Anna Malanushenko

Dana Longcope

Marika Mccarthy

Mckenzie, David E.

English

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Examination of Separator Reconnection Rates in a Series of 
Adjacent Emerging/Existing Active Region Pairs SH11D-3387
Marika I. McCarthy■, Dana W. Longcope■, Anna V. Malanushenko●, David E. McKenzie◆

■Montana State University, Bozeman MT, ●High Altitude Observatory, Boulder CO, ◆NASA Marshall Space Flight Center, Huntsville AL
References:  
1McCarthy et al. (2019). Accepted to ApJ.  

2Malanushenko et al. (2019). ApJ. 707, 1044.  

3Longcope et al. (2005).  ApJ. 630, 596.

4Aschwanden et al. (2013). Entrp. 15, 3007.
Acknowledgments:  This work was supported by NASA’s HGI program
time
Using active region pairs as a laboratory for measuring reconnection:  If each active 
region is a distinct magnetic system, any new flux linkage between two must be a result of 
coronal reconnection. 
Active regions not reconnecting:  For case 13 in the list of adjacent AR emergence 
events, no 171Å loops seem to appear between these two active regions in excess of days.  
The coronal image at left has a quadrupolar MCT model overplotted for reference on where 
we might expect to see reconnected loops
List of other adjacent active region emergences near existing ones
# date 
y-m-d
ARs 
old/new
# date 
y-m-d
ARs 
old/new1 2011-01-20 1147/1149 10 2012-04-18 1458/1460
2 2011-02-17 1161/1162 11 2013-01-10 1649/1655
3 2011-05-15 1214/1217 12 2013-02-19 1671/1678
4 2011-08-29 1277/1282 13 2013-10-13 1865/1870
5 2011-10-12 1313/1320 14 2013-11-11 1893/1900
6 2011-10-29 1334/1335 15 2013-12-03 1908/1914
7 2011-12-05 1367/1370 16 2014-04-14 2036/2037
8 2011-12-18 1381/1382 17 2016-03-03 2512/2514
9 2012-01-14 1395/1398
Other two-AR events for consideration:  [BLUE] Case has been studied in depth in 
McCarthy+ 2019 (see left column).  [GREEN] These pairs appear not to form coronal loops 
between them in excess of 24 hours post-emergence.

Improvement of loop selection procedure: [LEFT] In previous work1, we used local 
maxima in the intensity profile to select coronal loops.  [RIGHT] We make improvements to 
our analysis pipeline by implementing OCCULT4.  

Significant loop confirmation will be done by an REU student in summer 2020.
Distribution of 𝛂 in various magnetic domains: The emerging and existing AR’s were 
modeled in one snapshot.  The modeled interconnecting loops [center] were modeled at 
multiple instances in time.
Existing AR                 Interconnecting loops               Emerging AR
Distribution of twist for field lines within diﬀerent magnetic domains: Does the 
distribution of coronal alpha have an eﬀect on how inclined the two ARs are to 
reconnection between them?
Existing AR                                               Emerging AR
2011-01-21 00:40             14:01
Older AR
Emerging AR
Observations are supplemented with modeling of loops as 
a linear force-free field line2
+
trace field line
(LOS coronal image) magnetic info
= field line fitr⇥B = ↵B
B ·r↵ = 0
r ·B = 0
Non-Linear 
FFF equations
r↵ = 0
+
Observational evidence of reconnection: During the ~14 hours time diﬀerence between 
these two SDO/AIA 171Å images, we see evidence of coronal reconnection in the form of 
loops (areas of strong emission, dark in the reverse-color scale image) between the two 
regions.  The dark, horizontal bar indicates the slit of pixels used during the loop cataloging 
procedure.
Obtain 3d structure of traced loops, including ⍺:
Work thus far1: Improvement on methodology: An interesting case: No reconnected loops?
Goals:
Elucidate questions posed by 
previous work

• Time delays between new 
flux emerg. and 
reconnection have been 
shown on the order of 
~24hr…3 Is this typical?

• Studies1,3 have both under- 
and over counted flux 
interconnecting two ARs

• What about the emerging/
adjacent AR system 
accounts for these 
diﬀerences?
Questions for the extended study: A flux vs. time 
plot from McC+19 showing the overcounting of flux 
between two ARs (more than there is in either to 
begin with) and the delay between the new AR 
emergence and reconnection between the two.
Older AR
Emerging AR
https://ntrs.nasa.gov/search.jsp?R=20190033952 2020-03-11T13:37:17+00:00Z


Examination of Separator Reconnection Rates in a Series of Adjacent Emerging/Existing Active Region Pairs

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