Mapping active regions in Mapping active regions in the Far Side of the Sun using the Far Side of the Sun using

helioseismologyhelioseismology

I. González Hernández, F. Hill (1) C. Lindsey and D. Braun (2)

(1) National Solar Observatory, Tucson, AZ

(2) NorthWest Research Associates, Boulder, CO

ContentsContents

Helioseismic holography of the Far Side of the Helioseismic holography of the Far Side of the

Sun: a quick review.Sun: a quick review.

Prediction capability: NOAA10808 & NOAA10923Prediction capability: NOAA10808 & NOAA10923

Calibration of far-side seismic holography signalCalibration of far-side seismic holography signal

““Far-side” imaging of the near sideFar-side” imaging of the near side

CME and Flare connectionCME and Flare connection

Conclusions and future workConclusions and future work

Courtesy of D.

Braun

EARTH

Far Side Seismic HolographyFar Side Seismic Holography

Helioseismic imaging of sunspots at their antipodes. Helioseismic imaging of sunspots at their antipodes. Lindsey, C. & Braun, D.C, 1990, SoPh.Lindsey, C. & Braun, D.C, 1990, SoPh.

Seismic Images of the Far Side and Interior of the Sun Seismic Images of the Far Side and Interior of the Sun Lindsey, C. & Braun, D.C, 2000, Science.Lindsey, C. & Braun, D.C, 2000, Science.

Pupil

Prediction capabilityPrediction capability

Carrington Longitude

sin

(lati

tud

e)

Active Region NOAA-10808

Aug 29 -> Sep 9 2005

AR10808

Active Region NOAA-10923

Oct 31 -> Nov 10 2006

AR10923

sin

(lati

tud

e)

Calibrating the far-side signalCalibrating the far-side signal

Calibrating the far-side signalCalibrating the far-side signal

Calibrating the far-side signalCalibrating the far-side signal

Calibrating the far-side signalCalibrating the far-side signal

““far-side” imaging of the near far-side” imaging of the near sideside

Braun & Lindsey 2001, ApJ, 560, L189

NOAA 10808

(far side)

NOAA 10808 (near side)

““far-side” imaging of the far-side” imaging of the near sidenear side

1 x 3 skip method actually extends well onto the near side!

can fill in some of this area with 1 x 4 skip method (in progress…)

CME and Flare connectionCME and Flare connection

CME and Flare connectionCME and Flare connection

The left panel shows overlaid on the C2 LASCO image the front side of the Sun taken by the EIT instrument. The right panel shows the calculated farside map for that day as seeing from Earth perspective, i.e. looking directly through the Sun.

”….By 00:24 UT, signature of a huge and apparently backsided CME can be seen all above the E Limb (most likely related to Event #2). Though the timing seems to match that of the event from AR 10806, the event off limb is most probably from the back side of the Sun. In summary, the event as a whole can be determined as an asymmetric full halo CME. Several components contribute to the overall shape of the complex event, at least one of them frontsided, associated with a B-class X-ray flare on NOAA AR 10806. However, the bigger contribution seems to have its origins on the backside” (G. Stenborg, SOHO-LASCO Operations Scientist).

AR10806 AR10808

using both far-side and near-side using both far-side and near-side images to understand physics of phase-images to understand physics of phase-

shifts/travel-timesshifts/travel-times

2 mHz

3 mHz

4 mHz

5 mHz

trav

el-t

ime

pert

. (s

ec)

Braun & Birch 2007 (in prep.)

understanding physics can:

• lead to better calibration of far-side signatures

•lead to improved models of subsurface structure

•lead to detection of emerging ARs

Conclusions and future workConclusions and future work

Space weather: Space weather: MDI and GONG pipelines are providing daily full-MDI and GONG pipelines are providing daily full-

hemisphere farside maps.hemisphere farside maps. Large active regions are seen in consecutive far-side Large active regions are seen in consecutive far-side

maps.maps. Scientific Calibration Scientific Calibration

Empirical calibration: Statistics with far-side results Empirical calibration: Statistics with far-side results +front-side analysis+front-side analysis

Calibration of artificial “sunspots”Calibration of artificial “sunspots” Calibrate effect of several bounces and dispersion Calibrate effect of several bounces and dispersion

relationrelation Ghost signature --> solar features?Ghost signature --> solar features?

Collaboration with irradiance variation studiesCollaboration with irradiance variation studies