Browsing Institutt for teoretisk astrofysikk by Title
Now showing items 254-273 of 683
-
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2018)The IAU promotes astronomy as a tool to strengthen science education of young people in developing regions through its International Schools for Young Astronomers (ISYA) and a Teaching for Astronomy Development (TAD) ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)Context. The solar coronal heating problem has been an open question in the science community since 1939. One of the proposed models for the transport and release of mechanical energy generated in the sub-photospheric ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)We report the identification of extended Lyα nebulae at z ≃ 3.3 in the Hubble Ultra Deep Field (HUDF, ≃40 kpc × 80 kpc) and behind the Hubble Frontier Field galaxy cluster MACSJ0416 (≃40 kpc), spatially associated with ...
-
(Master thesis / Masteroppgave, 2014)The chromosphere is nearly translucent in the optical and infrared continuum, making it an elusive observational target. In this thesis, I use a CO5BOLD computational 3D radiation magnetohydrodynamics (MHD) model of the ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)We use 3D magnetohydrodynamic CO5BOLD model atmospheres to study the interplay between magnetic fields and convection in the atmospheres of red giant stars. We find that vortex-like structures occur prominently in stars ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)The role of type II spicules in the corona has been a much debated topic in recent years. This paper aims to shed light on the impact of type II spicules in the corona using novel 2.5D radiative MHD simulations, including ...
-
(Doctoral thesis / Doktoravhandling, 2012)
-
(Master thesis / Masteroppgave, 2015)In this thesis we have implemented a basic radiative transfer code to model the radial Lyα scattering rate around the epoch when the first stars and galaxies start forming, and ionizing their surroundings. The model, builds ...
-
Improved upper limits on the 21 cm signal power spectrum of neutral hydrogen at z ≈ 9.1 from LOFAR (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)A new upper limit on the 21 cm signal power spectrum at a redshift of z ≈ 9.1 is presented, based on 141 h of data obtained with the Low-Frequency Array (LOFAR). The analysis includes significant improvements in spectrally ...
-
(Master thesis / Masteroppgave, 2018)The Planck satellite has provided a multitude of data images of the full microwave sky, or sky maps, since it saw first light in 2009. Its observations of the Cosmic Microwave Background (CMB) data has been paramount in ...
-
(Doctoral thesis / Doktoravhandling, 2013)
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding rocket experiment that has provided the first successful measurement of the linear polarization produced by scattering processes in the hydrogen Lyα line ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)Upon its discovery, the low-density transiting Neptune HAT-P-26b showed a 2.1σ detection drift in its spectroscopic data, while photometric data showed a weak curvature in the timing residuals, the confirmation of which ...
-
(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts and most commonly found in the dense environment of star-forming galaxies. A recent study showed ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)The Interface Region Imaging Spectrograph (IRIS) is a NASA small explorer mission that provides high-resolution spectra and images of the Sun in the 133 – 141 nm and 278 – 283 nm wavelength bands. The IRIS data are archived ...
-
(Master thesis / Masteroppgave, 2020)
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)Solar spicules have eluded modelers and observers for decades. Since the discovery of the more energetic type II, spicules have become a heated topic but their contribution to the energy balance of the low solar atmosphere ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)Magnetic reconnection is thought to drive a wide variety of dynamic phenomena in the solar atmosphere. Yet, the detailed physical mechanisms driving reconnection are difficult to discern in the remote sensing observations ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)The Interface Region Imaging Spectrograph (IRIS) reveals small-scale rapid brightenings in the form of bright grains all over coronal holes and the quiet Sun. These bright grains are seen with the IRIS 1330, 1400, and 2796 ...
-
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)The first known interstellar object 'Oumuamua exhibited a nongravitational acceleration that appeared inconsistent with cometary outgassing, leaving radiation pressure as the most likely force. Barring the alien lightsail ...