cds active region results
DESCRIPTION
CDS active region results. Intense transition region brightenings. Oxygen and neon lines enhanced over q.s. by factors ≳ 20 Photospheric abundances (Young & Mason 1997) Velocity shifts? Line broadenings?. Intense transition region brightenings. Signatures: - PowerPoint PPT PresentationTRANSCRIPT
Dr Peter Young, Rutherford Appleton LaboratoryCD
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OH
OC
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HO
CDS active region results
Dr Peter Young, Rutherford Appleton LaboratoryCD
S/S
OH
OC
DS
/SO
HO
Intense transition region brightenings
• Oxygen and neon lines enhanced over q.s. by factors ≳ 20• Photospheric abundances (Young & Mason 1997)• Velocity shifts?• Line broadenings?
Files584
RegionQS
O V intensity299
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ARARAR
183101270010070
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Intense transition region brightenings
• Signatures:– Strong continuum (scattered Ly-alpha?)– O IV 625.8 strong ( high densities)– No response from corona
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Blinkers
• Parnell et al. (2002) extended blinker study of Bewsher et al. (2003) to active regions
• Properties are very similar, except– More frequent (up to 7 times more)– Intensity enhancement higher (up to factor 3)– Coronal response in some cases
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Oscillations
• Typical feature of transition region above sunspots (Fludra, Brynildsen, etc.). ~3 min period
• Other active region: Ireland et al. (1999), O’Shea et al. (2001)– 5 min oscillations most common photospheric driver– Mg IX, Fe XVI: more significant oscillations in velocity than
intensity
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Large TRACE loops
• Ubiquitous feature of TRACE 171 images of active regions• Often show strong Mg/Ne enhancement in CDS data• Footpoint density (Mg VII) is around 1010 cm-3
• Leg density (Si X) is around 108.5 cm-3
• What is relation to sunspot plumes?
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Mg VI
Mg VII
Si VIIIMg IXMg X
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Sunspot Plumes
• “A sunspot plume is observed if the contours for peak line intensity are located with a considerable fraction of the emission inside the white light sunspot.”– Brynildsen et al. 1999, Sol.Phys. 186, 141
• Very weak coronal emission usually seen above sunspots, sunspot plumes not visible in corona
• Are sunspot plumes the footpoints of TRACE loops?
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Dr Peter Young, Rutherford Appleton LaboratoryCD
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Active region structure
• Small active regions have a core-halo structure (Gallagher et al. 2001, Mason et al. 1999)
• High temperature (Fe XVI) core, with high density ~1010
cm-3
• Pressure falls off around this core
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Dynamic transition region loops
• Loops seen in, e.g., O V above the limb are very dynamic– Doppler shifts 50-300 km/s
• Independent of coronal loops• Can only be seen at limb! (Intensity is lower than average
QS)
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Coronal loop structure
• Controversial!• TRACE/EIT analyses give isothermal loops• Brkovic et al. (2001) find isothermal with CDS• Schmelz et al. (2002) do not find isothermal with CDS
Dr Peter Young, Rutherford Appleton LaboratoryCD
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Flare Observations
• Czaykowska et al. (1999) presented velocity measurements in O V, Fe XVI, Fe XIX in a flare
• What else can be obtained from CDS observations?