CONICET | Buscador de Institutos y Recursos Humanos

Using Advanced Composition Explorer (ACE) insitu data we identify and describe an interplanetary magneticcloud (MC) observed near Earth on 13 April 2006.We also use multi-instrument and multi-wavelength observationsfrom the Solar and Heliospheric Observatory (SOHO),the Transition Region and Coronal Explorer (TRACE) andground-based solar observatories to determine the solarsource of this magnetic cloud.A launch window for the MC between 9 and 11 April 2006was estimated from the propagation time of the ejecta observednear Earth. A number of large active regions (ARs)were present on the Sun during this period, which were initiallyconsidered to be the most likely candidate source regionsof the MC. However, it was determined that the solarsource of the MC was a small, spotless active region observedin the Northern Hemisphere. Following an eruptionfrom this region on 11 April 2006, the ACE spacecraft detected,59 h later, the passage of the MC, preceded by thearrival of a weak, forward fast shock.The link between the eruption in this active region and theinterplanetary MC is supported by several pieces of evidence,including the location of the solar source near to the disk centreand to the east of the central meridian (in agreement withthe spacecraft trajectory through the western leg of the magneticcloud), the propagation time of the ejecta, the agreementbetween the amount of flux in the magnetic cloud andin the active region, and the agreement between the signs ofhelicity of the magnetic cloud and the active region (whichdiffers from the sign of helicity of each of the other activeregions on the Sun at this time). In addition, the active regionis located on the boundary of a coronal hole, and a highspeed solar wind stream originating from this region is observednear Earth shortly after the passage of the magneticcloud.