Constellation of the Month - Pictor

Albert Brakel

Pictor is one of those corners of the sky that does not rate as a treasure house of goodies, but what it does contain is there to be seen. Lying just to the west and south of Canopus it is easy to locate, but its stars have no readily recognizable pattern.

The constellation started life as Equuleus Pictoris (the Painter's Easel), and was one of a number of constellations created by 18th Century astronomer La Caille (or Lacaille) to commemorate various artisan's tools - others are Caelum, Fornax, Circinus and Norma. The name was later shortened so that it became the Painter instead of his easel - it couldn't be called Equuleus because there was already a northern constellation of that name.

Beta Pictoris was one of the first stars found to be surrounded by a disk of dust by the IRAS satellite in 1984. The disk cannot be detected by amateur instruments of course. It is edge-on, 25" across, and has a hole in the centre about the size of the orbit of Pluto; in other words, a solar system the size of ours would fit neatly inside it. Last year the Hubble Space Telescope discovered that the inner edge of the disk is warped, apparently by a planet at least as big as Jupiter. The orbital period is not known.

Iota Pictoris (RA 4h 50.9m, -53 28') is a nice bright, wide, easy pair of pale yellowish stars, one a bit brighter than the other (mags. 5.6 and 6.5). With a separation of 12.5", it can be split by any telescope.

Less than a degree ENE of Iota Pic. you can try for the mag. 12.3 lenticular galaxy NGC 1705 (4h 54.2m, -53 22') if you have a dark sky. It eluded me in the light-polluted sky of suburban Canberra. The galaxy is 1.4' x 1.8' in size, and should appear as a dim oval of light.

Five degrees to the ENE, on a line between Iota and Beta, is Theta Pic (5h 24.8m, -52 19'), a very wide binary (38") and another very easy one to resolve. The white stars are mag. 6.3 and 6.8. The easterly component is itself a close double, but is currently way beyond amateur resolution.

The double Mu Pic (6h 32.0m, -58 45') can be found 6 deg. S of Canopus. The mag 5.8 and 9.3 white components lie 2.4" apart and are not terribly easy to split because of the magnitude difference, but careful inspection will show them if the seeing permits. I just managed it with 117x on a C8, but it was (of course) better with higher powers. On another night, 154x only showed them as elongate, and 235x was required to just split them.

In the northern reaches of the constellation, 8.5 deg. NW of Beta Pic, lies an 8.8 mag. red dwarf that would not merit special attention were it not for the fact that it is the second fastest star in the sky (after Barnard's Star in Ophiucus). Named after the Dutch astronomer Jacobus Kapteyn who discovered it, Kapteyn's Star (5h 11.4m, -44 56') was for some years the fastest star known. It moves 8.7" per year, or a degree every 414 years. This is because it moves through space at 280 km/second (compared to our Sun's 20 km/sec), as well as being fairly close at 12.7 light years. This region of the sky is not the easiest to navigate in if you're starhopping, because there are no really bright stars around, but once in the right area, Kapteyn's Star can be recognized by its color and as a member of one of three fairly wide optical pairs that lie near each other.