Author name code: fredvik
ADS astronomy entries on 2022-09-14
author:Fredvik, T.
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Title: Abundance diagnostics in active regions with Solar
Orbiter/SPICE
Authors: Giunta, Alessandra; Peter, Hardi; Parenti, Susanna; Buchlin,
Eric; Thompson, William; Auchere, Frederic; Kucera, Therese; Carlsson,
Mats; Janvier, Miho; Fludra, Andrzej; Hassler, Donald M.; Grundy,
Timothy; Sidher, Sunil; Guest, Steve; Leeks, Sarah; Fredvik, Terje;
Young, Peter
Bibcode: 2022cosp...44.2583G
Altcode:
With the launch of Solar Orbiter in February 2020, we are now able to
fully explore the link between the solar activity on the Sun and the
inner heliosphere. Elemental abundance measurements provide a key tracer
to probe the source regions of the solar wind and to track it from the
solar surface and corona to the heliosphere. Abundances of elements
with low first ionisation potential (FIP) are enhanced in the corona
relative to high-FIP elements, with respect to the photosphere. This is
known as the FIP effect, which is measured as abundance bias (FIP bias)
of low and high FIP elements. This effect is vital for understanding the
flow of mass and energy through the solar atmosphere. The comparison
between in-situ and remote sensing composition data, coupled with
modelling, will allow us to trace back the source of heliospheric
plasma. Solar Orbiter has a unique combination of in-situ and remote
sensing instruments that will help to make such a comparison. In
particular, the SPICE (Spectral Imaging of the Coronal Environment)
EUV spectrometer records spectra in two wavelength bands, 70.4-79.0
nm and 97.3-104.9 nm. SPICE is designed to provide spectroheliograms
using a core set of emission lines arising from ions of both low-FIP
and high-FIP elements such as C, N, O, Ne, Mg, S and Fe. These lines
are formed over a wide range of temperatures from 20,000 K to over 1
million K, enabling the analysis of the different layers of the solar
atmosphere. SPICE spectroheliograms can be processed to produce FIP
bias maps, which can be compared to in-situ measurements of the solar
wind composition of the same elements. During the Solar Orbiter Cruise
Phase, SPICE observed several active regions. We will present some of
these observations and discuss the SPICE diagnostic potential to derive
relative abundances (e.g., Mg/Ne) and the FIP bias in those regions.
Title: The SPICE spectrograph on Solar Orbiter: an introduction and
results from the first Orbits
Authors: Auchère, Frédéric; Peter, Hardi; Parenti, Susanna; Buchlin,
Eric; Thompson, William; Auchere, Frederic; Teriaca, Luca; Kucera,
Therese; Carlsson, Mats; Janvier, Miho; Fludra, Andrzej; Giunta,
Alessandra; Schuehle, Udo; Hassler, Donald M.; Grundy, Timothy;
Sidher, Sunil; Fredvik, Terje; Plowman, Joseph; Aznar Cuadrado, Regina
Bibcode: 2022cosp...44.1338A
Altcode:
The Spectral Imaging of the Coronal Environment (SPICE) instrument is
the EUV imaging spectrometer on board the Solar Orbiter mission. With
its ability to derive physical properties of the coronal plasma,
SPICE is a key component of the payload to establish the connection
between the source regions and the in-situ measurements of the solar
wind. The spacecraft was successfully launched in February 2020 and
completed its cruise phase in December 2021. During this period,
the remote sensing instruments were mostly operated during limited
periods of time for 'checkout' engineering activities and synoptic
observations. Nonetheless, several of these periods provided enough
opportunities already to obtain new insights on coronal physics. During
the march 2022 perihelion - close to 0.3 AU - SPICE will provide
its highest spatial resolution data so far. Coordinated observations
between the remote sensing and in-situ instruments will provide the
first opportunity to use the full potential of the Solar Orbiter
mission. We will review the instrument characteristics and present
initial results from the cruise phase and first close encounter.
Title: First observations from the SPICE EUV spectrometer on Solar
Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A.; Grundy, T.; Guest,
S.; Leeks, S.; Sidher, S.; Auchère, F.; Carlsson, M.; Hassler, D.;
Peter, H.; Aznar Cuadrado, R.; Buchlin, É.; Caminade, S.; DeForest,
C.; Fredvik, T.; Haberreiter, M.; Harra, L.; Janvier, M.; Kucera, T.;
Müller, D.; Parenti, S.; Schmutz, W.; Schühle, U.; Solanki, S. K.;
Teriaca, L.; Thompson, W. T.; Tustain, S.; Williams, D.; Young, P. R.;
Chitta, L. P.
Bibcode: 2021A&A...656A..38F
Altcode: 2021arXiv211011252F
Aims: We present first science observations taken during the
commissioning activities of the Spectral Imaging of the Coronal
Environment (SPICE) instrument on the ESA/NASA Solar Orbiter
mission. SPICE is a high-resolution imaging spectrometer operating at
extreme ultraviolet (EUV) wavelengths. In this paper we illustrate
the possible types of observations to give prospective users a
better understanding of the science capabilities of SPICE.
Methods: We have reviewed the data obtained by SPICE between April
and June 2020 and selected representative results obtained with
different slits and a range of exposure times between 5 s and 180
s. Standard instrumental corrections have been applied to the raw
data.
Results: The paper discusses the first observations
of the Sun on different targets and presents an example of the full
spectra from the quiet Sun, identifying over 40 spectral lines from
neutral hydrogen and ions of carbon, oxygen, nitrogen, neon, sulphur,
magnesium, and iron. These lines cover the temperature range between
20 000 K and 1 million K (10 MK in flares), providing slices of the
Sun's atmosphere in narrow temperature intervals. We provide a list
of count rates for the 23 brightest spectral lines. We show examples
of raster images of the quiet Sun in several strong transition region
lines, where we have found unusually bright, compact structures in the
quiet Sun network, with extreme intensities up to 25 times greater
than the average intensity across the image. The lifetimes of these
structures can exceed 2.5 hours. We identify them as a transition
region signature of coronal bright points and compare their areas and
intensity enhancements. We also show the first above-limb measurements
with SPICE above the polar limb in C III, O VI, and Ne VIII lines, and
far off limb measurements in the equatorial plane in Mg IX, Ne VIII,
and O VI lines. We discuss the potential to use abundance diagnostics
methods to study the variability of the elemental composition that can
be compared with in situ measurements to help confirm the magnetic
connection between the spacecraft location and the Sun's surface,
and locate the sources of the solar wind.
Conclusions: The
SPICE instrument successfully performs measurements of EUV spectra
and raster images that will make vital contributions to the scientific
success of the Solar Orbiter mission.
Title: SSTRED: Data- and metadata-processing pipeline for CHROMIS
and CRISP
Authors: Löfdahl, Mats G.; Hillberg, Tomas; de la Cruz Rodríguez,
Jaime; Vissers, Gregal; Andriienko, Oleksii; Scharmer, Göran B.;
Haugan, Stein V. H.; Fredvik, Terje
Bibcode: 2021A&A...653A..68L
Altcode: 2018arXiv180403030L
Context. Data from ground-based, high-resolution solar telescopes
can only be used for science with calibrations and processing, which
requires detailed knowledge about the instrumentation. Space-based
solar telescopes provide science-ready data, which are easier to
work with for researchers whose expertise is in the interpretation of
data. Recently, data-processing pipelines for ground-based instruments
have been constructed.
Aims: We aim to provide observers
with a user-friendly data pipeline for data from the Swedish 1-meter
Solar Telescope (SST) that delivers science-ready data together with
the metadata needed for proper interpretation and archiving.
Methods: We briefly describe the CHROMospheric Imaging Spectrometer
(CHROMIS) instrument, including its (pre)filters, as well as recent
upgrades to the CRisp Imaging SpectroPolarimeter (CRISP) prefilters and
polarization optics. We summarize the processing steps from raw data
to science-ready data cubes in FITS files. We report calibrations
and compensations for data imperfections in detail. Misalignment
of Ca II data due to wavelength-dependent dispersion is identified,
characterized, and compensated for. We describe intensity calibrations
that remove or reduce the effects of filter transmission profiles
as well as solar elevation changes. We present REDUX, a new version
of the MOMFBD image restoration code, with multiple enhancements and
new features. It uses projective transforms for the registration of
multiple detectors. We describe how image restoration is used with
CRISP and CHROMIS data. The science-ready output is delivered in FITS
files, with metadata compliant with the SOLARNET recommendations. Data
cube coordinates are specified within the World Coordinate System
(WCS). Cavity errors are specified as distortions of the WCS wavelength
coordinate with an extension of existing WCS notation. We establish
notation for specifying the reference system for Stokes vectors with
reference to WCS coordinate directions. The CRIsp SPectral EXplorer
(CRISPEX) data-cube browser has been extended to accept SSTRED output
and to take advantage of the SOLARNET metadata.
Results: SSTRED
is a mature data-processing pipeline for imaging instruments, developed
and used for the SST/CHROMIS imaging spectrometer and the SST/CRISP
spectropolarimeter. SSTRED delivers well-characterized, science-ready,
archival-quality FITS files with well-defined metadata. The SSTRED
code, as well as REDUX and CRISPEX, is freely available through git
repositories.
Title: Relative coronal abundance diagnostics with Solar Orbiter/SPICE
Authors: Zambrana Prado, N.; Buchlin, E.; Peter, H.; Young, P. R.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Aznar Cuadrado,
R.; Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra,
L.; Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Sidher, S.; Teriaca,
L.; Thompson, W. T.; Williams, D.
Bibcode: 2020AGUFMSH038..09Z
Altcode:
Linking solar activity on the surface and in the corona to the inner
heliosphere is one of Solar Orbiter's main goals. Its UV spectrometer
SPICE (SPectral Imaging of the Coronal Environment) will provide
relative abundance measurements which will be key in this quest
as different structures on the Sun have different abundances as a
consequence of the FIP (First Ionization Potential) effect. Solar
Orbiter's unique combination of remote sensing and in-situ instruments
coupled with observation from other missions such as Parker Solar
Probe will allow us to compare in-situ and remote sensing composition
data. With the addition of modeling, these new results will allow us
to trace back the source of heliospheric plasma. As high telemetry
will not always be available with SPICE, we have developed a method
for measuring relative abundances that is both telemetry efficient
and reliable. Unlike methods based on Differential Emission Measure
(DEM) inversion, the Linear Combination Ratio (LCR) method does not
require a large number of spectral lines. This new method is based
on linear combinations of UV spectral lines. The coefficients of
the combinations are optimized such that the ratio of two linear
combinations of radiances would yield the relative abundance of two
elements. We present some abundance diagnostics tested on different
combinations of spectral lines observable by SPICE.
Title: Dynamics and thermal structure in the quiet Sun seen by SPICE
Authors: Peter, H.; Aznar Cuadrado, R.; Schühle, U.; Teriaca, L.;
Auchere, F.; Carlsson, M.; Fludra, A.; Hassler, D.; Buchlin, E.;
Caminade, S.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Schmutz, W. K.; Sidher, S.; Thompson, W. T.; Williams,
D.; Young, P. R.
Bibcode: 2020AGUFMSH038..03P
Altcode:
We will present some of the early data of the Spectral Imaging of the
Coronal Environment (SPICE) instrument on Solar Orbiter. One of the
unique features of SPICE is its capability to record a wide range of
wavelengths in the extreme UV with the possibility to record spectral
lines giving access to a continuous plasma temperature range from 10.000
K to well above 1 MK. The data taken so far were for commissioning
purposes and they can be used for a preliminary evaluation of the
science performance of the instrument. Here we will concentrate on
sample spectra covering the whole wavelength region and on the early
raster maps acquired in bright lines in the quiet Sun close to disk
center. Looking at different quiet Sun features we investigate the
thermal structure of the atmosphere and flow structures. For this
we apply fits to the spectral profiles and check the performance in
terms of Doppler shifts and line widths to retrieve the structure of
the network in terms of dynamics. While the amount of data available
so far is limited, we will have a first look on how quiet Sun plasma
responds to heating events. For this, we will compare spectral lines
forming at different temperatures recorded at strictly the same time.
Title: First Results From SPICE EUV Spectrometer on Solar Orbiter
Authors: Fludra, A.; Caldwell, M.; Giunta, A. S.; Grundy, T.; Guest,
S.; Sidher, S.; Auchere, F.; Carlsson, M.; Hassler, D.; Peter, H.;
Aznar Cuadrado, R.; Buchlin, E.; Caminade, S.; DeForest, C.; Fredvik,
T.; Harra, L. K.; Janvier, M.; Kucera, T. A.; Leeks, S.; Mueller,
D.; Parenti, S.; Schmutz, W. K.; Schühle, U.; Teriaca, L.; Thompson,
W. T.; Tustain, S.; Williams, D.; Young, P. R.
Bibcode: 2020AGUFMSH038..02F
Altcode:
SPICE (Spectral Imaging of Coronal Environment) is one of the remote
sensing instruments onboard Solar Orbiter. It is an EUV imaging
spectrometer observing the Sun in two wavelength bands: 69.6-79.4 nm
and 96.6-105.1 nm. SPICE is capable of recording full spectra in these
bands with exposures as short as 1s. SPICE is the only Solar Orbiter
instrument that can measure EUV spectra from the disk and low corona
of the Sun and record all spectral lines simultaneously. SPICE uses
one of three narrow slits, 2"x11', 4''x11', 6''x11', or a wide slit
30''x14'. The primary mirror can be scanned in a direction perpendicular
to the slit, allowing raster images of up to 16' in size. We
present an overview of the first SPICE data taken on several days
during the instrument commissioning carried out by the RAL Space team
between 2020 April 21 and 2020 June 14. We also include results from
SPICE observations at the first Solar Orbiter perihelion at 0.52AU,
taken between June 16-21st. We give examples of full spectra
from the quiet Sun near disk centre and provide a list of key spectral
lines emitted in a range of temperatures between 10,000 K and over 1
million K, from neutral hydrogen and ions of carbon, oxygen, nitrogen,
neon, sulphur and magnesium. We show examples of first raster images
in several strong lines, obtained with different slits and a range
of exposure times between 5s and 180s. We describe the temperature
coverage and density diagnostics, determination of plasma flows, and
discuss possible applications to studies of the elemental abundances
in the corona. We also show the first off-limb measurements with SPICE,
as obtained when the spacecraft pointed at the limb.
Title: Calibrating optical distortions in the Solar Orbiter SPICE
spectrograph
Authors: Thompson, W. T.; Schühle, U.; Young, P. R.; Auchere, F.;
Carlsson, M.; Fludra, A.; Hassler, D.; Peter, H.; Aznar Cuadrado, R.;
Buchlin, E.; Caldwell, M.; DeForest, C.; Fredvik, T.; Harra, L. K.;
Janvier, M.; Kucera, T. A.; Giunta, A. S.; Grundy, T.; Müller, D.;
Parenti, S.; Caminade, S.; Schmutz, W. K.; Teriaca, L.; Williams,
D.; Sidher, S.
Bibcode: 2020AGUFMSH0360029T
Altcode:
The Spectral Imaging of the Coronal Environment (SPICE) instrument on
Solar Orbiter is a high-resolution imaging spectrometer operating
at extreme ultraviolet (EUV) wavelengths from 70.4-79.0 nm and
97.3-104.9 nm. A single-mirror off-axis paraboloid focuses the solar
image onto the entrance slit of the spectrometer section. A Toroidal
Variable Line Space (TVLS) grating images the entrance slit onto a
pair of MCP-intensified APS detectors. Ray-tracing analysis prior
to launch showed that the instrument was subject to a number of
small image distortions which need to be corrected in the final data
product. We compare the ray tracing results with measurements made in
flight. Co-alignment with other telescopes on Solar Orbiter will also
be examined.
Title: First results from the EUI and SPICE observations of Alpha
Leo near Solar Orbiter first perihelion
Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta,
V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.;
Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar
Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.;
Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.;
Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
Bibcode: 2020AGUFMSH0360024B
Altcode:
On June 16th 2020 Solar Orbiter made a dedicated observing campaign
where the spacecraft pointed to the solar limb to allow some of the
high resolution instruments to observe the ingress (at the east limb)
and later the egress (west limb) of the occultation of the star Alpha
Leonis by the solar disk. The star was chosen because its luminosity and
early spectral type ensure high and stable flux at wavelengths between
100 and 122 nanometers, a range observed by the High Resolution EUI
Lyman alpha telescope (HRI-LYA) and by the long wavelength channel
of the SPICE spectrograph. Star observations, when feasible, allow
to gather a great deal of information on the instrument performances,
such as the radiometric performance and the instrument optical point
spread function (PSF). We report here the first results from the
above campaign for the two instruments.
Title: First results from combined EUI and SPICE observations of
Lyman lines of Hydrogen and He II
Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.;
Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.;
Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus,
P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest,
C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp,
E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
Bibcode: 2020AGUFMSH0360003T
Altcode:
The Solar Orbiter spacecraft carries a powerful set of remote
sensing instruments that allow studying the solar atmosphere with
unprecedented diagnostic capabilities. Many such diagnostics require
the simultaneous usage of more than one instrument. One example of that
is the capability, for the first time, to obtain (near) simultaneous
spatially resolved observations of the emission from the first three
lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact,
the SPectral Imaging of the Coronal Environment (SPICE) spectrometer
can observe the Lyman beta and gamma lines in its long wavelength
(SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope
of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in
the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take
images dominated by the Lyman alpha line of ionized Helium at 30.4 nm
(FSI-304). Being hydrogen and helium the main components of our star,
these very bright transitions play an important role in the energy
budget of the outer atmosphere via radiative losses and the measurement
of their profiles and radiance ratios is a fundamental constraint to
any comprehensive modelization effort of the upper solar chromosphere
and transition region. Additionally, monitoring their average ratios
can serve as a check out for the relative radiometric performance of
the two instruments throughout the mission. Although the engineering
data acquired so far are far from ideal in terms of time simultaneity
(often only within about 1 h) and line coverage (often only Lyman beta
was acquired by SPICE and not always near simultaneous images from all
three telescopes are available) the analysis we present here still
offers a great opportunity to have a first look at the potential of
this diagnostic from the two instruments. In fact, we have identified
a series of datasets obtained at disk center and at various positions
at the solar limb that allow studying the Lyman alpha to beta radiance
ratio and their relation to He II 30.4 as a function of the position
on the Sun (disk center versus limb and quiet Sun versus coronal holes).
Title: SOLARNET Metadata Recommendations for Solar Observations
Authors: Haugan, Stein Vidar Hagfors; Fredvik, Terje
Bibcode: 2020arXiv201112139H
Altcode: 2020arXiv201112139V
Metadata descriptions of Solar observations have so far only been
standardized for space-based observations, but the standards have
been mostly within a single space mission at a time, at times with
significant differences between different mission standards. In the
context of ground-based Solar observations, data has typically not been
made freely available to the general research community, resulting in an
even greater lack of standards for metadata descriptions. This situation
makes it difficult to construct multi-instrument archives/virtual
observatories with anything more than the most basic metadata available
for searching, as well as making it difficult to write generic software
for instrument-agnostic data analysis. This document describes the
metadata recommendations developed under the SOLARNET EU project,
which aims foster more collaboration and data sharing between both
ground-based and space-based Solar observatories. The recommendations
will be followed by data pipelines developed under the SOLARNET
project as well as e.g. the Solar Orbiter SPICE pipeline and the SST
CHROMIS/CRISP common pipeline. These recommendations are meant to
function as a common reference to which even existing diverse data
sets may be related, for ingestion into solar virtual observatories
and for analysis by generic software.
Title: The Solar Orbiter SPICE instrument. An extreme UV imaging
spectrometer
Authors: SPICE Consortium; Anderson, M.; Appourchaux, T.; Auchère, F.;
Aznar Cuadrado, R.; Barbay, J.; Baudin, F.; Beardsley, S.; Bocchialini,
K.; Borgo, B.; Bruzzi, D.; Buchlin, E.; Burton, G.; Büchel, V.;
Caldwell, M.; Caminade, S.; Carlsson, M.; Curdt, W.; Davenne, J.;
Davila, J.; Deforest, C. E.; Del Zanna, G.; Drummond, D.; Dubau,
J.; Dumesnil, C.; Dunn, G.; Eccleston, P.; Fludra, A.; Fredvik, T.;
Gabriel, A.; Giunta, A.; Gottwald, A.; Griffin, D.; Grundy, T.; Guest,
S.; Gyo, M.; Haberreiter, M.; Hansteen, V.; Harrison, R.; Hassler,
D. M.; Haugan, S. V. H.; Howe, C.; Janvier, M.; Klein, R.; Koller,
S.; Kucera, T. A.; Kouliche, D.; Marsch, E.; Marshall, A.; Marshall,
G.; Matthews, S. A.; McQuirk, C.; Meining, S.; Mercier, C.; Morris,
N.; Morse, T.; Munro, G.; Parenti, S.; Pastor-Santos, C.; Peter, H.;
Pfiffner, D.; Phelan, P.; Philippon, A.; Richards, A.; Rogers, K.;
Sawyer, C.; Schlatter, P.; Schmutz, W.; Schühle, U.; Shaughnessy,
B.; Sidher, S.; Solanki, S. K.; Speight, R.; Spescha, M.; Szwec, N.;
Tamiatto, C.; Teriaca, L.; Thompson, W.; Tosh, I.; Tustain, S.; Vial,
J. -C.; Walls, B.; Waltham, N.; Wimmer-Schweingruber, R.; Woodward,
S.; Young, P.; de Groof, A.; Pacros, A.; Williams, D.; Müller, D.
Bibcode: 2020A&A...642A..14S
Altcode: 2019arXiv190901183A; 2019arXiv190901183S
Aims: The Spectral Imaging of the Coronal Environment (SPICE)
instrument is a high-resolution imaging spectrometer operating at
extreme ultraviolet wavelengths. In this paper, we present the concept,
design, and pre-launch performance of this facility instrument on the
ESA/NASA Solar Orbiter mission.
Methods: The goal of this paper
is to give prospective users a better understanding of the possible
types of observations, the data acquisition, and the sources that
contribute to the instrument's signal.
Results: The paper
discusses the science objectives, with a focus on the SPICE-specific
aspects, before presenting the instrument's design, including optical,
mechanical, thermal, and electronics aspects. This is followed by a
characterisation and calibration of the instrument's performance. The
paper concludes with descriptions of the operations concept and data
processing.
Conclusions: The performance measurements of the
various instrument parameters meet the requirements derived from the
mission's science objectives. The SPICE instrument is ready to perform
measurements that will provide vital contributions to the scientific
success of the Solar Orbiter mission.
Title: The SPICE (Spectral Imaging of the Coronal Environment)
Ultraviolet Imaging Spectrograph Investigation
Authors: Hassler, D.; Auchere, F.; Carlsson, M.; Fludra, A.; Giunta,
A. S.; Mueller, D.; Peter, H.; Parenti, S.; Teriaca, L.; Fredvik, T.
Bibcode: 2019AGUFMSH24A..02H
Altcode:
One of the primary objectives of the Solar Orbiter mission is to link
remote sensing observations of the solar surface structures with in-situ
observations of solar wind streams. The SPICE (Spectral Imaging of the
Coronal Environment) instrument will characterize the plasma properties
of regions near the Sun to directly compare with in-situ measurements
from both Solar Orbiter & Parker Solar Probe. Specifically, SPICE
will map outflow velocities of surface features to solar wind structures
with similar composition (FIP, M/q) measured in-situ by the SWA/HIS
instrument on Solar Orbiter. These observations will help discriminate
models of solar wind origin by matching composition signatures in
solar wind streams to surface feature composition, and discriminate
physical processes that inject material from closed structures into
solar wind streams. This presentation will provide an overview of
the SPICE investigation, including science & measurement objective,
instrument design, capabilities and performance as measured during
calibration prior to delivery to the Solar Orbiter spacecraft. The
presentation will also provide a description of the operations concept
and data processing during the mission.
Title: The Design Strategy of Scientific Data Quality Control Software
for Euclid Mission.
Authors: Brescia, Massimo; Cavuoti, Stefano; Fredvik, Terje;
Vidar Hagfors Haugan, Stein; Wiesmann, Martin; Gozaliasl, Ghassem;
Kirkpatrick, Charles; Kurki-Suonio, Hannu; Longo, Giuseppe; Nilsson,
Kari
Bibcode: 2019ASPC..521..228B
Altcode:
The most valuable asset of a space mission like Euclid are the
data. Due to their huge volume, the automatic quality control becomes
a crucial aspect over the entire lifetime of the experiment. Here
we focus on the design strategy for the Science Ground Segment (SGS)
Data Quality Common Tools (DQCT), which has the main role to provide
software solutions to gather, evaluate, and record quality information
about the raw and derived data products from a primarily scientific
perspective. The stakeholders for this system include Consortium
scientists, users of the science data, and the ground segment data
management system itself. The SGS DQCT will provide a quantitative
basis for evaluating the application of reduction and calibration
reference data (flat-fields, linearity correction, reference catalogs,
etc.), as well as diagnostic tools for quality parameters, flags,
trend analysis diagrams and any other metadata parameter produced
by the pipeline, collected in incremental quality reports specific
to each data level and stored on the Euclid Archive during pipeline
processing. In a large programme like Euclid, it is prohibitively
expensive to process large amount of data at the pixel level just for
the purpose of quality evaluation. Thus, all measures of quality at
the pixel level are implemented in the individual pipeline stages,
and passed along as metadata in the production. In this sense most
of the tasks related to science data quality are delegated to the
pipeline stages, even though the responsibility for science data
quality is managed at a higher level. The DQCT subsystem of the SGS
is currently under development, but its path to full realization will
likely be different than that of other subsystem; primarily because,
due to a high level of parallelism and to the wide pipeline processing
redundancy (for instance the mechanism of double Science Data Center
for each processing function) the data quality tools have not only
to be widely spread over all pipeline segments and data levels, but
also to minimize the occurrences of potential diversity of solutions
implemented for similar functions, ensuring the maximum of coherency
and standardization for quality evaluation and reporting in the SGS.
Title: The design strategy of scientific data quality control software
for Euclid mission
Authors: Brescia, Massimo; Cavuoti, Stefano; Fredvik, Terje; Vidar
Hagfors Haugan, Stein; Gozaliasl, Ghassem; Kirkpatrick, Charles;
Kurki-Suonio, Hannu; Longo, Giuseppe; Nilsson, Kari; Wiesmann, Martin
Bibcode: 2016arXiv161108467B
Altcode:
The most valuable asset of a space mission like Euclid are the data. Due
to their huge volume, the automatic quality control becomes a crucial
aspect over the entire lifetime of the experiment. Here we focus on the
design strategy for the Science Ground Segment (SGS) Data Quality Common
Tools (DQCT), which has the main role to provide software solutions
to gather, evaluate, and record quality information about the raw and
derived data products from a primarily scientific perspective. The SGS
DQCT will provide a quantitative basis for evaluating the application of
reduction and calibration reference data, as well as diagnostic tools
for quality parameters, flags, trend analysis diagrams and any other
metadata parameter produced by the pipeline. In a large programme like
Euclid, it is prohibitively expensive to process large amount of data
at the pixel level just for the purpose of quality evaluation. Thus, all
measures of quality at the pixel level are implemented in the individual
pipeline stages, and passed along as metadata in the production. In this
sense most of the tasks related to science data quality are delegated
to the pipeline stages, even though the responsibility for science data
quality is managed at a higher level. The DQCT subsystem of the SGS
is currently under development, but its path to full realization will
likely be different than that of other subsystems. Primarily because,
due to a high level of parallelism and to the wide pipeline processing
redundancy, for instance the mechanism of double Science Data Center
for each processing function, the data quality tools have not only
to be widely spread over all pipeline segments and data levels, but
also to minimize the occurrences of potential diversity of solutions
implemented for similar functions, ensuring the maximum of coherency
and standardization for quality evaluation and reporting in the SGS.
Title: Modeling of EIS Spectrum Drift from Instrumental Temperatures
Authors: Kamio, S.; Hara, H.; Watanabe, T.; Fredvik, T.; Hansteen,
V. H.
Bibcode: 2010SoPh..266..209K
Altcode: 2010SoPh..tmp..137K; 2010arXiv1003.3540K
An empirical model has been developed to reproduce the drift of the
spectrum recorded by the EIS on Hinode using instrumental temperatures
and relative motion of the spacecraft. The EIS spectrum shows an
artificial drift in wavelength dimension in sync with the revolution of
the spacecraft, which is caused by temperature variations inside the
spectrometer. The drift amounts to 70 km s−1 in Doppler
velocity and introduces difficulties in velocity measurements. An
artificial neural network is incorporated to establish a relationship
between the instrumental temperatures and the spectral drift. This
empirical model reproduces observed spectrum shift with an rms error
of 4.4 km s−1. This procedure is robust and applicable to
any spectrum obtained with EIS, regardless of the observing field. In
addition, spectral curvatures and spatial offset in the north - south
direction are determined to compensate for instrumental effects.
Title: Oscillations in the Umbral Atmosphere
Authors: Brynildsen, N.; Maltby, P.; Foley, C. R.; Fredvik, T.;
Kjeldseth-Moe, O.
Bibcode: 2004SoPh..221..237B
Altcode:
The results of simultaneous observations of oscillations in the
chromosphere, transition region, and corona above nine sunspots are
presented. The data are obtained through coordinated observing with the
Solar and Heliospheric Observatory — SOHO and the Transition Region
And Coronal Explorer — TRACE. Oscillations are detected above each
umbra. The power spectra show one dominant frequency corresponding to
a period close to 3 min. We show that the oscillations in the sunspot
transition region can be modeled by upwardly propagating acoustic
waves. In the corona the oscillations are limited to small regions that
often coincide with the endpoints of sunspot coronal loops. Spectral
observations show that oscillations in the corona contribute to the
observed oscillations in the TRACE 171 Å channel observations. We
show that a recent suggestion regarding a connection between sunspot
plumes and 3-min oscillations conflicts with the observations.
Title: Oscillations Above the Umbra of Sunspots
Authors: Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2004ESASP.547...45B
Altcode: 2004soho...13...45B
Oscillations above thirteen sunspots are investigated with the Coronal
Diagnostic Spectrometer (CDS) and the Transition Region And Coronal
Explorer (TRACE). The CDS observations give knowledge about the
oscillations in the chromosphere, transition region, and corona and
information regarding the contributions of different emission lines to
the TRACE 171 Å and 195 Å channel intensities. A period close to 3
min is observed above the umbra of each sunspot. The observations give
support to the idea that the 3 min oscillations are caused by upwardly
propagating acoustic waves. This is evident from the asymmetry of
the oscillation amplitudes in the red and blue wings of the emission
lines, where the oscillations are decidedly more pronounced in the
blue than in the red line wing. Additional support for the acoustic
wave hypothesis emerges from the agreement between the observed and
predicted relations in phase and magnitude between the oscillations in
intensity and line-ofsight velocity. The frequency of the oscillations
is above the acoustic cutoff frequency in the umbral atmosphere and
the observed phase differences between lines emitting at different
temperatures point to an upwardly propagating disturbance.
Title: Multi Wavelength Observations of Solar Active Region Loops
Authors: Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2004cosp...35.2832F
Altcode: 2004cosp.meet.2832F
Simultaneous observations with the UV/EUV spectrometers CDS and
SUMER on SOHO, and the UV/EUV imaging telescope, TRACE, have been
used to investigate rapid intensity variations in solar active
region loops. In lines formed at temperatures 10,000 - 250,000 K,
the loop structures seem to be dominated by quasiperiodic intensity
enhancements moving rapidly along the loops down to the surface
of the sun. We will demonstrate that it is difficult to understand
the nature of these changes without combining high cadence imaging
and spectroscopic observations. From the high cadence observations
the enhancements appear to be the result of plasma condensation: hot
coronal plasma at the top of loops may be cooled to transition region
or even chromospheric temperatures and slides down the loop legs at
speeds up to 100 km/s. At coronal temperatures, ~ 1 MK, the observed
loops are less variable and moving intensity enhancements are seen
less frequently than in the transition region.
Title: Sunspot Oscillations and Acoustic Wave Propagation
Authors: Brekke, P.; Brynildsen, N.; Maltby, P.; Fredvik, T.;
Kjeldseth-Moe, O.
Bibcode: 2003SPD....34.0401B
Altcode: 2003BAAS...35..810B
Observations with the Coronal Diagnostic Spectrometer of 3 min
oscillations in sunspot umbrae support the hypothesis that they are
caused by upwardly propagating acoustic waves. This is evident from
the asymmetry of oscillation amplitudes in the red and blue wings of
spectral lines, where the oscillations are decidedly more pronounced
in the blue than in the red line wing. Additional evidence include the
fact that the relation between oscillations in intensity and velocity
agree with that predicted for an acoustic wave with regard to phase
as well as magnitude. Finally, the observed phase difference between
lines formed at different temperatures points to an upward propagating
disturbance, and the value of dominant frequency of the oscillations,
close to 6 mHz, is above the acoustic cutoff frequency in the sunspot
atmosphere. SOHO is a mission of international cooperation between ESA
and NASA. This study was supported by the Research Council of Norway.
Title: Sunspot oscillations in the chromosphere, transition region,
and corona
Authors: Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2002ESASP.506..513B
Altcode: 2002ESPM...10..513B; 2002svco.conf..513B
The results of simultaneous observations with CDS on SOHO and TRACE
for thirteen sunspots in 2001 and 2002 are combined with previous
results for six sunspots observed with CDS and SUMER on SOHO. Intensity
oscillations are detected above each umbra and spectral observations
of chromospheric and transition region lines allow us to measure
oscillations in the line-of-sight velocity in several sunspots. The
power spectra show one dominant peak close to 6 mHz, corresponding
to a period of 3 minutes. The oscillation amplitude increases with
increasing temperature, reaches a maximum for lines emitting close
to 1-2×105K, and decreases for higher temperatures. Part
of the wave energy penetrates into the corona, channeled into small
areas that appear to coincide with the endpoints of sunspot coronal
lops. The observations support the hypothesis that the oscillations
are caused by upwardly propagating acoustic waves. The observations
are not compatible with the concept of a chromospheric resonator.
Title: On the nature of the 3 minute oscillations above sunspots
Authors: Hansteen, V. H.; Wikstøl, Ø.; Brynildsen, N.; Maltby, P.;
Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2002ESASP.505..183H
Altcode: 2002IAUCo.188..183H; 2002solm.conf..183H
Oscillations in the sunspot transition region and corona are observed
simultaneously with the Coronal Diagnostic Spectrometer - CDS on SOHO
and the Transition Region And Coronal Explorer - TRACE. Observations
of thirteen sunspots in 2001 and 2002 show that the amplitude in
the relative integrated line intensity increases with increasing
temperature, reaches a maximum for emission lines formed close to
1-2×105K, and decreases at higher temperatures. Part of the
wave energy penetrates into the corona, channeled into small areas that
appear to coincide with the endpoints of sunspot coronal loops. The
observed power spectra show one dominating peak close to 6 mHz. To
explore the nature of the waves we calculate upwardly propagating
acoustic waves confined to a magnetic flux tube and compare the results
with the observations.
Title: Oscillations Above Sunspots
Authors: Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2002SoPh..207..259B
Altcode:
The 3-min oscillations in the sunspot atmosphere are discussed, based
on joint observing with the Transition Region and Coronal Explorer -
TRACE and the Solar and Heliospheric Observatory - SOHO. We find that
the oscillation amplitude above the umbra increases with increasing
temperature, reaches a maximum for emission lines formed close to 1-2×
105 K, and decreases for higher temperatures. Oscillations
observed with a high signal-to-noise ratio show deviations from pure
linear oscillations. The results do not support the sunspot filter
theory, based on the idea of a chromospheric resonator. Whereas the
filter theory predicts several resonant peaks in the power spectra,
equally spaced ∼ 1 mHz in frequency, the observed power spectra show
one dominating peak, close to 6 mHz. Spectral observations show that the
transition region lines contribute less than 13 percent to the TRACE 171
Å channel intensity above the umbra. The 3-min oscillations fill the
sunspot umbra in the transition region. In the corona the oscillations
are concentrated to smaller regions that appear to coincide with the
endpoints of sunspot coronal loops, suggesting that wave propagation
along the magnetic field makes it possible for the oscillations to
reach the corona.
Title: 3 minute oscillations above sunspots
Authors: Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2002ESASP.508..283B
Altcode: 2002soho...11..283B
The aim of this investigation is a better understanding of the 3 minute
oscillations above sunspots. We present the first results from a joint
observing programme with SOHO and TRACE. Attention is given to the wave
amplitude as a function of the temperature and to the penetration of
part of the wave energy into the corona. The results appear to disagree
with the sunspot filter theory.
Title: The 6 mHz Oscillations above Sunspots
Authors: Brekke, P.; Brynildsen, N.; Maltby, P.; Fredvik, T.;
Kjeldseth-Moe, O.
Bibcode: 2002AAS...200.8806B
Altcode: 2002BAAS...34..790B
Sunspot oscillations in the transition region and corona are observed
simultaneously with CDS on SOHO and TRACE. Results obtained from
investigations of ten sunspots in 2001 and 2002 are presented. We
find that the oscillation amplitude above the umbra increases with
increasing temperature, reaches a maximum for lines emitted close to 200
000 K, and decreases for higher temperatures. Part of the wave energy
penetrates into the corona, channeled into small areas that appear
to coincide with the endpoints of sunspot coronal loops. The observed
power spectra show one dominating peak, near 6 mHz, and not several,
equally spaced resonances as predicted by theories based on the idea
of a chromospheric resonator. We conclude that the observations are
compatible with upwardly propagating acoustic waves.
Title: Variability and dynamic state of active region loops
Authors: Fredvik, T.; Kjeldseth-Moe, O.; Haugan, S. V. H.; Brekke,
P.; Gurman, J. B.; Wilhelm, K.
Bibcode: 2002AdSpR..30..635F
Altcode:
A set of 218 consecutive CDS rasters taken at the solar limb on October
26-28 1999 has been used to investigate the variability and plasma
dynamics of active region loops. Each raster contains simultaneous
images in 6 different lines, covering the full temperature range of
CDS, 10 000 K (He I) to 2.7 MK (Fe XVI). Activity is seen to go on
without breaks at temperatures below 1 MK for the full 39 hours of the
series. Transition region loops or extended sections of loops, 50-200
Mm long, appear and disappear in intervals as short as 11 minutes,
the observing cadence. In the corona the emission is less variable,
but significant changes are seen. Measured Doppler shifts correspond
to typical plasma velocities of 20 km s -1 to 100 km
s -1, at temperatures 10 000 K to 450 000 K, and siphon
flows may occur in some of the loops. High velocities are frequently
seen where the emitted intensities are weak, often on the outer edges
of loops as defined in that particular spectral line. At coronal
temperatures, 1 MK and higher, systematic loop velocities occur only
occasionally. Simultaneous observations with EIT and SUMER were made
during part of the raster series and are compared with the CDS result.
Title: An Upper Temperature Limit For Strong Dynamic Activity In
The Solar Transition Region and Corona
Authors: Fredvik, T.; Kjeldseth-Moe, O.
Bibcode: 2002EGSGA..27.5258F
Altcode:
The transition region plasmas in loop structures above active regions
display evi- dence of high velocities, 20-100 km/s, and rapid time
variations, < 10 min, see e.g. Kjeldseth-Moe and Brekke (1998,
in Solar Phys., vol. 182, 73) or Fredvik and Kjeldseth-Moe (2002, in
Adv. Space Res., forthcoming). We have compared mate- rial velocities
in the plasma over a wide temperature range using spectral data from
the Solar Ultraviolet Measurements of Emitted Radiation, SUMER, to give
the best possible angular resolution. Simultaneous observations in the
lines N V 1238 A, O V 629 A and Mg X 624 A, emitted at 1.8 × 105 K,
2.4 × 105 K, and 1.1 MK, re- spectively, demonstrate convincingly
the lack of any observable dynamic behavior at coronal temperatures,
in the form of Doppler shifts (v < 10 km/s) as well as strong
intensity variations. The results are compared to calculations of
line shifts caused by sound waves in the plasma. The observations are
relevant for the selection of future instrumentation to study physical
conditions in the upper solar atmosphere. Future ob- servations giving
an improved temperature mapping between 5 × 105 K and 1 MK is planned
for April 2002.
Title: Search for a chromospheric resonator above sunspots
Authors: Brynildsen, N.; Maltby, P.; Brekke, P.; Fredvik, T.;
Kjeldseth-Moe, O.
Bibcode: 2002cosp...34E.178B
Altcode: 2002cosp.meetE.178B
We have recently observed eleven sunspots, both with CDS on SOHO
and TRACE as part of our on-going investigations of the sunspot
atmosphere. For each sunspot we investigate the oscillations in
the chromosphere, transition region and corona. The observed power
spectra show one dominating peak corresponding to a period of 3
minutes. The oscillation amplitude above the umbra increases with
increasing temperature, reaches a maximum for lines emitting close to
200 000 K, and decreases for higher temperatures. Part of the wave
energy penetrates into the corona, channeled into small areas that
appear to coincide with the endpoints of sunspot coronal loops. The
observations support the hypothesis that the oscillations are caused
by upwardly propagating acoustic waves and show no signs of equally
spaced resonances as predicted by theories based on the idea of a
chromospheric resonator.
Title: Sunspot Plumes and Flow Channels
Authors: Brynildsen, N.; Maltby, P.; Fredvik, T.; Kjeldseth-Moe, O.;
Wilhelm, K.
Bibcode: 2001SoPh..198...89B
Altcode:
It is well known that sunspots are dark. This statement is not correct
in the sunspot atmosphere between the chromosphere and the corona,
where sunspots often are brighter than their surroundings. The brightest
feature in the sunspot transition region is called a sunspot plume. Not
all sunspots contain a plume. We find that 20 out of 21 sunspots show
a plume when one magnetic polarity dominates the sunspot region out
to a distance of 50 '' from the sunspot. Most sunspots show
downflows that exceed 25 km s−1 in the sunspot plumes at
temperatures close to 250 000 K. This downflow is not maintained by
inflow from the corona, but by gas at transition region temperatures,
streaming in flow channels from locations well outside the sunspot. We
suggest that this inflow is a necessary requirement for the sunspot
plume to occur and present a working hypothesis for the origin of
sunspot plumes. This paper is the first thorough spectral analysis of
sunspot plumes. It is based on simultaneous observations of ten or six
EUV emission lines in 42 sunspot regions with the Coronal Diagnostic
Spectrometer - CDS on the Solar and Heliospheric Observatory - SOHO. The
line profiles are studied in detail with another SOHO instrument,
the Solar Ultraviolet Measurements of Emitted Radiation - SUMER.
Title: Observed Variability and Dynamics of Active Region Loops
Authors: Haugan, S. V. H.; Brekke, P.; Fredvik, T.; Kjeldseth-Moe,
O.; Wilhelm, K.; Gurman, J. B.
Bibcode: 2000SPD....31.0205H
Altcode: 2000BAAS...32..811H
A series of 218 rasters taken with the Coronal Diagnostic Spectrometer
(CDS) on SOHO demonstrates the strong time variability and
dynamical state of the plasma in active region loops at transition
region temperatures, i.e. 10 000 K to 500 000 K, first reported
by Kjeldseth-Moe and Brekke (1998). The continuous raster series,
which covered 39 hours, show how transition region loops or sections
of loops, 50-200 Mm in length, appear and disappear in intervals as
short as 10 minutes, the observing cadence. At the same temperatures
plasma velocities of 20 km s-1 to 100 km s-1
are indicated from observed Doppler shifts. Siphon flows may occur in
some of the loops, but in other loops patterns are less obvious. High
velocities are frequently seen where the emitted intensities are weak,
often on the ``outside'' of the loops as defined by the emission in
that particular spectral line. At coronal temperatures the emission
is less time variable, but significant changes are seen. Systematic
loop velocities occur only occasionally in the corona. Simultaneous
observations with EIT and SUMER were made during part of the raster
series and is compared with the CDS result.
Title: On the sunspot transition region
Authors: Maltby, P.; Brynildsen, N.; Fredvik, T.; Kjeldseth-Moe, O.;
Wilhelm, K.
Bibcode: 1999SoPh..190..437M
Altcode:
The EUV line emission and relative line-of-sight velocity in the
transition region between the chromosphere and corona of 36 sunspot
regions are investigated, based on observations with the Coronal
Diagnostic Spectrometer - CDS and the Solar Ultraviolet Measurements of
Emitted Radiation - SUMER on the Solar and Heliospheric Observatory -
SOHO. The most prominent features in the transition-region intensity
maps are the sunspot plumes. In the temperature range between log T=5.2
and log T=5.6 we find that 29 of the 36 sunspots contain one or two
sunspot plumes. The relative line-of-sight velocity in sunspot plumes
is high and directed into the Sun in the transition region, for 19 of
the sunspots the maximum velocity exceeds 25 km s−1. The
velocity increases with increasing temperature, reaches a maximum
close to log T=5.5 and then decreases abruptly.
Title: Transition Region Oscillations in a Sunspot Region
Authors: Brynildsen, N.; Fredvik, T.; Kjeldseth-Moe, O.; Maltby, P.
Bibcode: 1999ASPC..184..146B
Altcode:
Umbral oscillations in the sunspot transition region have been detected
and described from SOHO observations, mainly taken with SUMER of
NOAA 8156 on 18 February 1998 between 16:00 UT and 21:07 UT. SUMER
recorded simultaneously in the transition regions lines O V λ629, N
V λ1238 and N V λ1242, combined with long exposures for wavelength
calibration. Transition region oscillations with periods close to 3
min were observed both in intensity and in line-of-sight velocity;
the maximum intensity is nearly in phase with maximum velocity
directed towards the observer. The wave characteristics appear to be
compatible with the results of Gurman et al. (1982) from UVSP on SMM,
who interpreted them as upward propagating acoustic waves.
Title: A Transition Region Eruption Observed with CDS, TRACE and EIT
Authors: Brekke, P.; Kjeldseth-Moe, O.; Fredvik, T.; Haugan, S. V. H.;
Tarbell, T. D.; Gurman, J. B.
Bibcode: 1999AAS...194.5905B
Altcode: 1999BAAS...31..918B
An ejection of plasma on the west limb has been observed with CDS,
TRACE and EIT on 19 May 1998. The start of the eruption coincided
with a weak flare observed with GOES. Erupting material rose to 120
Mm above the solar surface in 17 min, and then fell back to the solar
surface. Vertical velocities of 200 km s(-1) are estimated from a series
of TRACE images in the C(+3) resonance lines at 155 nm and from EIT
images in the 19.5 nm band, while Doppler shifts of the transition
region lines observed with CDS yield maximum horizontal velocities
of 300 km s(-1) at the top of the plasma trajectories. The similar
appearance and time variation of the eruption as seen with all three
instruments indicate the presence of a multi-temperature plasma in
spatial regions less than 1-2 arc seconds, with temperatures ranging
from 10(5) K to 1.5 MK. The material did not have the momentum to break
loose from the Sun and was not associated with any CME observed with
LASCO. However, we may speculate that CMEs are similar to the eruption
observed, with even higher speeds involved.
Title: Time Variation of Active Region Loops Observed with CDS on SOHO
Authors: Fredvik, T.; Kjeldseth-Moe, O.; Brekke, P.; Haugan, S. V. H.
Bibcode: 1999AAS...194.5904F
Altcode: 1999BAAS...31R.918F
The emission from plasma filled loops, 10(4) K < T <1.5 MK,
above active regions are much more time variable than previously
considered. These loops, which define the solar atmosphere above active
regions in this temperature range, appear or disappear, the emission
along their length change, or they change shape or expand outward,
all on time scales of 10-20 minutes. In this paper we report on an
investigation with CDS on SOHO of 20 loop systems observed on the solar
limb between September 1997 and May 1998. We describe the apparent
isothermal appearance of many loops and discuss to what extent loops
radiating in different emission lines, i.e. at different temperatures,
are co-located within their recorded widths. Finally, we demonstrate
the time variability of loop systems at different temperatures, and
show how the rapidly changing conditions require a new conception of
loop systems that has never before been seriously considered.
Title: Coronal Radiation and Helium λ584 Emission in Active Regions
Authors: Fredvik, T.; Maltby, P.
Bibcode: 1999SoPh..184..113F
Altcode:
Based on EUV observations of eleven sunspot regions obtained with
the Coronal Diagnostic Spectrometer, CDS, on SOHO we have studied the
spatial distribution, temporal variation and wavelength shift of the
He i λ584 line. We find a relatively high spatial correlation between
the coronal line Fe xvi λ360 and the He i λ584 line. This points to
coronal back-radiation as an important contributor to the formation
of the He i line in active regions. However, contribution to the
line formation from another source is suggested by the following two
findings: First, the red-shifted line profiles of both He i λ584 and
the transition region lines tend to be more intense than blue-shifted
profiles. Second, the He i λ584 emission changes significantly faster
than the coronal line emission.
Title: Flows in Sunspot Plumes Detected with SOHO
Authors: Brynildsen, N.; Maltby, P.; Brekke, P.; Fredvik, T.; Haugan,
S. V. H.; Kjeldseth-Moe, O.; Wikstol, O.
Bibcode: 1998ApJ...504L.135B
Altcode: 1998astro.ph..5249B
In the Letter, ``Flows in Sunspot Plumes Detected with the Solar and
Heliospheric Observatory'' by N. Brynildsen, P. Maltby, P. Brekke,
T. Fredvik, S. V. H. Haugan, O. Kjeldseth-Moe, and Ø. Wikstøl (ApJ,
502, L85 [1998]), the following correction should be made: In
the last line on page L86, which reads ``peak line intensity I>=5
are located (1) above the umbra or, '' an ``Ī'' should be inserted so
that the revised line reads ``peak line intensity I>=5Ī are located
(1) above the umbra or.''
Title: Flows in Sunspot Plumes Detected with the Solar and
Heliospheric Observatory
Authors: Brynildsen, N.; Maltby, P.; Brekke, P.; Fredvik, T.; Haugan,
S. V. H.; Kjeldseth-Moe, O.; Wikstøl, Ø.
Bibcode: 1998ApJ...502L..85B
Altcode:
Bright extreme-UV sunspot plumes have been observed in eight out of
11 different sunspot regions with the Coronal Diagnostic Spectrometer
on Solar and Heliospheric Observatory. From wavelength shifts, we
derive the line-of-sight velocity relative to the average velocity
in the rastered area, 120''×120''. In sunspot
plumes, we find that the motion is directed away from the observer
and increases with increasing line formation temperature, reaches a
maximum between 15 and 41 km s-1 close to log logT~5.5,
then decreases abruptly. The flow field in the corona is not well
correlated with the flow in the transition region, and we discuss
briefly the implication of this finding.
Title: SOHO Observations of the Connection Between Line Profile
Parameters in Active and Quiet Regions and the Net Red Shift in EUV
Emission Lines
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Wilhelm, K.
Bibcode: 1998SoPh..181...23B
Altcode:
We present high spatial and spectral resolution observations of
one active and one quiet-Sun region, obtained with CDS and SUMER on
SOHO. The connections between the line profile parameters are studied
and a systematic wavelength shift towards the red with increasing peak
line intensity (line broadening) is detected. The large scatter in
the data calls for another approach. We apply conditional probability
analysis to a series of EUV emission lines and find significant
correlations between line profile parameters. For a given interval in
wavelength shift we find that: (1) line profiles with large intensities
(line widths) and red shifts above the average constitute an increasing
fraction of the profiles as the relative wavelength shift increases,
(2) line profiles with large intensities (line widths) and blue
shifts compared to the average, on the other hand, constitute a
decreasing fraction of the profiles as the relative wavelength shift
increases. These results extend the findings of an earlier quiet-Sun
study from one to several emission lines and expand the validity to
include the active region. Interestingly, the active region observations
show correlations between peak line intensity and wavelength shift in
the coronal lines.
Title: EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO -
II. Velocities and Line Profiles
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele,
T.; Thompson, W. T.; Wilhelm, K.
Bibcode: 1998SoPh..179..279B
Altcode:
We have studied the dynamics in the sunspot transition region between
the chromosphere and the corona and investigated the extension of
the flow field into the corona. Based on EUV spectra of a medium size
sunspot and its surroundings, NOAA 7981, observed with CDS and SUMER
on SOHO, we derive line-of-sight velocities and study the line profiles
for a series of emission lines.
Title: EUV Spectroscopy of the Sunspot Region NOAA 7981 Using SOHO -
I. Line Emission and Time Dependence
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele,
T.; Thompson, W. T.; Wilhelm, K.
Bibcode: 1998SoPh..179...43B
Altcode:
EUV spectra of a medium-size sunspot and its surroundings, NOAA 7981,
were obtained on 2 August 1996 with the Coronal Diagnostic Spectrometer
(CDS) and the Solar Ultraviolet Measurements of Emitted Radiation
(SUMER) on the Solar and Heliospheric Observatory (SOHO). The spectral
lines formed in the transition region and corona show considerable
structure and large deviations from a uniform spatial distribution over
the active region. Enhanced EUV emissions in transition region lines
are concentrated in small regions outside the umbra of the sunspot
throughout most of the observing sequence. Only during a short,
active period do we find an enhanced line emission that reaches into
the umbra. Preliminary values for the umbral intensity are given.
Title: The Non-Uniformity in the Sunspot Transition Region
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Rimmele, T.;
Wilhelm, K.
Bibcode: 1997ESASP.404..257B
Altcode: 1997cswn.conf..257B
No abstract at ADS
Title: Transition Region Velocities and Line Profiles in the Sunspot
Region 7981
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele,
T. Thompson, W. T.; Wilhelm, K.
Bibcode: 1997ESASP.404..251B
Altcode: 1997cswn.conf..251B
No abstract at ADS
Title: CDS Observations of the Connection Between Line Intensity
and Doppler Shift in the Active Region NOAA 7981
Authors: Fredvik, T.; Brynildsen, N.; Maltby, P.; Kjeldseth-Moe, O.;
Brekke, P.; Haugen, S. V. H.; Harrison, R. A.
Bibcode: 1997ESASP.404..391F
Altcode: 1997cswn.conf..391F
No abstract at ADS
Title: The Net Redshifts in EUV Emission Lines and the Connection
Between Intensity and Doppler Shift
Authors: Brynildsen, N.; Fredvik, T.; Maltby, P.; Kjeldseth-Moe, O.;
Brekke, P.; Haugan, S. V. H.; Harrison, R. A.; Wilhelm, K.
Bibcode: 1997ESASP.404..263B
Altcode: 1997cswn.conf..263B
No abstract at ADS
Title: EUV Line Emission and Time Dependence in the Sunspot Region
NOAA 7981
Authors: Brynildsen, N.; Brekke, P.; Fredvik, T.; Haugan, S. V. H.;
Kjeldseth-Moe, O.; Maltby, P.; Harrison, R. A.; Pike, C. D.; Rimmele,
T.; Thompson, W. T.; Wilhelm, K.
Bibcode: 1997ESASP.404..245B
Altcode: 1997cswn.conf..245B
No abstract at ADS