Paper Review: THE HEIGHT OF A WHITE

By Juan-Carlos Mart´ınez Oliveros, Hugh S. Hudson, Gordon
J. Hurford, S¨am Krucker, R. P. Lin, Charles Lindsey, Sebastien
Couvidat, Jesper Schou, and W. T. Thompson
The Astrophysical Journal Letters, 753:L26 (5pp), 2012 July 10
Nengyi Huang
2015-02-12
 Event:
• Time: SOL 2011-02-24T07:35
• Location: NOAA coordinates N14E87
• GOES class: M3.5
 Data Origins:
• RHESSI (Hard X-ray 30-80 KeV)
• SDO HMI (6173 Å)
• STEREO-b EUVI (195 Å)
 Objects:
• To determine the heights of sources of whit-light continuum and hard X-ray
emission.
• To suggest the possibility that sources of WL and HXR should be lower than
expected.
• To strengthen the connection between WL continuum and HXR radiation.
A. WL continuum
1. It’s known that:
The intense energy release
of impulsive phase
Acceleration
of particles
High-energy non-thermal particles
penetrate into the lower
atmosphere
White light
emission
2. The energy release may drastically distort the structure of lower atmosphere
B. Hard X-ray
1. Standard thick-target model: primary particle acceleration is in corona
2. Fast electrons implicate chromosphere
3. etc.
C. Radiative backwarming:
• Explain the correlation of HXR and WL
• Irradiation and heating of the photosphere
HMI intensity continuum (6173 Å)
Difference image at 07:31:13.40 UT
Reference: Average data 07:25-07:28 UT
Time Series
HMI contrast reference: Average data 07:2507:28 UT
HMI intensity continuum (6173 Å)
Difference image at 07:31:13.40 UT
Reference: Average data 07:25-07:28 UT
Positions of STEREO A and B
for 2011-02-24 07:35 UT
Earth Ecliptic (HEE) longitude
of STEREO-B
-94.550
http://stereo-ssc.nascom.nasa.gov/cgi-bin/make_where_gif
• The line in the middle
shows the limb
• 16 columns(before
rotating) of the CCD
saturated
• Excess charge for each
saturated column
should spread equally
to both directions.
STEREO-B EUVI (195 Å)
HMI intensity continuum (6173 Å)
Difference image at 07:31:13.40 UT
Reference: Average data 07:25-07:28 UT
Zero of height is set at the projected position of corresponding STEREO sources.
HXR sources height: North FP 420±240 km ; South FP 210±240 km
WL sources height: North FP 230±100 km ; South FP 160±100 km
• The heights of WL/HXR sources match well  Association
between WL continuum and non-thermal electrons losses via
bremsstralung HXRs
• The depths of the sources lie well below the expected penetration
depth of the ~50keV electrons needed to produce the HXR.
 My opinion:
This method to measure the heights is an easy way, but because
of the complex structure around the flare and also the extreme
foreshortening of for the case of limb, this method is very inaccurate.
And we need more events to be surveyed before we can explain the
result of this analyses for this event.