A5030664482- Solar and Space Plasma Dynamics
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Solar Radiation and Photovoltaics
- Atmospheric Ozone and Climate
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Astronomy and Astrophysical Research
- Computational Physics and Python Applications
- History and Developments in Astronomy
- Astrophysics and Star Formation Studies
- Spectroscopy and Laser Applications
- Astronomical Observations and Instrumentation
- CCD and CMOS Imaging Sensors
- Adaptive optics and wavefront sensing
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Meteorological Phenomena and Simulations
- Spectroscopy Techniques in Biomedical and Chemical Research
- Laser-induced spectroscopy and plasma
- Gamma-ray bursts and supernovae
- Transport Systems and Technology
- Impact of Light on Environment and Health
- Statistical and numerical algorithms
- Atmospheric chemistry and aerosols
University of Oslo
2015-2024
Ames Research Center
2012-2014
Lockheed Martin (United States)
2012-2014
Australian National University
2008-2013
AlbaNova
2009
Royal Swedish Academy of Sciences
2009
Mount Stromlo Observatory
2008
Instituto Superior Técnico
2003-2007
University of Lisbon
2004-2005
The Interface Region Imaging Spectrograph (IRIS) small explorer spacecraft provides simultaneous spectra and images of the photosphere, chromosphere, transition region, corona with 0.33-0.4 arcsec spatial resolution, 2 s temporal resolution 1 km/s velocity over a field-of-view up to 175 x arcsec. IRIS was launched into Sun-synchronous orbit on 27 June 2013 using Pegasus-XL rocket consists 19-cm UV telescope that feeds slit-based dual-bandpass imaging spectrograph. obtains in passbands from...
Abstract The goal of the SunPy project is to facilitate and promote use development community-led, free, open source data analysis software for solar physics based on scientific Python environment. achieves this by developing maintaining sunpy core package supporting an ecosystem affiliated packages. This paper describes first official stable release (version 1.0) package, as well organization infrastructure. concludes with a discussion future project.
NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission will study how the solar atmosphere is energized. IRIS contains an imaging spectrograph that covers Mg II h&k lines as well a slit-jaw imager centered at k. Understanding observations requires forward modeling of line formation from 3D radiation-MHD models. We compute vertically emergent intensity snapshot dynamic model atmosphere, and investigate which diagnostic information about contained in synthetic profiles....
NASA's Interface Region Imaging Spectrograph (IRIS) space mission will study how the solar atmosphere is energized. IRIS contains an imaging spectrograph that covers Mg II h&k lines as well a slit-jaw imager centered at k. Understanding observations require forward modeling of line formation from 3D radiation-MHD models. This paper first in series where we undertake this modeling. We discuss atomic physics pertinent to formation, present quintessential model atom can be used radiative...
In the lower solar atmosphere, chromosphere is permeated by jets known as spicules, in which plasma propelled at speeds of 50 to 150 kilometers per second into corona. The origin spicules poorly understood, although they are expected play a role heating million-degree corona and associated with Alfv\'enic waves that help drive wind. We compare magnetohydrodynamic simulations observations from Interface Region Imaging Spectrograph Swedish 1-m Solar Telescope. Spicules shown occur when...
Understanding the dynamic solar chromosphere is fundamental in physics. Spicules are an important feature of chromosphere, connecting photosphere to corona, potentially mediating transfer energy and mass. The aim this work study properties spicules over different regions sun. Our goal investigate if there more than one type spicules, how behave quiet sun, coronal holes, active regions. We make use high-cadence high-spatial resolution Ca II H observations taken by Hinode/SOT. Making a...
The solar chromosphere and transition region (TR) form an interface between the Sun's surface its hot outer atmosphere. There, most of nonthermal energy that powers atmosphere is transformed into heat, although detailed mechanism remains elusive. High-resolution (0.33-arc second) observations with NASA's Interface Region Imaging Spectrograph (IRIS) reveal a TR are replete twist or torsional motions on sub-arc second scales, occurring in active regions, quiet Sun coronal holes alike. We...
The Mg II h&k lines are the prime chromospheric diagnostics of NASA's Interface Region Imaging Spectrograph (IRIS). In previous papers this series we used a realistic three-dimensional radiative magnetohydrodynamics model to calculate in detail and investigated how their spectral features relate underlying atmosphere. work, employ same approach investigate fare when taking into account finite resolution IRIS different noise levels. addition, diagnostic potential several other photospheric...
The emergence of three-dimensional magneto-hydrodynamic (MHD) simulations stellar atmospheres has sparked a need for efficient radiative transfer codes to calculate detailed synthetic spectra. We present RH 1.5D, massively parallel code based on the and capable performing Zeeman polarised multi-level non-local thermodynamical equilibrium (NLTE) calculations with partial frequency redistribution an arbitrary amount chemical species. calculates spectra from 3D, 2D or 1D atmospheric models...
In this work, we analyse coordinated observations spanning chromospheric, TR and coronal temperatures at very high resolution which reveal essential characteristics of thermally unstable plasmas. Coronal rain is found to be a highly multi-thermal phenomenon with degree co-spatiality in the multi-wavelength emission. EUV darkening quasi-periodic intensity variations are strongly correlated showers. Progressive cooling observed, leading height dependence A fast-slow two-step catastrophic...
The heating of the outer solar atmospheric layers, i.e., transition region and corona, to high temperatures is a long standing problem in (and stellar) physics. Solutions have been hampered by an incomplete understanding magnetically controlled structure these regions. spatial temporal resolution observations with Interface Region Imaging Spectrograph (IRIS) at limb reveal plethora short, low lying loops or loop segments transition-region that vary rapidly, on timescales minutes. We argue...
A spectacular manifestation of solar activity is the appearance transient brightenings in far wings H$\alpha$ line, known as Ellerman bombs (EBs). Recent observations obtained by Interface Region Imaging Spectrograph (IRIS) have revealed another type plasma "bombs" (UV bursts) with high temperatures perhaps up to $8\times 10^4$ K within cooler lower atmosphere. Realistic numerical modeling showing such events needed explain their nature. Here, we report on 3D radiative magneto-hydrodynamic...
Abstract Hinode is Japan’s third solar mission following Hinotori (1981–1982) and Yohkoh (1991–2001): it was launched on 2006 September 22 in operation currently. carries three instruments: the Solar Optical Telescope, X-Ray EUV Imaging Spectrometer. These instruments were built under international collaboration with National Aeronautics Space Administration UK Science Technology Facilities Council, its has been contributed to by European Agency Norwegian Center. After describing satellite...
Solar spicules have eluded modelers and observers for decades. Since the discovery of more energetic type II, become a heated topic but their contribution to energy balance low solar atmosphere remains unknown. Here we give first glimpse what quiet Sun look like when observed with NASA's recently launched Interface Region Imaging Spectrograph (IRIS). Using IRIS spectra filtergrams that sample chromosphere transition region compare properties evolution as in coordinated campaign Hinode...
Our ability to model the shapes and strengths of iron lines in solar spectrum is a critical test accuracy abundance, which sets absolute zero-point all stellar metallicities. We use an extensive 463-level Fe atom with new photoionisation cross-sections for FeI as well quantum mechanical calculations collisional excitation charge transfer neutral hydrogen; latter effectively remove free parameter that has hampered previous line formation studies non-local thermodynamic equilibrium (NLTE). For...
We use coordinated observations with the Interface Region Imaging Spectrograph (IRIS) and Swedish 1 m Solar Telescope to identify disk counterpart of type II spicules in upper-chromospheric transition region (TR) diagnostics. These counterparts were earlier identified through short-lived asymmetries chromospheric spectral lines: rapid blue- or red-shifted excursions (RBEs RREs). find clear signatures RBEs RREs Mg ii h & k, often central h3 k3 absorption features concert co-temporal...
Context. Recently, new solar model atmospheres have been developed to replace classical 1D local thermodynamical equilibrium (LTE) hydrostatic models and used for example derive the chemical composition.
Ellerman bombs (EBs) and UV bursts are both brightenings related to flux emergence regions specifically magnetic of opposite polarity that meet in the photosphere. These two reconnection-related phenomena, nominally formed far apart, occasionally occur same location at time, thus challenging our understanding reconnection heating lower solar atmosphere. We consider formation an active region, including long fibrils hot dense coronal plasma. The a untwisted sheet, injected $2.5$~Mm below...
Spicules are ubiquitous, fast moving jets observed off-limb in chromospheric spectral lines. Combining the recently launched Interface Region Imaging Spectrograph with Solar Dynamics Observatory and Hinode, we have a unique opportunity to study spicules simultaneously multiple passbands from seeing free environment. This makes it possible their thermal evolution over large range of temperatures. A recent showed that appear several transition region lines, suggesting continue hotter after...
Abstract We present the results of 1D hydrodynamic simulations coronal loops that are subject to nanoflares, caused by either in situ thermal heating or nonthermal electron (NTE) beams. The synthesized intensity and Doppler shifts can be directly compared with Interface Region Imaging Spectrograph ( IRIS ) Atmospheric Assembly (AIA) observations rapid variability transition region (TR) loops, associated transient heating. find NTEs high enough low-energy cutoff <?CDATA ${E}_{{\rm{C}}}$?>...
Radiative transfer modeling of spectral lines including partial redistribution (PRD) effects requires the evaluation ratio emission to absorption profile. This quantity a large amount computational work if one employs angle-dependent function, which prohibits its use in 3D radiative computations with model atmospheres containing velocity fields. We aim provide method compute profile that less but retains effect scattering resulting line profiles. present angle-averaged function and...
A triplet of subordinate lines Mg II exists in the region around h&k lines. In solar spectra these are seen mostly absorption, but some cases can become emission The aim this work is to study formation triplet, and investigate any diagnostic value they bring. Using 3D radiative magnetohydrodynamic simulations quiet Sun flaring flux emergence, we synthesize how spectral features respond underlying atmosphere. We find that rare typically caused by a steep temperature increase lower...
<i>Context. <i/>There is a lively debate about the solar oxygen abundance and role of 3D models in its recent downward revision. These have been tested using high-resolution atlases flux disk-centre intensity. Further testing can be done centre-to-limb variations.<i>Aims. <i/>Using high S/N observations neutral lines across surface, we seek to test that 1D reproduce their observed variation. In particular assess whether latest generation hydrodynamical model atmospheres NLTE line formation...
Abstract Magnetic reconnection is thought to drive a wide variety of dynamic phenomena in the solar atmosphere. Yet, detailed physical mechanisms driving are difficult discern remote sensing observations that used study In this Letter, we exploit high-resolution instruments Interface Region Imaging Spectrograph and new CHROMIS Fabry–Pérot instrument at Swedish 1-m Solar Telescope (SST) identify intermittency magnetic its association with formation plasmoids so-called UV bursts low The Si iv...