four solar cycles of space instrumentation p. brekke pål brekke esa space science department...

Four Solar Cycles of Space Instrumentation

P. Brekke

Pål BrekkeESA Space Science Department

NASA/Goddard Space Flight Center

The Importance of SUMER for SOHO


P. Brekke

High Resolution Telescope and Spectrograph

Since its first flight in 1975, the NRL High Resolution Telescope and Spectrograph (HRTS) has now recorded high quality ultraviolet spectra of the sun on 8 rocket flights and during extended operations on the Space Shuttle Spacelab 2 mission in 1985.

HRTS coverage


P. Brekke

Quiet Sun Doppler Shifts

The apparent net redshift of the transition region lines is still one of the most puzzling problems in solar physics. If interpreted as downflow it would empty the corona in a few minutes, if not balanced by a corresponding plasma upflow.


P. Brekke

Dopplershifts observed by SUMER

The extensive wavelength coverage of SUMER made it possible to extend the measurements to higher temperatures

Brekke et al. 1997Brekke et al. 1997

Chae et al. 1998Chae et al. 1998

Using the reference laboratory wavelengths for Ne VIII and Mg X the observations suggested that also the upper transition region and lower corona appeared to be redshifted.

- Could the laboratory wavelengths be wrong?


P. Brekke

Dopplershifts in Ne VIII

SUMER observations:

Dammasch et al. A&A 346, p285, 1999

Corona (off limb): 770.428 Å 0.0 km/s

Coronal hole: 770.412 Å -6.2 km/s

Quiet Sun: 770.426 Å -0.8 km/s

Accepted rest wavelength: 770.409 Å

QS shift using this value: +6.6 km/s


P. Brekke

SUMER Full disk observations

Derived statistical properties of line profiles (C IV and Ne VIII) from full disk scans.

Studied the center-to-limb variation of lineshifts and the non-thermal broadening.

Ne VIIINe VIII

C IVC IV

(Peter, ApJ 516, 490, 1999)


P. Brekke

Find the Ne VIII to be blueshifted on the disk when assuming no net shift at the limb.

Derive rest wavelength: 770.425 Å

In agreement with Dammasch.


P. Brekke

SOHO Detects Source of High Speed Solar Wind?Hassler et al. Science, 5 Feb 1999 (V283, p810)

Stacki et al. 1999 (SOHO 8): Also found profound blueshifts in coronal holes for T > 250,000 K with larger flows in the network.

Peter 1999, ApJL, 522, L77: Also found blueshifts in coronal holes (Ne VIII).

He concludes that the blueshifts are not consistent with a uniform outflow.

Suggest that optical depth effects might be responsible for the observed blueshift and line widths.Made the front page of Science


P. Brekke

Is the Quiet Sun “Redshift Puzzle” Solved?

Our conclusions from any such study depends on the reference wavelengths used!

Thus, many of the high temperature lines need to be re-evaluated and re-measured in laboratory!!

This result has major implications for the transition region and solar wind modeling as well as on our understanding of the structure of the solar atmosphere.


P. Brekke

Re-measure reference wavelengths

Observed Ne VIII wavelengths (SUMER) Observed Ne VIII wavelengths (SUMER) illustrating the line shifts along the illustrating the line shifts along the North-South axis in Quiet Sun (A) and North-South axis in Quiet Sun (A) and coronal hole (B).coronal hole (B).

Wavelengths are measured relaitive to Wavelengths are measured relaitive to Si II 1533 Å.Si II 1533 Å.

We measure variations in line shifts We measure variations in line shifts smaller than the accuracy of the smaller than the accuracy of the reference wavelengths.reference wavelengths.

““Zero velocity” reference from off Zero velocity” reference from off limblimb

““Zero velocity” reference Fawcett Zero velocity” reference Fawcett (1961)(1961)

““Zero velocity” reference Bockasten et al. Zero velocity” reference Bockasten et al. 19631963

Many lines need to be re-Many lines need to be re-measured!measured!


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High cadence time series obtained with SUMER

(Hansteen, Carlsson, and Judge)

O VIO VI

Oscillation: 120-200s in C II and O VI velocity data, and the continuum emission

Oscillation most clearly in Cell interior, i.e. Different physical behaviour of network and cell center.

Continuum intensity precedes the upward velocity in C II by 40-60s , and the C II velocity precede O VI by 3-10s.

This may indicate the presence of upward propagating waves in the upper chromosphere, which are only partially reflected by the above layers and trigger oscillations in the T.R.

Muglach and Fleck 1999 also find oscillation but do not distinguish between network and cell interior


P. Brekke

Blinkers vs EE

Are “blinkers” and explosive events the same feature?

How do these transient events relate to one another? Why don’t CDS observe the explosive events?

One can ask: Do these transient events belong the a unique class of phenomena appearing in different ways, depending on the spectral band?

Harrison et al: 1999 (in preparation) compares the two features:

“Blinkers” Explosive events

EUV brightening Show little or no brightening

Last for tens of minutes Last about 1 minute

Birth rate: 12 per sec Birth rate: 600 per sec

Little evidence for flows (20 km/s) Large shifts (100 - 150 km/s)

Observed in the network Often observed in network boundary

Chae et al. 1999 (in prep.) find:

EE tends to keep away from the centers of “blinkers”


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Sunspot plumes

Brynildsen et al. 1999,Brynildsen et al. 1999,

CDS observations of NOAA 8598 on June 27 1999

Green contour: I > 2.5 x <I>

Yellow contour: I > 5.0 x <I>

Plumes brightest in O V and Ne VI

Nearly all sunspots contain one or two plumes in the temperature range 250,000 - 400,000 K

Relatively high velocities in plumes and in most cases directed downward.

The flows appear to be maintained by TR plasma moving into the spot from regions outside the spot.


P. Brekke

Sunspot oscillations

SUMER O V observations on 11 November 1998 NOAA 8378 (Brynildsen et al. ApJL 517, 159, 1999)

Period of the oscillations is 3 min.

Find the peak intensity (dashed line) and the upflows (solid line) to be correlated as expected for an upward propagating acoustic wave


P. Brekke

7. March 2001: 5 hours sit-and-stare


P. Brekke

SUMER spectrograms


P. Brekke

Intensity maps


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Velocity maps

Max v = ± 40 km/s


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Conclusions

Transition region loop structures show strong temporal variability in the form of large Doppler shifts and intensity variations.

At coronal temperatures (T > 0.63 MK) the line of sight velocities and the intensity variations are small.

We need observations of transition region lines to study the dynamics and the physical conditions of non-flaring active regions.


P. Brekke

UV/EUV Spectral Atlas 670 – 1609Å

Best ever analysis of the ultraviolet spectrum of the Sun from 670 to 1609 Å

1100 emission lines identified

150 of these had not been recorded or identified before

Particular improvement for Å

Atlas contains spectra of the quiet Sun, a coronal hole, and a sunspot.

Rich source of new diagnostic tools to study physical parameters in the solar atmosphere.

Important product both for solar and stellar communities.

Curdt et al.: 2001, A&A 375, 591


P. Brekke

Irradiance measurements with SUMER

Wilhelm et al. 1999, Adv. Space Res., 24, 229

Dammasch et al. 1999, ESA SP-488, 1165

Wilhelm el at. 2000, Phys. And Chem. Of the Earth, 25, 389

Wilhelm et al. 1999, A&A, 352, 321

Wilhelm et al. 2000, Metrologia, 37, 393

Irradiance measurments can be derived from:

Full disk scans

Quite Sun disk center scans taking into accound the center- to-limb variations of the emission


P. Brekke

Comparison between SUMER and SOLSTICE

Wilhelm et al. 1999, Adv. Space Res., 24, 229

Dammasch et al. 1999, ESA SP-488, 1165

Wilhelm el at. 2000, Phys. And Chem. Of the Earth, 25, 389

Wilhelm et al. 1999, A&A, 352, 321

Wilhelm et al. 2000, Metrologia, 37, 393


P. Brekke

Comparison between SUMER and SOLSTICE

SOLSTICE and SUMER observe the same N V and C IV irradiances within the combined uncertainty margin of both instruments.

SUMER gives about 10-15% lower values than SOLSTICE.


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SUMER Flare Observation

SUMER) spectra showing the corona dynamics above a C4.7 flare that occurred on the South-East limb of the Sun on 11 May 1999.

The movie shows sudden heating of the corona and ejection of high temperature (8 million degrees) plasma due to the flare at 21:30.

The highest velocities (200 km/s) are seen in the hottest lines at the time of the flare.

Curdt et al.: 2001, A&A 375, 591


P. Brekke

SUMER slit placed off-limb above active region. Observe in sit and stare for many hours.

Results for fairly small active region with only C-type flares and no CMEs.

Many events seen only in Fe XIX. EIT only shows cooling loops.

Fe XIX - Temp~7 MK

About 25 events, lasting 20 min

Ca XIII – Temp ~4 MK

Subtle dimming with Fe XIX. 1 hour later brightens.

S III – Temp ~0.04 MK

1 with Fe XIX. Low lying cold loop activity.

13 Hours

Fe XII – Temp ~2 MK

Like Ca XIII. It only shows cooling loops.

SUMER slit 15-40 Mm

Off-limb active region loops

Thanks to D. Innes


P. Brekke

1 45

15 min oscillation events

all <30 km/s

up to 100 km/s

up to 50 km/s

Off-limb Doppler velocities

Thanks to D. Innes


P. Brekke

SXT

SUMER Fe XIX loop oscillationsInnes & Wang 2004 (SOHO-15)

Fe XIX Doppler velocities ±50 km/s

line profiles at different positions

SXT loop structure

Thanks to D. Innes


P. Brekke

Loop Oscillations

One of the best examples of loop oscillations. Taken in Fe XIX on 2000 Sep 29. (a) SXT image with SUMER slit position, loop and limb. (b) EIT image with same. (c) SUMER Fe XIX intensity (d) SUMER Fe XIX Doppler shift.

Wang et al 2000.

(c)(d)

timetime

Dis

tan

ce a

lon

g s

lit

Thanks to D. Innes


P. Brekke

T. Kucera & E. Landi

DEM of Moving Features in a Cool Loop near Prominence Channel

four solar cycles of space instrumentation p. brekke pål brekke esa space science department...

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