J/A+A/304/563 Cool X-ray flares of Sun with GOES (Phillips+, 1995)
Properties of Cool Flares with GOES class B5 to C2
Phillips K.J.H., Feldman U.
<Astron. Astrophys. 304, 563 (1995)>
=1995A&A...304..563P 1995A&A...304..563P (SIMBAD/NED BibCode)
Keywords: Sun: flares - Sun: X-rays
Description:
Observed parameters for 208 small flares with GOES classification B5
to C2 are discussed using data from the broad-band detectors on the
Geostationary Operational Environmental Satellites (GOES) and the
Bragg Crystal Spectrometer (BCS) on the Yohkoh solar flare spacecraft.
Peak temperatures derived from He-like sulfur spectra are in the range
8±2x106K and are similar to those derived from the ratio of the
1-8A and 0.5-4A GOES channels, but a little less than those from
He-like calcium spectra, showing that even these small flares are
non-isothermal. The absence of He-like iron emission shows that the
temperatures are less than 14x106K. There is a slight positive
correlation between temperature and emission measure from the calcium
and sulfur data. Differences in this distribution and that derived for
larger flares in a separate study can be reconciled in terms of the
fact that temperatures were measured from He-like iron spectra for the
larger flares. The emission measure of the flares in our sample are
correlated with GOES class. A detailed study of a subset of 20 flares
shows that the temperatures generally reach peak flux slightly before
(up to 30s) or coincident with the light curve maximum. It is found
that even small flux enhancements which are frequently present are
associated with temperature enhancements.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1 96 208 Properties of cool flares observed by Yohkoh
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Byte-by-byte Description of file: table1
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Bytes Format Units Label Explanations
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1- 11 A11 "YY/MM/DD" Date Date of each event
13- 14 I2 h UTh Universal Time for each event
16- 17 I2 min UTm Universal Time for each event
19- 20 I2 s UTs Universal Time for each event
22- 28 E7.1 ct/cm2/s Flux(Ca) Peak flux of photons in the He-like
Ca resonance (w) line
31- 37 E7.1 ct/cm2/s Flux(S) Peak flux of photons in the He-like
S resonance (w) line
40- 43 F4.1 MK Te(Ca) Temperature deduced from the Ca
X-ray spectrum
45- 48 F4.1 MK Te(S) Temperature deduced from the S X-ray
spectrum
50- 56 E7.1 cm-3 Ne2V(Ca) Emission measure for Ca
59- 65 E7.1 cm-3 Ne2V(S) Emission measure for S
68- 74 E7.1 W/m2 MaxFlux X-ray emission at peak as determined
from GOES detectors (1)
76- 82 E7.1 W/m2 Preflare X-ray emission before the flare as
determined from GOES detectors (1)
84- 87 F4.1 MK Te(GOES) Temperatures measure from the ratio of
GOES detectors
89- 94 E6.1 cm-3 Ne2V(GOES) Emission measure from the ratio of GOES
detectors
96 A1 --- n_Ne2V(GOES) [c] When 'c': event selected for detailed
study
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Note (1): In the 1-8 Angstroem band
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(End) Simona Mei [CDS] 29-Jun-1995