Coronal hole parameters Virtual Observatory Resource

Authors
  1. Heinemann S.G.
  2. Temmer M.
  3. Heinemann N.
  4. Dissauer K.
  5. Samara E.
  6. Jercic V.,Hofmeister S.J.
  7. Veronig A.M.
  8. Published by
    CDS
Abstract

Coronal holes are usually defined as dark structures seen in the extreme ultraviolet and X-ray spectrum which are generally associated with open magnetic fields. Deriving reliably the coronal hole boundary is of high interest, as its area, underlying magnetic field, and other properties give important hints as regards high speed solar wind acceleration processes and compression regions arriving at Earth. In this study we present a new threshold-based extraction method, which incorporates the intensity gradient along the coronal hole boundary, which is implemented as a user-friendly SSW-IDL GUI. The Collection of Analysis Tools for Coronal Holes (CATCH) enables the user to download data, perform guided coronal hole extraction and analyze the underlying photospheric magnetic field. We use CATCH to analyze non-polar coronal holes during the SDO-era, based on 193{AA} filtergrams taken by the Atmospheric Imaging Assembly (AIA) and magnetograms taken by the Heliospheric and Magnetic Imager (HMI), both on board the Solar Dynamics Observatory (SDO). Between 2010 and 2019 we investigate 707 coronal holes that are located close to the central meridian. We find coronal holes distributed across latitudes of about +/-60{deg}, for which we derive sizes between 1.6x10^9^ and 1.8x10^11^km^2^. The absolute value of the mean signed magnetic field strength tends towards an average of 2.9+/-1.9G. As far as the abundance and size of coronal holes is concerned, we find no distinct trend towards the northern or southern hemisphere. We find that variations in local and global conditions may significantly change the threshold needed for reliable coronal hole extraction and thus, we can highlight the importance of individually assessing and extracting coronal holes.

Keywords
  1. The Sun
  2. Magnetic fields
  3. Stellar atmospheres
Bibliographic source Bibcode
2019SoPh..294..144H
See also HTML
https://cdsarc.cds.unistra.fr/viz-bin/cat/J/other/SoPh/294.144
IVOA Identifier IVOID
ivo://CDS.VizieR/J/other/SoPh/294.144

Access

Web browser access HTML
http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/other/SoPh/294.144
https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/other/SoPh/294.144
http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/other/SoPh/294.144
IVOA Table Access TAP
http://tapvizier.cds.unistra.fr/TAPVizieR/tap
Run SQL-like queries with TAP-enabled clients (e.g., TOPCAT).

History

2019-11-06T13:29:46Z
Resource record created
2019-11-06T12:30:22Z
Updated
2019-11-06T13:29:46Z
Created

Contact

Name
CDS support team
Postal Address
CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France
E-Mail
cds-question@unistra.fr