Study of Coronal Jets Ejected from Anemone-type Active Regions

ar052.shibata07
Posted:  04-Oct-93
Updated: 13-Apr-94
Events specified: Active Regigon NOAA 7001 and associated gigantic jet on Jan 11, 1992, etc.
  

K. Shibata, N. Nitta, R. Matsumoto, T. Yokoyama, H. Hudson, K. Strong

subject:

SXT has revealed that active region appearing in a coronal hole has a shape similar to "sea-anemone"; such ARs are called here "anemone-AR". We found that often jets are ejected from these anemone-ARs in vertical direction associated with small flares occured in the ARs. One of the largest such jets is a jet ejected from NOAA 7001 on Jan. 11, 1992. There are more than 10 examples until now. We will study these phenomena in detail.

how to do it:

We will measure temperature, emission measure, electron density, mass, thermal energy content, etc. using filter ratio method, for both jets and footpoint ARs. We will also compare the SXT images with while light, Halpha, magnetogram data.

Update 13-Apr-94

This project has been finished, and a letter was submitted to Ap.J. Letter in March 1994. The title, authors, abstract are as follows;


Title: A Gigantic Coronal Jet Ejected from A Compact Active Region in A Coronal Hole

author: K. Shibata, N. Nitta, K. T. Strong, R. Matsumoto, T. Yokoyama, T. Hirayama, H. Hudson, and Y. Ogawara

ABSTRACT:

A gigantic coronal jet greater than $3 \times 10^5$ km long (nearly half the solar radius) has been found with the soft X-ray telescope (SXT) on board the solar X-ray satellite, {\it Yohkoh}. The jet was ejected on 11 January 1992 from an \lq \lq anemone-type" active region (AR) appearing in a coronal hole and is one of the largest coronal X-ray jets observed so far by SXT. This gigantic jet is the best-observed example of many other smaller X-ray jets, because the spatial structures of both the jet and the AR located at its base are more easily resolved. The range of apparent translational velocities of the bulk of the jet was between 90 and 240 km/s, with the corresponding kinetic energy estimated to be of order of $10^{28}$ erg. A detailed analysis reveals that the jet was associated with a loop brightening (a small flare) that occurred in the active region. Several features of this observations suggest and are consistent with a magnetic reconnection mechanism for the production of such a ``jet---loop-brightening'' event.