We report on observations of the three-dimensional structure of a sunspot magnetic field from the photosphere to the chromosphere, obtained with the new visible/infrared spectropolarimeter SPINOR. The observations, interpreted with a non-LTE modeling technique, reveal a surprisingly complex topology with areas of opposite-sign torsion, suggesting

We report follow-up observations confirming the near-infrared (NIR) counterpart to the X-ray transient XTE J1747-274/IGR J17473-2721 (ATEL #467, #498). A Ks=16.2 mag candidate was suggested in ATEL #521 on the basis of its coincidence with the Chandra localization for the X-ray source. The candidate appeared extended and/or blended with a nearby

We present results from the most recent (2002-2004) observing campaigns of the eclipsing system KH 15D, in addition to rereduced data obtained at Van Vleck Observatory (VVO) between 1995 and 2000. Phasing 9 yr of photometric data shows substantial evolution in the width and depth of the eclipses. The most recent data indicate that the eclipses are

We present the first automated fitting method for the quantitative spectroscopy of O- and early B-type stars with stellar winds. The method combines the non-LTE stellar atmosphere code fastwind from Puls et al. (2005, A&A, 435, 669) with the genetic algorithm based optimization routine pikaia from Charbonneau (1995, ApJS, 101, 309), allowing for a

Resonantly damped fast kink quasi-modes are computed in fully resistive magnetohydrodynamics (MHD) for two-dimensional equilibrium models. The equilibrium model is a straight cylindrically symmetric flux tube with a plasma density that is non-uniform both across and along the loop. The non-uniform layer across the loop is not restricted to be thin

An X-ray transient was detected in outburst on 18 October 2005 during one of our Chandra/HRC-I observations as part of the XMM-Newton/Chandra monitoring campaign of the 1.7 square degree around Sgr A* (Wijnands et al. 2005, A&A submitted, astro-ph/0508648). The source was located ~15 arcminutes away from the aim-point which did not allow a sub