2MASS Picture of the Week Archive Captions

Atlas Image Mosaic, covering 10.0´ × 10.0´ on the sky, of the HII region W48. There is no optical counterpart to this radio emission region, due to its proximity to the Galactic plane, its distance of 3.4 kpc (11084 light years), and about 23 visual magnitudes of extinction (Vallee & MacLeod 1990, ApJ, 358, 183), but it is obvious in the 2MASS near-infrared image. The center of W48 is still heavily obscured, with dark dust lanes running through it. W48 is at the edge of more extended molecular gas cloud. The dusty nebula appears to be the site of ongoing massive star formation. Image mosaic by S. Van Dyk (IPAC).


Atlas Image Mosaic, covering 7.0´ × 7.0´ on the sky, of the carbon star IRAS 06088+1909. Carbon stars are evolved stars, similar to the Sun, which are nearing the ends of their lives, in the so-called asymptotic giant branch phase. Many form dusty, carbon-rich envelopes, due to mass loss, which makes the very red in color, especially in the near-infrared. IRAS 06088+1909 is a very dusty carbon star toward the Galactic anticenter (Jura & Kleinmann 1990, ApJ 364, 663). 2MASS is particularly sensitive to carbon stars. Liebert et al. (2000, PASP, 112, 1315) report on several very cool carbon stars in or beyond the Galactic halo, some of which are heavily dust enshrouded. They conclude that 2MASS can be used to define a useful sample of carbon stars at high Galactic latitude as tracers of the halo out to distances comparable to the Magellanic Clouds. In the 2MASS image, the fainter reddish "stars" immediately east of due north and west of due south of both IRAS 06088+1909 and the bluer bright star to its northeast are known 2MASS "filter glint" artifacts; known diffraction spike and persistence artifacts are also seen associated with these two bright stars. Image mosaic by S. Van Dyk (IPAC).


Atlas Image Mosaic, covering 13.0´ × 13.0´ on the sky, of the galaxy IC 10, a member of the Local Group of galaxies, which includes the Milky Way. IC 10 is a dwarf irregular galaxy; dwarfs are smaller, as their name implies, and contain less mass than giant elliptical and spiral galaxies, such as our own Galaxy. The irregulars have little ordered morphology, are typically gas-rich, and show evidence for ongoing star formation, i.e., hot, blue stars, HII regions, and dust. Including the Magellanic Clouds, there are 9 dwarf irregular out of 35 member galaxies in the Local Group (van den Bergh 1999, A&ARev, 9, 273). IC 10 is at a distance of 500-660 kpc (1.6-2.2 million light years; Sakai, Madore, & Freedman 1999, ApJ, 511, 671) and low galactic latitude (b=-3.3°); the high visual extinction to the galaxy leads to the uncertainty in its distance. 2MASS is not particularly sensitive to dwarf galaxies, due to their generally low surface brightness. In the case of the Local Group dwarfs, however, individual stars, e.g., bright carbon and asymptotic giant branch stars, are resolved and measured by 2MASS. Image mosaic by S. Van Dyk (IPAC).


Atlas Image Mosaic, covering 7.0´ × 7.0´ on the sky, of the high-mass star formation region NS 14, also known as RAFGL 5216, BFS 57, and BIP 14. NS 14 is the region to the south in the image (BFS 56 is the smaller star formation region to the north). First identified by Neckel & Staude (1984, A&A, 131, 200) as a bipolar nebula at a distance of 2.3 kpc (7500 light years), NS 14 is excited by four stars closely packed toward the brighter center of the nebula, in an ultracompact HII region. A dense dust lane, or torus, bisects the nebula, giving it a bipolar appearance. Howard, Pipher, & Forrest (1998, ApJ, 509, 749) recently imaged the region in the near-infrared, studying the stellar population of the cluster. Click here to obtain a color-color diagram for NS 14, based on 2MASS photometry. Image mosaic by S. Van Dyk (IPAC).


Atlas Image, covering 5.0´ × 5.0´ on the sky, of the planet Pluto. In IAU Circular No. 7518, Sykes et al. (2000) report the detection and photometry of Pluto obtained by the 2MASS Southern Facility on 1999 April 10.33 UT, at J = 12.78, H = 12.62, and Ks = 12.92.































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