Association of mid-infrared solar plages with Calcium K line emissions and magnetic structures

Solar mid-IR observations in the 8-15 micrometer band continuum with moderate angular resolution (18 arcseconds) reveal the presence of bright structures surrounding sunspots. These plage-like features present good association with calcium CaII K1v plages and active region magnetograms. We describe a new optical setup with reflecting mirrors to produce solar images on the focal plane array of uncooled bolometers of a commercial camera preceded by germanium optics. First observations of a sunspot on September 11, 2006 show a mid-IR continuum plage exhibiting spatial distribution closely associated with CaII K1v line plage and magnetogram structures. The mid-IR continuum bright plage is about 140 K hotter than the neighboring photospheric regions, consistent with hot plasma confined by the magnetic spatial structures in and above the active regionComment: 5 pages, 4 figures. Accepted by PAS

Narrow-line magneto-optical cooling and trapping of strongly magnetic atoms

Laser cooling on weak transitions is a useful technique for reaching ultracold temperatures in atoms with multiple valence electrons. However, for strongly magnetic atoms a conventional narrow-line magneto-optical trap (MOT) is destabilized by competition between optical and magnetic forces. We overcome this difficulty in Er by developing an unusual narrow-line MOT that balances optical and magnetic forces using laser light tuned to the blue side of a narrow (8 kHz) transition. The trap population is spin-polarized with temperatures reaching below 2 microkelvin. Our results constitute an alternative method for laser cooling on weak transitions, applicable to rare-earth-metal and metastable alkaline earth elements.Comment: To appear in Phys. Rev. Lett. 4 pages, 5 figure