The Solar Transition Region

57 Pages·2014·33.55 MB·English

by  Hui Tian

The Solar Transition Region:
From SUMER to IRIS
Hui Tian
Harvard-Smithsonian Center for Astrophysics
April 15, 2014 @ MPS
Outline
•  SUMER – an extremely successful UV
spectrograph
•  What we have learned from SUMER
observations
•  From SUMER to IRIS
SUMER – Solar Ultraviolet
Measurements of Emitted Radiation
•  An extremely
successful UV
spectrograph
onboard SOHO
•  PI institute: MPS
•  PIs:
Klaus Wilhelm
Werner Curdt
(after Feb 2002)
Wilhelm et al. 1995, Sol. Phys.
Very broad wavelength range
EUV FUV
Fontenla et al.2009, ApJ
SUMER reference spectrum (part)
Curdt et al. 2001, A&A
An instrument designed for TR studies
Vernazza et al. 1981, ApJS
Peter, 2004, Reviews in
Modern Astronomy
SUMER images of the TR
Quiet-Sun, FOV 550”x300” Dammasch et al. 1999, A&A
Intensity Doppler shift Line width
Ne VIII (6.3x105K)
C IV (1.0x105K)
Si II (1.8x104K)
High
spatial
resolution
C III 977Å
Image courtesy
of SUMER Atlas
Spicules at south pole, C III 977Å
High temporal
resolution
•  Typically 10-60s:
detailed
investigation of
transient events
(e.g., spicules,
EEs)
•  ~3s for strong
lines: e.g.,
Teriaca et al.
2004 (O VI
1032Å)
Xia et al.2005, A&A
High accuracy of
velocity
determination
•  spectral pixel size:
~10 km/s
•  accuracy of velocity
determination:
1-2 km/s
Brekke et al. 1997, Sol. Phys.