scholarly journals Analysis of Supergranule Sizes and Velocities Using Solar Dynamics Observatory (SDO)/Helioseismic Magnetic Imager (HMI) and Solar and Heliospheric Observatory (SOHO)/Michelson Doppler Imager (MDI) Dopplergrams

Solar Physics ◽  
2013 ◽  
Vol 289 (1) ◽  
pp. 11-25 ◽  
Author(s):  
Peter E. Williams ◽  
W. Dean Pesnell ◽  
John G. Beck ◽  
Shannon Lee
Keyword(s):  
Michelson Doppler Imager ◽  
Solar Dynamics Observatory ◽  
Heliospheric Observatory ◽  
Doppler Imager ◽  
Solar Dynamics

scholarly journals The Solar and Heliospheric Observatory

1984 ◽  
Vol 86 ◽  
pp. 155-158 ◽  
Author(s):  
Giancarlo Noci
Keyword(s):  
Solar Physics ◽  
Grazing Incidence ◽  
Spectral Irradiance ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Solar Constant ◽  
Heliospheric Observatory ◽  
Explorer Mission ◽  
Solar Dynamics ◽  
Euv Spectrum

In the past years several space missions have been proposed for the study of the Sun and of the Heliosphere. These missions were intended to clarify various different aspects of solar physics. For example, the GRIST (Grazing Incidence Solar Telescope) mission was intended as a means to improve our knowledge of the upper transition region and low corona through the detection of the solar EUV spectrum with a spatial resolution larger than in previous missions; the DISCO (Dual Spectral Irradiance and Solar Constant Orbiter) and SDO (Solar Dynamics Observatory) missions were proposed to gat observational data about the solar oscillations better than those obtained from ground based instruments; the SOHO (Solar and Heliospheric Observatory) mission was initially proposed to combine the properties of GRIST with the study of the extended corona (up to several radii of heliocentric distance) by observing the scattered Ly-alpha and OVI radiation, which was also the basis of the SCE (Solar Corona Explorer) mission proposal; the development of the interest about the variability of the Sun, both in itself and for its consequences in the history of the Earth, led to propose observations of the solar constant (included in DISCO).

scholarly journals One solar cycle of solar astrometry with MDI/SOHO

2009 ◽  
Vol 5 (S264) ◽  
pp. 21-32 ◽  
Author(s):  
Marcelo Emilio ◽  
Jeff R. Kuhn ◽  
Rock I. Bush
Keyword(s):  
Solar Cycle ◽  
Solar Radius ◽  
Michelson Doppler Imager ◽  
Heliospheric Observatory ◽  
Radius Variation ◽  
Doppler Imager ◽  
Upper Limit ◽  
The Absolute ◽  
The Difference

AbstractIn this work we describe the method and results of precise solar astrometry made with the Michelson Doppler Imager (MDI), on board the Solar and Heliospheric Observatory (SOHO), during one complete solar cycle. We measured an upper limit to the solar radius variation, the absolute solar radius value and the solar shape. Our results are 22 mas peak-to-peak upper limit for the solar radius variation over the solar cycle, the absolute radius was measured as 959.28 ± 0.15 arcsec at 1 AU and the difference between polar and equatorial solar radii in 1997 was 5 km and about three times larger in 2001.

scholarly journals Evolution and decay of an active region: Magnetic shear, flare and CME activity

2000 ◽  
Vol 39 (1) ◽  
pp. 73-80
Author(s):  
L. van Driel-Gresztelyi ◽  
B. Thompson ◽  
S. Punkett ◽  
P. Démoulin ◽  
G. Aulanier
Keyword(s):  
Active Region ◽  
Michelson Doppler Imager ◽  
Magnetic Shear ◽  
Heliospheric Observatory ◽  
Doppler Imager

Desde abril de 1996 y hasta febrero de 1997, se observó en el disco solar un complejo de actividad. Este complejo exhibió su nivel más alto de actividad durante el nacimiento de la región activa (AR) 7978. Nuestro análisis se extiende a lo largo de seis rotaciones solares, desde la aparición de AR 7978 (julio de 1996) hasta el decaimiento y dispersión de su flujo (noviembre de 1996). Los datos en varias longitudes de onda provistas por los instrumentos a bordo del Solar and Heliospheric Observatory (SOHO) y del satélite japonés Yohkoh, nos permiten seguir la evolución de la región desde la fotosfera hasta la corona. Usando los magnetogramas del disco completo obtenidos por el Michelson Doppler Imager (SOHO/MDI) como condiciones de contorno, calculamos el campo magnético coronal y determinamos su apartamiento de la potencialidad ajustando las líneas de campo calculadas a los arcos observados en rayos X blandos. Discutimos la evolución de la torsión del campo magnético coronal y su probable relación con la actividad observada en forma de eyecciones de masa coronal (CMEs) y fulguraciones.

scholarly journals The behavior of the spotless active regions during the solar minimum 23-24

2016 ◽  
Vol 12 (S328) ◽  
pp. 137-139
Author(s):  
Alexandre José de Oliveira e Silva ◽  
Caius Lucius Selhorst
Keyword(s):  
Solar Minimum ◽  
Solar Surface ◽  
Active Regions ◽  
Physical Parameters ◽  
Michelson Doppler Imager ◽  
Heliospheric Observatory ◽  
Doppler Imager

AbstractIn this work, we analysed the physical parameters of the spotless actives regions observed during solar minimum 23 – 24 (2007 – 2010). The study was based on radio maps at 17 GHz obtained by the Nobeyama Radioheliograph (NoRH) and magnetograms provided by the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO). The results shows that the spotless active regions presents the same radio characteristics of a ordinary one, they can live in the solar surface for long periods (>10 days), and also can present small flares.

scholarly journals New Homogeneous Dataset of Solar EUV Synoptic Maps from SOHO/EIT and SDO/AIA

Solar Physics ◽  
2019 ◽  
Vol 295 (1) ◽  
Author(s):  
A. Hamada ◽  
T. Asikainen ◽  
K. Mursula
Keyword(s):  
Extreme Ultraviolet ◽  
Solar Surface ◽  
Intensity Scale ◽  
Solar Dynamics Observatory ◽  
Heliospheric Observatory ◽  
Imaging Telescope ◽  
Solar Dynamics ◽  
Sensor Degradation ◽  
Full Disk

AbstractSynoptic maps of solar EUV intensities have been constructed for many decades in order to display the distribution of the different EUV emissions across the solar surface, with each map representing one Carrington rotation (i.e. one rotation of the Sun). This article presents a new solar EUV synoptic map dataset based on full-disk images from the Solar and Heliospheric Observatory/Extreme Ultraviolet Imaging Telescope (SOHO/EIT) and Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA). In order to remove the significant and complicated drift of EIT and AIA EUV intensities due to sensor degradation, we construct the synoptic maps in standardized intensity scale. We describe a method of homogenizing the SOHO/EIT maps with SDO/AIA maps by transforming the EIT intensity histograms to AIA levels. The new maps cover the years from 1996 to 2018 with 307 SOHO/EIT and 116 SDO/AIA synoptic maps, respectively. These maps provide a systematic and homogeneous view of the entire solar surface in four EUV wavelengths, and are well suited, e.g., for studying long-term coronal hole evolution.

scholarly journals Solar microflares: a case study on temperatures and the Fe XVIII emission

2019 ◽  
Vol 628 ◽  
pp. A134 ◽  
Author(s):  
U. Mitra-Kraev ◽  
G. Del Zanna
Keyword(s):  
Extreme Ultraviolet ◽  
Atomic Data ◽  
Solar Dynamics Observatory ◽  
Imaging Spectrometer ◽  
Heliospheric Observatory ◽  
X Ray ◽  
Solar Dynamics ◽  
Peak Emission ◽  
Good Agreement

In this paper, we discuss the temperature distribution and evolution of a microflare, simultaneously observed by Hinode’s X-Ray Telescope (XRT), its Extreme Ultraviolet Imaging Spectrometer (EIS), as well as the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO). Using EIS lines, we find that during peak emission the distribution is nearly isothermal and peaked around 4.5 MK. This temperature is in good agreement with that obtained from the XRT filter ratio, validating the use of XRT to study these small events, invisible to full-Sun X-ray monitors such as the Geostationary Operational Environmental Satellite (GOES). The increase in the estimated Fe XVIII emission in the AIA 94 Å band can mostly be explained with the small temperature increase from the background temperatures. The presence of Fe XVIII emission does not guarantee that temperatures of 7 MK are reached, as is often assumed. With the help of new atomic data, we also revisit the temperatures measured by a Solar and Heliospheric Observatory (SoHO) Solar Ultraviolet Measurements of Emitted Radiation (SUMER) observation of an active region that produced microflares, also finding low temperatures (3–4 MK) from an Fe XVIII/Ca XIV ratio.

scholarly journals Spatial Inhomogeneity in Solar Faculae

2017 ◽  
Vol 13 (S335) ◽  
pp. 17-19
Author(s):  
A. Elek ◽  
N. Gyenge ◽  
M. B. Korsós ◽  
R. Erdélyi
Keyword(s):  
Solar Surface ◽  
Spatial Inhomogeneity ◽  
Longitudinal Distribution ◽  
Dynamo Model ◽  
Latitudinal Distribution ◽  
Solar Dynamics Observatory ◽  
Active Longitude ◽  
Heliospheric Observatory ◽  
Oscillatory Pattern ◽  
Solar Dynamics

AbstractIn this paper, we investigate the inhomogeneous spatial distribution of solar faculae. The focus is on the latitudinal and longitudinal distributions of these highly localised features covering ubiquitously the solar surface. The statistical analysis is based on white light observations of the Solar and Heliospheric Observatory (SOHO) and Solar Dynamics Observatory (SDO) between 1996 and 2014. We found that the fine structure of the latitudinal distribution of faculae displays a quasi-biennial oscillatory pattern. Furthermore, the longitudinal distribution of photospheric solar faculae does not show homogeneous behaviour either. In particular, the non-axisymmetric behaviour of these events show similar properties as that of the active longitude (AL) found in the distribution of sunspots. Our results, preliminary though, may provide a valuable observational constrain for developing the next-generation solar dynamo model.

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