Four Solar Cycles of Space Instrumentation P. Brekke Pål Brekke ESA Space Science Department NASA/Goddard Space Flight Center The Importance of SUMER for SOHO

Four Solar Cycles of Space Instrumentation 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 HRTS coverage

Four Solar Cycles of Space Instrumentation 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.

Four Solar Cycles of Space Instrumentation 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 Chae et al 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?

Four Solar Cycles of Space Instrumentation P. Brekke Dopplershifts in Ne VIII SUMER observations: Dammasch et al. A&A 346, p285, 1999 Corona (off limb): Å 0.0 km/s Coronal hole: Å-6.2 km/s Quiet Sun: Å-0.8 km/s Accepted rest wavelength: Å QS shift using this value: +6.6 km/s

Four Solar Cycles of Space Instrumentation 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 VIII C IV (Peter, ApJ 516, 490, 1999)

Four Solar Cycles of Space Instrumentation P. Brekke Find the Ne VIII to be blueshifted on the disk when assuming no net shift at the limb. Derive rest wavelength: Å In agreement with Dammasch.

Four Solar Cycles of Space Instrumentation P. Brekke SOHO Detects Source of High Speed Solar Wind? Hassler et al. Science, 5 Feb 1999 (V283, p810) Stacki et al (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

Four Solar Cycles of Space Instrumentation 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.

Four Solar Cycles of Space Instrumentation P. Brekke Re-measure reference wavelengths Observed Ne VIII wavelengths (SUMER) illustrating the line shifts along the North- South axis in Quiet Sun (A) and coronal hole (B). Wavelengths are measured relaitive to Si II 1533 Å. We measure variations in line shifts smaller than the accuracy of the reference wavelengths. “Zero velocity” reference from off limb “Zero velocity” reference Fawcett (1961) “Zero velocity” reference Bockasten et al Many lines need to be re-measured!

Four Solar Cycles of Space Instrumentation P. Brekke High cadence time series obtained with SUMER (Hansteen, Carlsson, and Judge) O VI Oscillation: s 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

Four Solar Cycles of Space Instrumentation 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 brighteningShow little or no brightening Last for tens of minutesLast about 1 minute Birth rate: 12 per secBirth rate: 600 per sec Little evidence for flows (20 km/s)Large shifts ( km/s) Observed in the networkOften observed in network boundary Chae et al (in prep.) find: EE tends to keep away from the centers of “blinkers”

Four Solar Cycles of Space Instrumentation P. Brekke Sunspot plumes Brynildsen et al. 1999, CDS observations of NOAA 8598 on June Green contour: I > 2.5 x Yellow contour: I > 5.0 x Plumes brightest in O V and Ne VI Nearly all sunspots contain one or two plumes in the temperature range 250, ,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.

Four Solar Cycles of Space Instrumentation 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

Four Solar Cycles of Space Instrumentation P. Brekke 7. March 2001: 5 hours sit-and-stare

Four Solar Cycles of Space Instrumentation P. Brekke SUMER spectrograms

Four Solar Cycles of Space Instrumentation P. Brekke Intensity maps

Four Solar Cycles of Space Instrumentation P. Brekke Velocity maps Max v = ± 40 km/s

Four Solar Cycles of Space Instrumentation P. Brekke 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.

Four Solar Cycles of Space Instrumentation 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

Four Solar Cycles of Space Instrumentation 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

Four Solar Cycles of Space Instrumentation 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

Four Solar Cycles of Space Instrumentation 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.

Four Solar Cycles of Space Instrumentation P. Brekke 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  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

Four Solar Cycles of Space Instrumentation 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 Mm Off-limb active region loops Thanks to D. Innes

Four Solar Cycles of Space Instrumentation P. Brekke 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

Four Solar Cycles of Space Instrumentation P. Brekke SXT SUMER Fe XIX loop oscillations Innes & Wang 2004 (SOHO-15) Fe XIX Doppler velocities ±50 km/s line profiles at different positions SXT loop structure Thanks to D. Innes

Four Solar Cycles of Space Instrumentation 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 ( c) (d) time Distance along slit Thanks to D. Innes

Four Solar Cycles of Space Instrumentation P. Brekke T. Kucera & E. Landi DEM of Moving Features in a Cool Loop near Prominence Channel