J/ApJ/775/121 X-ray events in Earth's magnetosphere (Yamamoto+, 2013)
0.5-4Å X-ray brightenings in the magnetosphere observed by the Geostationary
Operational Environmental Satellites.
Yamamoto T.T., Miyoshi Y.
<Astrophys. J., 775, 121 (2013)>
=2013ApJ...775..121Y 2013ApJ...775..121Y (SIMBAD/NED BibCode)
ADC_Keywords: Earth ; X-ray sources ; Sun
Keywords: Earth; Sun: activity; Sun: X-rays, gamma rays
Abstract:
We found 217 X-ray brightening events in Earth's magnetosphere. These
events occur in the high-energy band (0.5-4Å) of the Geostationary
Operational Environmental Satellite (GOES) X-ray light curves,
although GOES X-ray light curves are frequently used as indices of
solar flare magnitudes. We found that (1) brightening events are
absent in the low-energy band (1-8Å), unlike those associated with
solar flares; and (2) the peak fluxes, durations, and onset times of
these events depend on the magnetic local time (MLT). The events were
detected in 2006, 2010, and 2011 at around 19-10MLT, that is, from
night to morning. They typically lasted for 2-3hr. Their peak fluxes
are less than 3x10-8W/m2 in the 0.5-4Å band and are maximized
around 0-5MLT. From these MLT dependencies, we constructed an MLT time
profile of X-ray brightening events. Because 0.5-4 and 1-8Å fluxes
were observed and had the same order of magnitude when GOES 14 passed
through Earth's shadow, we expected that X-ray brightening events in
the 1-8Å band are obscured by high-background X-ray fluxes coming
from the Sun. We also found coincidence between X-ray brightening
events and aurora substorms. In the majority of our events, the
minimum geomagnetic field values (AL index) are below -400nT. From
these results and consideration of the GOES satellite orbit, we expect
that these X-ray brightening events occur in the magnetosphere. We
cannot, however, clarify the radiative process of the observed X-ray
brightening events.
Description:
The analyzed data sets comprise GOES X-ray light curves observed in
2006, 2010, and 2011. The 2006 data were obtained by GOES 11
(longitude:135°, shifted to 105° west at the end of 2006 June)
and 12 (longitude:75°), which automatically detected 89 and 55
events, respectively. The 2010 and 2011 data (116 events) were
observed by GOES 14 (longitude:105°).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 69 217 List of events observed by the Geostationary
Operational Environmental Satellites.
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See also:
J/ApJ/757/94 : Solar flares observed with GOES and AIA (Aschwanden, 2012)
J/A+A/304/563 : Cool X-ray flares of Sun with GOES (Phillips+, 1995)
http://goes.gsfc.nasa.gov/ : GOES Project Science home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/217] Event number
5- 6 I2 --- GOES [11/14] GOES satellite number
8- 18 A11 "DD/MMM/YYYY" Start.date Start date; UT
20- 27 A8 "h:m:s" Start.time Start time; UT
29- 39 A11 "DD/MMM/YYYY" Peak.date Peak date; UT
41- 48 A8 "h:m:s" Peak.time Peak time; UT
50- 60 A11 "DD/MMM/YYYY" End.date End date; UT
62- 69 A8 "h:m:s" End.time End time; UT
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Mar-2015