Search Publications
Intranight optical variability of γ-ray-loud narrow-line Seyfert 1 galaxies
Stalin, C. S.; Yadav, R. K. S.; Pandey, S. B. +4 more
The Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope has detected γ-ray emission in about half a dozen narrow-line Seyfert 1 (NLSy1) galaxies. This indicates the presence of relativistic jets in these sources similar to blazars and radio galaxies. In an attempt to have an idea of the intranight optical variability (INOV) cha…
The Solar Connection of Enhanced Heavy Ion Charge States in the Interplanetary Medium: Implications for the Flux-Rope Structure of CMEs
Gopalswamy, N.; Yashiro, S.; Mäkelä, P. +3 more
We investigated a set of 54 interplanetary coronal mass ejection (ICME) events whose solar sources are very close to the disk center (within ± 15∘ from the central meridian). The ICMEs consisted of 23 magnetic-cloud (MC) events and 31 non-MC events. Our analyses suggest that the MC and non-MC ICMEs have more or less the same eruption ch…
Herschel far-infrared observations of the Carina Nebula complex. III. Detailed cloud structure and feedback effects
Preibisch, T.; Roccatagliata, V.; Gaczkowski, B. +1 more
Context. The star formation process in large clusters/associations can be strongly influenced by the feedback from high-mass stars. Whether the resulting net effect of the feedback is predominantly negative (cloud dispersal) or positive (triggering of star formation due to cloud compression) is still an open question.
Aims: The Carina Nebula …
Transitional Disks and Their Origins: An Infrared Spectroscopic Survey of Orion A
Manoj, P.; Megeath, S. T.; Calvet, Nuria +10 more
Transitional disks are protoplanetary disks around young stars, with inner holes or gaps which are surrounded by optically thick outer, and often inner, disks. Here we present observations of 62 new transitional disks in the Orion A star-forming region. These were identified using the Spitzer Space Telescope's Infrared Spectrograph and followed up…
Negative ion densities in the ionosphere of Titan-Cassini RPWS/LP results
Wahlund, J. -E.; Edberg, N. J. T.; Ågren, K. +3 more
The Cassini spacecraft Radio and Plasma Wave Science (RPWS) Langmuir Probe (LP) provides in-situ measurements of Titan's ionosphere. We present here data from 47 deep flybys in the time period October 2004-July 2012 of charge densities of positive and negative ions as well as electrons. These densities have been mapped with respect to altitude and…
Seismic constraints on rotation of Sun-like star and mass of exoplanet
Auvergne, M.; Baudin, F.; Michel, E. +32 more
Rotation is thought to drive cyclic magnetic activity in the Sun and Sun-like stars. Stellar dynamos, however, are poorly understood owing to the scarcity of observations of rotation and magnetic fields in stars. Here, inferences are drawn on the internal rotation of a distant Sun-like star by studying its global modes of oscillation. We report as…
Physical properties of high-mass clumps in different stages of evolution
Molinari, S.; Giannetti, A.; Beltrán, M. T. +6 more
Context. The details of the process of massive star formation are still elusive. A complete characterization of the first stages of the process from an observational point of view is needed to constrain theories on the subject. In the past 20 years we have made a thorough investigation of colour-selected IRAS sources over the whole sky. The source…
The Structural Evolution of Milky-Way-like Star-forming Galaxies since z ~ 1.3
van Dokkum, Pieter G.; Franx, Marijn; Muzzin, Adam +14 more
We follow the structural evolution of star-forming galaxies (SFGs) like the Milky Way by selecting progenitors to z ~ 1.3 based on the stellar mass growth inferred from the evolution of the star-forming sequence. We select our sample from the 3D-HST survey, which utilizes spectroscopy from the HST/WFC3 G141 near-IR grism and enables precise redshi…
Cosmic Rays in the Inner Heliosphere: Insights from Observations, Theory and Models
Potgieter, M. S.
The global modulation of galactic cosmic rays in the inner heliosphere is determined by four major mechanisms: convection, diffusion, particle drifts (gradient, curvature and current sheet drifts), and adiabatic energy losses. When these processes combine to produce modulation, the complexity increases significantly especially when one wants to de…
Radio observations of extreme ULXs: revealing the most powerful ULX radio nebula ever or the jet of an intermediate-mass black hole?
Roberts, T. P.; Mezcua, M.; Sutton, A. D. +1 more
The most extreme ultraluminous X-ray sources (ULXs), with LX > 5 × 1040 erg s-1, are amongst the best candidates for hosting intermediate-mass black holes (IMBHs) in the haloes of galaxies. Jet radio emission is expected from a sub-Eddington accreting IMBH in the low/hard (radio bright) state. In a search for su…