User profiles for Viggo Hansteen
Viggo HansteenProfessor, Institute of Theoretical Astrophysics, University of Oslo Verified email at astro.uio.no Cited by 12450 |
A tale of two spicules: the impact of spicules on the magnetic chromosphere
We use high-resolution observations of the Sun in Ca II H (3968 Å) from the Solar Optical
Telescope on Hinode to show that there are at least two types of spicules that dominate the …
Telescope on Hinode to show that there are at least two types of spicules that dominate the …
Alfvénic waves with sufficient energy to power the quiet solar corona and fast solar wind
Energy is required to heat the outer solar atmosphere to millions of degrees (refs 1 , 2 ) and
to accelerate the solar wind to hundreds of kilometres per second (refs 2 ). Alfvén waves (…
to accelerate the solar wind to hundreds of kilometres per second (refs 2 ). Alfvén waves (…
The stellar atmosphere simulation code Bifrost-code description and validation
Context. Numerical simulations of stellar convection and photospheres have been developed
to the point where detailed shapes of observed spectral lines can be explained. Stellar …
to the point where detailed shapes of observed spectral lines can be explained. Stellar …
Dynamic fibrils are driven by magnetoacoustic shocks
VH Hansteen, B De Pontieu… - The Astrophysical …, 2006 - iopscience.iop.org
The formation of jets such as dynamic fibrils, mottles, and spicules in the solar chromosphere
is one of the most important, but also most poorly understood, phenomena of the Sun's …
is one of the most important, but also most poorly understood, phenomena of the Sun's …
Observing the roots of solar coronal heating—in the chromosphere
The Sun's corona is millions of degrees hotter than its 5000 K photosphere. This heating
enigma is typically addressed by invoking the deposition at coronal heights of nonthermal …
enigma is typically addressed by invoking the deposition at coronal heights of nonthermal …
Right ventricular dysfunction and remodeling in chronic obstructive pulmonary disease without pulmonary hypertension
JM Hilde, I Skjørten, OJ Grøtta, V Hansteen… - Journal of the American …, 2013 - jacc.org
Objectives : The aim of the present study was to elucidate right ventricular (RV) function and
structure in patients with chronic obstructive pulmonary disease (COPD) without pulmonary …
structure in patients with chronic obstructive pulmonary disease (COPD) without pulmonary …
A publicly available simulation of an enhanced network region of the Sun
M Carlsson, VH Hansteen, BV Gudiksen… - Astronomy & …, 2016 - aanda.org
Context. The solar chromosphere is the interface between the solar surface and the solar
corona. Modelling of this region is difficult because it represents the transition from optically …
corona. Modelling of this region is difficult because it represents the transition from optically …
On the generation of solar spicules and Alfvénic waves
J Martínez-Sykora, B De Pontieu, VH Hansteen… - Science, 2017 - science.org
In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in
which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. …
which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. …
A New Interpretation of the Red-Shift Observed in Optically Thin Transition Region Lines
V Hansteen - Solar Wind Seven, 1992 - Elsevier
We propose that the pervasive red-shift observed in transition region spectral lines is caused
by propagating acoustic (slow-mode) waves. The waves are assumed generated in the …
by propagating acoustic (slow-mode) waves. The waves are assumed generated in the …
Coronal heating, densities, and temperatures and solar wind acceleration
VH Hansteen, E Leer - Journal of Geophysical Research …, 1995 - Wiley Online Library
The outflow of coronal plasma into interplanetary space is a consequence of the coronal
heating process. Therefore the formation of the corona and the acceleration of the solar wind …
heating process. Therefore the formation of the corona and the acceleration of the solar wind …