2MASS Picture of the Week Archive Captions
Atlas Image mosaic, covering 6´ × 6´ on the sky of IRAS 17244-3536. This appears to be a region of high gas density, which is a source of CS molecular emission (Chan, Henning, & Streyer 1996, A&AS, 115, 285), where one or more young massive stellar objects are forming. Little else is known about IRAS 17244-3536. Image mosaic by S. Van Dyk (IPAC).


Atlas Image mosaic, covering 7´ × 7´ on the sky of the lenticular (S0) galaxy, Messier 102 (M102). Or is it??? As the Students for the Exploration and Development of Space (SEDS) page indicates, M102 is the most mysterious of the Messier objects. It is thought that the designation is either a 'bookkeeping' error made by Charles Messier, being a duplicate referral to the giant spiral M101, or it refers to this early-type lenticular galaxy, NGC 5866, aka the Spindle Galaxy. Lenticular, or S0, galaxies are intermediate in Hubble type to elliptical galaxies, such as M87, and early-type spiral galaxies, such as M31, in that the light from S0's is dominated by a large bulge of old stars, and yet these galaxies also possess a stellar disk, like spirals, although the prominent spiral arms seen in spiral galaxies are no longer prominent in S0's. (The smooth near-infrared light seen in the 2MASS image is dominated by the old stars in both the bulge and disk of the Spindle.) The properties of S0 galaxies, like the true identity of M102, will likely be a subject of intense study by astronomers into the future. Image mosaic by S. Van Dyk (IPAC).


Atlas Image mosaic, covering 10´ × 10´ on the sky of the HII, or ionized hydrogen, region RCW 122, aka BFS 65. See the 2MASS color-color and color-magnitude diagrams for the embedded star cluster. Image mosaic by S. Van Dyk (IPAC).


Atlas Image mosaic, covering 8´ × 8´ on the sky of the emission-line star V1735 Cygni, aka Elias 1-12 and IRAS 21454+4718. The star is a FU Orionis-like variable discovered by Elias (1978, ApJ, 223, 859). FU Ori stars are protostellar, or pre-main sequence, objects likely surrounded by a disk of accreting matter, with an outflowing, outbursting wind. These objects are similar to T Tauri. V1735 Cyg is heavily embedded in a dark molecular cloud, also associated with the nebula and young stellar cluster IC 5146. Image mosaic by S. Van Dyk (IPAC).


Atlas Image mosaic, covering 6´ × 6´ on the sky of the planetary nebula Messier 76 (M76), aka NGC 650/651, and the Little Dumbbell, or Cork, Nebula. The nebula has a striking bipolar appearance, although it is faint and diffuse in the 2MASS image. Planetary nebulae are formed as low-mass stars, like our Sun, and stars somewhat more massive, reach the end of their lives and lose their outer envelopes to the interstellar medium. Abundances of chemical elements in the nebula indicate that the dying star may have been at the upper mass range of those stars which end as planetaries. The central star, which is seen faintly near the center of the nebula, is quite hot and was originally the core of the dying star. It will eventually become a white dwarf and cool off over billions of years. Image mosaic by S. Van Dyk (IPAC).

































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