Abstract
Abstract. Collimated ejections of plasma called "coronal hole jets" are commonly observed in polar coronal holes. However, such coronal jets are not only a specific features of polar coronal holes but they can also be found in coronal holes appearing at lower heliographic latitudes. In this paper we present some observations of "equatorial coronal hole jets" made up with data provided by the STEREO/SECCHI instruments during a period comprising March 2007 and December 2007. The jet events are selected by requiring at least some visibility in both COR1 and EUVI instruments. We report 15 jet events, and we discuss their main features. For one event, the uplift velocity has been determined as about 200 km s−1, while the deceleration rate appears to be about 0.11 km s−2, less than solar gravity. The average jet visibility time is about 30 min, consistent with jet observed in polar regions. On the basis of the present dataset, we provisionally conclude that there are not substantial physical differences between polar and equatorial coronal hole jets.
Highlights
The STEREO (Solar TErrestrial RElations Observatory) mission represents a milestone in the exploration and observation of the Sun and of the inner Heliosphere
In this paper we present observations of equatorial coronal hole jets identified in images of the STEREO Extreme-UltraViolet Imager (EUVI) and COR 1 telescopes, of the SECCHI instruments suites on board the twin STEREO spacecraft
From a detailed inspection of the observations derived from the two perspectives, we can show that the bright points previously observed in association with polar jets, corresponded to the footpoint of the jets, and that the collimated plasma beam became visible only when it appeared as bright structure at the solar limb against a dark background
Summary
The STEREO (Solar TErrestrial RElations Observatory) mission represents a milestone in the exploration and observation of the Sun and of the inner Heliosphere. Jets have a duration of tens of minutes to slightly longer than 1h (Savcheva et al, 2007; Cirtain et al, 2007), lengths of 1– 20×104 km , thickness of 1–4×104 km, and speed ranging from 150 km s−1 to over 800 km s−1 (Shimojo et al, 1996; Cirtain et al, 2007) These phenomena are thought to be triggered by reconnection process between the large-scale open unipolar magnetic field of the coronal hole and small-scale closed bipoles, emerging from the photosphere (Shibata et al, 1992).
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