[38.13] Transient Coronal Holes as seen in the HeI 1083nm Observations

AAS 200th meeting, Albuquerque, NM, June 2002
Session 38. Solar Photosphere, Chromosphere and Transition Region
Display, Tuesday, June 4, 2002, 10:00am-6:30pm, SW Exhibit Hall

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[38.13] Transient Coronal Holes as seen in the HeI 1083nm Observations

G. de Toma, T. E. Holzer, H. R. Gilbert, J. T. Burkepile (NCAR/HAO), K. L. Harvey (SPRC)

Observations from Yohkoh/SXT and SOHO/EIT have shown that dimming regions often appear on the solar disk near the location of a Coronal Mass Ejection (CME). We can now see in HeI observations made at Mauna Loa Solar Observatory (MLSO) brightenings that form at the time of a CME and are co-spatial with the ultraviolet and X-ray dimmings. Both dimmings and brightenings can be interpreted as different manifestations of the decreased density of the overlying corona caused by the ejection of coronal material during the eruption, i.e. as transient coronal holes.

Because of the 3-minute cadence of the HeI 1083nm observations at MLSO, we can now determine the appearance and evolution of transient coronal holes with high accuracy. In this paper, we present examples of transient coronal holes as seen in HeI data and compare them with simultaneous observations in the H alpha line and in the ultraviolet.

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