years from our Sun. There are 4 stars seemingly immersed within the 0.45 solar mass nebula including the star that gave rise to NGC 5189. This off centre WC8 Wolf Rayet star has an extremely close white dwarf companion that orbits the main star every 4.04 days.

Staying within sight of NGC 5189, there is a double star nearby. Look for the brightest object to it's west. LDS 444 is a lovely yellow double discovered by J. Luyten. It can be resolved in a 20cm mirror, the components of magnitude 8.6 and 8.9 are separated by 2.9".

Another planetary nebula worth discovering is MyCn 18, The Hourglass Nebula. Lying 1.5 degrees to the south southeast of NGC 5189, a 20cm mirror will struggle somewhat with this small and faint glow. Lying 8,000 light years distant, it was discovered by Annie Jump Cannon and Margaret W. Mayall whilst working on an extension to the Henry Draper Catalogue.

Born from a star similar to our own, it's nuclear resources have been exhausted and the outer layers of this once vibrant star have been puffed off to enrich the imagination of observers who seek it.

It took the Hubble Space Telescope to unlock the secret beauty of this celestial 'jewel'. Raghvendra Sahai and John Trauger uncovered the now distinct 'houglass' shape. National Geographic probably captured the thought of many when they featured it on the cover of their April 1997 edition, writing "Astronomers looked 8,000 light years into the cosmos with the Hubble Space Telescope and it seemed that the eye of God was staring back."

Musca does not have many enemies though one does provide enough menace to put the little fly on edge. Careful flight is a must as Musca flies through this region for the heavenly lizard lies in wait. Yes, the Chamaeleon lies very patient and still as Musca buzzes above, waiting to pounce. With not much in the way of tasty morsels here, who can blame the Chamaeleon's indulgence.

Chamaeleon is one of Pieter Keyser and Fredrick de Houtman's constellations, appearing alongside Musca on Johann Bayer's Uranometria. Only 132 square degrees in size, the stars here are rather faint with the brightest alpha at magnitude 4. Lying around 78 light years distant, this F6 subgiant appear creamy in colour.

Gamma is a red star of spectral class M, shining at magnitude 4.1 and lying around 250 light years away. Of more interest is delta1 and delta2. Delta1 is an orange giant of magnitude 5.4 and has a computed distance of 360 light years. It is a double star of magnitudes 6.0 and 6.5, however the separation is very close at 0.6" so is very difficult. Delta2 is an optical companion only but with a blue-white hue of magnitude 4.6. It is in lovely contrast to delta1.

NGC 3195 is a planetary nebula discovered by Sir John Herschel in 1835. It appears to the eye as a bluish and evenly lit round glow, spanning 30" in diameter and similar in size to Jupiter.

An open cluster of faint scattered stars around eta was discovered through xray observations in 1999. Named Mamajek1 or the eta Chamaeleontis Cluster, it lies around 316 light years from our Sun. In an article published in The Astrophysical Journal, the authors wrote "...the eta Cha cluster is far from any significant molecular cloud and thus has mysterious origins. The cluster appears to share proper motions with other young stars in the Chamaeleon region and may be a compact extension of the Sco-Cen OB association."

Don't expect to see much here as the stars are faint and only mentioned here for interest sake.