Transcript Tripathy

Characteristics of Mode Parameters in the
Source Regions of CMEs: A First Look
Sushanta C. Tripathy
National Solar Observatory
Outline
• Identification of CME source locations
• Case study of 2 individual CMEs
• Summary and plan for future
Procedure
• CMEs are selected from the catalogue of Zhou et al. (2006) who
have studied a total of 288 halo CMEs during 1997-2003 and have
identified their source locations by associating the events with
surface activity.
• CMEs are associated with extended bipolar regions, trans-equatorial
magnetic loops, trans-equatorial filaments and long filaments.
• We use the standard ring-diagram procedure and analyze an area of
15x15 degrees in heliographic longitude and latitude covering
128x128 pixels giving a resolution of 0.03232 Mm–1 or 22.497 RΘ–1.
• Each region is tracked for 1664 minutes
• We have analyzed 44 events using the GONG+ data during 20012003 within 30º of the central meridian to avoid fore-shortening
effect.
• The mode parameters of CME regions are compared with those
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of quiet region at the same latitude and in the same Carrington
rotation to avoid errors arising from the systematic effects and
foreshortening.
Compare mode Frequency, amplitude, width and total power
CME associated with AR NOAA 10225
• CME associated with AR located at
N22W12 (CR 1997, CR Long: 113º)
on 021219
• First seen in C2 data at 22:06:00
• Magnetic activity Index (MAI): 97.6
Gauss
• No Flare observed
• Quiet region at same position on
021212 (CR Long 204) and MAI 2.7
Gauss
CME source
location:
N22W12
Active Region NOAA 9628
• Location: S22.5 E15 (CR Long: 292.5) on
23 March 2001
• MAI 146.3 Gauss
• Compared with a quiet region at same
latitude and at 0º longitude on 16 March
2001 with a MAI of 0.08 Gauss (CR Long:
45º)
Comparison of 2 quiet regions
Relative frequency differences
f
P1
P2
p3
CME region
Active Region
Av. error in each point
3.5 mHz ~ 10-4 μHz
4.5 mHz ~ 10-3 μHz
Ratio of the peak power
CME region
f
P1
P2
p3
Av. error in each point
3.5 mHz ~ 0.05
4.5 mHz ~ 0.12
Active Region
From Rajaguru, Basu, & Antia (2001)
f
P1
P2
p3
Relative difference in half-width
CME region
Active Region
Av. error in each point
3.5 mHz ~ 0.07
4.5 mHz ~ 0.13
Relative difference in total power
CME region
Active Region
CME associated with a Filament
• CME associated with
filament located at
S25W18 (CR 1986, CR
Long:231º)
• First seen in C2 data on
020214 at 02:30
• MAI: 11.3 Gauss
• Quiet region at CR Long
169º (020217), MAI 3.7
Relative frequency differences
f
P1
P2
p3
CME region
Active Region
Ratio of the amplitudes
A / A (Quiet)
CME region
Active Region
f
P1
P2
p3
Relative differences in half-width
f
P1
P2
p3
CME region
Active Region
Ratio of the mode area
A*Γ / A*Γ (Quiet)
CME region
Active Region
f
P1
P2
p3
Temporal evolution of line-width in
AR and CME regions
CME1: N22 w12
CME2: S25w18
f-modes: 2550 to 2750 μ Hz
p-modes 3000-3500 μ Hz
Summary
• The widths of the peaks is a function of the frequency
and the radial order ‘n’. For most CMEs, the widths are
smaller implying longer life times.
• The f- and p-mode frequencies of high degree modes are
significantly larger compared to quiet regions if the CME is
in active region.
• The power in both f- and p-modes is lower in CME regions
• The increase in mode frequency is monotonic in frequency
while all other properties show more complex frequency
dependence.
Areas for Further Study
• Look at ring diagrams produced over shorter time
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•
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spans and/or smaller patches to isolate more
transient features.
Look at magnetograms to see how MAI changes
day-to-day to see if this explains daily variations
Look at flow maps and other fluid descriptors.
MORE STATISTICS