Search Publications
A New Code for Nonlinear Force-free Field Extrapolation of the Global Corona
Feng, Xueshang; Jiang, Chaowei; Xiang, Changqing
Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolations from photospheric magnetograms using physical models, e.g., the nonlinear force-free field (NLFFF) model that is usually adopted. Most of the current…
V900 Mon and Thommes' Nebula: A New FUor in Monoceros
Reipurth, Bo; Aspin, Colin; Herbig, G. H.
Detailed observations of a recently recognized eruptive variable, V900 Mon, are presented. The star is located in the small cloud L1656, a little-studied region of modest star formation activity in Monoceros, and is presently at a magnitude of r ~ 16, surrounded by a bright compact reflection nebula, where only a 20th magnitude star was seen on th…
Spatial gradients from irregular, multiple-point spacecraft configurations
Dunlop, M. W.; Rème, H.; Liu, Z. X. +8 more
We present a generalized multipoint analysis of physical quantities, such as magnetic field and plasma flow, based on spatial gradient properties, where the multipoint data may be taken by irregular (distorted) configurations of any number of spacecraft. The methodology is modified from a previous, fully 3-D gradient analysis technique, designed t…
Globular cluster systems of early-type galaxies in low-density environments
Blakeslee, J. P.; Sharples, R. M.; Kundu, A. +4 more
Deep images of 10 early-type galaxies in low-density environments have been obtained with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The global properties of the globular cluster (GC) systems of the galaxies have been derived in order to investigate the role of the environment in galaxy formation and evolution. Using …
Keck/NIRC2 Imaging of the Warped, Asymmetric Debris Disk around HD 32297
Currie, Thayne; Debes, John; Robitaille, Thomas +8 more
We present Keck/NIRC2 Ks -band high-contrast coronagraphic imaging of the luminous debris disk around the nearby, young A star HD 32297 resolved at a projected separation of r = 0farcs3-2farcs5 (≈35-280 AU). The disk is highly warped to the north and exhibits a complex, "wavy" surface brightness (SB) profile interior to r ≈ 110 AU, wher…
A catalog of extended clusters and ultra-compact dwarf galaxies. An analysis of their parameters in early- and late-type galaxies
Kroupa, P.; Brüns, R. C.
Context. In the past decade, very extended old stellar clusters with masses in the range from a few 104 to 108 M⊙ and effective radii larger than 10 pc have been found in various types of galaxies in different environments. Objects with masses comparable to normal globular clusters (GCs) are called extended cluster…
Destruction of Sun-Grazing Comet C/2011 N3 (SOHO) Within the Low Solar Corona
Schrijver, C. J.; Battams, K.; Brown, J. C. +4 more
Observations of comets in Sun-grazing orbits that survive solar insolation long enough to penetrate into the Sun's inner corona provide information on the solar atmosphere and magnetic field as well as on the makeup of the comet. On 6 July 2011, the Solar Dynamics Observatory (SDO) observed the demise of comet C/2011 N3 (SOHO) within the low solar…
An upper limit for the water outgassing rate of the main-belt comet 176P/LINEAR observed with Herschel/HIFI
Küppers, M.; Hartogh, P.; Lellouch, E. +15 more
176P/LINEAR is a member of the new cometary class known as main-belt comets (MBCs). It displayed cometary activity shortly during its 2005 perihelion passage, which may be driven by the sublimation of subsurface ices. We have therefore searched for emission of the H2O 110-101 ground state rotational line at 557 GHz…
The abundance and vertical distribution of the unknown ultraviolet absorber in the venusian atmosphere from analysis of Venus Monitoring Camera images
Esposito, Larry W.; Molaverdikhani, Karan; McGouldrick, Kevin
Observations of Venus using the ultraviolet filter of the Venus Monitoring Camera (VMC) on ESA's Venus Express Spacecraft (VEX) provide the best opportunity for study of the spatial and temporal distribution of the venusian unknown ultraviolet absorber since the Pioneer Venus (PV) mission. We compare the results of two sets of 125 radiative transf…
Transport of thermal-energy ionospheric oxygen (O+) ions between the ionosphere and the plasma sheet and ring current at quiet times preceding magnetic storms
Peterson, W. K.; Yau, Andrew W.; Abe, Takumi +1 more
The presence of energetic O+ ions in the ring current at the onset of a magnetic storm prompts the question of the possible role of “in-transit” ionospheric O+ ions between the ionosphere and the plasma sheet and ring current in the quiet periods immediately preceding the main phase of a magnetic storm. Thermal-energy O+…