Type IV Radio Bursts and Source Type IV Radio Bursts and Source RegionsRegions

Observed by NoRH: ResultsObserved by NoRH: ResultsSara Petty, CUA/ GSFC

Advisor: Dr. Nat Gopalswamy

Type IV Radio Bursts RevisitedResearch Goals at NobeyamaResults & Questions

Type IV Source AnalysisProminence Events Measurements

Future Research

Type IV Radio BurstsType IV Radio Bursts Type IV's occur less often than type II'sHave a broad spectral structure over many frequency ranges (MHz-GHz) and up to several hours in durationOccur within 30 minutes of flare onsetCorrelated CME's are faster and widerStationary IV's are caused by electrons trapped in the magnetic loop structure (What I observe) Moving IV's are plasmoids containing their own magnetic fields moving 100-1000kms-1 and are very difficult to observe without spacial resolution (See Stewart 1985)

Model of different radio burst signatures

WIND/WAVES Observations of Type WIND/WAVES Observations of Type IV'sIV's

These are Type IV's that range from ~4MHz – 14MHz and have deca-hectometric (DH) wavelengths. DH IV's are continuations of metric IV's. Limb events appear very faint, if at all. Position is discerned by correlating impulsive flare time with the type III event preceding the metric IV.

Metric and DH IV event –note the IV minimum begins at the flare peak time.

Flare model of accelerated particles

Goals and Expectations for VisitGoals and Expectations for Visit

Learn analysis tools for NoRH data Look at DH IV source regions with radioheliograph data and compare dynamics with metric IV bursts Make height-time and mass measurements of limb events (prominence eruptions) and compare with CME measurements (see Gopalswamy and Hanaoka 1998)Obtain a relation between PE's and CME's masses

Results: Source Regions of 3 Type IV Results: Source Regions of 3 Type IV EventsEvents

9 DH events fit within the NoRH observation windowSynthesized images for all 9 events with a 1 minute intervalI will discuss 3 events:

Events: 2001-04-10 (05:26), 2004-11-06 (00:34), & 2005-07-27 (05:02)

Stats tableDynamic Spectra for Metric and DH IV'sTSX time-series dataNoRH polarization imagesHeight-time & mass measurements for 1 limb event: 2005-07-27 (05:02)

Flare Peak

Type IV StatsType IV Stats

DH DH Metric Metric IV Flare Flare Flare Flare Flare CME CME CME

Event

20010410 06:15 7.1 05:16 14:47 9.52 S23W09 05:06 05:42 05:26 X2.3 05:21 2411 -8820041106 02:00 7.1 00:33 02:56 2.38 N08E04 00:11 00:42 00:34 M9.3 00:52 818 -81.520050727 04:55 9.8 04:46 05:24 0.63 N11E90 04:33 05:30 05:02 M3.7 04:41 1787 -75.4

Min. Freq. Time

Min Freq. (MHz)

Start Time

End Time

Dur. (hours)

Flare Position

Start Time

End Time

Peak Time

GOES Type

Start Time

Speed km/s

Accel. (m/s2)

Height-time measurements could not be obtained for any of the events, except 2005-07-27, the only limb event from the list.The CME data comes from the CDAW LASCO Catalog

Metric and DH dynamic spectra –note the ~15MHz gap between spectra

Minimum occurs at 06:15 at 7.1MHz

Overlap in frequency is denoted by the dashed line.

Minimum occurs at 02:00 at 7.1MHz

The flare correlation may not be correct, NoRH data shows different –this is

“confused” spectra

Flare

The Type IV Dynamic Spectra for the Limb The Type IV Dynamic Spectra for the Limb Event Event

BIRS/GDRT 2005-07-27

overlap in frequency is denoted by the dashed line.

Minimum occurs at 04:55 at 9.8MHz

very faint and small compared with other

events

Left: TSX Polarization time-series; dashed lines indicate type IV start and minimum times.Below: 17GHz polarization images

Left: TSX Polarization time-series; dashed lines indicate type IV start and minimum times.Below: 17GHz polarization images

Left: TSX Polarization time-series; dashed lines indicate type IV start and minimum times.Below: 17GHz polarization images

2005-07-27 Limb Event2005-07-27 Limb Event

Maximum height before eruption (left) ~51,000kmMaximum height before leaving field of view (right) ~200,600km

Mass: ~4.7x1028cm3 Mean Speed: 422 kms-1

Height-Time Plot for PE 2005-07-27Height-Time Plot for PE 2005-07-27

Time (sec) starting from 27-Jul-05 04:37:30The mean speed is ~ 422 km/s

2.5x105

2.0x105

1.0x105

1.5x105

5.0x104

The DH IV events 2001-04-10, 2004-11-06, 20050727 have different structure and duration.The time-series data shows mixed results

How does this fit with previous study finding flare peak time correlates with the Type IV minimum?

Modeling of type IV based on polarization plots

Questions and FeedbackQuestions and Feedback

PE Mass Measurements & CME'sPE Mass Measurements & CME'sChecked measuring methods with Gopalswamy and Hanaoka (1998)

Used a simple box volume calculation, multiplied by density of 1010cm-3 (Tandberg-Hanssen 1995) and mass 2x10-24gGopalswamy and Hanaoka had a volume ~3x1030 cm3--> 6x1016gMy calculations

volume: ~7x1030cm3 mass: ~1.4x1017

Fine structures were ignored (i.e., loop structure); the actual mass of the PE is smaller.

PE Measurement from Gopalswamy & PE Measurement from Gopalswamy & Hanaoka (1998)Hanaoka (1998)

The measurements were made during final height before eruption.

PE 1994-04-04 ~23:00 UT

Future PlansFuture Plans

Analyze more synthesized NoRH images to compare the remaining type IV events.

Develop a working model for type IV's Compare with MDI plots

Complete PE mass and height-time measurements for the NoRH prominence events from 2002-2005.

Compare mass and speed with LASCO CME data