Search Publications
Simulated magnetic flows in the solar photosphere
Solanki, S. K.; Danilovic, S.; Cameron, R. H.
Context. Recent Sunrise/IMaX observations have revealed supersonic magnetic flows.
Aims: Our aim is to determine the origin of these flows by using realistic magnetohydrodynamics simulations.
Methods: We simulated cancellation and emergence of magnetic flux through the solar photosphere. Our first numerical experiment started with a magn…
New Mn II energy levels from the STIS-HST spectrum of the HgMn star HD 175640
Castelli, F.; Kurucz, R. L.; Cowley, C. R.
Aims: The NIST database lists several Mn ii lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700 Å interval. We aimed to assign energy levels and log gf values to these lines.
Methods: Semi-empiric…
Evolution of the central stars of young planetary nebulae
Zijlstra, A. A.; van Hoof, P. A. M.; Hajduk, M.
Aims: The evolution of central stars of planetary nebulae was so far documented in just a few cases. However, spectra collected a few decades ago may provide a good reference for studying the evolution of central stars using the emission line fluxes of their nebulae. We investigated evolutionary changes of the [O iii] 5007 Å line flux in the …
Magnetic balltracking: Tracking the photospheric magnetic flux
Innes, D. E.; Attie, R.
Context. One aspect of understanding the dynamics of the quiet Sun is to quantify the evolution of the flux within small-scale magnetic features. These features are routinely observed in the quiet photosphere and were given various names, such as pores, knots, magnetic patches.
Aims: This work presents a new algorithm for tracking the evoluti…
Mid-J CO shock tracing observations of infrared dark clouds. I.
Johnstone, D.; Caselli, P.; Jiménez-Serra, I. +5 more
Infrared dark clouds (IRDCs) are dense, molecular structures in the interstellar medium that can harbour sites of high-mass star formation. IRDCs contain supersonic turbulence, which is expected to generate shocks that locally heat pockets of gas within the clouds. We present observations of the CO J = 8-7, 9-8, and 10-9 transitions, taken with th…
The infrared massive stellar content of M 83
Whitmore, B. C.; Bonanos, A. Z.; Prieto, J. L. +2 more
Aims: We present an analysis of archival Spitzer images and new ground-based and Hubble Space Telescope (HST) near-infrared (IR) and optical images of the field of M 83 with the goal of identifying rare, dusty, evolved massive stars.
Methods: We present point source catalogs consisting of 3778 objects from Spitzer Infrared Array Camera (…
An imaging and spectroscopic study of the planetary nebulae in NGC 5128 (Centaurus A). Planetary nebulae catalogues
Rejkuba, M.; Walsh, J. R.; Walton, N. A.
Context. Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy, offers the possibility to gather a large sample.
Aims: Imaging and spectroscopic o…
Revealing a hard X-ray spectral component that reverberates within one light hour of the central supermassive black hole in Ark 564
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +4 more
Context. Arakelian 564 (Ark 564, z = 0.0247) is an X-ray-bright narrow-line Seyfert 1 galaxy. By using advanced X-ray timing techniques, an excess of "delayed" emission in the hard X-ray band (4-7.5 keV) following about 1000 s after "flaring" light in the soft X-ray band (0.4 - 1 keV) was recently detected.
Aims: We report on the X-ray spectr…
Pre-hibernation performances of the OSIRIS cameras onboard the Rosetta spacecraft
Barbieri, M.; Jorda, L.; Sierks, H. +12 more
Context. The ESA cometary mission Rosetta was launched in 2004. In the past years and until the spacecraft hibernation in June 2011, the two cameras of the OSIRIS imaging system (Narrow Angle and Wide Angle Camera, NAC and WAC) observed many different sources. On 20 January 2014 the spacecraft successfully exited hibernation to start observing the…
Infrared dark clouds on the far side of the Galaxy
Menten, K. M.; Csengeri, T.; van der Tak, F. F. S. +5 more
Context. Infrared dark clouds are the coldest and densest portions of giant molecular clouds. The most massive ones represent some of the most likely birthplaces for the next generation of massive stars in the Milky Way. Because a strong mid-IR background is needed to make them appear in absorption, they are usually assumed to be nearby.
Aims…