We present deep optical imaging of three face-on disk galaxies together with a detailed description of the reduction and calibration methods used, in order to measure the intrinsic shape of their outer stellar edges. Whereas it is now well accepted that disks of spiral galaxies are not infinite exponential beyond galactocentric distances of about 3

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The solar chromosphere is an important boundary, through which all of the plasma, magnetic fields and energy in the corona and solar wind are supplied. Since the Zeeman splitting is typically smaller than the Doppler line broadening in the chromosphere and transition region, it is not effective to explore weak magnetic fields. However, this is not

Airglow in a planetary atmosphere is diagnostic of the combined effects of transport, both vertical and horizontal, and chemistry. Airglow emission on the night side in the OH(3-2, 2-1, 2-0, and 1-0), O2(c-X and a-X), and NO(C-A) bands has been reported in the past two years based on observations by VIRTIS on Venus Express [1,2,3]. Previous

The dynamic properties of the quiet Sun photosphere can be investigated by analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic elements). By using 25 h-long Hinode magnetograms at high spatial resolution (0.3 arcsec), we tracked 68 490 magnetic element pairs within a supergranular cell near the disk center. The computed

The behavior of charged particles near X-type magnetic neutral lines is investigated. The magnetic field is taken to be hyperbolic and time stationary, with a uniform electric field perpendicular to the magnetic field. The general properties of the orbits of noninteracting particles in that field geometry are examined. Approximate analytic