Matter flow velocities in active region emission loop observed in H- alpha

Delone, A. B.; Макарова, Е. А.; Porfir'eva, G. A.; Roschina, E. M.; Yukunina, G.

doi:10.1007/bfb0025675

Cited by 2 publications

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“…Most observations are taken in chromospheric lines like the Ca -line and Hα (e.g. Loughhead & Bray 1984;Delone et al 1989;Heinzel et al 1992;Wiik et al 1996). Since the loops are usually only partly filled with Hα-or Ca -emitting material, the fine structure revealed by high spatial resolution observations consists of bright blobs moving downwards which are often almost equidistant leading to terms like "train of blobs".…”

Section: Introductionmentioning

confidence: 99%

Intensity variations in EIT shutterless mode: Waves or flows?

Groof

Berghmans²,

Driel-Gesztelyi

et al. 2004

A&A

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Abstract. On 11 July 2001 an EIT shutterless campaign was conducted which provided 120 high-cadence (68 s) 304 Å images of the north eastern quarter of the Sun. The most interesting feature seen in the data is an off-limb half loop structure along which systematic intensity variations are seen which appear to propagate from the top of the loop towards its footpoint. We investigate the underlying cause of these propagating disturbances, i.e. whether they are caused by waves or by plasma flows. First we identify 7 blobs with the highest intensities and follow them along the loop. By means of a location-time plot, bulk velocities can be measured at several locations along the loop. The velocity curve found this way is then compared with characteristic wave speeds and with the free-fall speed in order to deduce the nature of the intensity variations. Additional information on density and temperature is derived by measuring the relative intensity enhancements and comparing the EIT 304 Å sequence with Big Bear data and 171 Å data (TRACE/EIT). The combination of all these constraints gives us an insight on the nature and origin of these intensity variations. The idea of slow magneto-acoustic waves is rejected, and we find several arguments supporting that these intensity variations are due to flowing/falling plasma blobs.

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Section: Introductionmentioning

confidence: 99%

Intensity variations in EIT shutterless mode: Waves or flows?

Groof

Berghmans²,

Driel-Gesztelyi

et al. 2004

A&A

View full text Add to dashboard Cite

show abstract

“…Engvold et al 1979;Loughhead & Bray 1984;Delone et al 1989;Heinzel et al 1992;Wiik et al 1996). Since the loops/prominences are usually only partly filled with Hα or Ca  emitting material, the fine structure revealed by high spatial resolution observations consists of (a "train" of) bright blobs moving downwards.…”

Section: Introductionmentioning

confidence: 99%

Detailed comparison of downflows seen both in EIT 30.4 nm and Big Bear Hα movies

Groof

Bastiaensen

Müller

et al. 2005

A&A

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An EIT shutterless campaign was conducted on 11 July 2001 and provided 120 high-cadence (68 s) 30.4 nm images of the north-eastern quarter of the Sun. Systematic intensity variations are seen which appear to propagate along an off-disk loop-like structure. In this paper we study the nature of these intensity variations by confronting the EIT observations studied in De Groof et al. (2004Groof et al. ( , A&A, 415, 1141 with simultaneous Hα images from Big Bear Solar Observatory. With the goal to carefully co-register the two image sets, we introduce a technique designed to compare data of two different instruments. The image series are first co-aligned and later overplotted in order to visualize and compare the behaviour of the propagating disturbances in both data sets. Since the same intensity variations are seen in the EIT 30.4 nm and in the Hα images, we confirm the interpretation of De Groof et al. (2004Groof et al. ( , A&A, 415, 1141) that we are observing downflows of relatively cool plasma. The origin of the downflows is explained by numerical simulations of "catastrophic cooling" in a coronal loop which is heated predominantly at its footpoints.

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Matter flow velocities in active region emission loop observed in H- alpha

Cited by 2 publications

References 0 publications

Intensity variations in EIT shutterless mode: Waves or flows?

Intensity variations in EIT shutterless mode: Waves or flows?

Detailed comparison of downflows seen both in EIT 30.4 nm and Big Bear Hα movies

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