EIT Observations of Coronal Mass Ejections

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A CME with an eruptive prominence
well observed from the ground

HAO MLSO H alpha limb movie (1.1 Mbyte)	SOHO EIT Fe XII 195 Å movie 0.25 Mbyte	SOHO EIT Fe XII difference movie 6.5 Mbyte

All movies are QuickTime with MPEG-4 compression. Requires a href = "http://www.apple.com/quicktime/download/">QuickTime 6.5 or higher for Mac OS X or Windows.

A CME without a flare

Click on thumbnail for full-resolution image

On 1999 September 20, EIT observed a large-scale eruptive filament near central meridian. the filament exhibited significant, large-scale twist-up (not unravelling), or at least the transfer of helicity from small to filament-long scales.

Perhaps the most intriguing feature of this filament eruption is that it was evidently involved in a halo CME but apparently had no associated flare (unless, of course, you consider the post-CME loops to be a flare). This appears to be at least a single case of a CME without a flare.

Another CME without a flare

Click on thumbnail for full-resolution image

On 1999 September 23, EIT observed a large-scale eruptive filament from the southwest quadrant of the disk, from the same region as our first example of a "flareless CME" (something Hugh Hudson refers to as an oxymoron).

This event may not be a perfect example, since it is preceded (by about 4 hours) by a backside CME from the southeast limb, and at roughly the same time as the backside CME, a "mini-CME" (tiny loop brightening, small puff dimming, and runtish arcade) in a prominent EUV bright point in the NW quadrant. One could argue that a "global coronal disturbance" unites all three events somwhow, and that that disturbance is initiated by a flare that is conveniently located on the backside of the Sun.

I find that inherently implausible, though, since the distance between the mini-CME and the eruptive filament site is only half a solar radius or so, and a wave propagating between the two would only be moving at around 24 km/s, an order of magnitude slower than we know CME-related waves travel in the corona seen in the EIT 195 Å channel.

There is no GOES event at the time of this eruptive, but there is a LASCO CME, moving quite rapidly, visible in the C2 images shortly after the eruption seen in EIT.

So one man's oxymoron may be another man's paradigm.

SOHO's first post-recovery halo CME!!

The image below on the left is an EIT image taken at 23:59 UT on the 14th of October, showing the location of filament. The image on the right is a LASCO C3 image of the halo CME, taken at 14:37 UT on 15 October. The EIT image has been rotated by 53 degrees to correct for the SOHO's angle at the time, so Solar North corresponds to the top of the image. However, the LASCO image has not been rotated (it is tilted 53 degrees counterclockwise, so Solar North points to the upper left). The bright dot with the line through it spanning the top of the image is Venus (to fully understand why Venus looks that way in a C3 image, refer to Dr. SOHO's answer to this question.

Pre-event	Filament is rising, fading	Still fading
It finally erupts	Arcades forming	Strong, two-ribbon flare visible

A Javascript Movie of this event shows the evolution really well. Movies and images of the LASCO coronagraph's observations of the halo CME are available at ftp://lasco-www.nrl.navy.mil/pub/lasco/halo/981015/.

The CME/Moreton wave of Thanksgiving Day, 1997 (1997/11/27)

1997 November 27, 13:11 - 14:19 UT (Note that all times are ~ 1 m earlier than marked.)

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The following pages are available for the use of our collaborators in analyzing individual events. Nothing in these pages is citable without an approved EIT data analysis proposal.

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Pre-event	Filament motion	Filament gone
Dimming grows	...and grows	Arcade still visible

Note that the filament visibility descriptions in the table refer to Fe XII 195 Å observations only.

A GIF movie of closeups from the EIT full-field, full-resolution CME watch, covering 1997 October 23, 12:13 - 18:57 UT.

If you're interested in analyzing these data, please contact Joe Gurman or another member of the EIT consortium.

Moreton waves: The "ground track" of a CME

Note: See the official International Solar-Terrestrial Physics (ISTP) program Sun-Earth Connections event page for this event (lots more detail on prediction criteria, other measurements, &c.)

Moreton waves from AR 8088, 1997 September 23

Mini-CME's?

• Subset of the EIT Fe XII 195 Å CME watch for 1997 August 25

• Difference movie, 1997 August 25

• Subset of the EIT Fe XII 195 Å CME watch for 1997 August 26

• Difference movie, 1997 August 26

Regular, economy size CME's

• The W limb event of 1996/06/06

• The disk event of 1996/09/25 - 26

• The E limb events of 1996 October 19 - 20

• The W limb event of 1996/11/28 - 29

• The W limb event of 1996/11/30 - 12/01

• The W limb events of 1996/12/23 - 24

• The S, W limb events of 1997/02/06 - 07

• The Disk center events of 1997/04/01

• The Disk center events of 1997/04/07

• The Disk center events of 1997/05/12